Aging - specific failures

A study comparing the language abilities of 22 healthy young individuals, 24 healthy older individuals and 22 people with MCI, has found that those with MCI:

  • were much less concise in conveying information
  • produced much longer sentences
  • had a hard time staying on point
  • were much more roundabout in getting their point across.

So, for example, when given an exercise in which they had to join up three words (e.g., “pen”, “ink” and “paper”), the healthy volunteers typically joined the three in a simple sentence, while the MCI group gave circuitous accounts such as going to the shop and buying a pen.

Additionally, when asked to repeat phrases read out by the interviewer, those with MCI had trouble when given phrases involving ambiguous pronouns (e.g., “Fred visited Bob after his graduation”), although they had no trouble with more complex sentences.

A caveat: if you're just one of those people who has always talked like this, don't panic! It's a matter of change and deterioration, not a stable personality trait.

https://www.theguardian.com/society/2017/feb/21/long-winded-speech-could-be-early-sign-of-alzheimers-says-study

Janet Sherman presented the findings at the annual meeting of the American Association for the Advancement of Science in Boston, in February 2017.

A study involving 66 healthy young adults (average age 24) has revealed that different individuals have distinct brain connectivity patterns that are associated with different ways of experiencing and remembering the past.

The participants completed an online questionnaire on how well they remember autobiographical events and facts, then had their brains scanned. Brain scans found that those with richly-detailed autobiographical memories had higher mediotemporal lobe connectivity to regions at the back of the brain involved in visual perception, whereas those tending to recall the past in a factual manner showed higher mediotemporal lobe connectivity to prefrontal regions involved in organization and reasoning.

The finding supports the idea that those with superior autobiographical memory have a greater ability or tendency to reinstate rich images and perceptual details, and that this appears to be a stable personality trait.

The finding also raises interesting questions about age-related cognitive decline. Many people first recognize cognitive decline in their increasing difficulty retrieving the details of events. But this may be something that is far more obvious and significant to people who are used to retrieving richly-detailed memories. Those who rely on a factual approach may be less susceptible.

http://www.eurekalert.org/pub_releases/2015-12/bcfg-wiy121015.php

Full text available at http://www.sciencedirect.com/science/article/pii/S0010945215003834

Training in a mental imagery technique has been found to help multiple sclerosis patients in two memory domains often affected by the disease: autobiographical memory and episodic future thinking.

The study involved 40 patients with relapsing-remitting MS, all of whom were receiving regular drug therapy and all of whom had significant brain atrophy. Participants were randomly assigned to one of three groups, one of which received the imagery training (17 participants), while the other two were controls — a control receiving a sham verbal training (10) and a control receiving no training (13). The six training sessions lasted two hours and occurred once or twice a week.

The training involved:

  • mental visualization exercises of increasing difficulty, using 10 items that the patient had to imagine and describe, looking at both static aspects (such as color and shape) and an action carried out with the item
  • guided construction exercises, using 5 scenarios involving several characters (so, for example, the patient might start with the general idea of a cook preparing a meal, and be guided through more complexities, such as the type of table, the ingredients being used, etc)
  • self-visualization exercises, in which the patient imagined themselves within a scenario.

Autobiographical memory and episodic future thinking were assessed, before and after, using an adapted version of the Autobiographical Interview, which involves subjects recalling events from earlier periods in their life, in response to specific cue words. The events are supposed to be unique, and the subjects are asked to recall as many details as possible.

Only those receiving the training showed a significant improvement in their scores.

Those who had the imagery training also reported an increase in general self-confidence, with higher levels of control and vitality.

Remembering past events and imagining future ones are crucial cognitive abilities, with more far-reaching impacts than may be immediately obvious. For example, episodic future thought is important for forming and carrying out intentions.

These are also areas which may be affected by age. A recent study, for example, found that older adults are less likely to spontaneously acquire items that would later allow a problem to be solved, and are also less likely to subsequently use these items to solve the problems. An earlier study found that older adults have more difficulty in imagining future experiences.

These results, then, that show us that people with deficits in specific memory domains can be helped by specific training, is not only of interest to those with MS, but also more generally.

http://www.eurekalert.org/pub_releases/2015-08/ip-mvi082515.php

A study involving 218 participants aged 18-88 has looked at the effects of age on the brain activity of participants viewing an edited version of a 1961 Hitchcock TV episode (given that participants viewed the movie while in a MRI machine, the 25 minute episode was condensed to 8 minutes).

While many studies have looked at how age changes brain function, the stimuli used have typically been quite simple. This thriller-type story provides more complex and naturalistic stimuli.

Younger adults' brains responded to the TV program in a very uniform way, while older adults showed much more idiosyncratic responses. The TV program (“Bang! You're dead”) has previously been shown to induce widespread synchronization of brain responses (such movies are, after all, designed to focus attention on specific people and objects; following along with the director is, in a manner of speaking, how we follow the plot). The synchronization seen here among younger adults may reflect the optimal response, attention focused on the most relevant stimulus. (There is much less synchronization when the stimuli are more everyday.)

The increasing asynchronization with age seen here has previously been linked to poorer comprehension and memory. In this study, there was a correlation between synchronization and measures of attentional control, such as fluid intelligence and reaction time variability. There was no correlation between synchronization and crystallized intelligence.

The greatest differences were seen in the brain regions controlling attention (the superior frontal lobe and the intraparietal sulcus) and language processing (the bilateral middle temporal gyrus and left inferior frontal gyrus).

The researchers accordingly suggested that the reason for the variability in brain patterns seen in older adults lies in their poorer attentional control — specifically, their top-down control (ability to focus) rather than bottom-up attentional capture. Attentional capture has previously been shown to be well preserved in old age.

Of course, it's not necessarily bad that a watcher doesn't rigidly follow the director's manipulation! The older adults may be showing more informed and cunning observation than the younger adults. However, previous studies have found that older adults watching a movie tend to vary more in where they draw an event boundary; those showing most variability in this regard were the least able to remember the sequence of events.

The current findings therefore support the idea that older adults may have increasing difficulty in understanding events — somthing which helps explain why some old people have increasing trouble following complex plots.

The findings also add to growing evidence that age affects functional connectivity (how well the brain works together).

It should be noted, however, that it is possible that there could also be cohort effects going on — that is, effects of education and life experience.

http://www.eurekalert.org/pub_releases/2015-08/uoc-ymt081415.php

A new study adds more support to the idea that the increasing difficulty in learning new information and skills that most of us experience as we age is not down to any difficulty in acquiring new information, but rests on the interference from all the old information.

Memory is about strengthening some connections and weakening others. A vital player in this process of synaptic plasticity is the NMDA receptor in the hippocampus. This glutamate receptor has two subunits (NR2A and NR2B), whose ratio changes as the brain develops. Children have higher ratios of NR2B, which lengthens the time neurons talk to each other, enabling them to make stronger connections, thus optimizing learning. After puberty, the ratio shifts, so there is more NR2A.

Of course, there are many other changes in the aging brain, so it’s been difficult to disentangle the effects of this changing ratio from other changes. This new study genetically modified mice to have more NR2A and less NR2B (reflecting the ratio typical of older humans), thus avoiding the other confounds.

To the researchers’ surprise, the mice were found to be still good at making strong connections (‘long-term potentiation’ - LTP), but instead had an impaired ability to weaken existing connections (‘long-term depression’ - LTD). This produces too much noise (bear in mind that each neuron averages 3,000 potential points of contact (i.e., synapses), and you will see the importance of turning down the noise!).

Interestingly, LTD responses were only abolished within a particular frequency range (3-5 Hz), and didn’t affect 1Hz-induced LTD (or 100Hz-induced LTP). Moreover, while the mice showed impaired long-term learning, their short-term memory was unaffected. The researchers suggest that these particular LTD responses are critical for ‘post-learning information sculpting’, which they suggest is a step (hitherto unknown) in the consolidation process. This step, they postulate, involves modifying the new information to fit in with existing networks of knowledge.

Previous work by these researchers has found that mice genetically modified to have an excess of NR2B became ‘super-learners’. Until now, the emphasis in learning and memory has always been on long-term potentiation, and the role (if any) of long-term depression has been much less clear. These results point to the importance of both these processes in sculpting learning and memory.

The findings also seem to fit in with the idea that a major cause of age-related cognitive decline is the failure to inhibit unwanted information, and confirm the importance of keeping your mind actively engaged and learning, because this ratio is also affected by experience.

Previous research has pointed to a typical decline in our sense of control as we get older. Maintaining a sense of control, however, appears to be a key factor in successful aging. Unsurprisingly, in view of the evidence that self-belief and metacognitive understanding are important for cognitive performance, a stronger sense of control is associated with better cognitive performance. (By metacognitive understanding I mean the knowledge that cognitive performance is malleable, not fixed, and strategies and training are effective in improving cognition.)

In an intriguing new study, 36 older adults (aged 61-87, average age 74) had their cognitive performance and their sense of control assessed every 12 hours for 60 days. Participants were asked questions about whether they felt in control of their lives and whether they felt able to achieve goals they set for themselves.

The reason I say this is intriguing is that it’s generally assumed that a person’s sense of control — how much they feel in control of their lives — is reasonably stable. While, as I said, it can change over the course of a lifetime, until recently we didn’t think that it could fluctuate significantly in the course of a single day — which is what this study found.

Moreover, those who normally reported having a low sense of control performed much better on inductive reasoning tests during periods when they reported feeling a higher sense of control. Similarly, those who normally reported feeling a high sense of control scored higher on memory tests when feeling more in control than usual.

Although we can’t be sure (since this wasn’t directly investigated), the analysis suggests that the improved cognitive functioning stems from the feeling of improved control, not vice versa.

The study builds on an earlier study that found weekly variability in older adults’ locus of control and competency beliefs.

Assessment was carried out in the form of a daily workbook, containing a number of measures, which participants completed twice daily. Each assessment took around 30-45 minutes to complete. The measures included three cognitive tests (14 alternate forms of each of these were used, to minimize test familiarity):

  • Letter series test: 30 items in which the next letter in a series had to be identified. [Inductive reasoning]
  • Number comparison: 48 items in which two number strings were presented beside each other, and participants had to identify where there was any mismatch. [Perceptual speed]
  • Rey Auditory Verbal Learning Task: participants have to study a list of 15 unrelated words for one minute, then on another page recall as many of the words as they could. [Memory]

Sense of control over the previous 12 hours was assessed by 8 questions, to which participants indicated their agreement/disagreement on a 6-point scale. Half the questions related to ‘locus of control’ and half to ‘perceived competence’.

While, unsurprisingly, compliance wasn’t perfect (it’s quite an arduous regime), participants completed on average 115 of 120 workbooks. Of the possible 4,320 results (36 x 120), only 166 were missing.

One of the things that often annoys me is the subsuming of all within-individual variability in cognitive scores into averages. Of course averages are vital, but so is variability, and this too often is glossed over. This study is, of course, all about variability, so I was very pleased to see people’s cognitive variability spelled out.

Most of the variance in locus of control was of course between people (86%), but 14% was within-individual. Similarly, the figures for perceived competence were 88% and 12%. (While locus of control and perceived competence are related, only 26% of the variability in within-person locus of control was associated with competence, meaning that they are largely independent.)

By comparison, within-individual variability was much greater for the cognitive measures: for the letter series (inductive reasoning), 32% was within-individual and 68% between-individual; for the number matching (perceptual speed), 21% was within-individual and 79% between-individual; for the memory test, an astounding 44% was within-individual and 56% between-individual.

Some of this within-individual variability in cognitive performance comes down to practice effects, which were significant for all cognitive measures. For the memory test, time of day was also significant, with performance being better in the morning. For the letter and number series tests, previous performance also had a small effect on perceived competence. For the number matching, increase in competence subsequent to increased performance was greatest for those with lower scores. However, lagged analyses indicated that beliefs preceded performance to a greater extent than performance preceding beliefs.

While it wasn’t an aspect of this study, it should also be noted that a person’s sense of control may well vary according to domain (e.g., cognition, social interaction, health) and context. In this regard, it’s interesting to note the present findings that sense of control affected inductive reasoning for low-control individuals, but memory for high-control individuals, suggesting that the cognitive domain also matters.

Now this small study was a preliminary one and there are several limitations that need to be tightened up in subsequent research, but I think it’s important for three reasons:

  • as a demonstration that cognitive performance is not a fixed attribute;
  • as a demonstration of the various factors that can affect older adults’ cognitive performance;
  • as a demonstration that your beliefs about yourself are a factor in your cognitive performance.

[2794] Neupert SD, Allaire JC. I think I can, I think I can: Examining the within-person coupling of control beliefs and cognition in older adults. Psychology and Aging. 2012 :No Pagination Specified - No Pagination Specified.

A telephone survey of around 17,000 older women (average age 74), which included questions about memory lapses plus standard cognitive tests, found that getting lost in familiar neighborhoods was highly associated with cognitive impairment that might indicate Alzheimer’s. Having trouble keeping up with a group conversation and difficulty following instructions were also significantly associated with cognitive impairment. But, as most of us will be relieved to know, forgetting things from one moment to the next was not associated with impairment!

Unsurprisingly, the more memory complaints a woman had, the more likely she was to score poorly on the cognitive test.

The 7 memory lapse questions covered:

  • whether they had recently experienced a change in their ability to remember things,
  • whether they had trouble remembering a short list of items (such as a shopping list),
  • whether they had trouble remembering recent events,
  • whether they had trouble remembering things from one second to the next,
  • whether they had difficulty following spoken or written instructions,
  • whether they had more trouble than usual following a group conversation or TV program due to memory problems,
  • whether they had trouble finding their way around familiar streets.

Because this survey was limited to telephone tests, we can’t draw any firm conclusions. But the findings may be helpful for doctors and others, to know which sort of memory complaints should be taken as a flag for further investigation.

A study comparing activity in the dorsolateral prefrontal cortex in young, middle-aged and aged macaque monkeys as they performed a spatial working memory task has found that while neurons of the young monkeys maintained a high rate of firing during the task, neurons in older animals showed slower firing rates. The decline began in middle age.

Neuron activity was recorded in a particular area of the dorsolateral prefrontal cortex that is most important for visuospatial working memory. Some neurons only fired when the cue was presented (28 CUE cells), but most were active during the delay period as well as the cue and response periods (273 DELAY neurons). Persistent firing during the delay period is of particular interest, as it is required to maintain information in working memory. Many DELAY neurons increased their activity when the preferred spatial location was being remembered.

While the activity of the CUE cells was unaffected by age, that of DELAY cells was significantly reduced. This was true both of spontaneous activity and task-related activity. Moreover, the reduction was greatest during the cue and delay periods for the preferred direction, meaning that the effect of age was to reduce the ability to distinguish preferred and non-preferred directions.

It appeared that the aging prefrontal cortex was accumulating excessive levels of an important signaling molecule called cAMP. When cAMP was inhibited or cAMP-sensitive ion channels were blocked, firing rates rose to more youthful levels. On the other hand, when cAMP was stimulated, aged neurons reduced their activity even more.

The findings are consistent with rat research that has found two of the agents used — guanfacine and Rp-cAMPS — can improve working memory in aged rats. Guanfacine is a medication that is already approved for treating hypertension in adults and prefrontal deficits in children. A clinical trial testing guanfacine's ability to improve working memory and executive functions in elderly subjects who do not have dementia is now taking place.

A standard test of how we perceive local vs global features of visual objects uses Navon figures — large letters made up of smaller ones (see below for an example). As in the Stroop test when colors and color words disagree (RED), the viewer can focus either on the large letter or the smaller ones. When the viewer is faster at seeing the larger letter, they are said to be showing global precedence; when they’re faster at seeing the component letters, they are said to be showing local precedence. Typically, the greater the number of component letters, the easier it is to see the larger letter. This is consistent with the Gestalt principles of proximity and continuity — elements that are close together and form smooth lines will tend to be perceptually grouped together and seen as a unit (the greater the number of component letters, the closer they will be, and the smoother the line).

In previous research, older adults have often demonstrated local precedence rather than global, although the results have been inconsistent. One earlier study found that older adults performed poorly when asked to report in which direction (horizontal or vertical) dots formed smooth lines, suggesting an age-related decline in perceptual grouping. The present study therefore investigated whether this decline was behind the decrease in global precedence.

In the study 20 young men (average age 22) and 20 older men (average age 57) were shown Navon figures and asked whether the target letter formed the large letter or the smaller letters (e.g., “Is the big or the small letter an E?”). The number of component letters was systematically varied across five quantities. Under such circumstances it is expected that at a certain level of letter density everyone will switch to global precedence, but if a person is impaired at perceptual grouping, this will occur at a higher level of density.

The young men were, unsurprisingly, markedly faster than the older men in their responses. They were also significantly faster at responding when the target was the global letter, compared to when it was the local letter (i.e. they showed global precedence). The older adults, on the other hand, had equal reaction times to global and local targets. Moreover, they showed no improvement as the letter-density increased (unlike the young men).

It is noteworthy that the older men, while they failed to show global precedence, also failed to show local precedence (remember that results are based on group averages; this suggests that the group was evenly balanced between those showing local precedence and those showing global precedence). Interestingly, previous research has suggested that women are more likely to show local precedence.

The link between perceptual grouping and global precedence is further supported by individual differences — older men who were insensitive to changes in letter-density were almost exclusively the ones that showed persistent local precedence. Indeed, increases in letter-density were sometimes counter-productive for these men, leading to even slower reaction times for global targets. This may be the result of greater distractor interference, to which older adults are more vulnerable, and to which this sub-group of older men may have been especially susceptible.

Example of a Navon figure:

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As we get older, when we suffer memory problems, we often laughingly talk about our brain being ‘full up’, with no room for more information. A new study suggests that in some sense (but not the direct one!) that’s true.

To make new memories, we need to recognize that they are new memories. That means we need to be able to distinguish between events, or objects, or people. We need to distinguish between them and representations already in our database.

We are all familiar with the experience of wondering if we’ve done something. Is it that we remember ourselves doing it today, or are we remembering a previous occasion? We go looking for the car in the wrong place because the memory of an earlier occasion has taken precedence over today’s event. As we age, we do get much more of this interference from older memories.

In a new study, the brains of 40 college students and older adults (60-80) were scanned while they viewed pictures of everyday objects and classified them as either "indoor" or "outdoor." Some of the pictures were similar but not identical, and others were very different. It was found that while the hippocampus of young students treated all the similar pictures as new, the hippocampus of older adults had more difficulty with this, requiring much more distinctiveness for a picture to be classified as new.

Later, the participants were presented with completely new pictures to classify, and then, only a few minutes later, shown another set of pictures and asked whether each item was "old," "new" or "similar." Older adults tended to have fewer 'similar' responses and more 'old' responses instead, indicating that they could not distinguish between similar items.

The inability to recognize information as "similar" to something seen recently is associated with “representational rigidity” in two areas of the hippocampus: the dentate gyrus and CA3 region. The brain scans from this study confirm this, and find that this rigidity is associated with changes in the dendrites of neurons in the dentate/CA3 areas, and impaired integrity of the perforant pathway — the main input path into the hippocampus, from the entorhinal cortex. The more degraded the pathway, the less likely the hippocampus is to store similar memories as distinct from old memories.

Apart from helping us understand the mechanisms of age-related cognitive decline, the findings also have implications for the treatment of Alzheimer’s. The hippocampus is one of the first brain regions to be affected by the disease. The researchers plan to conduct clinical trials in early Alzheimer's disease patients to investigate the effect of a drug on hippocampal function and pathway integrity.

What makes one person so much better than another in picking up a new motor skill, like playing the piano or driving or typing? Brain imaging research has now revealed that one of the reasons appears to lie in the production of a brain chemical called GABA, which inhibits neurons from responding.

The responsiveness of some brains to a procedure that decreases GABA levels (tDCS) correlated both with greater brain activity in the motor cortex and with faster learning of a sequence of finger movements. Additionally, those with higher GABA concentrations at the beginning tended to have slower reaction times and less brain activation during learning.

It’s simplistic to say that low GABA is good, however! GABA is a vital chemical. Interestingly, though, low GABA has been associated with stress — and of course, stress is associated with faster reaction times and relaxation with slower ones. The point is, we need it in just the right levels, and what’s ‘right’ depends on context. Which brings us back to ‘responsiveness’ — more important than actual level, is the ability of your brain to alter how much GABA it produces, in particular places, at particular times.

However, baseline levels are important, especially where something has gone wrong. GABA levels can change after brain injury, and also may decline with age. The findings support the idea that treatments designed to influence GABA levels might improve learning. Indeed, tDCS is already in use as a tool for motor rehabilitation in stroke patients — now we have an idea why it works.

Comparison of young adults (mean age 24.5) and older adults (mean age 69.1) in a visual memory test involving multitasking has pinpointed the greater problems older adults have with multitasking. The study involved participants viewing a natural scene and maintaining it in mind for 14.4 seconds. In the middle of the maintenance period, an image of a face popped up and participants were asked to determine its sex and age. They were then asked to recall the original scene.

As expected, older people had more difficulty with this. Brain scans revealed that, for both groups, the interruption caused their brains to disengage from the network maintaining the memory and reallocate resources to processing the face. But the younger adults had no trouble disengaging from that task as soon as it was completed and re-establishing connection with the memory maintenance network, while the older adults failed both to disengage from the interruption and to reestablish the network associated with the disrupted memory.

This finding adds to the evidence that an important (perhaps the most important) reason for cognitive decline in older adults is a growing inability to inhibit processing, and extends the processes to which that applies.

A study involving 125 younger (average age 19) and older (average age 69) adults has revealed that while younger adults showed better explicit learning, older adults were better at implicit learning. Implicit memory is our unconscious memory, which influences behavior without our awareness.

In the study, participants pressed buttons in response to the colors of words and random letter strings — only the colors were relevant, not the words themselves. They then completed word fragments. In one condition, they were told to use words from the earlier color task to complete the fragments (a test of explicit memory); in the other, this task wasn’t mentioned (a test of implicit memory).

Older adults showed better implicit than explicit memory and better implicit memory than the younger, while the reverse was true for the younger adults. However, on a further test which required younger participants to engage in a number task simultaneously with the color task, younger adults behaved like older ones.

The findings indicate that shallower and less focused processing goes on during multitasking, and (but not inevitably!) with age. The fact that younger adults behaved like older ones when distracted points to the problem, for which we now have quite a body of evidence: with age, we tend to become more easily distracted.

We have thought of memory problems principally in terms of forgetting, but using a new experimental method with amnesic animals has revealed that confusion between memories, rather than loss of memory, may be more important.

While previous research has found that amnesic animals couldn't distinguish between a new and an old object, the new method allows responses to new and old objects to be measured separately. Control animals, shown an object and then shown either the same or another object an hour later, spent more time (as expected) with the new object. However, amnesic animals spent less time with the new object, indicating they had some (false) memory of it.

The researchers concluded that the memory problems were the result of the brain's inability to register complete memories of the objects, and that the remaining, less detailed memories were more easily confused. In other words, it’s about poor encoding, not poor retrieval.

Excitingly, when the amnesic animals were put in a dark, quiet space before the memory test, they performed perfectly on the test.

The finding not only points to a new approach for helping those with memory problems (for example, emphasizing differentiating details), but also demonstrates how detrimental interference from other things can be when we are trying to remember something — an issue of particular relevance in modern information-rich environments. The extent to which these findings apply to other memory problems, such as dementia, remains to be seen.

An imaging study reveals why older adults are better at remembering positive events. The study, involving young adults (ages 19-31) and older adults (ages 61-80) being shown a series of photographs with positive and negative themes, found that while there was no difference in brain activity patterns between the age groups for the negative photos, there were age differences for the positive photos. In older adult brains, but not the younger, two emotion-processing regions (the ventromedial prefrontal cortex and the amygdala) strongly influenced the memory-encoding hippocampus.

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

Failing recall not an inevitable consequence of aging

New research suggests age-related cognitive decay may not be inevitable. Tests of 36 adults with an average age of 75 years found that about one out of four had managed to avoid memory decline. Those adults who still had high frontal lobe function had memory skills “every bit as sharp as a group of college students in their early 20s." (But note that most of those older adults who participated were highly educated – some were retired academics). The study also found that this frontal lobe decline so common in older adults is associated with an increased susceptibility to false memories – hence the difficulty often experienced by older people in recalling whether they took a scheduled dose of medication.

The research was presented on August 8 at the American Psychological Association meeting in Toronto.

http://www.eurekalert.org/pub_releases/2003-08/wuis-fmf080703.php

Older adults better at forgetting negative images

It seems that this general tendency, to remember the good, and let the bad fade, gets stronger as we age. Following recent research suggesting that older people tend to regulate their emotions more effectively than younger people, by maintaining positive feelings and lowering negative feelings, researchers examined age differences in recall of positive, negative and neutral images of people, animals, nature scenes and inanimate objects. The first study tested 144 participants aged 18-29, 41-53 and 65-80. Older adults recalled fewer negative images relative to positive and neutral images. For the older adults, recognition memory also decreased for negative pictures. As a result, the younger adults remembered the negative pictures better. Preliminary brain research suggests that in older adults, the amygdala is activated equally to positive and negative images, whereas in younger adults, it is activated more to negative images. This suggests that older adults encode less information about negative images, which in turn would diminish recall.

Charles, S.T., Mather, M. & Carstensen, L.L. 2003. Aging and Emotional Memory: The Forgettable Nature of Negative Images for Older Adults. Journal of Experimental Psychology: General, 132(2), 310-24.