stress

More evidence that stress increases risk of Alzheimer's

  • A stress hormone has been found to be associated with more amyloid-beta protein, in mice and human neurons.
  • The finding helps explain why stress is a risk factor for Alzheimer's.
  • A previous 38-year study supports this with the finding that women who scored highly in "neuroticism" in middle age, had a greater chance of later developing Alzheimer's.
  • This link was largely accounted for by chronic stress experienced by these women over the four decades.

A study involving both mice and human cells adds to evidence that stress is a risk factor for Alzheimer's.

The study found that mice who were subjected to acute stress had more amyloid-beta protein in their brains than a control group. Moreover, they had more of a specific form of the protein, one that has a particularly pernicious role in the development of Alzheimer's disease.

When human neurons were treated with the stress hormone corticotrophin releasing factor (CRF), there was also a significant increase in the amyloid proteins.

It appears that CRF causes the enzyme gamma secretase to increase its activity. This produces more amyloid-beta.

The finding supports the idea that reducing stress is one part of reducing your risk of developing Alzheimer's.

A neurotic personality increases the risk of Alzheimer's disease

An interesting study last year supports this.

The study, involving 800 women who were followed up some 40 years after taking a personality test, found that women who scored highly in "neuroticism" in middle age, have a greater chance of later developing Alzheimer's. People who have a tendency to neuroticism are more readily worried, distressed, and experience mood swings. They often have difficulty in managing stress.

The women, aged 38 to 54, were first tested in 1968, with subsequent examinations in 1974, 1980, 1992, 2000, and 2005. Neuroticism and extraversion were assessed in 1968 using the Eysenck Personality Inventory. The women were asked whether they had experienced long periods of high stress at each follow-up.

Over the 38 years, 153 developed dementia (19%), of whom 104 were diagnosed with Alzheimer's (13% of total; 68% of those with dementia).

A greater degree of neuroticism in midlife was associated with a higher risk of Alzheimer's and long-standing stress. This distress accounted for a lot of the link between neuroticism and Alzheimer's.

Extraversion, while associated with less chronic stress, didn't affect Alzheimer's risk. However, high neuroticism/low extraversion (shy women who are easily worried) was associated with the highest risk of Alzheimer's.

The finding supports the idea that long periods of stress increase the risk of Alzheimer's, and points to people with neurotic tendencies, who are more sensitive to stress, as being particularly vulnerable.

http://www.eurekalert.org/pub_releases/2015-09/uof-uhr091615.php

http://www.eurekalert.org/pub_releases/2014-10/uog-anp101414.php

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High stress in middle age may increase women's risk of dementia

A study that followed 800 Swedish middle-aged women from 1968 to 2005 has found that high levels of stress in middle age increased Alzheimer’s risk by 21% and risk of any dementia by 15%.

Of the 800 women, 425 died during the course of the study while 153 (19%) developed dementia (of whom 104 developed Alzheimer’s), at an average age of 78. The number of stressors and long-standing distress were independently associated with Alzheimer’s.

The finding doesn’t tell us whether stress is contributing to the development of dementia, or whether it is simply an indicator of another underlying risk factor.

http://www.theguardian.com/society/2013/sep/30/stress-middle-age-women-dementia

The open access paper is available at https://bmjopen.bmj.com/content/3/9/e003142.abstract.

 

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Stress & anxiety

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

Short stressful events may improve working memory

We know that chronic stress has a detrimental effect on learning and memory, but a new rat study shows how acute stress (a short, sharp event) can produce a beneficial effect. The rats, trained to a level of 60-70% accuracy on a maze, were put through a 20-minute forced swim before being run through the maze again. Those who experienced this stressful event were better at running the maze 4 hours later, and a day later, than those not forced through the stressful event. It appears that the stress hormone corticosterone (cortisol in humans) increases transmission of the neurotransmitter glutamate in the prefrontal cortex and improves working memory. It also appears that chronic stress suppresses the transmission of glutamate in the prefrontal cortex of male rodents, while estrogen receptors in female rodents make them more resilient to chronic stress than male rats.

[1157] Yuen, E. Y., Liu W., Karatsoreos I. N., Feng J., McEwen B. S., & Yan Z.
(2009).  Acute stress enhances glutamatergic transmission in prefrontal cortex and facilitates working memory.
Proceedings of the National Academy of Sciences of the United States of America. 106(33), 14075 - 14079.

http://www.eurekalert.org/pub_releases/2009-07/uab-sse072309.php

Stressed brains rely on habit

And another rat study has found that rats stressed repeatedly and unpredictably for three weeks were more likely than unstressed animals to continue performing habitual behaviors, even when it no longer made sense to do so. This behavior was correlated with reductions in the prelimbic cortex of the medial prefrontal cortex and the dorsomedial striatum (both implicated in goal-directed actions), and increases in the size of the dorsolateral striatum (necessary for habit). The finding follows on from previous research showing that habit formation involves a switch between neural circuits associated with goal-directed behavior and those controlling habitual behavior. The findings have implications for therapies for stress-related disorders and addictive behavior.

[517] Dias-Ferreira, E., Sousa J. C., Melo I., Morgado P., Mesquita A. R., Cerqueira J. J., et al.
(2009).  Chronic Stress Causes Frontostriatal Reorganization and Affects Decision-Making.
Science. 325(5940), 621 - 625.

http://www.the-scientist.com/blog/display/55873/

Stress disrupts task-switching, but the brain can bounce back

A new neuroimaging study involving 20 male M.D. candidates in the middle of preparing for their board exams has found that they had a harder time shifting their attention from one task to another after a month of stress than other healthy young men who were not under stress. The finding replicates what has been found in rat studies, and similarly correlates with impaired function in an area of the prefrontal cortex that is involved in attention. However, the brains recovered their function within a month of the end of the stressful period.

[829] Liston, C., McEwen B. S., & Casey B. J.
(2009).  Psychosocial stress reversibly disrupts prefrontal processing and attentional control.
Proceedings of the National Academy of Sciences. 106(3), 912 - 917.

Full text available at http://www.pnas.org/content/106/3/912.abstract
http://www.eurekalert.org/pub_releases/2009-01/ru-sdh012709.php

Psychological distress, not depression, linked to increased risk of stroke

A study following 20,627 people for an average of 8.5 years has found that psychological distress was associated with an increased risk of stroke and that the risk of stroke increased the more distress the participants reported. This association remained the same regardless of cigarette smoking, systolic blood pressure, overall blood cholesterol, obesity, previous heart attack, diabetes, social class, education, high blood pressure treatment, family history of stroke and recent antidepressant medication use. However, there was no increased risk for people who had experienced an episode of major depression in the past year or at any point in their lifetime.

[1298] Surtees, P. G., Wainwright N. W. J., Luben R. N., Wareham N. J., Bingham S. A., & Khaw K. - T.
(2008).  Psychological distress, major depressive disorder, and risk of stroke.
Neurology. 70(10), 788 - 794.

http://www.eurekalert.org/pub_releases/2008-03/aaon-pdn022608.php

Short-term stress can affect learning and memory

We know that long-lasting, severe stress can impair cell communication in the hippocampus. Now rodent studies have demonstrated that the same outcome can happen with short-term stress. But rather than involving the familiar stress hormone cortisol, acute stress activated corticotropin releasing hormones, which led to the rapid disintegration of dendritic spines in the hippocampus, thus limiting the ability of synapses to collect and store memories.

[981] Chen, Y., Dube C. M., Rice C. J., & Baram T. Z.
(2008).  Rapid Loss of Dendritic Spines after Stress Involves Derangement of Spine Dynamics by Corticotropin-Releasing Hormone.
J. Neurosci.. 28(11), 2903 - 2911.

http://www.eurekalert.org/pub_releases/2008-03/uoc--ssc031008.php

Correct levels of stress hormones boost learning

Although it’s known that cortisol production is related to stress and has an impact on learning in humans, that impact is not well understood, because of the difficulties of controlling cortisol levels in humans. A study using ground squirrels has now found that they learn more quickly if they have a modest amount of cortisol, rather than either high or low levels of cortisol.

[252] Mateo, J. M.
(2008).  Inverted-U shape relationship between cortisol and learning in ground squirrels.
Neurobiology of Learning and Memory. 89(4), 582 - 590.

http://www.eurekalert.org/pub_releases/2008-03/uoc-rws031208.php

Stress hormone impacts memory, learning in diabetic rodents

A rodent study sheds light on why diabetes can impair cognitive function. The study found that increased levels of a stress hormone (called cortisol in humans) in diabetic rats impaired synaptic plasticity and reduced neurogenesis in the hippocampus. When levels returned to normal, the hippocampus recovered. Cortisol production is controlled by the hypothalamic-pituitary axis (HPA). People with poorly controlled diabetes often have an overactive HPA axis and excessive cortisol.

[1050] Stranahan, A. M., Arumugam T. V., Cutler R. G., Lee K., Egan J. M., & Mattson M. P.
(2008).  Diabetes impairs hippocampal function through glucocorticoid-mediated effects on new and mature neurons.
Nature Neuroscience. 11(3), 309 - 317.

http://www.eurekalert.org/pub_releases/2008-02/nioa-shi021508.php

How stress affects memory

We know stress affects memory. Now a rat study tells us one of the ways it does that. Cell recordings in the hippocampus revealed that, when a mouse moves from one location to another, particular cells fired at each location. When the mouse returned to an earlier location, the same cells fire. However, following stress, the cells that fired in a particular location still fired at the same location, but tended to fire at a different frequency. Stress also reduce the level of LTP at the synapses.

[1295] Kim, J. J., Lee H. J., Welday A. C., Song EY., Cho J., Sharp P. E., et al.
(2007).  Stress-induced alterations in hippocampal plasticity, place cells, and spatial memory.
Proceedings of the National Academy of Sciences. 104(46), 18297 - 18302.

http://www.sciencentral.com/articles/view.php3?article_id=218393035

Highly accomplished people more prone to failure than others when under stress

One important difference between those who do well academically and those who don’t is often working memory capacity. Those with a high working memory capacity find it easier to read and understand and reason, than those with a smaller capacity. However, a new study suggests there is a downside. Such people tend to heavily rely on their abundant supply of working memory and are therefore disadvantaged when challenged to solve difficult problems, such as mathematical ones, under pressure — because the distraction caused by stress consumes their working memory. They then fall back on the less accurate short-cuts that people with less adequate supplies of working memory tend to use, such as guessing and estimation. Such methods are not made any worse by working under pressure. In the study involving 100 undergraduates, performance of students with strong working memory declined to the same level as those with more limited working memory, when the students were put under pressure. Those with more limited working memory performed as well under added pressure as they did without the stress.

The findings were presented February 17 at the annual meeting of the American Association for the Advancement of Science.

http://www.eurekalert.org/pub_releases/2007-02/uoc-hap021607.php

Lifestyle changes improve seniors’ memory surprisingly quickly

A small 14-day study found that those following a memory improvement plan that included memory training, a healthy diet, physical exercise, and stress reduction, showed a 5% decrease in brain metabolism in the dorsal lateral prefrontal region of the brain (involved in working memory) suggesting they were using their brain more efficiently. This change in activity was reflected in better performance on a cognitive measure controlled by this brain region, and participants reported that they felt their memory had improved. The memory training involved doing brainteasers, crossword puzzles and memory exercises. Diet involved eating 5 small meals daily (to prevent fluctuations in blood glucose levels) that were rich in omega-3 fats, low-glycemic index carbohydrates (e.g., whole grains) and antioxidants. Physical exercise involved brisk walking and stretching, and stress reduction involved stretching and relaxation exercises.

The study was presented at the American College of Neuropsychopharmacology's Annual Meeting on December 11-15, in Hawaii.

http://www.eurekalert.org/pub_releases/2005-12/g-nsf121205.php

Stress interferes with problem-solving; Beta-blocker may help

New research suggests that an experience as simple as watching graphically violent or emotional scenes in a movie can induce enough stress to interfere with problem-solving abilities, and that a beta-blocker medication could promote the ability to think flexibly under stressful conditions. Neither the stress nor the beta-blocker affected memory. The research not only has implications for understanding the range of effects of stress on thinking, but could also have broader clinical implications for patients with anxiety disorders or substance abuse problems.

Renner, K., Alexander, J., Hillier, A., Smith, R. & Tivarus, M. 2005. Presented at the annual Society for Neuroscience meeting in Washington, D.C.

http://www.eurekalert.org/pub_releases/2005-11/osu-siw110905.php

Early life stress can lead to memory loss and cognitive decline in middle age

Age-related cognitive decline is probably a result of both genetic and environmental factors. A rat study has demonstrated that some of these environmental factors may occur in early life. Among the rats, emotional stress in infancy showed no ill effects by the time the rats reached adulthood, but as the rats reached middle age, cognitive deficits started to appear in those rats who had had stressful infancies, and progressed much more rapidly with age than among those who had had nurturing infancies. Middle-aged rats who had been exposed to early life emotional stress showed deterioration in brain-cell communication in the hippocampus.

[1274] Brunson, K. L., Kramar E., Lin B., Chen Y., Colgin L L., Yanagihara T. K., et al.
(2005).  Mechanisms of Late-Onset Cognitive Decline after Early-Life Stress.
J. Neurosci.. 25(41), 9328 - 9338.

http://www.eurekalert.org/pub_releases/2005-10/uoc--els100605.php

Stress bad for the brain

A study of older adults for three to six years has found that those with continuous high levels of the stress hormone cortisol performed poorly on memory tests and had a 14% smaller hippocampus. A further study involving young adults and children between the ages of six and fourteen found that even an acute increase in cortisol can lead to reversible memory impairments in young adults, and that children from low socio-economic status environments had higher cortisol levels than those from high SES homes. Children from low SES homes tended to process positive and negative attributes more negatively than children from high SES homes, and this type of processing was significantly related to basal cortisol levels at ages 10, 12 and 14.

[1415] Lupien, S. J., Fiocco A. J., Wan N., Maheu F., Lord C., Schramek T., et al.
(2005).  Stress hormones and human memory function across the lifespan.
Psychoneuroendocrinology. 30(3), 225 - 242.

http://www.eurekalert.org/pub_releases/2005-05/mu-tst051705.php

Anxiety adversely affects those who are most likely to succeed at exams

It has been thought that pressure harms performance on cognitive skills such as mathematical problem-solving by reducing the working memory capacity available for skill execution. However, a new study of 93 students has found that this applies only to those high in working memory. It appears that the advantage of a high working memory capacity disappears when that attention capacity is compromised by anxiety.

[355] Beilock, S. L., & Carr T. H.
(2005).  When high-powered people fail: working memory and "choking under pressure" in math.
Psychological Science: A Journal of the American Psychological Society / APS. 16(2), 101 - 105.

http://www.eurekalert.org/pub_releases/2005-02/bpl-wup020705.php

Anxiety good for memory recall, bad for solving complex problems

Cognitive tests given to 19 first-year medical students one to two days before a regular classroom exam, and then a week after the exam, found that, before the exam, students were better able to accurately recall a list of memorized numbers, but did less well on tests that required them to consider many possibilities in order to come up with a reasonable answer. A week after the exam, the opposite was true. It is assumed that the difference in results reflects the effects of stress.

Jessa Alexander & David Beversdorf presented their findings on October 25 in San Diego at the annual Society for Neuroscience conference.

http://www.eurekalert.org/pub_releases/2004-10/osu-agf101904.php

Estrogen effect on memory influenced by stress

The question of whether estrogen helps memory and cognition in women has proven surprisingly difficult to answer, with studies giving conflicting results. Now it seems the answer to that confusion is: it depends. And one of the things it depends on may be the level of stress the woman is experiencing. A rat study has found that the performance of female rats in a water maze was affected by the interaction of hormone level (whether the rat was estrous or proestrous) with water temperature (a source of physical stress). Those rats with high hormone levels did better when the water was warm, while those with low hormone levels did better when the water was cold. The researchers suggest both timing and duration of stress might be factors in determining the effect of hormones on cognition.

[384] Rubinow, M. J., Arseneau L. M., Beverly L. J., & Juraska J. M.
(2004).  Effect of the Estrous Cycle on Water Maze Acquisition Depends on the Temperature of the Water..
Behavioral Neuroscience. 118(4), 863 - 868.

http://www.eurekalert.org/pub_releases/2004-08/uoia-sss082704.php

Stress reactions no guarantee of authenticity

Physical stress reactions have often been taken as evidence for the authenticity of a memory. A recent study investigated people with “memories” of alien abductions (on the grounds that these are the memories least likely to be true) and found that those who believed they had been abducted by aliens responded physically to recall of that memory in the same way as to recall of other, true, stressful events. The finding suggests that a person’s reaction to a memory is no evidence for whether or not it truly happened.

[1161] McNally, R. J., Lasko N. B., Clancy S. A., Macklin M. L., Pitman R. K., & Orr S. P.
(2004).  Psychophysiological responding during script-driven imagery in people reporting abduction by space aliens.
Psychological Science: A Journal of the American Psychological Society / APS. 15(7), 493 - 497.

http://www.eurekalert.org/pub_releases/2004-06/aps-ptw062104.php

Stress no aid to memory

Numerous studies have questioned the accuracy of recall of traumatic events, but the research is often dismissed as artificial and not intense enough to simulate real-life trauma. A new study has used real stress: 509 active duty military personnel enrolled in survival school training were deprived of food and sleep 48 hours and then interrogated. A day later, only 30% of those presented with a line-up could identify the right person, only 34% identified their interrogator from a photo-spread and 49% from single photos shown sequentially (putting the interrogator in the same clothing boosted correct identification to 66%). Thirty people even got the gender wrong. Those subjected to physical threats (half the participants) performed worse.

[269] Morgan, C. A., Hazlett G., Doran A., Garrett S., Hoyt G., Thomas P., et al.
(Submitted).  Accuracy of eyewitness memory for persons encountered during exposure to highly intense stress.
International Journal of Law and Psychiatry. 27(3), 265 - 279.

http://www.newscientist.com/news/news.jsp?id=ns99995089
http://www.eurekalert.org/pub_releases/2004-06/yu-emp060304.php
http://www.eurekalert.org/pub_releases/2004-06/ns-mfy060904.php

Anxiety over math blocks learning

The so-called "math block" is notorious - why do we have such a term? Do we talk about a "geography block", or a "physics block"? But we do talk of a reading block. Perhaps the reason for both is the same.
The amount of information you can work with at one time has clear limits, defined by your working memory capacity. When we are anxious, part of our working memory is taken up with our awareness of these fears and worries, leaving less capacity available for processing (which is why students who are very anxious during exams usually perform well below their capabilities). Processes such as reading and working with numbers are very sensitive to working memory capacity because they place such demands on it.
A recently reported study by Mark H. Ashcraft and Elizabeth P. Kirk, both psychologists at Cleveland (Ohio) State University, provides the first solid evidence that, indeed, math-anxious people have working memory problems as they do math.

[2549] Ashcraft, M. H., & Kirk E. P.
(2001).  The relationships among working memory, math anxiety, and performance.
Journal of Experimental Psychology: General. 130(2), 224 - 237.

http://www.sciencenews.org/20010630/fob4.asp

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Chronic stress heightens vulnerability to diet-related metabolic risk

A study involving 61 women, of whom 33 were chronically stressed caring for a spouse or parent with dementia, has found that highly stressed people who ate a lot of high-fat, high-sugar food were likely to have:

  • a larger waistline,
  • more truncal fat,
  • higher oxidative damage, and
  • more insulin resistance.

This association was not found among the low-stress women who ate the same amount of unhealthy food.

The findings are consistent with animal studies.

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How stress increases your risk for stroke and heart attack

A study in which 157 healthy adult volunteers were asked to regulate their emotional reactions to unpleasant pictures, has found that those who showed greater brain activation when regulating their negative emotions also had higher blood levels of interleukin-6 (a marker for inflammation) and increased thickness of the carotid artery wall (a marker of atherosclerosis).

The finding helps explain why stress increases the risk for stroke and heart attack.

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A little stress can make brains sharper

While it’s well-established that chronic stress has all sorts of harmful effects, including on memory and cognition, the judgment on brief bouts of acute stress has been more equivocal. There is a certain amount of evidence that brief amounts of stress can be stimulating rather than harmful, and perhaps even necessary if we are to reach our full potential.

04/2013

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Math anxiety starts before school, impacts math achievement

"The general consensus is that math anxiety doesn't affect children much before fourth grade.” New research contests that.

Study 1: found many first grade students do experience negative feelings and worry related to math. This math anxiety negatively affects their math performance when it comes to solving math problems in standard arithmetic notation.

Study 2: found that second grade math anxiety affected second grade computations and math applications. Additionally, children with higher levels of math anxiety in second grade learned less math in third grade.

03/2013

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Worry & fatigue main reason for ‘chemo-brain’?

January, 2013

A new study points to pre-treatment reasons for declined cognitive function following chemotherapy, and suggests that anxiety may be the main driver.

The issue of ‘chemo-brain’ — cognitive impairment following chemotherapy — has been a controversial one. While it is now (I hope) accepted by most that it is, indeed, a real issue, there is still an ongoing debate over whether the main cause is really the chemotherapy. A new study adds to the debate.

The study involved 28 women who received adjuvant chemotherapy for breast cancer, 37 who received radiotherapy, and 32 age-matched healthy controls. Brain scans while doing a verbal working memory task were taken before treatment and one month after treatment.

Women who underwent chemotherapy performed less accurately on the working memory task both before treatment and one month after treatment. They also reported a significantly higher level of fatigue. Greater fatigue correlated with poorer test performance and more cognitive problems, across both patient groups and at both times (although the correlation was stronger after treatment).

Both patient groups showed reduced function in the left inferior frontal gyrus, before therapy, but those awaiting chemotherapy showed greater impairment than those in the radiotherapy group. Pre-treatment difficulty in recruiting this brain region in high demand situations was associated with greater fatigue after treatment.

In other words, reduced working memory function before treatment began predicted how tired people felt after treatment, and how much their cognitive performance suffered. All of which suggests it is not the treatment itself that is the main problem.

But the fact that reduced working memory function precedes the fatigue indicates it’s not the fatigue that’s the main problem either. The researchers suggest that the main driver is level of worry —worry interfered with the task; level of worry was related to fatigue. And worry, as we know, can reduce working memory capacity (because it uses up part of it).

All of which is to say that support for cancer patients aimed at combating stress and anxiety might do more for ‘chemo-brain’ than anything else. In this context, I note also that there have been suggestions that sleep problems have also been linked to chemo-brain — a not unrelated issue!

Reference: 

Cimprich, B. et al. 2012. Neurocognitive impact in adjuvant chemotherapy for breast cancer linked to fatigue: A Prospective functional MRI study. Presented at the 2012 CTRC-AACR San Antonio Breast Cancer Symposium, Dec. 4-8

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Feeling lonely linked to increased dementia risk

January, 2013

A study that attempts to separate the effects of social isolation from subjective feelings of loneliness concludes that feelings of loneliness have a greater effect on dementia risk.

There's quite a bit of evidence now that socializing — having frequent contact with others — helps protect against cognitive impairment in old age. We also know that depression is a risk factor for cognitive impairment and dementia. There have been hints that loneliness might also be a risk factor. But here’s the question: is it being alone, or feeling lonely, that is the danger?

A large Dutch study, following 2173 older adults for three years, suggests that it is the feeling of loneliness that is the main problem.

At the start of the study, some 46% of the participants were living alone, and some 50% were no longer or never married (presumably the discrepancy is because many older adults have a spouse in a care facility). Some 73% said they had no social support, while 20% reported feelings of loneliness.

Those who lived alone were significantly more likely to develop dementia over the three year study period (9.3% compared with 5.6% of those who lived with others). The unmarried were also significantly more likely to develop dementia (9.2% vs 5.3%).

On the other hand, among those without social support, 5.6% developed dementia compared with 11.4% with social support! This seems to contradict everything we know, not to mention the other results of the study, but the answer presumably lies in what is meant by ‘social support’. Social support was assessed by the question: Do you get help from family, neighbours or home support? It doesn’t ask the question of whether help would be there if they needed it. So this is not a question of social networks, but more one of how much you need help. This interpretation is supported by the finding that those receiving social support had more health problems.

So, although the researchers originally counted this question as part of the measure of social isolation, it is clearly a poor reflection of it. Effectively, then, that leaves cohabitation and marriage as the only indices of social isolation, which is obviously inadequate.

However, we still have the interesting question re loneliness. The study found that 13.4% of those who said they felt lonely developed dementia compared with 5.7% of those who didn’t feel this way. This is a greater difference than that found with the ‘socially isolated’ (as measured!). Moreover, once other risk factors, such as age, education, and other health factors, were accounted for, the association between living alone and dementia disappeared, while the association with feelings of loneliness remained.

Of course, this still doesn’t tell us what the association is! It may be that feelings of loneliness simply reflect cognitive changes that precede Alzheimer’s, but it may be that the feelings themselves are decreasing cognitive and social activity. It may also be that those who are prone to such feelings have personality traits that are in themselves risk factors for cognitive impairment.

I would like to see another large study using better metrics of social isolation, but, still, the study is interesting for its distinction between being alone and feeling lonely, and its suggestion that it is the subjective feeling that is more important.

This is not to say there is no value in having people around! For a start, as discussed, the measures of social isolation are clearly inadequate. Moreover, other people play an important role in helping with health issues, which in turn greatly impact cognitive decline.

Although there was a small effect of depression, the relationship between feeling lonely and dementia remained after this was accounted for, indicating that this is a separate factor (on the other hand feelings of loneliness were a risk factor for depression).

A decrease in cognitive score (MMSE) was also significantly greater for those experiencing feelings of loneliness, suggesting that this is also a factor in age-related cognitive decline.

The point is not so much that loneliness is more detrimental than being alone, but that loneliness in itself is a risk factor for cognitive decline and dementia. This suggests that we should develop a better understanding of loneliness, how to identify the vulnerable, and how to help them.

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Poverty affects brain development through attention needs

December, 2012

One reason for the association between poverty and poorer cognition in children may lie in how poverty affects attention, with poor children tending to use more cognitive resources in monitoring the environment.

There have been a number of studies in the past few years showing how poverty affects brain development and function. One of these showed specifically that children of high and low socioeconomic status showed differences in brain wave patterns associated with an auditory selective attention task. This was thought to indicate that the groups were using different mechanisms to carry out the task, with the lower SES children employing extra resources to attend to irrelevant information.

In a follow-up study, 28 young adolescents (12-14 years) from two schools in neighborhoods of different socioeconomic status answered questions about their emotional and motivational state at various points during the day, and provided saliva samples to enable monitoring of cortisol levels. At one point in the afternoon, they also had their brainwaves monitored while they carried out an auditory selective attention task (hearing different sounds played simultaneously into both ears, they were required to press a button as fast as possible when they heard one particular sound).

While performance on the task was the same for both groups, there were, once again, differences in the brain wave patterns. Higher SES children exhibited far larger theta waves in the frontal lobes in response to sounds they attended to than to compared to those they should have ignored, while lower SES children showed much larger theta waves to the unattended sounds than for the attended sounds.

While the lower SES children had higher cortisol levels throughout the school day, like the higher SES children, they showed little change around the task, suggesting neither group was particularly stressed by the task. Both groups also showed similar levels of boredom and motivation.

What the findings suggest is that lower SES children have to exert more cognitive control to avoid attending to irrelevant stimuli than higher SES children — perhaps because they live in more threatening environments.

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