attention problems

The effect of stress on performance depends on individual and situational factors

September, 2011

A new study shows how stress only impacts math performance in those with both higher working memory capacity and math anxiety, while another shows that whether or not pressure impacts your performance depends on the nature of the pressure and the type of task.

Working memory capacity and level of math anxiety were assessed in 73 undergraduate students, and their level of salivary cortisol was measured both before and after they took a stressful math test.

For those students with low working memory capacity, neither cortisol levels nor math anxiety made much difference to their performance on the test. However, for those with higher WMC, the interaction of cortisol level and math anxiety was critical. For those unafraid of math, the more their cortisol increased during the test, the better they performed; but for those anxious about math, rising cortisol meant poorer performance.

It’s assumed that low-WMC individuals were less affected because their performance is lower to start with (this shouldn’t be taken as an inevitability! Low-WMC students are disadvantaged in a domain like math, but they can learn strategies that compensate for that problem). But the effect on high-WMC students demonstrates how our attitude and beliefs interact with the effects of stress. We may all have the same physiological responses, but we interpret them in different ways, and this interpretation is crucial when it comes to ‘higher-order’ cognitive functions.

Another study investigated two theories as why people choke under pressure: (a) they’re distracted by worries about the situation, which clog up their working memory; (b) the stress makes them pay too much attention to their performance and become self-conscious. Both theories have research backing from different domains — clearly the former theory applies more to the academic testing environment, and the latter to situations involving procedural skill, where explicit attention to the process can disrupt motor sequences that are largely automatic.

But it’s not as simple as one effect applying to the cognitive domain, and one to the domain of motor skills, and it’s a little mysterious why pressure could have too such opposite effects (drawing attention away, or toward). This new study carried out four experiments in order to define more precisely the characteristics of the environment that lead to these different effects, and suggest solutions to the problem.

In the first experiment, participants were given a category learning task, in which some categories had only one relevant dimension and could be distinguished according to one easily articulated rule, and others involved three relevant dimensions and one irrelevant one. Categorization in this case was based on a complex rule that would be difficult to verbalize, and so participants were expected to integrate the information unconsciously.

Rule-based category learning was significantly worse when participants were also engaged in a secondary task requiring them to monitor briefly appearing letters. However it was not affected when their secondary task involved them explicitly monitoring the categorization task and making a confidence judgment. On the other hand, the implicit category learning task was not disrupted by the letter-monitoring task, but was impaired by the confidence-judgment task. Further analysis revealed that participants who had to do the confidence-judgment task were less likely to use the best strategy, but instead persisted in trying to verbalize a one- or two-dimension rule.

In the second experiment, the same tasks were learned in a low-pressure baseline condition followed by either a low-pressure control condition or one of two high-pressure conditions. One of these revolved around outcome — participants would receive money for achieving a certain level of improvement in their performance. The other put pressure on the participants through monitoring — they were watched and videotaped, and told their performance would be viewed by other students and researchers.

Rule-based category learning was slower when the pressure came from outcomes, but not when the pressure came from monitoring. Implicit category learning was unaffected by outcome pressure, but worsened by monitoring pressure.

Both high-pressure groups reported the same levels of pressure.

Experiment 3 focused on the detrimental combinations — rule-based learning under outcome pressure; implicit learning under monitoring pressure — and added the secondary tasks from the first experiment.

As predicted, rule-based categories were learned more slowly during conditions of both outcome pressure and the distracting letter-monitoring task, but when the secondary task was confidence-judgment, the negative effect of outcome pressure was counteracted and no impairment occurred. Similarly, implicit category learning was slowed when both monitoring pressure and the confidence-judgment distraction were applied, but was unaffected when monitoring pressure was counterbalanced by the letter task.

The final experiment extended the finding of the second experiment to another domain — procedural learning. As expected, the motor task was significantly affected by monitoring pressure, but not by outcome pressure.

These findings suggest two different strategies for dealing with choking, depending on the situation and the task. In the case of test-taking, good test preparation and a writing exercise can boost performance by reducing anxiety and freeing up working memory. If you're worried about doing well in a game or giving a memorized speech in front of others, you instead want to distract yourself so you don't become focused on the details of what you're doing.




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Sleep's role in cognition

Older news items (pre-2010) brought over from the old website

A midday nap markedly boosts the brain's learning capacity

Following on from research showing that pulling an all-nighter decreases the ability to cram in new facts by nearly 40%, a study involving 39 young adults has found that those given a 90-minute nap in the early afternoon, after being subjected to a rigorous learning task, did markedly better at later round of learning exercises, compared to those who remained awake throughout the day. The former group actually improved in their capacity to learn, while the latter became worse at learning. The findings reinforce the hypothesis that sleep is needed to clear the brain's short-term memory storage and make room for new information. Moreover, this refreshing of memory capacity was related to Stage 2 non-REM sleep (an intermediate stage between deep sleep and the REM dream stage).

The preliminary findings were presented February 21, at the annual meeting of the American Association of the Advancement of Science (AAAS) in San Diego, Calif.

Helping memory consolidation while you sleep

The role of sleep in consolidating new learning is now well-established, but now a study intriguingly reveals that you can improve that learning by playing sounds associated with the learning while you are asleep. The study involved 12 volunteers learning to associate each of 50 images with a random location on a computer screen. Each object was paired with its associated sound. Some 45 minutes after they had successfully mastered this task, each participant lay down in a quiet, darkened room. Once deeply asleep, 25 of these sounds were played. Although none of the participants noticed these sounds, performance was subsequently more accurate for those objects whose sounds had been played during sleep. The findings reveal that memory consolidation can be directed to specific memories through use of such cues. Another recent study found smells could also be used in this way.

[1056] Rudoy, J. D., Voss J. L., Westerberg C. E., & Paller K. A.
(2009).  Strengthening Individual Memories by Reactivating Them During Sleep.
Science. 326(5956), 1079 - 1079.

Sleep helps reduce errors in memory

A study in which college students were shown lists of words and then, 12 hours later, asked to identify which words they had seen or heard earlier, found that those who trained at night and tested the following morning were less prone to falsely recognizing semantically similar words than those who trained in the morning and tested in the evening. It’s suspected that sleep may help strengthen the source of the memory, thus helping protect against false memories.

[254] Fenn, K. M., Gallo D. A., Margoliash D., Roediger H. L., & Nusbaum H. C.
(2009).  Reduced false memory after sleep.
Learning & Memory. 16(9), 509 - 513.

How sleep consolidates memory

A rat study provides clear evidence that "sharp wave ripples", brainwaves that occur in the hippocampus when it is "off-line", most often during stage four sleep, are responsible for consolidating memory and transferring the learned information from the hippocampus to the neocortex, where long-term memories are stored. The study found that when these waves were eliminated during sleep, the rats were less able to remember a spatial navigation task.

[1083] Girardeau, G., Benchenane K., Wiener S. I., Buzsaki G., & Zugaro M. B.
(2009).  Selective suppression of hippocampal ripples impairs spatial memory.
Nat Neurosci. 12(10), 1222 - 1223.

Memories practiced throughout the day, not just while sleeping

It is known that a certain amount of replaying of experiences occurs in the hippocampus immediately afterwards, but it has been thought that this is confined to the immediate past, while the replaying that occurs during sleep and is thought to be part of the memory consolidation process, ranges far more widely. Now a new rat study indicates that the replaying that occurs while the animal is awake is more extensive than thought, and more accurate than that which occurs during sleep. Data from the neurons indicated that the events being replayed (repeatedly) were from 20 to 30 minutes earlier, and involved different settings, indicating the replay wasn’t dependent on incoming sensory cues. It’s suggested that the less-accurate replays seen during sleep are more aimed at making connections, rather than consolidating the actual experience. The waking replays occurred during pauses in activity, perhaps suggesting the importance of making pauses for reflection during your day!

[933] Karlsson, M. P., & Frank L. M.
(2009).  Awake replay of remote experiences in the hippocampus.
Nature Neuroscience. 12(7), 913 - 918.

Creative problem solving enhanced by REM sleep

A study investigating the role of sleep in creative problem-solving has found that those who experienced REM sleep between two tests performed significantly better on the later test compared to those who simply had a quiet rest, or those who napped but had no REM sleep. The findings support the idea that REM sleep (when dreams occur) has a role in forming new associations. It’s suggested that the process may be facilitated by changes to neurotransmitter systems (cholinergic and noradrenergic) during REM sleep.

[1326] Cai, D. J., Mednick S. A., Harrison E. M., Kanady J. C., & Mednick S. C.
(2009).  REM, not incubation, improves creativity by priming associative networks.
Proceedings of the National Academy of Sciences. 106(25), 10130 - 10134.

Sleep may be important in regulating emotional responses

A study involving 44 college students who were asked to remember scenes with neutral or negative objects on a neutral background has found that those who trained and tested on the scenes in the evening remembered the negative scenes better than those who were trained and tested in the morning. However, neutral objects were not better remembered, and the backgrounds associated with negative objects were more poorly remembered by this group. The pattern persisted when the students were tested four months later. The findings suggest that the sleeping brain calculates what is most important about an experience and selects only what is adaptive for consolidation and long term storage.

Payne, J.D., Kensinger, E., Wamsley, E. & Stickgold, R. 2009. Sleep Promotes Lasting Changes in Memory for Emotional Scenes. Presented on June 11 at SLEEP 2009, the 23rd Annual Meeting of the Associated Professional Sleep Societies; Abstract ID: 1244.

Sleep may help clear the brain for new learning

Although fruit flies may seem little like us, their response to sleep deprivation is similar, and so they are useful models for sleep effects on the human brain. In a recent study, flies genetically altered to make it easier to track individual synapses have revealed that during sleep the number of new synapses formed during earlier learning decreased. This decline didn’t happen if the flies were deprived of sleep. It’s theorized that this activity during sleep is a way of pruning the less relevant and important synapses (clearing away the junk, as it has been conceptualized). The study follows earlier fruit fly research showing that more learning resulted in longer sleep. It also supports recent rat research that found synaptic strength increases during the day, then weakens during sleep. The study also identified three genes essential to the links between learning and increased need for sleep, one of which is equivalent to a human gene known as serum response factor (SRF) and previously linked to brain plasticity.

[360] Donlea, J. M., Ramanan N., & Shaw P. J.
(2009).  Use-Dependent Plasticity in Clock Neurons Regulates Sleep Need in Drosophila.
Science. 324(5923), 105 - 108.

Sleep helps you learn complicated tasks & recover forgotten skills

A study involving 200 mostly female college students, who had little experience of video games. The students were taught to play a complicated, multisensory video game in which players must use both hands to deal with continually changing visual and auditory signals. Half were tested 12 hours after the training session, and the others 24 hours later. Some were given a night’s sleep before testing, others were tested the same day. Performance in the former dropped by half at testing, but when tested again the following morning, they showed a 10 percentage point improvement over their pre-test performance. For those given evening training, scores improved by about 7 percentage points, then went to 10 percentage points the next morning – which was maintained over the day. The findings indicate that although people may appear to forget much of their learning over the course of a day, a night’s sleep will restore it; moreover, sleep protected the memory from loss over the course of the next day. The findings confirm the role of sleep in consolidating memory for skills, and extends the research to complicated tasks.

[486] Brawn, T. P., Fenn K. M., Nusbaum H. C., & Margoliash D.
(2008).  Consolidation of sensorimotor learning during sleep.
Learning & Memory. 15(11), 815 - 819.

Sleep selectively preserves emotional memories

It’s now generally accepted that sleep plays an important role in consolidating procedural (skill) memories, but the position regarding other types of memory has been less clear.  A new study has found that sleep had an effect on emotional aspects of a memory. The study involved showing 88 students neutral scenes (such as a car parked on a street in front of shops) or negative scenes (a badly crashed car parked on a similar street). They were then tested for their memories of both the central objects in the pictures and the backgrounds in the scenes, either after 12 daytime hours, or 12 night-time hours, or 30 minutes after viewing the images, in either the morning or evening.  Those tested after 12 daytime hours largely forgot the entire negative scene, forgetting both the central objects and the backgrounds equally. But those tested after a night’s sleep remembered the emotional item (e.g., the smashed car) as well as those who were tested only 30 minutes later. Their memory of the neutral background was however, as bad as the daytime group. The findings are consistent with the view that the individual components of emotional memory become 'unbound' during sleep, enabling the brain to selectively preserve only that information it considers important.

[875] Payne, J. D., Stickgold R., Swanberg K., & Kensinger E. A.
(2008).  Sleep preferentially enhances memory for emotional components of scenes.
Psychological Science: A Journal of the American Psychological Society / APS. 19(8), 781 - 788.

Aging impairs the 'replay' of memories during sleep

During sleep, the hippocampus repeatedly "replays" brain activity from recent experiences, in a process believed to be important for memory consolidation. A new rat study has found reduced replay activity during sleep in old compared to young rats, and rats with the least replay activity performed the worst in tests of spatial memory. The best old rats were also the ones that showed the best sleep replay. Indeed, the animals who more faithfully replayed the sequence of neural activity recorded during their earlier learning experience were the ones who performed better on the spatial memory task, regardless of age. The replay activity occurs during slow-wave sleep.

[1319] Gerrard, J. L., Burke S. N., McNaughton B. L., & Barnes C. A.
(2008).  Sequence Reactivation in the Hippocampus Is Impaired in Aged Rats.
J. Neurosci.. 28(31), 7883 - 7890.

A nap can help you learn

A study of 33 younger adults (average are 23) has found that a 45 minute afternoon nap (containing only non-REM sleep) improved performance on 3 different declarative memory tasks, but only when the subjects had reached a certain level of performance during training.

[672] Tucker, M. A., & Fishbein W.
(2008).  Enhancement of declarative memory performance following a daytime nap is contingent on strength of initial task acquisition.
Sleep. 31(2), 197 - 203.

Brain connections strengthen during waking hours, weaken during sleep

New research provides support for a much-debated theory that we need sleep to give our synapses time to rest and recover. The human brain is said to expend up to 80% of its energy on synaptic activity, constantly adding and strengthening connections in response to stimulation. The researchers have theorized that we need an ‘off-line period’, when we are not exposed to the environment, to take synapses down. The rodent study has revealed by several measures that synapses — the all-important points of connection between neurons — are very active when the animal is awake and very quiet during sleep. The researchers feel that these findings support the idea that our brain circuits get progressively stronger during wakefulness and that sleep helps to recalibrate them to a sustainable baseline. This theory is of course opposite to the currently dominant hypothesis, that during sleep synapses are hard at work replaying the information acquired during the previous waking hours, consolidating that information by becoming even stronger.

[631] Vyazovskiy, V. V., Cirelli C., Pfister-Genskow M., Faraguna U., & Tononi G.
(2008).  Molecular and electrophysiological evidence for net synaptic potentiation in wake and depression in sleep.
Nat Neurosci. 11(2), 200 - 208.

Sleep reinforces the temporal sequence in memory

Following on from research showing long-term memory is consolidated during sleep through the replaying of recently encoded experiences, a study has found that the particular order in which they were experienced is also strengthened, probably by a replay of the experiences in "forward" direction. The study involved students being asked to learn triplets of words presented one after the other. Those whose recall of the order of the words was tested after sleep showed better recall, but only when they were asked to reproduce the learned words in forward direction.

[368] Drosopoulos, S., Windau E., Wagner U., & Born J.
(2007).  Sleep Enforces the Temporal Order in Memory.
PLoS ONE. 2(4), e376 - e376.

Sleep protects against interference

A study involving 48 people (aged 18—30) found that those who learned 20 pairs of words at 9pm and were tested at 9am the following morning, after a night’s sleep, performed better than those who learned them at 9am and were tested at 9pm of the same day. Moreover, for those who were given a second list of word pairs to remember just before testing, where the first word in each pair was the same as on the earlier list, the advantage of sleep was dramatically better. For those who experienced the interference manipulation, those in the sleep group recalled 12% more word pairs than the wake group, but with interference, the recall rate was 44% higher for the sleep group.

The findings were presented by Dr Jeffrey Ellenbogen at the American Academy of Neurology’s 59th Annual Meeting in Boston, April 28 – May 5, 2007.

Sleeping helps us put facts together

And in yet another sleep study, researchers found evidence that sleep also helps us see the big picture. The study involved 56 students who were shown oval images of colorful abstract patterns nicknamed "Fabergé eggs." Participants were first shown a combination of five pairs of the eggs, all of which were given ratings. The students were given 30 minutes to learn which shape rated higher and so should be chosen over another shape. They were not told the hidden connection that linked all five pairs together. They were then tested either after 20 minutes, after 12 hours, or after 24 hours. Half of those in the 12-hour group slept before the test, the other half did not. The 20-minute group performed the worst, showing no evidence of seeing the pattern. Those who had longer before being tested were much more likely to show signs of inferential judgment (75% vs 52%), and for the most distant (and difficult) inferential judgment, the students who had had periods of sleep in between learning and testing significantly outperformed those who hadn’t slept (93% vs 69%). The researchers are interested in exploring whether meditation can provide a similar benefit.

[749] Ellenbogen, J. M., Hu P. T., Payne J. D., Titone D., & Walker M. P.
(2007).  Human relational memory requires time and sleep.
Proceedings of the National Academy of Sciences. 104(18), 7723 - 7728.

More on how memories are consolidated during sleep

A new study sheds more light on how memory is consolidated during sleep. Using a new technique, the research confirms that new information is transferred between the hippocampus and the cerebral cortex, and, unexpectedly, provides evidence suggesting that the cerebral cortex actively controls this transfer.

[834] Hahn, T. T. G., Sakmann B., & Mehta M. R.
(2006).  Phase-locking of hippocampal interneurons' membrane potential to neocortical up-down states.
Nat Neurosci. 9(11), 1359 - 1361.

Still more on how memories are consolidated during sleep

In research following up an earlier study in which rats were shown to form complex memories for sequences of events experienced while they were awake, and that these memories were replayed while they slept, it has been shown that these replayed memories do contain the visual images that were present during the running experience. By showing that the brain is replaying memory events in the visual cortex and in the hippocampus at the same time, the finding suggests that this process may contribute to or reflect the result of the memory consolidation process.

[317] Ji, D., & Wilson M. A.
(2007).  Coordinated memory replay in the visual cortex and hippocampus during sleep.
Nat Neurosci. 10(1), 100 - 107.

Brainwave oscillations responsible for memory benefits of sleep?

Passing a mild electrical current through the brain while students were asleep improved their ability to remember words on waking up. 13 medical students were given 46 pairs of words to learn. Before sleeping, they remembered an average 37.42 words; after sleep, those not given the stimulation remembered an average of 39.5, while those given the stimulation remembered an average of 41.27. The memory enhancement only occurred at a certain frequency and during a particular part of the sleep cycle, confirming the idea that slow oscillations of electrical activity are responsible for the memory consolidation effects of sleep. The benefit also only applied to fact learning; skill learning was not affected.

[238] Marshall, L., Helgadottir H., Molle M., & Born J.
(2006).  Boosting slow oscillations during sleep potentiates memory.
Nature. 444(7119), 610 - 613.,,1940475,00.html

More support that sleep helps consolidate learning

An experiment involving fruitflies has found that those in a social environment with at least 30 other flies slept four times as long during their daytime naps as flies in isolation. There was no difference in night-time sleep. The length of the nap increased with the size of the group they socialized with. Confirming that this effect was due to an increase in social interactions, rather than, for example, physical exhaustion from flying around more, flies deprived of their sight and sense of smell (meaning they could still fly around but could not socialize) showed no difference in daytime sleep patterns. Of 49 genes known to be involved in learning and memory, switching off seventeen (all related to long-term memory) made the flies sleep equally long regardless of whether they were social or not.

[894] Ganguly-Fitzgerald, I., Donlea J., & Shaw P. J.
(2006).  Waking Experience Affects Sleep Need in Drosophila.
Science. 313(5794), 1775 - 1781.

Human study supports value of daytime napping for learning

REM sleep, when most dreaming occurs, has been shown in a number of studies to be important in consolidating procedural (skill) learning, while non-REM (slow-wave) sleep seems to be more important for declarative (knowledge-based) learning. However, because normal sleep contains both REM and non-REM cycles, research hasn’t been able to clearly distinguish the effects. Now a new study using brief daytime napping confirms the role of non-REM sleep for declarative learning. Volunteers who memorized pairs of words and practiced tracing images in a mirror test scored 15% better in the word test if they had been allowed a nap in the six hour period before being tested. However, they did no better at the action test.

[414] Tucker, M. A., Hirota Y., Wamsley E. J., Lau H., Chaklader A., & Fishbein W.
(2006).  A daytime nap containing solely non-REM sleep enhances declarative but not procedural memory.
Neurobiology of Learning and Memory. 86(2), 241 - 247.

Sleep makes memories resistant to interference

It’s pretty clear now that sleep consolidates procedural (skill) learning, but the question of whether or not it helps other types of memory is still very much a matter of debate. However, a new study has found a marked effect of sleep on our ability to remember information. The study involved 60 healthy college-aged adults, who were asked them to memorize 20 pairs of random words. Half were given the words at 9am and tested at 9pm, and the other half were given the words at 9pm and tested at 9am. While the sleepers did perform better (94% recall compared to 82%), it was the introduction of another factor that made the benefits of sleep undeniable. Participants who were given a new set of words to learn just 12 minutes before testing revealed a dramatic difference — sleepers recalled 76% of the original words compared to 32% of the sleepless.

[974] Ellenbogen, J. M., Hulbert J. C., Stickgold R., Dinges D. F., & Thompson-Schill S. L.
(2006).  Interfering with Theories of Sleep and Memory: Sleep, Declarative Memory, and Associative Interference.
Current Biology. 16(13), 1290 - 1294.

Asleep or awake we retain memory

We’ve learned that skill memory is reinforced during sleep, but now new imaging technology reveals that this kind of reinforcement occurs while we’re awake too — even while we’re learning something new.

[475] Peigneux, P., Orban P., Balteau E., Degueldre C., Luxen A., Laureys S., et al.
(2006).  Offline Persistence of Memory-Related Cerebral Activity during Active Wakefulness.
PLoS Biol. 4(4), e100 - e100.

How sleep improves memory

While previous research has been conflicting, it does now seem clear that sleep consolidates learning of motor skills in particular. A new imaging study involving 12 young adults taught a sequence of skilled finger movements has found a dramatic shift in activity pattern when doing the task in those who were allowed to sleep during the 12 hour period before testing. Increased activity was found in the right primary motor cortex, medial prefrontal lobe, hippocampus and left cerebellum — this is assumed to support faster and more accurate motor output. Decreased activity was found in the parietal cortices, the left insular cortex, temporal pole and fronto-polar region — these are assumed to reflect less anxiety and a reduced need for conscious spatial monitoring. It’s suggested that this is one reason why infants need so much sleep — motor skill learning is a high priority at this age. The findings may also have implications for stroke patients and others who have suffered brain injuries.

[670] Walker, M. P., Stickgold R., Alsop D., Gaab N., & Schlaug G.
(2005).  Sleep-dependent motor memory plasticity in the human brain.
Neuroscience. 133(4), 911 - 917.

More evidence that learning is consolidated during sleep

A new study provides more evidence for the role of sleep in the consolidation of long-term memories. In the study, volunteers learned the layout of a virtual town, and were then tested by having to quickly find routes to various locations in the town. Those so trained showed greater activity in their hippocampus and an adjacent learning-related region (compared to those not trained) as they took the route tests, with greater activity correlated with better performance. They also showed greater hippocampal brain activity during sleep. Most importantly, the higher the gain in post-sleep performance on the tests, the higher had been their NREM brain activity during sleep. No such correlation was found in REM brain activity. The findings support the view that spatial memory traces are processed during NREM sleep in humans.

[1182] Aerts, J., Luxen A., Maquet P., Peigneux P., Laureys S., Fuchs S., et al.
(2004).  Are spatial memories strengthened in the human hippocampus during slow wave sleep?.
Neuron. 44(3), 535 - 545.

Mentally, sleep may be as active a state as waking state

Why do we sleep? A question we keep asking. Recent research leads us another step in the road. The study has identified a number of genes upregulated specifically during sleep – at least as many as are turned on while we are awake. These "sleep genes" largely fall into four categories: genes involved in synaptic plasticity (supporting the view that sleep aids memory consolidation); genes underlying translation (supporting observations that protein synthesis increases during sleep); genes regulating membrane and vesicle trafficking; and genes for synthesizing cholesterol (which may be crucial for synapse formation and maintenance, which could, in turn, enhance neural plasticity (the brain's ability to change and learn)). The study also found, to the researchers’ surprise, that the cerebellum showed largely the same pattern of gene-expression during sleep as the cortex.

[1021] Cirelli, C., Gutierrez C. M., & Tononi G.
(2004).  Extensive and divergent effects of sleep and wakefulness on brain gene expression.
Neuron. 41(1), 35 - 43.

More on what goes on during sleep

Brain activity patterns vary during sleep, with particular distinction being made between “REM” sleep and “deep” sleep. Both these phases of sleep have been associated with memory processing. The chemical composition of the brain also varies a great deal in the sleep and wakefulness cycle. New research from Germany now report that some of these differences are crucial in memory formation during sleep. In particular, the level of acetylcholine (a neurotransmitter) is high during wakefulness and REM sleep but drops to the minimum in deep sleep. In an experiment that involved subjects performing two memory tasks – learning 40 pairs of semantically related words, and learning to trace figures seen in a mirror – before sleeping for four hours, it was found that those who were given a cholinesterase inhibitor, (cholinesterase being an enzyme that breaks down acetylcholine), performed significantly less well in the wordlist task on wakening. The mirror-tracing task didn't seem to be affected. This supports the idea that a low level of acetylcholine is necessary for strengthening explicit memory during deep sleep, and fits in with a proposed two-stage model of long-term memory formation, in which the cortex transfers newly acquired experiential data to the hippocampus for processing and temporary storage (a process requiring high levels of acetylcholine), and then, during sleep, the processed memory traces in the hippocampus are relayed back to the cortex for long-term storage. This feedback process is blocked by acetylcholine and, thus, only happens in sleep when the acetylcholine level drops to the minimum.
The research may also have important implications for treating memory loss associated with Alzheimer's disease, as cholinesterase inhibitors are widely used in such treatment. Because of common side-effects of the drug, patients are usually told to take it at night, which may well weaken the drug’s effectiveness.

[999] Gais, S., & Born J.
(2004).  Low acetylcholine during slow-wave sleep is critical for declarative memory consolidation.
Proceedings of the National Academy of Sciences of the United States of America. 101(7), 2140 - 2144.

Now definite? Memories are consolidated during sleep

Researchers of a new study claim that their research finally settles the question of whether or not sleep consolidates new memories. The study involved detailed recording of specific learning- and memory- related areas (hippocampus and forebrain) in the brains of rats. The rats were exposed to four kinds of novel objects. Analysis of brain signals before, during, and after this experience, revealed "reverberations" of distinctive brain wave patterns across all the areas being monitored for up to 48 hours after the novel experience. This pattern was much more prevalent in slow-wave sleep than in REM sleep. Previous studies by the same researchers have found that the activation of genes that affect memory consolidation occurs during REM sleep, not slow-wave sleep. It is proposed that both stages of sleep are important for memory consolidation. Previous studies have tended to focus solely on the hippocampus, and have observed brain activity for a much shorter period.

[793] Ribeiro, S., Gervasoni D., Soares E. S., Zhou Y., Lin S-C., Pantoja J., et al.
(2004).  Long-lasting novelty-induced neuronal reverberation during slow-wave sleep in multiple forebrain areas.
PLoS Biology. 2(1), E24 - E24.
Full text available at

Sleep helps insight

A new German study provides evidence for what we all suspected — “sleeping on” a problem can really work. In the study, participants were given a mathematical puzzle to solve; a puzzle which could be solved by trial-by-trial learning, or almost immediately if participants grasped the hidden rule. After training in the trial-by-trial learning, some of the participants were allowed to sleep through the night, while others were prevented from sleeping. When they returned to the problem eight hours later, those that had slept were twice as likely to realize the rule. Another group that trained in the morning, and were then tested later that day, were also slower at finding the rule, suggesting that the slowness was not solely due to fatigue. Sleep did not, however, help participants who had not had the initial training. It is suggested that sleep can act to restructure new memory representations.

[1382] Wagner, U., Gais S., Haider H., Verleger R., & Born J.
(2004).  Sleep inspires insight.
Nature. 427(6972), 352 - 355.

Stages of memory clarified in sleep studies

Two new studies add to our understanding of the effects of sleep on memory. Both studies involved young adults and procedural (skill) learning, and found temporary declines in performance in particular contexts (a brief description of these studies is given here). On the basis of these studies, researchers identified three stages of memory processing: the first stage of memory — its stabilization — seems to take around six hours. During this period, the memory appears particularly vulnerable to being “lost”. The second stage of memory processing — consolidation — occurs during sleep. The third and final stage is the recall phase, when the memory is once again ready to be accessed and re-edited. (see my article on consolidation for more explanation of the processes of consolidation and re-consolidation). The surprising aspect to this is the time it appears to take for memories to initially stabilize. The studies also confirm the role of sleep in the consolidation process.

[1027] Fenn, K. M., Nusbaum H. C., & Margoliash D.
(2003).  Consolidation during sleep of perceptual learning of spoken language.
Nature. 425(6958), 614 - 616.

[518] Walker, M. P., Brakefield T., Allan Hobson J., & Stickgold R.
(2003).  Dissociable stages of human memory consolidation and reconsolidation.
Nature. 425(6958), 616 - 620.,9865,1059138,00.html

More support for the theory that sleep is necessary to consolidate memories

A study used fear conditioning in mice to investigate the effect of sleep deprivation on memory. The mice were given a mild electric shock either in a distinctive setting, or subsequent to a tone. Those who experienced the tone continued to freeze when they heard the tone on the following day, whether or not they had been deprived of sleep. Those who associated the environment with the shock, however, were less likely to freeze after sleep deprivation. Mice who had been deprived of sleep during the five hours following training, spent just 4% of their time frozen when returned to the ‘shock environment’ the following day, compared to 15% among mice who were allowed to sleep during this period. The five hours following training was a critical period – those who were deprived of sleep in the 5-10 hours after training showed no sign of memory impairment. The fact that the context association was affected but not the tone cue, suggests that sleep is affecting processes in the hippocampus (important in context memory but not memory for specific facts or events).

[625] Graves, L. A.
(2003).  Sleep Deprivation Selectively Impairs Memory Consolidation for Contextual Fear Conditioning.
Learning & Memory. 10(3), 168 - 176.

Another step in understanding how sleep affects memory

The value of sleep for memory takes a further step in being understood in new rodent research, which found that, as the rodents slept, the thalamus at the base of their brains originated bursts of electrical activity (“sleep spindles”), which were then detected in the somatosensory neocortex. Some 50 msec later, the hippocampus responded with a pulse of electricity (a “ripple”). "This neocortical-hippocampal dialogue may provide a selection mechanism for the time-compressed replay of information learned during the day." It’s suggested that the ripple is the hippocampus sending back neat, compact waves of memory to the neocortex where they are filed away for future reference. Most of this activity took place during slow wave sleep, the stage which makes up the majority of the sleep cycle.

[907] Wirth, S., Yanike M., Frank L. M., Smith A. C., Brown E. N., & Suzuki W. A.
(2003).  Single Neurons in the Monkey Hippocampus and Learning of New Associations.
Science. 300(5625), 1578 - 1581.

Napping reverses information overload

Evidence is mounting that sleep helps information processing and learning. A new study has showed that subjects performing a visual task (reporting the horizontal or vertical orientation of three diagonal bars against a background of horizontal bars in the corner of a computer screen) got worse over the course of four daily practice sessions. However, allowing subjects a 30-minute nap after the second session prevented any further deterioration, and a 1-hour nap actually boosted performance in the third and fourth sessions back to morning levels. It appears that the fatigue is limited to the brain visual system circuits involved in the task. When the image was switched to a different right corner of the computer screen on the fourth practice session, subjects performed about as well as they did in the first session -- or after a short nap. Recordings of brain activity reveal that the 1-hour naps contained more than four times as much deep, or slow wave sleep and rapid eye movement (REM) sleep than the half-hour naps.

[758] Mednick, S. C., Nakayama K., Cantero J. L., Atienza M., Levin A. A., Pathak N., et al.
(2002).  The restorative effect of naps on perceptual deterioration.
Nat Neurosci. 5(7), 677 - 681.

Improving motor skills through sleep

People taught a simple motor sequence (to type a sequence of keys on a computer keyboard as quickly and accurately as possible) practised it for 12 minutes and were then re-tested 12 hours later. Those who practised in the morning and tested later that same day improved their performance by about 2%. Those trained in the evening and re-tested after a good night's sleep, however, improved by about 20%. The amount of improvement was directly correlated with the amount of Stage 2 (a stage of non-rapid eye movement or NREM) sleep experienced, particularly late in the night. "This is the part of a good night's sleep that many people will cut short by getting up early in the morning."

[767] Laureys, S., Peigneux P., Perrin F., & Maquet P.
(2002).  Sleep and motor skill learning.
Neuron. 35(1), 5 - 7.

Controversy over sleep's role in memory

Does sleep play a role in memory or not? Two new research papers reach opposite conclusions. One is from Robert Stickgold, who has published several papers supporting the role of sleep in memory consolidation. But the other is a new review of REM sleep studies concluding that REM (rapid eye movement) sleep, or dreaming, plays little role in memory formation, chiefly on the basis that depriving animals and humans of REM sleep by awakening them or by drug treatments does not impair their ability to form long-term memories. In addition, the time spent in REM sleep does not correlate with learning ability across humans, nor is there a positive relation between amount or intensity of REM sleep and learning ability across species.

[987] Stickgold, R., Hobson J. A., Fosse R., & Fosse M.
(2001).  Sleep, Learning, and Dreams: Off-line Memory Reprocessing.
Science. 294(5544), 1052 - 1057.

[1388] Siegel, J. M.
(2001).  The REM sleep-memory consolidation hypothesis.
Science (New York, N.Y.). 294(5544), 1058 - 1063.

New motor skills consolidated during sleep

An imaging study that sheds light on the gain in performance observed during the day after learning a new task. Following training in a motor skill, certain brain areas appear to be reactived during REM sleep, resulting in an optimization of the network that subtends the subject's visuo–motor response.

[775] van der Linden, M., Cleeremans A., Smith C., Maquet P., Laureys S., Peigneux P., et al.
(2001).  Experience-dependent changes in cerebral functional connectivity during human rapid eye movement sleep.
Neuroscience. 105(3), 521 - 525.

Deep "slow wave" sleep necessary to consolidate memories

Sleep is necessary to consolidate memories. Remembering a new task is more difficult if you don't sleep within 30 hours of learning the task. "Catch-up" sleep on subsequent nights doesn't make up for losing that first night's sleep. Moreover, it appears that the deep "slow wave" sleep that occurs in the first half of the night is the type of sleep necessary to consolidate memories. Other types of memory however, may require "REM" sleep (that occurs while you are dreaming).

Stickgold, R., James, L. & Hobson, J.A. 2000. Visual discrimination learning requires sleep after training. Nature Neuroscience,3, 1237-1238.

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Folic acid tied to better grades in Swedish teens

August, 2011

More evidence of the importance of adequate folate consumption for cognitive functioning at all ages.

Most research into the importance of folate and B12 levels has centered on seniors, and it does seem clear now that having adequate levels of these vitamins is important for maintaining cognitive functioning as you get older. Folic acid levels are of course also regarded as crucial when the brain is developing, which is why pregnant women are urged to take supplements, and why some countries fortify their bread with it. There is less research in the extensive ground between these two end-points.

A Swedish study involving 386 15-year-olds has now found that those in the top third of folic acid intake (more than 253 micrograms per day for girls and 335 for boys) performed significantly better on their school grades compared to those in the bottom third (less than 173 micrograms folic acid per day for girls and 227 for boys).

Interestingly, while homocysteine levels in the blood were initially significant, this association disappeared after other significant predictors (gender, smoking, and SES) were controlled for. Neither was a genotype linked to higher homocysteine levels (MTHFR 677 TT homozygosity) significantly related to academic achievement. Low folate and B12 levels are associated with higher homocysteine levels in the blood, and there is evidence that it is this increase in homocysteine that is the reason for the cognitive impairment seen in age-related cognitive decline. This finding, then, suggests that this is only one part of the story.

Sweden does not fortify flour with folic acid as the United States, Canada and Australia do. Folate is a B vitamin found particularly in citrus fruit, green leafy vegetables, whole-wheat bread, and dried beans and peas; however, they are often destroyed by cooking or processing.

The sum of school grades in 10 core subjects obtained in the final semester of compulsory 9 years of schooling was used as the measure of academic achievement




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Alcohol's damage to the brain

While moderate drinking seems to have a protective effect against age-related cognitive decline and dementia, cognitive impairment produced by excess alcohol is only too evident. Here are a few less obvious cognitive effects:

Simulated laparoscopic surgery was impaired in both novices and experts on the day following an evening during which excessive alcohol was consumed, although experts were less impaired than novices. Performance had returned to baseline levels by 4:00 p.m.

When people drank before viewing a video of serious road traffic accidents, those given a smaller amount of alcohol experienced more flashbacks during the next week than those given a larger amount of alcohol, and those given no alcohol. Those who had large amounts of alcohol had poorer memories of the event. It’s suggested that alcohol impairs contextual memory first.

Another study found that recognition of different-race faces was unaffected by alcohol, but recognition of own-race faces was — meaning recognition of same-race faces was at about the same level of accuracy as different-race faces.

Cognitive impairment produced by excess alcohol is of course only too evident. Here are a few less obvious cognitive effects:

Simulated laparoscopic surgery was impaired in both novices and experts on the day following an evening during which excessive alcohol was consumed, although experts were less impaired than novices. Performance had returned to baseline levels by 4:00 p.m.

When people drank before viewing a video of serious road traffic accidents, those given a smaller amount of alcohol experienced more flashbacks during the next week than those given a larger amount of alcohol, and those given no alcohol. Those who had large amounts of alcohol had poorer memories of the event. It’s suggested that alcohol impairs contextual memory first.

Another study found that recognition of different-race faces was unaffected by alcohol, but recognition of own-race faces was — meaning recognition of same-race faces was at about the same level of accuracy as different-race faces.

Heavy drinking

Heavy drinking can be chronic, or occasional. Both have their price.

A rat study suggests that it doesn’t take all that long before heavy drinking produces long-lasting cognitive deficits. Rats drinking for eight weeks (but not four) developed deficits that lasted at least 12 weeks after drinking stopped — “equivalent to a human that drank six to eight beers or one bottle of wine a day every day for six years experiencing learning and memory deficits up to nine years after they stopped drinking alcohol."

Brain scans of heavy social drinkers have revealed damage to white matter that was associated with lower executive and working memory functions. This is consistent with a self-report study that found that heavy users of alcohol were more likely to miss appointments, forget birthdays and pay bills on time, and to forget whether they had done something or where they had put something.

One study suggests that heavy drinking is particularly a problem for those infected with HIV. The mediotemporal lobe is affected early in both these conditions, so it is not surprising that those positive for HIV with a history of chronic heavy drinking were found to have trouble encoding new information for long-term memory.

Smoking and alcohol

Smoking has a particularly negative effect in conjunction with alcohol (and unfortunately they are often found in tandem). While moderate drinking can in some circumstances have positive effects on the brain, this is probably not the case for those who smoke. Moreover, smoking makes it much harder for the brain to recover from the effects of alcohol abuse, the damage done to the brain by heavy alcohol consumption is likely to be much worse if the individual is a smoker.


One of the characteristics of alcoholics is that they don’t recognize the extent of their problem. So perhaps it’s no surprise that a study found that alcoholics were relatively unaware of their memory deficits and believed that their memory was much better than it was. Moreover, the greater their deficits, the less they were aware of them!

Years of heavy alcohol consumption impair executive functions, including judgment, problem solving, decision making, planning, and social conduct.

Imaging studies indicate that the brains of alcoholics develop compensatory mechanisms to maintain cognitive skills despite alcohol's damages. It seems likely that this wider activity comes at the expense of other tasks, thus reducing their ability to multitask.

Excessive chronic drinking is also associated with deficits in comprehending emotional information, such as recognizing different facial expressions, and visuospatial deficits, characterized by difficulties completing tasks such as putting pieces of a puzzle together or map reading. While long-term abstinence can recover most of the cognitive function lost, spatial processing abilities seem much harder to recover.

In line with these problems of executive function, episodic and spatial memory, the prefrontal cortex and the hippocampus are especially vulnerable to the effects of chronic alcoholism.

Alcoholics have also been found to have an impaired cortisol response to stress, and this is associated with lower scores on measures of problem-solving ability and memory. Another exacerbating factor may come from poorer sleep — recovering alcoholics have been found to have significantly poorer sleep quality.

There is some evidence that women are more vulnerable to the effects of binge drinking and chronic heavy drinking.

Alcohol and the adolescent brain

Binge drinking is particularly evident among young people. Several studies point to effects on executive functions, including attention and working memory. This has consequences for planning and decision-making, as well as memory tasks.

Memory impairment following too much alcohol is particularly common among adolescent drinkers, possibly because of disruption in the hippocampus, which is still developing during adolescence.

Other physiological consequences of teenage binge drinking may be damaged white matter connectivity, and reduced activity of many neurotransmitter genes. There is some indication that some of these effects may persist into adulthood.

Prenatal exposure

Studies suggest that there is no safe dose, nor safe time to drink, for pregnant women, although the timing does affect the nature of the damage. It seems that alcohol is especially damaging for the development of the dopamine system.

Children prenatally exposed to alcohol are not consistently impaired however. A monkey study suggests why — it seems a gene variant makes the carrier more susceptible to the effects of fetal alcohol exposure. The gene has previously been implicated in increased depression risk.

Other research has suggested that children whose mothers are older than 30 years, those whose mothers have alcohol dependence, those whose parents provide a less stimulating environment, and those whose mothers reported drinking during the time of conception, are at greater risk from prenatal alcohol exposure.

It’s also the case that cognitive deficits are not always evident. One study found that children prenatally exposed to moderate-to-heavy levels of alcohol were perfectly competent at simple tasks, but failed when asked to multi-task. Such working memory deficits may partly be a result of slower processing speed.

Hope comes from a finding that two factors can considerably mitigate the negative effects of prenatal alcohol exposure: being diagnosed early in life and being raised in a stable and nurturing environment.

Children with fetal alcohol spectrum disorder are particularly impaired in mathematical ability, possibly due to specific deficits in memory for numbers and sequences.

Distinguishing Fetal Alcohol Spectrum Disorder from other developmental disorders may have got easier, with a simple test that measures eye movement.

Older news items (pre-2010) brought over from the old website

Alcoholism's effect on sleep persists

A study involving 42 long-term alcoholics who had not had a drink for up to 719 days (mean age 49 years, 27 men) has found that, compared to controls, alcoholics had significantly poorer sleep quality, measured by a significantly lower percentage of slow wave sleep and significantly more stage 1 non-rapid eye movement (NREM) sleep. Moreover, estimated lifetime alcohol consumption was significantly related to the scores on the Pittsburgh Sleep Quality Index, with higher lifetime consumption predicting less sleep satisfaction. The reduction in slow wave activity was specific to NREM sleep. This could act as an exacerbating factor in alcoholics' cognitive decline.

[792] Colrain, I. M., Turlington S., & Baker F. C. (2009).  Impact of alcoholism on sleep architecture and EEG power spectra in men and women. Sleep. 32(10), 1341 - 1352.

Alcoholics show abnormal brain activity when processing facial expressions

Excessive chronic drinking is known to be associated with deficits in comprehending emotional information, such as recognizing different facial expressions. Now an imaging study of abstinent long-term alcoholics has found that they show decreased and abnormal activity in the amygdala and hippocampus when looking at facial expressions. They also show increased activity in the lateral prefrontal cortex, perhaps in an attempt to compensate for the failure of the limbic areas. The finding is consistent with other studies showing alcoholics invoking additional and sometimes higher-order brain systems to accomplish a relatively simple task at normal levels. The study compared 15 abstinent long-term alcoholics and 15 healthy, nonalcoholic controls, matched on socioeconomic backgrounds, age, education, and IQ.

[1044] Marinkovic, K., Oscar-Berman M., Urban T., O'Reilly C. E., Howard J. A., Sawyer K., et al. (2009).  Alcoholism and dampened temporal limbic activation to emotional faces. Alcoholism, Clinical and Experimental Research. 33(11), 1880 - 1892.

Binge drinking affects attention and working memory in young university students

A Spanish study of 95 first-year university students, 42 of them binge drinkers, has found that those who engaged in binge drinking required greater attentional processing during a visual working memory task in order to carry it out correctly. They also had difficulties differentiating between relevant and irrelevant stimuli. Binge drinkers are defined as males who drink five or more standard alcohol drinks, and females who drink four or more, on one occasion and within a two-hour interval. Some 40% of university students in the U.S. are considered binge drinkers.

[231] Crego, A., Holguín S R., Parada M., Mota N., Corral M., & Cadaveira F.
(2009).  Binge drinking affects attentional and visual working memory processing in young university students.
Alcoholism, Clinical and Experimental Research. 33(11), 1870 - 1879.

HIV infection and chronic drinking together impair encoding of new experiences

A study involving 40 individuals with HIV, 38 with chronic alcoholism, 47 with both HIV and chronic alcoholism, and 39 controls, has found that although those with only one of these disorders mostly performed at levels comparable to controls on episodic and working memory tasks, those who were both positive for HIV and had a history of chronic heavy drinking were impaired on tests of immediate episodic memory (but not working memory) — meaning that they have trouble encoding new information for long-term memory. The finding is consistent with the fact that the mediotemporal lobe is affected early by both these conditions. Heavy drinking is very common among those infected with HIV.

[440] Fama, R., Rosenbloom M. J., Nichols N. B., Pfefferbaum A., & Sullivan E. V.
(2009).  Working and episodic memory in HIV infection, alcoholism, and their comorbidity: baseline and 1-year follow-up examinations.
Alcoholism, Clinical and Experimental Research. 33(10), 1815 - 1824.

Adolescent binge drinking may compromise white matter

An imaging study of 28 teens, of whom half had a history of binge drinking (but did not meet the criteria for alcohol abuse), has found that those who had engaged in binge drinking episodes had lower coherence of white matter fibers in 18 different areas across the brain. The findings add to a growing literature indicating that adolescent alcohol involvement is associated with specific brain characteristics. White matter integrity is essential to the efficient relay of information in the brain.

[1426] McQueeny, T., Schweinsburg B. C., Schweinsburg A. D., Jacobus J., Bava S., Frank L. R., et al.
(2009).  Altered white matter integrity in adolescent binge drinkers.
Alcoholism, Clinical and Experimental Research. 33(7), 1278 - 1285.

Alcoholics’ brains maintain language skills at a cost

Despite the damage done by alcoholism to the frontal lobes and cerebellum, areas involved in language processing, alcoholics' language skills appear to be relatively spared from alcohol's damaging effects. A new study of 12 alcoholic males and 12 healthy controls suggests that alcoholics develop compensatory mechanisms to maintain their language skills despite alcohol's damages. The comparable performance on an auditory language task between the two groups was underlain by different neural activity (specifically, the alcoholic group showed greater activity in the left middle frontal gyrus, the right superior frontal gyrus, and the cerebellar vermis). It seems likely that this wider activity comes at the expense of other tasks, thus reducing their ability to multitask.

[926] Chanraud-Guillermo, S., Andoh J., Martelli C., Artiges E., Pallier C., Aubin H. - J., et al. (2009).  Imaging of language-related brain regions in detoxified alcoholics. Alcoholism, Clinical and Experimental Research. 33(6), 977 - 984.

Drinking alcohol associated with smaller brain volume

It is estimated that brain volume decreases by 1.9% per decade, accompanied by an increase in white matter lesions. Because moderate alcohol consumption has been associated with a lower risk of cardiovascular disease, it’s been thought that small amounts of alcohol might also reduce age-related declines in brain volume, although it’s known that large amounts of alcohol will reduce brain volume. However, a large, long-running study, has now found that, even at low levels of alcohol consumption, brain volume was negatively affected. Moreover, although men were more likely to be heavier drinkers, the association between drinking and brain volume was stronger in women.

[1191] Paul, C A., Au R., Fredman L., Massaro J. M., Seshadri S., DeCarli C., et al.
(2008).  Association of Alcohol Consumption With Brain Volume in the Framingham Study.
Arch Neurol. 65(10), 1363 - 1367.

Heavy, chronic drinking can cause significant hippocampal tissue loss

An imaging study of 8 heavy-drinking alcoholics and 8 age and ethnicity matched non-alcoholics (all male) found that total hippocampus volume was significantly reduced among the alcoholics.

[677] Beresford, T. P., Arciniegas D. B., Alfers J., Clapp L., Martin B., Du Y., et al. (2006).  Hippocampus Volume Loss Due to Chronic Heavy Drinking. Alcoholism: Clinical and Experimental Research. 30(11), 1866 - 1870.

Most of the cognitive deficits associated with alcoholism recoverable

Results of a study involving middle-aged alcoholics who have been sober for six months to 13 years, suggest that long-term abstinent alcoholics can recover most of their neurocognitive deficits. However, deficits in spatial-processing abilities continued. Visuospatial processes are important for many daily activities, including driving, reading a map, assembling things, and performing tasks that require spatial orientation. The study doesn’t however know how much damage had been done when the alcoholics ceased drinking; further studies are exploring the recovery of older abstinent alcoholics who ceased drinking at different ages.

[856] Fein, G., Torres J., Price L. J., & Sclafani V. D. (2006).  Cognitive Performance in Long-Term Abstinent Alcoholic Individuals. Alcoholism: Clinical and Experimental Research. 30(9), 1538 - 1544.

Brain atrophy occurs faster in women alcoholics

A study of 34 male and 42 female alcoholics has found that, although the women had been alcoholics for just 5.5 years on average, compared to the average 10.4 years for the men, the women had lost as much proportionate brain volume as the men. The findings are consistent with other studies suggesting that women suffer from the effects of alcohol abuse faster.

[1258] Mann, K., Ackermann K., Croissant B., Mundle G., Nakovics H., & Diehl A. (2005).  Neuroimaging of Gender Differences in Alcohol Dependence: Are Women More Vulnerable?. Alcoholism: Clinical and Experimental Research. 29(5), 896 - 901.

Drinking for just eight weeks impairs learning and memory in mice

It’s well established that chronic alcohol consumption can produce deficits in learning and memory. A new rodent study, however, is the first to show that continuous drinking for as little as eight weeks can produce deficits in learning and memory that last at least 12 weeks after drinking stopped — “equivalent to a human that drank six to eight beers or one bottle of wine a day every day for six years experiencing learning and memory deficits up to nine years after they stopped drinking alcohol." These deficits were global — that is, they affected long-term memory for every type of task tested. Short-term memory was not affected. Rats who drank for only four weeks did not experience the same effects.

[522] Farr, S. A., Scherrer J. F., Banks W. A., Flood J. F., & Morley J. E.
(2005).  Chronic Ethanol Consumption Impairs Learning and Memory After Cessation of Ethanol.
Alcoholism: Clinical and Experimental Research. 29(6), 971 - 982.

Cognitive effects of binge drinking worse for women

A new study looked at the cognitive effects of binge drinking, which apparently is on the rise in several countries, including Britain and the US. The study involved 100 healthy moderate-to-heavy social drinkers aged between 18 and 30. There were equal numbers of males and females. The study found that female binge drinkers performed worse on the working-memory and vigilance tasks than did the female non-binge drinkers.

[1311] Townshend, J. M., & Duka T.
(2005).  Binge Drinking, Cognitive Performance and Mood in a Population of Young Social Drinkers.
Alcoholism: Clinical and Experimental Research. 29(3), 317 - 325.

Alcohol's damaging effects on adolescent brain function

A number of speakers at Symposium speakers at the June 2004 Research Society on Alcoholism meeting in Vancouver, reported on research concerning the vulnerability of the adolescent brain to the damaging effects of alcohol. Some of the findings presented were:

  • The adolescent brain is more vulnerable than the adult brain to disruption from activities such as binge drinking. Adolescent rats that were exposed to binge drinking appear to have permanent damage in their adult brains.
  • Subtle but important brain changes occur among adolescents with Alcohol Use Disorder, resulting in a decreased ability in problem solving, verbal and non-verbal retrieval, visuospatial skills, and working memory.
  • The association between antisocial behavior during adolescence and alcoholism may be explained by abnormalities in the frontal limbic system, which appears to cause "blunted emotional reactivity".
  • Alcohol-induced memory impairments, such as "blackouts", are particularly common among young drinkers and may be at least in part due to disrupted neural plasticity in the hippocampus, which is centrally involved in the formation of autobiographical memories.

[1238] Monti, P. M., Miranda, Jr R., Nixon K., Sher K. J., Swartzwelder S. H., Tapert S. F., et al.
(2005).  Adolescence: Booze, Brains, and Behavior.
Alcoholism: Clinical and Experimental Research. 29(2), 207 - 220.

Alcoholics can have deficits in visuoperception and frontal executive function despite sobriety

Detoxified alcoholics often have visuospatial and visuoperceptual deficits, characterized by difficulties completing tasks such as putting pieces of a puzzle together or map reading. A new study has found that, even with prolonged sobriety, alcoholics show deficits in visuoperception and frontal executive functioning of the brain. Furthermore, alcoholics utilize a more complex higher-order cognitive system (frontal executive functions) to perform the same tasks as individuals without a history of alcoholism. The potential problem with this is that if that same system is needed for a competing task, alcoholics may be at a disadvantage because that system would otherwise be engaged. The study involved 51 recently detoxified nonamnesic alcoholic men (ages 29 to 66 years) compared with 63 "normal," control men (ages 21 to 70 years).

Fama, R., Pfefferbaum, A. & Sullivan, E. V. 2004. Perceptual Learning in Detoxified Alcoholic Men: Contributions From Explicit Memory, Executive Function, and Age. Alcoholism: Clinical & Experimental Research, 28(11), 1657-1665.

New brain cells develop during alcohol abstinence

A rat study has found that the detrimental effect of alcohol on the formation of new neurons in the adult rat hippocampus is followed by a pronounced increase in new neuron formation in the hippocampus within four-to-five weeks of abstinence. This included a twofold burst in brain cell proliferation at day seven of abstinence. The findings may have significant implications for treatment of alcoholism during recovery. The discovery of regeneration of neurons in recovery opens up new avenues of therapies aimed at regeneration of brain cells.

[393] Nixon, K., & Crews F. T. (2004).  Temporally Specific Burst in Cell Proliferation Increases Hippocampal Neurogenesis in Protracted Abstinence from Alcohol. J. Neurosci.. 24(43), 9714 - 9722.

Cognitive function of alcohol abuse patients may influence treatment outcome

Years of heavy alcohol consumption are known to impair many abilities generally referred to as “executive functions.” Such functions include judgment, problem solving, decision making, planning, and social conduct. But alcohol affects executive functioning both chronically and acutely. New research has found that alcohol abuse patients show significant deficits in executive functioning (specifically, abstract reasoning, memory discrimination, and effectiveness on timed tasks) during the critical first weeks of abstinence. The finding has implications for treatment programs, as the early phases of most treatment programs for alcohol abusers commonly require working in groups, making plans for the future, inhibiting behaviors related to their addiction, and remembering specific things. It is suggested that clinicians should scale down their expectations of what patients can do until more of their executive functioning comes back. The researchers are now intending to explore how long it takes the majority of people to regain most of their executive functioning.

[194] Zinn, S., Stein R., & Swartzwelder S. H. (2004).  Executive Functioning Early in Abstinence From Alcohol. Alcoholism: Clinical and Experimental Research. 28(9), 1338 - 1346.

Brain damage found among heavy social drinkers

Almost all knowledge about brain damage due to chronic alcohol consumption has been gathered from alcoholics, generally toward the end of an institutionalized treatment program or many months into abstinence. A new study however, uses magnetic resonance technology to examine brain damage in heavy drinkers who are not in treatment and function relatively well in the community. The study found that frontal white matter NAA – generally considered to be a marker of neuronal damage – was lower in heavy drinkers than light drinkers, and was associated with lower executive and working memory functions. Some of the behaviors that could be associated with the metabolite changes include the inability to apply consequences from past actions, difficulties with abstract concepts of time and money, difficulties with storing and retrieving information, and frequently needing external motivators.

[220] Weiner, M. W., Meyerhoff D. J., Blumenfeld R., Truran D., Lindgren J., Flenniken D., et al.
(2004).  Effects of Heavy Drinking, Binge Drinking, and Family History of Alcoholism on Regional Brain Metabolites.
Alcoholism: Clinical and Experimental Research. 28(4), 650 - 661.

Even small amounts of alcohol or anesthetics may damage the developing brain

Mouse studies suggest that even small amounts of alcohol or anesthetic drugs can trigger nerve cell death in the developing brain. The brain appears most sensitive to this effect during the development stage known as the brain growth spurt. In humans this lasts from about the sixth month of pregnancy to a child's third birthday. Nerve cells are genetically programmed to commit suicide if they fail to make synaptic connections on time. Alcohol and anesthetic drugs interfere with the brain's neurotransmitter systems and with the formation of those synaptic connections, automatically activating a signal within the neuron that directs it to commit suicide.

Olney, J.W. 2004. Perinatal Drug/Alcohol Exposure and Neuronal Suicide – Public Health Implications. Paper presented February 14 at the annual meeting of the American Association for the Advancement of Science in Seattle.

Hippocampal damage seen in those with alcoholic memory disorder and those with Alzheimer's

A comparison between the brains of five men with alcoholic Korsakoff's syndrome and the brains of men with Alzheimer's disease as well as the brains of healthy men, found that the brains of all Korsakoff's patients and Alzheimer's patients were comparable in significant volume loss in the hippocampus. Greater hippocampal damage (for Korsakoff's patients) and smaller hippocampal size (for Alzheimer’s) was correlated with poorer memory performance. It is suggested that, although there are of course a number of differences between these disorders, the nature of the memory impairment may be the same. Awareness of the similarities may help detection of both disorders.

[262] Sullivan, E. V., & Marsh L. (2003).  Hippocampal volume deficits in alcoholic Korsakoff's syndrome. Neurology. 61(12), 1716 - 1719.

Alcohol damages day-to-day memory function

A new study involving 763 participants (465 female, 298 males) used self-report questionnaires: the Prospective Memory Questionnaire (PMQ), the Everyday Memory Questionnaire (EMQ), and the UEL (University of East London) Recreational Drug Use Questionnaire, and found that heavy users of alcohol reported making consistently more errors than those who said that they consumed little or no alcohol. More specifically, those who reported higher levels of alcohol consumption were more likely to miss appointments, forget birthdays and pay bills on time (prospective memory), as well as more problems remembering whether they had done something, like locking the door or switching off the lights or oven, or where they had put items like house keys. The study also found a significant increase in reported memory problems by people who claimed to drink between 10 and 25 units each week in comparison to non-drinkers – this is within the ’safe drinking’ limits suggested by U.K. government guidelines.

[1042] Ling, J., Heffernan T. M., Buchanan T., Rodgers J., Scholey A. B., & Parrott A. C.
(2003).  Effects of Alcohol on Subjective Ratings of Prospective and Everyday Memory Deficits.
Alcoholism: Clinical and Experimental Research. 27(6), 970 - 974.

Study of alcoholics reveals connection between cerebellum and prefrontal cortex

Two functions commonly compromised by chronic alcoholism are executive functions (such as problem solving, putting things in order, working memory, doing multiple tasks at once) and balance (the ability to walk a straight line or stand on one foot, especially with eyes closed or in the dark). Executive functions are primarily processed in the prefrontal cortex, while balance and postural stability are functions of the cerebellum. Previous studies have shown that the prefrontal cortex and regions of the cerebellum are especially vulnerable to the effects of chronic alcoholism. Although these areas are spatially far apart (the former in the frontal lobes, the latter in the hindbrain), they are connected in a variety of ways, most particularly through the pons and the thalamus. An imaging study of 25 nonamnesic alcoholic men suggests that these connections may compound the damaging effects of alcohol on these brain regions, and that the cerebellum, through these connections, can exert a significant effect on functions of the prefrontal cortex.

[356] Sullivan, E. V. (2003).  Compromised Pontocerebellar and Cerebellothalamocortical Systems: Speculations on Their Contributions to Cognitive and Motor Impairment in Nonamnesic Alcoholism. Alcoholism: Clinical and Experimental Research. 27(9), 1409 - 1419.

Alcoholics' cognitive impairment associated with impaired reaction to stress

The body secretes a hormone called cortisol in response to stress. Areas of the brain involved in memory and problem-solving are responsive to cortisol. A new study has found impaired release of cortisol in recently detoxified alcoholics when performing two tasks known to induce stress: mental arithmetic problems and a "cold pressor" task, which requires submerging one hand in ice water for 90 seconds. This was associated with lower scores on measures of problem-solving ability and memory. The study also found that, among alcoholics, the number of withdrawals from alcohol was the strongest predictor of memory impairments, but not of problem-solving ability. The greater the alcoholics' relative cortisol levels were during alcohol withdrawal, the more likely they were to have low scores on one of the problem-solving tests. Nonalcoholic participants showed a connection between higher post-stress cortisol levels and impaired memory, a finding supported by earlier research.

[340] Errico, A. L., King A. C., Lovallo W. R., & Parsons O. A. (2002).  Cortisol Dysregulation and Cognitive Impairment in Abstinent Male Alcoholics. Alcoholism: Clinical and Experimental Research. 26(8), 1198 - 1204.

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tags problems: 

Prenatal dangers

Older news items (pre-2010) brought over from the old website

Too much licorice in pregnancy may affect child's IQ and behavior

A Finnish study involving 321 eight year old children has found that those whose mothers ate more than 500mg of glycyrrhizin per week (found in the equivalent of 100g of pure licorice) had significant decrements in verbal and visuospatial abilities and in narrative memory, compared to those whose mothers consumed less licorice. They were also more likely to have poor attention spans and show disruptive behaviour such as ADHD. The effects on cognitive performance appeared dose related (that is, higher consumption correlated with greater impairment). Glycyrrhizin may impair the placenta, allowing stress hormones to cross from the mother to the baby. These hormones (glucocorticoids) are thought to affect fetal brain development and have been linked to behavioural disorders in children. Consumption of licorice among young women is common in Finland.

Raikkonen, K., Pesonen, A., Heinonen, K., Lahti, J., Komsi, N., Eriksson, J. G., et al. (2009). Maternal Licorice Consumption and Detrimental Cognitive and Psychiatric Outcomes in Children. Am. J. Epidemiol., 170(9), 1137-1146. doi: 10.1093/aje/kwp272.

Vitamin C deficiency impairs early brain development

A guinea pig study has found that newborn guinea pigs subjected to moderate vitamin C deficiency had 30% fewer hippocampal neurons and markedly worse spatial memory than guinea pigs given a normal diet. For several reasons the neonatal brain is thought to be particularly vulnerable to even a slight lowering of the vitamin C level. Vitamin C deficiency is very common in some parts of the world, and even in wealthy nations occurs in an estimated 5-10% of the adult population.

Tveden-Nyborg, P. et al. 2009. Vitamin C deficiency in early postnatal life impairs spatial memory and reduces the number of hippocampal neurons in guinea pigs. American Journal of Clinical Nutrition, 90 (3), 540-546.

Children of older fathers perform less well in intelligence tests during infancy

Reanalysis of a dataset of over 33,000 children born between 1959 and 1965 and tested at 8 months, 4 years, and 7 years, has revealed that the older the father, the more likely the child was to have lower scores on the various tests used to measure the ability to think and reason, including concentration, learning, memory, speaking and reading skills. In contrast, the older the mother, the higher the scores of the child in the cognitive tests.

Saha, S. et al. 2009. Advanced paternal age is associated with impaired neurocognitive outcomes during infancy and childhood. PLoS Medicine 6(3), e1000040. doi:10.1371/journal.pmed.1000040 
Full text available at

Early maternal experience can affect memory in her offspring

A study of pre-adolescent mice with a genetically-created defect in memory has found that a mere two weeks exposure to a stimulating environment resulted in a reversal of the memory defect. But most surprisingly, it was also found that this effect was passed on to the next generation, even though they had the same genetic defect and even though they had no such experience themselves, and even when they were reared by other mice (not their mothers). It’s worth emphasising that the enrichment occurs for the mother long before she’s fertile, yet still benefits her offspring. The finding adds to many recent studies showing that genes are more malleable than we thought.

Arai, J., Li, S., Hartley, D.M. & Feig, L.A. 2009. Transgenerational Rescue of a Genetic Defect in Long-Term Potentiation and Memory Formation by Juvenile Enrichment. Journal of Neuroscience, 29(5), 1496-1502.

Breaking fish advice during pregnancy may benefit babies

Fears of the effects of mercury have led to government warnings to pregnant women to limit their consumption of seafood. However, a study involving nearly 12,000 women has found that children whose mothers ate the least amount of seafood during pregnancy showed the worst performance on tests of social development and verbal IQ, and beneficial effects were evident among children of women who ate more than the recommended guidelines.

Hibbeln, J.R. et al. 2007. Maternal seafood consumption in pregnancy and neurodevelopmental outcomes in childhood (ALSPAC study): an observational cohort study. The Lancet,369 (9561), 578-585.

Ingredient commonly found in shampoos may inhibit brain development

An ingredient found in many shampoos and other personal care products (Diethanolamine (DEA)) appears to interfere with normal brain development in baby mice when applied to the skin of their pregnant mothers. DEA appears to block the body's ability to absorb the nutrient choline, which is essential for normal development of the brain. Whether the amounts most people absorb from personal care products would cause harm remains unclear. A list of some products that contain DEA can be found at

Craciunescu, C.N., Wu, R. & Zeisel, S.H. 2006. Diethanolamine alters neurogenesis and induces apoptosis in fetal mouse hippocampus. FASEB Journal, 20, 1635-1640.

Lead exposure leads to brain cell loss and damage years later

A study of 532 former employees of a chemical manufacturing plant who had not been exposed to lead for an average of 18 years has found that the higher their lead levels were, the more likely they were to have smaller brain volumes and greater amounts of brain damage. 36% had white matter lesions. The results confirm earlier findings in this same population that people with occupational lead exposure experience declines in their thinking and memory skills years after their exposure.

Stewart, W.F. et al. 2006. Past adult lead exposure is linked to neurodegeneration measured by brain MRI. Neurology, 66, 1476-1484.

Prenatal exposure to urban air pollutants affects cognitive development

A study of 183 three-year-old children of non-smoking African-American and Dominican women residing in New York City has found that exposure during pregnancy to combustion-related urban air pollutants (specifically, polycyclic aromatic hydrocarbons) was linked to significantly lower scores on mental development tests and more than double the risk of developmental delay at age three.

Perera, F.P. et al. 2006. Effect of Prenatal Exposure to Airborne Polycyclic Aromatic Hydrocarbons on Neurodevelopment in the First Three Years of Life Among Inner-City Children. Environmental Health Perspectives, published online ahead of print.
Full text is available at

Prenatal exposure to marine toxin causes lasting damage

A rat study has found that a single dose of the naturally occurring marine toxin domoic acid caused subtle but permanent cognitive damage in rats exposed to the chemical before birth. The effect occurred at levels below those generally deemed safe, and suggest that the toxin might negatively affect unborn children at levels that do not cause symptoms in expectant mothers. It was already known that toxic doses of domoic acid can damage the hippocampus.

Levin, E.D., Pizarro, K., Pang, W.G., Harrison, J. & Ramsdell, J.S. 2005. Persisting behavioral consequences of prenatal domoic acid exposure in rats. Neurotoxicology and Teratology, in press.

Rats infected as newborns vulnerable to memory problems when infected in adulthood

Underscoring the value of good prenatal care, a new rat study has found that rats who experienced a one-time infection as newborns didn't learn as well as adult rats who were not infected as pups, after their immunity was challenged. The findings fit into a growing body of evidence that even a one-time infection can potentially permanently change physiological systems, a phenomenon called "perinatal programming." The findings implicate prenatal infections, as the rats were infected on their 4th day, a time that corresponds, in terms of brain development, with the 3rd trimester in humans. It should be noted that adult rats who were not infected as pups did not suffer memory impairment as the result of adult infection, and those who were infected as newborns were completely normal until they received the second immune system challenge in adulthood. It’s suggested that this phenomenon may help explain some of the individual variability in disease susceptibility.

Bilbo, S.D., Levkoff, L.H., Mahoney, J.H., Watkins, L.R., Rudy, J.W. & Maier, S.F. 2005. Neonatal Infection Induces Memory Impairments Following an Immune Challenge in Adulthood. Behavioral Neuroscience, 119 (1)

Prenatal exposure to solvents associated with negative cognitive effects

A study of 64 children aged 3 to 9 found that those children whose mothers were exposed to organic solvents during their pregnancies had lower scores on certain tests of language, behavior, and cognitive functioning. Organic solvents (used for example in dry cleaning, manufacturing, jobs involving paints and plastic adhesives, nail salons and medical laboratories) are some of the most common sources of workplace chemical exposure reported by pregnant women.

Laslo-Baker, D., Barrera, M., Knittel-Keren, D., Kozer, E., Wolpin, J., Khattak, S., Hackman, R., Rovet, J. & Koren, G. 2004. Child Neurodevelopmental Outcome and Maternal Occupational Exposure to Solvents. Archives of Pediatrics & Adolescent Medicine, 158, 956-961.

Environmental damage to brains of children

A new report suggests that the brains of children in many parts of Europe are suffering greater damage from environmental risks than previously recognized. A meeting in Malta of European delegates preparing for a ministerial conference on environment and health, being held in Budapest in June, were given preliminary results from a comprehensive study on environmental threats to children's health, being conducted by the WHO and the University of Udine, Italy. The full report is to be published at the Budapest conference. The findings suggest lead is the single most important damaging chemical for children. In 2001, the estimated percentage of European children in urban areas with elevated blood levels (above 10 micrograms per decilitre) ranged from 0.1% to 30.2%.

Vital role in brain development for the nutrient choline

The nutrient choline is known to play a critical role in memory and brain function by positively affecting the brain's physical development through increased production of stem cells (the parents of brain cells). New research demonstrates that this occurs through the effect of choline on the expression of particular genes. The important finding is that diet during pregnancy turns on or turns off division of stem cells that form the memory areas of the brain. Developing babies get choline from their mothers during pregnancy and from breast milk after they are born. Other foods rich in choline include eggs, meat, peanuts and dietary supplements. Breast milk contains much more of this nutrient than many infant formulas. Choline is a vitamin-like substance that is sometimes treated like B vitamins and folic acid in dietary recommendations.
A choline food database is available at:

Niculescu, M.D., Yamamuro, Y. & Zeisel, S.H. 2004. Choline availability modulates human neuroblastoma cell proliferation and alters the methylation of the promoter region of the cyclin-dependent kinase inhibitor 3 gene. Journal of Neurochemistry, 89 (5), 1252-1259.

Prenatal exposure to secondhand smoke associated with greater risk of developmental delay

A new study funded by the National Institute of Environmental Health Sciences has found that children whose mothers are exposed during pregnancy to second-hand smoke have reduced scores on tests of cognitive development at age two, when compared to children from smoke-free homes. In addition, the children exposed to second-hand smoke during pregnancy are approximately twice as likely to have developmental scores below 80, which is indicative of developmental delay. These differences were magnified for children whose mothers lived in inadequate housing or had insufficient food or clothing during pregnancy. The combined effect results in a developmental deficit of about seven points in tests of cognitive performance.

Rauh, V.A., Whyatt, R.M., Garfinkel, R., Andrews, H., Hoepner, L., Reyes, A., Diaz, D., Camann, D. & Perera, F.P. 2004. Developmental effects of exposure to environmental tobacco smoke and material hardship among inner-city children. Neurotoxicology and Teratology, 26 (3), 373-385.

Pre-term labor drug sensitizes brain to pesticide injury

A rat study has found that unborn rats exposed to terbutaline - a drug commonly prescribed to halt pre-term labor and stave off premature birth - suffered greater brain cell damage than those not given the drug upon secondary exposure to the common insecticide chlorpyrifos. This suggests that this drug might leave the brains of children susceptible to other chemicals ubiquitously present in the environment, and may help explain earlier suggestions that children whose mothers are administered terbutaline suffer cognitive deficits.

Rhodes, M.C., Seidler, F.J., Qiao, D., Tate, C.A., Cousins, M.M. & Slotkin, T.A. 2004. Does pharmacotherapy for preterm labor sensitize the developing brain to environmental neurotoxicants? Cellular and synaptic effects of sequential exposure to terbutaline and chlorpyrifos in neonatal rats. Toxicology and Applied Pharmacology, 195 (2), 203-217.

Impact of prenatal environment on learning abilities

In a fascinating study that points to the importance of environment (including prenatal environment) in determining behavioral and cognitive abilities, embryos from mice with a low response to stress were transferred to high-stress surrogate mice. The two strains of mice differed not only in their response to stress but also in their learning abilities. At birth, the mice were cross-fostered again and reared by either a low-stress mother or a high-stress mother. The mice were tested at three months, and researchers found that the low-stress mice that were transferred as embryos to and also later reared by high-stress females were less likely to explore new environments than those carried and reared by low-stress mothers. The low-stress mice reared by high-stress surrogates also performed more poorly on cognitive tests of their ability to navigate mazes.

Francis, D.D., Szegda, K., Campbell, G., Martin, W.D. & Insel, T.R. 2003. Epigenetic sources of behavioral differences in mice. Nature Neuroscience, 6 (5),445–446.

Fetuses recognize mother's voice in the womb

A study of 60 third-term fetuses found that they could distinguish between their mother’s voice and the voice of a stranger, as measured by changes in heart rate. Previous research has shown that newborns prefer their own mother's voice to that of a female stranger, but this demonstrates that this preference and recognition begins in the womb.

Kisilevsky, B.S., Hains, S.M.J., Lee, K., Xie, X., Huang, H., Ye, H.H., Zhang K. & Wang, Z. 2003. Effects of experience on fetal voice recognition. Psychological Science, 14 (3), 220-224(5).

Cognitive development affected in babies exposed prenatally to cocaine

In the first study to use measures of both the mothers’ self report of their prenatal drug use, and infant meconium, which provided a physical measure of the amount of drug exposure, 415 cocaine-exposed infants born in Cleveland were compared to non-exposed infants on cognitive and motor development until age 2. Infants were tested at 6.5, 12 and 24 months. Mental retardation in the cocaine-exposed children at age 2 was 4.89 times higher than would be expected in the general population. The percentage of children with mild delays requiring intervention was almost double the rate of the high risk, non-cocaine group. The study also found that tobacco exposure had significant negative effects on infant development.

Singe, L.T., Arendt, R., Minnes, S., Salvator, A., Kirchner, H.L., Farkas, K., & Kliegman, R. 2002. Cognitive and Motor Outcomes of Cocaine-Exposed Infants. Journal of the American Medical Association, 287,1952-1960.

Use of ecstasy during pregnancy may produce learning and memory impairments in child

Researchers today reported the first evidence that a mother’s use of MDMA (ecstasy) during pregnancy may result in specific types of long-term learning and memory impairments in her offspring.
The research was conducted by scientists from Children’s Hospital Research Foundation and the University of Cincinnati College of Medicine, on rats. It appears the damage to offspring occurs only if the drug is taken during a particular critical period of pregnancy.

Broening, H.W., Morford, L.L., Inman-Wood, S.L., Fukumura, M. & Vorhees, C.V. 2001. 3,4-Methylenedioxymethamphetamine (Ecstasy)-Induced Learning and Memory Impairments Depend on the Age of Exposure during Early Development. Journal of Neuroscience, 21, 3228-3235.

Prenatal exposure to Alcohol

Where math takes place normally and in children with fetal alcohol spectrum disorder

An imaging study involving 21 children with fetal alcohol spectrum disorder confirms the importance of the left parietal area for mathematical tasks. Children with FASD are particularly impaired in mathematical ability. Brain activity patterns also revealed that the involvement of regions in the left cerebellum and the brainstem in math processing may be specific to children with FASD.

[291] Lebel, C., Rasmussen C., Wyper K., Andrew G., & Beaulieu C.
(2010).  Brain Microstructure Is Related to Math Ability in Children With Fetal Alcohol Spectrum Disorder.
Alcoholism: Clinical and Experimental Research. 34(2), 354 - 363.

Possible genetic risk for fetal alcohol disorders

In partial explanation of why children who are exposed to alcohol because their mothers drank during pregnancy are differently affected, new research with rhesus monkeys has found evidence of a gene variant that appears to make the carrier more susceptible to the effects of fetal alcohol exposure. The gene involved is the serotonin transporter gene promoter, and this variant has previously been implicated in increased depression risk.

[499] Kraemer, G. W., Moore C. F., Newman T. K., Barr C. S., & Schneider M. L.
(2008).  Moderate Level Fetal Alcohol Exposure and Serotonin Transporter Gene Promoter Polymorphism Affect Neonatal Temperament and Limbic-Hypothalamic-Pituitary-Adrenal Axis Regulation in Monkeys.
Biological Psychiatry. 63(3), 317 - 324.

Post-natal choline supplements may reduce cognitive effects associated with prenatal alcohol exposure

A rat study has found that giving choline to rat pups exposed to alcohol during the equivalent of the third trimester, when there’s a spurt in brain growth, significantly reduced the severity of alcohol-related over-activity and spatial learning deficits. The benefits lasted months after choline treatment, suggesting that choline’s effects are long-lasting. Further studies are needed to establish exactly how choline helps and how late in development it can reduce fetal alcohol effects, and then, whether the effects also apply to humans. However, although early postnatal choline may reduce learning deficits and hyperactivity following early alcohol exposure, it doesn’t help reduce motor coordination deficits.

Thomas, J.D. et al. 2007. Choline Supplementation Following Third-Trimester Equivalent Alcohol Exposure Attenuates Behavioral Alterations in Rats. Behavioral Neuroscience, 121 (1), 120-130.

Eye movement tasks can be used to assess fetal alcohol spectrum disorders

Fetal alcohol spectrum disorders (FASD) cover a wide array of adverse developmental outcomes in children due to prenatal alcohol exposure and is harder to diagnose than the more severe Fetal Alcohol Syndrome. Now new research indicates than simple eye-movement tasks can be used to assess individuals with FASD.

Green, C.R. et al. 2007. Deficits in Eye Movement Control in Children With Fetal Alcohol Spectrum Disorders. Alcoholism: Clinical and Experimental Research, 31 (3), 500–511.

Numbers, sequences pose problems for Fetal Alcohol Syndrome children

An assessment of 50 Canadian children aged six to 15 years, who had been diagnosed with Fetal Alcohol Spectrum Disorder, has revealed that they had specific deficits in memory for numbers and sequences, which may contribute to common math difficulties faced by these children. The study also found differences between Aboriginal children and Caucasian children with FASD.

[1041] Rasmussen, C., Horne K., & Witol A.
(2006).  Neurobehavioral Functioning in Children with Fetal Alcohol Spectrum Disorder.
Child Neuropsychology. 12(6), 453 - 453.

Prenatal exposure to alcohol linked to lower I.Q.

Analysis of data from the Maternal Health Practices and Child Development Project, an examination of prenatal substance use among women who attended a prenatal clinic from 1983 to 1985, has found that even light to moderate drinking – especially during the second trimester – is associated with lower IQs in African-American offspring at 10 years of age, but not Caucasian children. The difference was not due to differences in the amount or pattern of alcohol use during pregnancy or by differences in socioeconomic status.

[364] Willford, J., Leech S., & Day N.
(2006).  Moderate prenatal alcohol exposure and cognitive status of children at age 10.
Alcoholism, Clinical and Experimental Research. 30(6), 1051 - 1059.

New 'eye movement' test may help treat fetal alcohol syndrome

At present there are no objective diagnostic tools that can be used to distinguish between children with Fetal Alcohol Spectrum Disorder (FASD) and those with other developmental disorders such as Attention-Deficit Hyperactivity Disorder (ADHD). Many of the behavioural tests used to assess children with FASD are geared to white, middle-class English-speaking people. Now a pilot study involving 25 children aged 8-12 has found that the specific brain abnormalities associated with FASD can be identified using a simple test that measures eye movement.

Reynolds, J. & Green, C. 2005. Presented at the annual meeting of the international Society for Neuroscience in Washington, D.C.

Key neural system at risk from fetal alcohol exposure

A study of pregnant rhesus monkeys has found that prenatal exposure to alcohol has pronounced effects on the development and function later in life of the brain's dopamine system. Dopamine is a key chemical messenger in the brain. The study indicates there is no safe dose, nor safe time to drink, for pregnant women. The monkeys consumed the equivalent of one to two drinks a day. Abnormalities in dopamine functioning can contribute to addiction, memory, attention and problem solving, and more pronounced conditions such as schizophrenia. The nature of the damage is significantly different depending on the timing of the alcohol exposure.

[511] Kraemer, G. W., Schneider M. L., Moore C. F., Barnhart T. E., Larson J. A., DeJesus O. T., et al.
(2005).  Moderate-Level Prenatal Alcohol Exposure Alters Striatal Dopamine System Function in Rhesus Monkeys.
Alcoholism: Clinical and Experimental Research. 29(9), 1685 - 1697.

Prenatal alcohol exposure can lead to lasting changes in cognitive processing

A study involving 337 African-American children, 7.5 years of age, selected from the Detroit Prenatal Alcohol Longitudinal Cohort, has found that although children known to have been prenatally exposed to moderate-to-heavy levels of alcohol were able to perform as well as other children when tasks were simple – such as naming colors within a timed period – when pressed to respond quickly while having to think about the response, their processing speed slowed down significantly. The observed deficits in working memory are thought to be partly a result of the slower processing speed. The study also confirmed earlier suggestions that number processing is particularly affected.

[946] Burden, M. J., Jacobson S. W., & Jacobson J. L.
(2005).  Relation of Prenatal Alcohol Exposure to Cognitive Processing Speed and Efficiency in Childhood.
Alcoholism: Clinical and Experimental Research. 29(8), 1473 - 1483.

Prenatal alcohol exposure has effects far beyond fetal alcohol syndrome

Numerous studies have documented IQ deficits in children with fetal alcohol syndrome (FAS). Little research, however, has found IQ deficits in children with alcohol-related neurodevelopmental disorder (ARND), who generally exhibit less severe neurobehavioral deficits than children with FAS. A new study demonstrates that what was interpreted in prior studies as a lack of any IQ effects in nonsyndromal, alcohol-exposed children was really due to a differential effect of exposure related to several risk/protective factors. Specifically, children whose mothers are older than 30 years, those whose mothers have alcohol dependence, those whose parents provide a less stimulating environment, and those whose mothers reported drinking during the time of conception, are at greater risk from prenatal alcohol exposure.

Jacobson, S.W., Jacobson, J.L., Sokol, R.J., Chiodo, L.M. & Corobana, R. 2004. Maternal Age, Alcohol Abuse History, and Quality of Parenting as Moderators of the Effects of Prenatal Alcohol Exposure on 7.5-Year Intellectual Function. Alcoholism: Clinical & Experimental Research, 28(11), 1732-1745.

New hope for children with fetal alcohol syndrome

A study of 415 people diagnosed with either fetal alcohol syndrome (FAS) or fetal alcohol effect (FAE) found two factors greatly increased the chances of escaping the negative experiences common to those with such problems - being diagnosed early in life and being raised in a stable and nurturing environment. These findings offer hope in a situation that many have regarded as hopeless.

[1051] Streissguth, A. P., Bookstein F. L., Barr H. M., Sampson P. D., O'Malley K., & Young J K.
(2004).  Risk factors for adverse life outcomes in fetal alcohol syndrome and fetal alcohol effects.
Journal of Developmental and Behavioral Pediatrics: JDBP. 25(4), 228 - 238.

Light drinking during pregnancy may lead to learning and memory deficits in adolescents

The dangers for the developing child of heavy drinking during pregnancy are well-known, but an ongoing longitudinal study of 580 children and their mothers has found that even light to moderate drinking may have significant effects on the cognitive development of the child – effects which show up in adolescents in subtle difficulties with learning and memory, specifically in the auditory/verbal domain.

Willford, J.A., Richardson, G.A., Leech, S.L. & Day, N.L. 2004. Verbal and Visuospatial Learning and Memory Function in Children With Moderate Prenatal Alcohol Exposure. Alcoholism: Clinical & Experimental Research, 28(3), 497-507.

Deficits associated with prenatal alcohol exposure can be seen as early as infancy

Most of the research on arousal and attention deficits caused by prenatal alcohol exposure has been conducted with children. A new study examined different components of attention through use of heart-rate data collected from six-month-old infants. The findings indicate that slower processing speeds and arousal-regulation problems exist as early as infancy.

Kable, J.A. & Coles, C.D. 2004. The Impact of Prenatal Alcohol Exposure on Neurophysiological Encoding of Environmental Events at Six Months. Alcoholism: Clinical & Experimental Research, 28(3), 489-496.

Prenatal exposure to alcohol affects executive functioning in young children

A study of 316 four-year-old children whose mothers had used various combinations of cocaine, alcohol, and/or marijuana during pregnancy, found that children in the alcohol-exposed group performed significantly worse at an inhibition task than the children in the control group (no maternal use of such substances during pregnancy). This effect persisted even after controlling for prenatal drug exposure, postnatal environmental factors, and child verbal IQ, and suggests that children exposed prenatally to alcohol find it more difficult to inhibit inappropriate behaviors. This may partly explain why such children are at greater risk for social and academic problems. The subtle effect may not be noticeable in most children, but for those who operate at lower levels of functioning, the effect may make all the difference between coping and not. This effect occurred with prenatal alcohol exposure of less than one drink per day. In the United States, it is estimated that among women who know they are pregnant, 2% continue to drink at a moderate level and 5% continue to have at least two drinks per week.

[560] Noland, J. S., Singer L. T., Arendt R. E., Minnes S., Short E. J., & Bearer C. F.
(2003).  Executive Functioning in Preschool-Age Children Prenatally Exposed to Alcohol, Cocaine, and Marijuana.
Alcoholism: Clinical and Experimental Research. 27(4), 647 - 656.

Motor skill training may help children with fetal alcohol exposure

The disorders associated with fetal exposure to alcohol are a leading cause of mental retardation and developmental delay.Research with rats has looked at the effect of motor skill training on the development of rats similarly exposed to alcohol at a critical stage of their prenatal development. Those rats trained in increasingly difficult challenges involving motor skills were found to develop 20% more synapses in the cerebellum than the rats that did not train, even though they had the expected 30% loss of Purkinje cells. The research brings hope that, despite the damage done to the motor function, it may be possible to rehabilitate these deficits if caught early enough.

[1369] Klintsova, A. Y., Scamra C., Hoffman M., Napper R. M. A., Goodlett C. R., & Greenough W. T.
(2002).  Therapeutic effects of complex motor training on motor performance deficits induced by neonatal binge-like alcohol exposure in rats: : II. A quantitative stereological study of synaptic plasticity in female rat cerebellum.
Brain Research. 937(1-2), 83 - 93.

tags development: 

tags lifestyle: 

tags problems: 

Cancer & the brain

Older news items (pre-2010) brought over from the old website

Helping 'chemobrain'

Mouse study points to possible treatment for chemobrain

A mouse study has found that four commonly used chemotherapy drugs disrupt neurogenesis, and that the condition could be partially reversed with the growth hormone IGF-1. Surprising the researchers, both the drugs which cross the blood-brain barrier (cyclophosphamide and fluorouracil) and the two that don’t (paclitaxel and doxorubicin) reduced neurogenesis, with fluorouracil producing a 15.4% reduction, compared to 22.4% with doxorubicin, 30.5% with cyclophosphamide, 36% with paclitaxel. A second study of a single high dose of cyclophosphamide, a mainstay of breast cancer treatment, resulted in a 40.9% reduction. Administration of the experimental growth hormone IGF-1 helped in all cases, but was more effective with the high dose.
[448] Gross, R. A., Janelsins M. C., Roscoe J. A., Berg M. J., Thompson B. D., Gallagher M. J., et al.
(2010).  IGF-1 partially restores chemotherapy-induced reductions in neural cell proliferation in adult C57BL/6 mice.
Cancer Investigation. 28(5), 544 - 553.

Stem cells restore cognitive abilities impaired by brain tumor treatment

A rat study has found that transplanted stem cells restored learning and memory to normal levels four months after radiotherapy. This compares with a greater than 50% decline in cognitive function in those rats that didn’t receive the therapy. Cranial irradiation is a common treatment for brain tumors.
[803] Acharya, M. M., Christie L. - A., Lan M. L., Donovan P. J., Cotman C. W., Fike J. R., et al.
(2009).  Rescue of radiation-induced cognitive impairment through cranial transplantation of human embryonic stem cells.
Proceedings of the National Academy of Sciences. 106(45), 19150 - 19155.

Exercise can aid recovery after brain radiation

A mouse study has found that exercise can prevent a decline in memory after whole-brain radiation treatment. Mice that had radiation plus access to a running wheel did as well at remembering where an escape hole in maze was as normal mice that didn't exercise. Irradiated mice that had no access to an exercise wheel eventually showed no particular preference for the section of the maze with the escape hole. The irradiated mice who didn’t exercise also showed depressive-like behavior, while those who exercised did not.
Wong-Goodrich, S.J. et al. 2009. Exercise promotes recovery from cognitive dysfunction, depressive-like behavior, and loss of hippocampal neurogenesis following whole-brain irradiation in adult mice. Presented October 20 at the annual Society for Neuroscience meeting in Chicago.

Potential remedy for the 'mental fog' in cancer patients

A rat study has found that injections of the antioxidant N-acetyl cysteine (a modified form of the dietary amino acid cysteine), fully prevented the memory loss induced by the commonly used chemotherapy drugs adriamycin and cyclophosphamide. The findings suggest that the cause of impairment is oxidative stress. More research will be needed to determine the safety of NAC for chemotherapy patients.
[846] Konat, G. W., Kraszpulski M., James I., Zhang H-T., & Abraham J.
(2008).  Cognitive dysfunction induced by chronic administration of common cancer chemotherapeutics in rats.
Metabolic Brain Disease. 23(3), 325 - 333.

Anastrozole does not impair cognition in postmenopausal women at risk of breast cancer

Trials have demonstrated that anastrozole is superior to tamoxifen in preventing breast cancer recurrence, and contralateral breast cancer in postmenopausal women, however other research has suggested that women receiving endocrine therapies show significantly poorer performance on verbal memory and processing tasks. In a substudy of the International Breast Intervention Study (IBIS II), which was specifically designed to investigate the clinical benefit of anastrozole, given daily for 5 years, as a primary chemopreventive treatment, cognitive function was assessed at baseline and at 6 and 24 months after the start of treatment. There were no significant differences between the anastrozole group and the placebo group in attention or memory, however, at 24 months significantly more women in the anastrozole group reported hot flushes. I note the recent study indicating the number of hot flushes in postmenopausal women is correlated with cognitive impairment.
[640] Jenkins, V. A., Ambroisine L. M., Atkins L., Cuzick J., Howell A., & Fallowfield L. J.
(2008).  Effects of anastrozole on cognitive performance in postmenopausal women: a randomised, double-blind chemoprevention trial (IBIS II).
The Lancet Oncology. 9(10), 953 - 961.

Narcolepsy drug alleviates post-chemotherapy fogginess

A trial involving 68 breast cancer survivors suffering from ‘chemo-brain’ has had positive results with modafinil (Provigil), a drug that promotes wakefulness. The women who took modafinil for eight weeks reported major improvements in memory, concentration and learning.
The findings were presented on June 3 at the American Society of Clinical Oncology meeting in Chicago.

Diabetes drug shows promise for preventing brain injury from radiation therapy

Hope for preventing the memory and learning problems that cancer patients often experience after whole-brain radiation treatments comes from a rat study. Rats receiving the diabetes drug piolitazone (Actos®) before, during and after radiation treatments did not experience cognitive impairment. The drug is thought to work by preventing inflammation.
[1156] Zhao, W., Payne V., Tommasi E., Diz D. I., Hsu F-C., & Robbins M. E.
(2007).  Administration of the peroxisomal proliferator-activated receptor gamma agonist pioglitazone during fractionated brain irradiation prevents radiation-induced cognitive impairment.
International Journal of Radiation Oncology, Biology, Physics. 67(1), 6 - 9.
Full text available at

Possible treatment found for 'chemobrain'

A common consequence of chemotherapy is memory problems, confusion and difficulty in concentrating ("chemobrain"). While nearly all breast and ovarian cancer patients receiving chemotherapy or radiation treatments seem to suffer chemobrain, 61% continue to experience memory problems long after their cancer treatment has stopped. A new study involving 154 cancer survivors suggests a possible new treatment using the drug dexmethyphenidate (d-MPH). The drug significantly reduced fatigue and improved memory.
Results of the study were presented to the annual meeting of the American Society of Clinical Oncology.

Estrogen boosts memory in men with prostate cancer

A new study suggests that high doses of estrogen may improve long-term memory and decrease feelings of confusion in men whose testosterone levels have been lowered to treat advanced prostate cancer. The findings suggest that hormone deprivation, prostate cancer or a combination of the two significantly impair verbal memory, while estrogen therapy significantly improves verbal memory performance. Hormone deprivation appears to slow working memory performance, but did not affect accuracy. Supplementation with estrogen did not affect working memory.
Beer, T.M. & Janowsky, J. 2004. High dose estrogen may enhance memory in men with prostate cancer. Presented at the American Society for Clinical Oncology annual meeting in New Orleans, La. on June 6.

Evidence for 'chemobrain'

Childhood brain tumors permanently impact cognition & lifestyle

A survey involving 785 CNS cancer survivors, 5,870 survivors of non-CNS cancers (such as leukemia, Hodgkin's disease, and bone tumors), and 379 siblings of CNS cancer survivors, sent at least 16 years after diagnosis, has found that CNS cancer survivors reported significantly greater neurocognitive dysfunction than their siblings and survivors of other types of cancer. Moreover, these problems were linked to lower achievement in education and in full-time employment and income, as well as less chance of being married. The worst problems were found in those who had tumors in the cortex, and those who had cranial radiation treatment.
Ellenberg, L. et al. 2009. Neurocognitive Status in Long-Term Survivors of Childhood CNS Malignancies: A Report From the Childhood Cancer Survivor Study. Neuropsychology, 23 (6), 705-717.
Full text available at

Whole-brain radiation therapy for tumors results in worse cognitive function

In a randomised controlled trial, 58 patients with one to three brain tumors were treated either with stereotactic radiosurgery (SRS) plus whole-brain radiotherapy (WBRT), or with SRS alone. Those who were randomly assigned to SRS plus WBRT were more likely to show a significant drop on a verbal learning & memory test at 4 months than patients randomly assigned to SRS alone (52% vs 24%, despite patients in the SRS alone group having a higher overall brain tumour recurrence rate. This finding persisted at 6-month follow-up. However, tumors didn’t recur in 73% of patients in the SRS plus WBRT group at 1 year, compared with 27% of patients who received SRS alone. Mortality rates were also higher in the SRS alone group. Despite this, the authors advise against WBRT because it causes more of decline in brain function — but point to the need for close clinical monitoring in that case (but see report below).
[1211] Maor, M. H., Chang E. L., Wefel J. S., Hess K. R., Allen P. K., Lang F. F., et al.
(2009).  Neurocognition in patients with brain metastases treated with radiosurgery or radiosurgery plus whole-brain irradiation: a randomised controlled trial.
The Lancet Oncology. 10(11), 1037 - 1044.
Full Article at:

Increased risk of cognitive problems for brain cancer patients who have whole brain radiation

A six-year study of 58 cancer patients with tumors that have spread to the brain has found that those who had whole brain radiation as well as stereotactic radiosurgery (SRS) had more than double the risk of developing learning and memory problems compared to those who only had stereotactic radiosurgery. The trial was halted when interim results showed that patients who received both had a 49% decline in learning and memory functioning at four months, while those who underwent stereotactic radiosurgery alone experienced only a 23% decline in neurocognitive functioning. Nearly half of the patients who had both treatments lost the ability to recall five words from the same list over three attempts.
The study was presented September 22, 2008, at the American Society for Therapeutic Radiology and Oncology's 50th Annual Meeting in Boston.

Chemotherapy may not affect memory in breast cancer patients

A study that tested 30 women with breast cancer repeatedly before each cycle of chemotherapy and one month after the final cycle, comparing them to healthy controls, found the women with breast cancer had slight problems in attention and learning skills before chemotherapy started. Only three women (10%) developed cognitive problems during chemotherapy, and interestingly, these were not the women who reported that they had problems.
Another study compared 40 women with breast cancer not yet treated, 27 women who had recently had a breast biopsy that was not cancerous, and 20 breast cancer survivors who had completed treatment at least one year before. On tests of working memory and spatial learning, the women recently diagnosed with breast cancer performed about the same as the women with the recent benign biopsy, but both groups were slower and less accurate than the breast cancer survivors. The results suggest the cognitive difficulties may be related to stress as a result of the diagnosis and other quality-of-life factors.
The studies were presented at the American Academy of Neurology Annual Meeting in Chicago, April 12–19.

Chemotherapy's damage to the brain identified

On the other hand, studies have shown that upwards of 82% of breast cancer patients report that they suffer from some form of cognitive impairment, and that a significant proportion of these (reports range from 15-20% to 50%) have lingering cognitive problems a year or more after treatment. And following their demonstration that three common chemotherapy drugs used to treat a wide range of cancers are more toxic to healthy brain cells than the cancer cells they were intended to treat, researchers have now found in cell and mouse studies that the widely used chemotherapy drug 5-fluorouracil (5-FU) is associated with a progressing collapse of support cells that are responsible for producing myelin. The next step will be to find out why some patients are vulnerable to this, and others not.
[935] Han, R., Yang Y. M., Dietrich J., Luebke A., Mayer-Pröschel M., & Noble M.
(2008).  Systemic 5-fluorouracil treatment causes a syndrome of delayed myelin destruction in the central nervous system.
Journal of Biology. 7(4), 12 - 12.
Full text available at

Cognitive deficits among cancer patients insufficiently recognized problem

A survey of 471 cancer patients has found that the cognitive impairment experienced by 14 to 45% of cancer patients can be long-lasting and severely affect their personal and professional lives. Patients report that the lack of concentration, short-term memory loss, difficulty with word recall and the inability to organize or multi-task have led to significant problems at home and in the workplace. 42% described their doctors as dismissive or indifferent when it came to addressing their concerns.
To view the executive summary, visit

How whole-brain radiation might cause dementia

Whole-brain radiation is widely used to treat recurrent brain tumors as well as to prevent other cancers from spreading to the brain. About a half of patients later develop progressive memory problems. A new study has now identified changes in brain chemistry that may be responsible. Using middle-aged rats, researchers found changes in brain receptors for the neurotransmitter glutamate. The changes may impair synaptic communication.
The research was reported at the annual meeting of the Radiation Research Society in Philadelphia.

Common cancer treatments toxic to healthy brain cells

A new study may explain ‘chemo-brain’ (cognitive dysfunction following chemotherapy). The study reveals that common drugs used to treat cancer are far more toxic to healthy brain cells than cancer cells — typical exposure levels killed 70-100% of brain cells but just 40-80% of the cancer cells. Moreover, the healthy cells continued to die for at least six weeks after treatment. Now the task is to find out how to protect healthy cells from the drugs.
The full article is available at:
[568] Dietrich, J., Han R., Yang Y., Mayer-Pröschel M., & Noble M.
(2006).  CNS progenitor cells and oligodendrocytes are targets of chemotherapeutic agents in vitro and in vivo.
Journal of Biology. 5(7), 22 - 22.

Chemotherapy temporarily affects the brain

A new study has found that although significant regions of the brain associated with cognitive function were significantly smaller in breast cancer patients within 12 months of receiving adjuvant chemotherapy, after three years, there were no differences in these regions between those who had received chemotherapy and those who had not.
[418] Uchitomi, Y., Inagaki M., Yoshikawa E., Matsuoka Y., Sugawara Y., Nakano T., et al.
(2007).  Smaller regional volumes of brain gray and white matter demonstrated in breast cancer survivors exposed to adjuvant chemotherapy.
Cancer. 109(1), 146 - 156.

Chemo drugs for treating breast cancer may cause changes in cognitive function

A study involving female mice confirms the existence of "chemobrain", finding mild to moderate learning and memory deficits in mice receiving methotrexate and 5-fluorouracil (5FU), two drugs widely used in women to prevent recurrence of breast cancer. The deficits extended only to those types of memory that involve the hippocampus or the frontal lobes (spatial memory and working memory, in this instance). The study only looked at short-term effects (2—4 weeks).
[1069] Winocur, G., Vardy J., Binns M. A., Kerr L., & Tannock I.
(2006).  The effects of the anti-cancer drugs, methotrexate and 5-fluorouracil, on cognitive function in mice.
Pharmacology Biochemistry and Behavior. 85(1), 66 - 75.

Brain scans reveal 'chemobrain' no figment of the imagination

A PET study of 21 women who had undergone surgery to remove breast tumors five to 10 years earlier found that the 16 who had been treated with chemotherapy regimens near the time of their surgeries to reduce the risk of cancer recurrence had specific alterations in activity of frontal cortex, cerebellum, and basal ganglia compared to 5 breast cancer patients who underwent surgery only, and 13 control subjects who did not have breast cancer or chemotherapy. The alterations suggested the chemotherapy patients’ brains were working harder to recall the same information.
[542] Ganz, P. A., Silverman D. H. S., Dy C. J., Castellon S. A., Lai J., Pio B. S., et al.
(2007).  Altered frontocortical, cerebellar, and basal ganglia activity in adjuvant-treated breast cancer survivors 5-10 years after chemotherapy.
Breast Cancer Research and Treatment. 103(3), 303 - 311.

Cancer survivors may be at higher risk for cognitive dysfunction

A study involving 702 cancer survivors and their cancer-free twins has found that cancer survivors are twice as likely to develop cognitive problems as individuals who have never been treated for cancer. About 15% of the cancer survivors showed cognitive dysfunction. The study did not involve patients who had tumors involving the central nervous system. A follow-up study is planned, to compare those who received different treatments for their cancer.
[284] Heflin, L. H., Meyerowitz B. E., Hall P., Lichtenstein P., Johansson B., Pedersen N. L., et al.
(2005).  Cancer as a risk factor for long-term cognitive deficits and dementia.
Journal of the National Cancer Institute. 97(11), 854 - 856. 

Impaired neuromotor function following cancer treatment can improve

A study of 142 patients who had blood disorders and who underwent hematopoietic cell transplant (preceded by high-dose chemotherapy) found that, at three months after transplant, patients experienced a significant decline in all cognitive and motor functions tested. By one year, however, the neuromotor functions for most patients had come back to the level experienced before the transplant, with the exception of two capabilities: grip strength and motor dexterity. Patients who had no chemotherapy or chemotherapy with only hydroxyurea prior to the transplant and those who did not receive certain immune suppressants were better off.
Syrjala, K.L., Dikmen, S., Langer, S.L., Roth-Roemer, S. & Abrams, J.R. 2004. Neuropsychologic changes from before transplantation to 1 year in patients receiving myeloablative allogeneic hematopoietic cell transplant. Blood, 104, 3386-3392.

New radiation therapy of brain tumors in children spares cognitive functions

The second phase of a clinical trial for ependymoma (a malignant brain tumor that occurs predominately in children) suggests a radiation therapy technique called conformal radiation therapy (CRT) allows young patients to enjoy normal development of their cognitive functions. About 75% of the 88 children treated for ependymoma with CRT did not experience progression of their cancer after three years, and their cognitive development was not significantly impaired by radiation therapy. Although radiation treatment is more effective than chemotherapy for brain tumors, physicians have been reluctant to use it because of fears of impairing cognitive development in young children.
[637] Boop, F. A., Sanford R. A., Merchant T. E., Mulhern R. K., Krasin M. J., Kun L. E., et al.
(2004).  Preliminary Results From a Phase II Trial of Conformal Radiation Therapy and Evaluation of Radiation-Related CNS Effects for Pediatric Patients With Localized Ependymoma.
J Clin Oncol. 22(15), 3156 - 3162.

Cognitive dysfunction found in women with breast cancer prior to treatment

The first study to evaluate cognitive skills prior to chemotherapy has found significant deficits in neuropsychological function in breast cancer patients before undergoing chemotherapy, and suggests the incidence of "chemobrain," a widely reported side effect in women undergoing treatment for breast cancer, may be overestimated. The study found 35% of the women demonstrated baseline cognitive impairment with significant deficits in verbal learning and memory prior to chemotherapy. Psychomotor processing speed and attention, non-verbal memory, naming, complex visual tasks and hand fine motor dexterity also trended toward significant impairment compared to the controls.
[544] Wefel, J. S., Lenzi R., Theriault R., Buzdar A. U., Cruickshank S., & Meyers C. A.
(2004).  'Chemobrain' in breast carcinoma?: a prologue.
Cancer. 101(3), 466 - 475.

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Meditation's cognitive benefits

A critical part of attention (and working memory capacity) is being able to ignore distraction. There has been growing evidence that meditation training (in particular mindfulness meditation) helps develop attentional control, and that this can start to happen very quickly.

For example:

  • after an eight-week course that included up to 30 minutes of daily meditation, novices improved their ability to quickly and accurately move and focus attention.
  • three months of rigorous training in Vipassana meditation improved attentional control.
  • after eight weeks of Mindfulness Training, Marine reservists during pre-deployment showed increased working memory capacity and decreased negative mood (this training also included concrete applications for the operational environment and information and skills about stress, trauma and resilience in the body).
  • after a mere four sessions of 20 minutes, students produced a significant improvement in critical cognitive skills — and a dramatic improvement when conditions became more stressful (provided by increasingly challenging time-constraints).

There seem to be several factors involved in these improvements: better control of brainwaves; increased gray matter density in some brain regions; improved white-matter connectivity.

Thus, after ten weeks of Transcendental Meditation (TM) practice, students showed significant changes in brainwave patterns during meditation compared to eyes-closed rest for the controls. These changes reflected greater coherence and power in brainwave activity in areas that overlap with the default mode network (the brain’s ‘resting state’). Similarly, after an eight-week mindfulness meditation program, participants had better control of alpha brainwaves. Relatedly, perhaps, experienced Zen meditators have shown that, after interruptions designed to mimic spontaneous thoughts, they could bring activity in most regions of the default mode network back to baseline faster than non-meditators.

Thus, after an 8-week mindfulness meditation program, participants showed increased grey-matter density in the left hippocampus , posterior cingulate cortex, temporo-parietal junction , and cerebellum , as well as decreased grey-matter density in the amygdala . Similarly, another study found experienced meditators showed significantly larger volumes of the right hippocampus and the right orbitofrontal cortex, and to a lesser extent the right thalamus and the left inferior temporal gyrus.

These areas of the brain are all closely linked to emotion, and may explain meditators' improved ability in regulating their emotions.

Thus, long-term meditators showed pronounced differences in white-matter connectivity between their brains and those of age-matched controls, meaning that meditators’ brains were better able to quickly relay electrical signals. The brain regions linked by these white-matter tracts include many of those mentioned as showing increased gray matter density. Another study found that a mere 11 hours of meditation training (IBMT) produced measurable changes in the integrity and efficiency of white matter in the corona radiata (which links to the anterior cingulate cortex, an area where attention and emotion are thought to be integrated).

It’s an interesting question, the extent to which poor attentional control is a reflection of poor emotional regulation. Obviously there is more to distractability than that, but emotion and attention are clearly inextricably entwined. So, for example, a pilot study involving 10 middle school students with ADHD found that those who participated in twice-daily 10 minute sessions of Transcendental Meditation for three months showed a dramatic reduction in stress and anxiety and improvements in ADHD symptoms and executive function.

The effects of emotion regulation are of course wider than the effects on attention. Another domain they impact is that of decision-making. A study involving experienced Buddhist meditators found that they used different brain regions than controls when making decisions in a ‘fairness’ game. The differences reflected less input from emotional reactions and more emphasis on the actual benefits.

Similarly, brain scans taken while experienced and novice meditators meditated found that periodic bursts of disturbing noise had less effect on brain areas involved in emotion and decision-making for experienced meditators compared to novices — and very experienced meditators (at least 40,000 hours of experience) showed hardly any activity in these areas at all.

Attention is also entwined with perception, so it’s also interesting to observe that several studies have found improved visual perception attendant on meditation training and/or experience. Thus, participants attending a three-month meditation retreat, showed significant improvements in making fine visual distinctions, and ability to sustain attention.

But such benefits may depend on the style of meditation. A study involving experienced practitioners of two styles of meditation (Deity Yoga (DY) and Open Presence (OP)) found that DY meditators were dramatically better at mental rotation and visual memory tasks compared to OP practitioners and controls (and only if they were given the tasks immediately after meditating). Similarly, a study involving Tibetan Buddhist monks found that, during "one-point" meditation, monks were significantly better at maintaining their focus on one image, when two different images were presented to each eye. This superior attentional control was not found during compassion-oriented meditation. However, even under normal conditions the monks showed longer stable perception compared to meditation-naïve control subjects. And three months of intense training in Vipassana meditation produced an improvement in the ability of participants to detect the second of two visual signals half a second apart (the size of the improvement was linked to reduced brain activity to the first target — which was still detected with the same level of accuracy). Similarly, three months of intensive meditation training reduced variability in attentional processing of target tones.


You can read about these studies below in more detail. Three studies were mentioned here without having appeared in the news reports:

Lutz, A., Slagter, H. A., Rawlings, N. B., Francis, A. D., Greischar, L. L., & Davidson, R. J. (2009). Mental Training Enhances Attentional Stability: Neural and Behavioral Evidence. J. Neurosci., 29(42), 13418-13427. doi:10.1523/JNEUROSCI.1614-09.2009

Tang, Y.-Y., Lu, Q., Geng, X., Stein, E. A., Yang, Y., & Posner, M. I. (2010). Short-term meditation induces white matter changes in the anterior cingulate. Proceedings of the National Academy of Sciences, 107(35), 15649 -15652. doi:10.1073/pnas.1011043107

Travis, F., Haaga, D., Hagelin, J., Tanner, M., Arenander, A., Nidich, S., Gaylord-King, C., et al. (2010). A self-referential default brain state: patterns of coherence, power, and eLORETA sources during eyes-closed rest and Transcendental Meditation practice. Cognitive Processing, 11(1), 21-30. doi:10.1007/s10339-009-0343-2

Older news items (pre-2010) brought over from the old website

More on how meditation can improve attention

Another study adds to research showing meditation training helps people improve their ability to focus and ignore distraction. The new study shows that three months of rigorous training in Vipassana meditation improved people's ability to stabilize attention on target tones, when presented with tones in both ears and instructed to respond only to specific tones in one ear. Marked variability in response time is characteristic of those with ADHD.

[1500] Lutz, A., Slagter H. A., Rawlings N. B., Francis A. D., Greischar L. L., & Davidson R. J.
(2009).  Mental Training Enhances Attentional Stability: Neural and Behavioral Evidence.
J. Neurosci.. 29(42), 13418 - 13427.

Meditation may increase gray matter

Adding to the increasing evidence for the cognitive benefits of meditation, a new imaging study of 22 experienced meditators and 22 controls has revealed that meditators showed significantly larger volumes of the right hippocampus and the right orbitofrontal cortex, and to a lesser extent the right thalamus and the left inferior temporal gyrus. There were no regions where controls had significantly more gray matter than meditators. These areas of the brain are all closely linked to emotion, and may explain meditators' improved ability in regulating their emotions.

[1055] Luders, E., Toga A. W., Lepore N., & Gaser C.
(2009).  The underlying anatomical correlates of long-term meditation: Larger hippocampal and frontal volumes of gray matter.
NeuroImage. 45(3), 672 - 678.

Meditation technique can temporarily improve visuospatial abilities

And continuing on the subject of visual short-term memory, a study involving experienced practitioners of two styles of meditation: Deity Yoga (DY) and Open Presence (OP) has found that, although meditators performed similarly to nonmeditators on two types of visuospatial tasks (mental rotation and visual memory), when they did the tasks immediately after meditating for 20 minutes (while the nonmeditators rested or did something else), practitioners of the DY style of meditation showed a dramatic improvement compared to OP practitioners and controls. In other words, although the claim that regular meditation practice can increase your short-term memory capacity was not confirmed, it does appear that some forms of meditation can temporarily (and dramatically) improve it. Since the form of meditation that had this effect was one that emphasizes visual imagery, it does support the idea that you can improve your imagery and visual memory skills (even if you do need to ‘warm up’ before the improvement is evident).

[860] Kozhevnikov, M., Louchakova O., Josipovic Z., & Motes M. A.
(2009).  The enhancement of visuospatial processing efficiency through Buddhist Deity meditation.
Psychological Science: A Journal of the American Psychological Society / APS. 20(5), 645 - 653.

Transcendental Meditation reduces ADHD symptoms among students

A pilot study involving 10 middle school students with ADHD has found that those who participated in twice-daily 10 minute sessions of Trancendental Meditation for three months showed a dramatic reduction in stress and anxiety and improvements in ADHD symptoms and executive function. The effect was much greater than expected. ADHD children have a reduced ability to cope with stress.
A second, recently completed study has also found that three months practice of the technique resulted in significant positive changes in brain functioning during visual-motor skills, especially in the circuitry of the brain associated with attention and distractibility. After six months practice, measurements of distractibility moved into the normal range.

Grosswald, S. J., Stixrud, W. R., Travis, F., & Bateh, M. A. (2008, December). Use of the Transcendental Meditation technique to reduce symptoms of Attention Deficit Hyperactivity Disorder (ADHD) by reducing stress and anxiety: An exploratory study. Current Issues in Education [On-line], 10(2). Available:

Meditation speeds the mind's return after distraction

Another study comparing brain activity in experienced meditators and novices has looked at what happens when people meditating were interrupted by stimuli designed to mimic the appearance of spontaneous thoughts. The study compared 12 people with more than three years of daily practice in Zen meditation with 12 others who had never practiced meditation. It was found that, after interruption, experienced meditators were able to bring activity in most regions of the default mode network (especially the angular gyrus, a region important for processing language) back to baseline faster than non-meditators. The default mode network is associated with the occurrence of spontaneous thoughts and mind-wandering during wakeful rest. The findings indicate not only the attentional benefits of meditation, but also suggest a value for disorders characterized by excessive rumination or an abnormal production of task-unrelated thoughts, such as obsessive-compulsive disorder, anxiety disorder and major depression.

[910] Pagnoni, G., Cekic M., & Guo Y.
(2008).  “Thinking about Not-Thinking”: Neural Correlates of Conceptual Processing during Zen Meditation.
PLoS ONE. 3(9), e3083 - e3083.

Full text available at

Improved attention with mindfulness training

More evidence of the benefits of meditation for attention comes from a study looking at the performance of novices taking part in an eight-week course that included up to 30 minutes of daily meditation, and experienced meditators who attended an intensive full-time, one-month retreat. Initially, the experienced participants demonstrated better executive functioning skills, the cognitive ability to voluntarily focus, manage tasks and prioritize goals. After the eight-week training, the novices had improved their ability to quickly and accurately move and focus attention, while the experienced participants, after their one-month intensive retreat, also improved their ability to keep attention "at the ready."

[329] Jha, A. P., Krompinger J., & Baime M. J.
(2007).  Mindfulness training modifies subsystems of attention.
Cognitive, Affective & Behavioral Neuroscience. 7(2), 109 - 119.

Brain scans show how meditation affects the brain

An imaging study comparing novice and experienced meditators found that experienced meditators showed greater activity in brain circuits involved in paying attention. But the most experienced meditators with at least 40,000 hours of experience showed a brief increase in activity as they started meditating, and then a drop to baseline, as if they were able to concentrate in an effortless way. Moreover, while the subjects meditated inside the MRI, the researchers periodically blasted them with disturbing noises. Among the experienced meditators, the noise had less effect on the brain areas involved in emotion and decision-making than among novice meditators. Among meditators with more than 40,000 hours of lifetime practice, these areas were hardly affected at all. The attention circuits affected by meditation are also involved in attention deficit hyperactivity disorder.

[1364] Brefczynski-Lewis, J. A., Lutz A., Schaefer H. S., Levinson D. B., & Davidson R. J.
(2007).  Neural correlates of attentional expertise in long-term meditation practitioners.
Proceedings of the National Academy of Sciences. 104(27), 11483 - 11488.

Full text is available at

Meditation may improve attentional control

Paying attention to one thing can keep you from noticing something else. When people are shown two visual signals half a second apart, they often miss the second one — this effect is called the attentional blink. In a study involving 40 participants being trained in Vipassana meditation (designed to reduce mental distraction and improve sensory awareness), one group of 17 attended a 3 month retreat during which they meditated for 10–12 hours a day (practitioner group), and 23 simply received a 1-hour meditation class and were asked to meditate for 20 minutes daily for 1 week prior to each testing session (control group). The three months of intense training resulted in a smaller attentional blink and reduced brain activity to the first target (which was still detected with the same level of accuracy. Individuals with the most reduction in activity generally showed the most reduction in attentional blink size. The study demonstrates that mental training can result in increased attentional control.

[1153] Slagter, H. A., Lutz A., Greischar L. L., Francis A. D., Nieuwenhuis S., Davis J. M., et al.
(2007).  Mental Training Affects Distribution of Limited Brain Resources.
PLoS Biol. 5(6), e138 - e138.

Full text available at

Meditation skills of Buddhist monks yield clues to brain's regulation of attention

Recent research has suggested that skilled meditation can alter certain aspects of the brain's neural activity. A new study has now found evidence that certain types of trained meditative practice can influence the conscious experience of visual perceptual rivalry, a phenomenon thought to involve brain mechanisms that regulate attention and conscious awareness. Perceptual rivalry arises normally when two different images are presented to each eye, and it is manifested as a fluctuation in the "dominant" image that is consciously perceived. The study involved 76 Tibetan Buddhist monks with training ranging from 5 to 54 years. Tested during the practice of two types of meditation: a "compassion"-oriented meditation (contemplation of suffering within the world), and "one-point" meditation (involving the maintained focus of attention on a single object or thought). Major increases in the durations of perceptual dominance were experienced by monks practicing one-point meditation, but not during compassion-oriented meditation. Additionally, under normal conditions the monks showed longer stable perception (average 4.1 seconds compared to 2.6 seconds for meditation-naïve control subjects). The findings suggest that processes particularly associated with one-point meditation can considerably alter the normal fluctuations in conscious state that are induced by perceptual rivalry.

[350] Carter, O., Presti D., Callistemon C., Ungerer Y., Liu G., & Pettigrew J.
(2005).  Meditation alters perceptual rivalry in Tibetan Buddhist monks.
Current Biology. 15(11), R412-R413 - R412-R413.

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Long-term meditation fights age-related cognitive decline

August, 2011

Another study adds to the weight of evidence that meditating has cognitive benefits. The latest finding points to brain-wide improvements in connectivity.

Following on from research showing that long-term meditation is associated with gray matter increases across the brain, an imaging study involving 27 long-term meditators (average age 52) and 27 controls (matched by age and sex) has revealed pronounced differences in white-matter connectivity between their brains.

The differences reflect white-matter tracts in the meditators’ brains being more numerous, more dense, more myelinated, or more coherent in orientation (unfortunately the technology does not yet allow us to disentangle these) — thus, better able to quickly relay electrical signals.

While the differences were evident among major pathways throughout the brain, the greatest differences were seen within the temporal part of the superior longitudinal fasciculus (bundles of neurons connecting the front and the back of the cerebrum) in the left hemisphere; the corticospinal tract (a collection of axons that travel between the cerebral cortex of the brain and the spinal cord), and the uncinate fasciculus (connecting parts of the limbic system, such as the hippocampus and amygdala, with the frontal cortex) in both hemispheres.

These findings are consistent with the regions in which gray matter increases have been found. For example, the tSLF connects with the caudal area of the temporal lobe, the inferior temporal gyrus, and the superior temporal gyrus; the UNC connects the orbitofrontal cortex with the amygdala and hippocampal gyrus

It’s possible, of course, that those who are drawn to meditation, or who are likely to engage in it long term, have fundamentally different brains from other people. However, it is more likely (and more consistent with research showing the short-term effects of meditation) that the practice of meditation changes the brain.

The precise mechanism whereby meditation might have these effects can only be speculated. However, more broadly, we can say that meditation might induce physical changes in the brain, or it might be protecting against age-related reduction. Most likely of all, perhaps, both processes might be going on, perhaps in different regions or networks.

Regardless of the mechanism, the evidence that meditation has cognitive benefits is steadily accumulating.

The number of years the meditators had practiced ranged from 5 to 46. They reported a number of different meditation styles, including Shamatha, Vipassana and Zazen.




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Working memory capacity affects emotional regulation

June, 2011

A new study confirms earlier indications that those with a high working memory capacity are better able to regulate their emotions.

Once upon a time we made a clear difference between emotion and reason. Now increasing evidence points to the necessity of emotion for good reasoning. It’s clear the two are deeply entangled.

Now a new study has found that those with a higher working memory capacity (associated with greater intelligence) are more likely to automatically apply effective emotional regulation strategies when the need arises.

The study follows on from previous research that found that people with a higher working memory capacity suppressed expressions of both negative and positive emotion better than people with lower WMC, and were also better at evaluating emotional stimuli in an unemotional manner, thereby experiencing less emotion in response to those stimuli.

In the new study, participants were given a test, then given either negative or no feedback. A subsequent test, in which participants were asked to rate their familiarity with a list of people and places (some of which were fake), evaluated whether their emotional reaction to the feedback affected their performance.

This negative feedback was quite personal. For example: "your responses indicate that you have a tendency to be egotistical, placing your own needs ahead of the interests of others"; "if you fail to mature emotionally or change your lifestyle, you may have difficulty maintaining these friendships and are likely to form insecure relations."

The false items in the test were there to check for "over claiming" — a reaction well known to make people feel better about themselves and control their reactions to criticism. Among those who received negative feedback, those with higher levels of WMC were found to over claim the most. The people who over claimed the most also reported, at the end of the study, the least negative emotions.

In other words, those with a high WMC were more likely to automatically use an emotion regulation strategy. Other emotional reappraisal strategies include controlling your facial expression or changing negative situations into positive ones. Strategies such as these are often more helpful than suppressing emotion.


Schmeichel, Brandon J.; Demaree, Heath A. 2010. Working memory capacity and spontaneous emotion regulation: High capacity predicts self-enhancement in response to negative feedback. Emotion, 10(5), 739-744.

Schmeichel, Brandon J.; Volokhov, Rachael N.; Demaree, Heath A. 2008. Working memory capacity and the self-regulation of emotional expression and experience. Journal of Personality and Social Psychology, 95(6), 1526-1540. doi: 10.1037/a0013345



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Exposure to vehicle pollution bad for brains old and young

May, 2011

Two recent studies have come out implicating traffic pollutants as factors in age-related cognitive decline and dementia and as prenatal risk factors for attention problems.

A study in which mice were exposed to polluted air for three 5-hour sessions a week for 10 weeks, has revealed that such exposure damaged neurons in the hippocampus and caused inflammation in the brain. The polluted air was laden with particles collected from an urban freeway.

Another recent study found that, of 215 children, those whose cord blood showed high levels of combustion-related pollutants such as polycyclic aromatic hydrocarbons (PAH), had more attention (and anxiety) problems at ages 5 and 7. The children were born to nonsmoking African-American and Dominican women residing in New York City.





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