The brain changes as we age, but it's not all bad! Experience changes our brains in a good way.
Data from the very large and long-running Cognitive Function and Ageing Study, a U.K. study involving 13,004 older adults (65+), from which 329 brains are now available for analysis, has found that cognitive lifestyle score (CLS) had no effect on Alzheimer’s pathology. Characteristics typical of Alzheimer’s, such as plaques, neurofibrillary tangles, and hippocampal atrophy, were similar in all CLS groups.
However, while cognitive lifestyle may have no effect on the development of Alzheimer's pathology, that is not to say it has no effect on the brain. In men, an active cognitive lifestyle was associated with less microvascular disease. In particular, the high CLS group showed an 80% relative reduction in deep white matter lesions. These associations remained after taking into account cardiovascular risk factors and APOE status.
This association was not found in women. However, women in the high CLS group tended to have greater brain weight.
In both genders, high CLS was associated with greater neuronal density and cortical thickness in Brodmann area 9 in the prefrontal lobe (but not, interestingly, in the hippocampus).
Cognitive lifestyle score is produced from years of education, occupational complexity coded according to social class and socioeconomic grouping, and social engagement based on frequency of contact with relatives, neighbors, and social events.
The findings provide more support for the ‘cognitive reserve’ theory, and shed some light on the mechanism, which appears to be rather different than we imagined. It may be that the changes in the prefrontal lobe (that we expected to see in the hippocampus) are a sign that greater cognitive activity helps you develop compensatory networks, rather than building up established ones. This would be consistent with research suggesting that older adults who maintain their cognitive fitness do so by developing new strategies that involve different regions, compensating for failing regions.
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.
Older news items (pre-2010) brought over from the old website
Experienced air traffic controllers work smarter, not harder, making up for normal mental aging
A study involving 36 air traffic controllers and 36 age- and education-matched non-controllers, with 18 older (average age 57) and 18 younger adults (average age 24) per group has found that although predictable age-related declines were observed in most of the standard tests of cognitive function, in the simulated air traffic control task, experience helped the older controllers to compensate to a significant degree for age-related declines, especially in their performance of the more complex simulations.
When emotions involved, older adults may perform memory tasks better than young adults
A study involving 72 young adults (20-30 years old) and 72 older adults (60-75) has found that regulating emotions – such as reducing negative emotions or inhibiting unwanted thoughts – is a resource-demanding process that disrupts the ability of young adults to simultaneously or subsequently perform tasks, but doesn’t affect older adults. In the study, most of the participants watched a two-minute video designed to induce disgust, while the rest watched a neutral two-minute clip. Participants then played a computer memory game. Before playing 2 further memory games, those who had watched the disgusting video were instructed either to change their negative reaction into positive feelings as quickly as possible or to maintain the intensity of their negative reaction, or given no instructions. Those young adults who had been told to turn their disgust into positive feelings, performed significantly worse on the subsequent memory tasks, but older adults were not affected. The feelings of disgust in themselves did not affect performance in either group. It’s speculated that older adults’ greater experience allows them to regulate their emotions without cognitive effort.
Aging brains allow negative memories to fade
Another study has found that older adults (average age 70) remember fewer negative images than younger adults (average age 24), and that this has to do with differences in brain activity. When shown negative images, the older participants had reduced interactions between the amygdala and the hippocampus, and increased interactions between the amygdala and the dorsolateral frontal cortex. It seems that the older participants were using thinking rather than feeling processes to store these emotional memories, sacrificing information for emotional stability. The findings are consistent with earlier research showing that healthy seniors are able to regulate emotion better than younger people.
While we take for granted that we’ll lose some cognitive ability as we get older, it’s also true that some very old people have brains just as quick as they always were. Now a post-mortem study of the brains of five of these "super aged" has revealed that these brains do indeed differ from normal elderly brains; specifically, by having much fewer tau tangles. Tau tangles are characteristic of Alzheimer's patients, but they are not restricted to them; until now, it’s been assumed that aging brings about the accumulation of these tangles. However, amyloid plaques, also characteristic of Alzheimer’s and found in smaller quantities in aging brains, were found in “normal” quantities, pointing to the tangles as the critical factor.
The findings were presented November 16, at the Society for Neuroscience annual meeting in Washington, D.C.
Confidence in memory performance helps older adults remember
A study involving 335 adults aged 21 to 83 found that control beliefs were related to memory performance on a word list recall task for middle-aged and older adults, but not for younger adults. This was partly because middle-aged and older adults who perceived greater control over cognitive functioning were more likely to use strategies to help their memory. In other words, the more you believe there are things you can do to remember information, the more likely you are to make an effort to remember.
Lachman, M.E. & Andreoletti, C. 2006. Strategy Use Mediates the Relationship Between Control Beliefs and Memory Performance for Middle-Aged and Older Adults. J Gerontol B Psychol Sci Soc Sci, 61, P88-P94.
'Sharp' older brains are not the same as younger brains
We know that many older adults still retain the mental sharpness of younger people, but studies comparing brain activity in older and younger adults suggests they perform differently. A rat study has now found the first solid evidence that still "sharp" older brains do indeed store and encode memories differently than younger brains. Comparison of those older rats who had retained their cognitive abilities with those who had not, also revealed that those with impaired cognition had lost the ability to modify the strength of the communications between synapses (synaptic communication is the means by which memories are encoded and stored). But the competent seniors also differed from the younger rats in the mechanism most used to bring about synaptic change.
An advantage of age
A study comparing the ability of young and older adults to indicate which direction a set of bars moved across a computer screen has found that although younger participants were faster when the bars were small or low in contrast, when the bars were large and high in contrast, the older people were faster. The results suggest that the ability of one neuron to inhibit another is reduced as we age (inhibition helps us find objects within clutter, but makes it hard to see the clutter itself). The loss of inhibition as we age has previously been seen in connection with cognition and speech studies, and is reflected in our greater inability to tune out distraction as we age. Now we see the same process in vision.
Effect of expectations on older adults’ memory performance
A study involving 193 participants and two experiments, each with a younger (17 – 35 years old) and older (57 – 82 years old) group of adults, has investigated how negative stereotypes about aging influences older adults' memory. Participants were exposed to stereotype-related words in the context of another task (scrambled sentence, word judgment) in order to prime positive and negative stereotypes of aging. Results show memory performance in older adults was lower when they were primed with negative stereotypes than when they were primed with positive stereotypes. Age differences in memory between young and older adults were significantly reduced following a positive stereotype prime, with young and older adults performing at almost identical levels in some situations.
Cognitive abilities are fairly stable and may be correlated with longevity
The Scottish Mental Survey assessed 87,498 eleven-year-olds in 1932, and another 70,805 in 1947. In a fascinating follow-up to this study, over 1000 of these students have been contacted and re-assessed, on the exact same tests. It was found that, first of all, the seniors did rather better than they had at age 11, and that differences in mental ability remained fairly stable with age. Mental ability at 11 was also found to be significantly correlated with survival — those who scored highly were more likely to have survived, with the exception that men with high ability were more likely to die in active service in World War II. People of lower ability had a greater tendency to lung and stomach cancer. More results from this landmark study are expected.
These preliminary findings were presented by Professor Ian Deary from the Department of Psychology, University of Edinburgh at a symposium on aging at the Australian National University.
Compensating strategies for aging memories
PET scans of the prefrontal cortex reveal that older adults who perform better on a simple memory task display more activity on both sides of the brain, compared to both older adults who do less well, and younger adults. Although this seems counter-intuitive – the older adults who perform less well show activity patterns more similar to that of younger adults, this supports recent theory that the brain may change tactics as it ages, and that older people whose brain is more flexible can compensate for some aspects of memory decline. Whether this flexibility is neurological, or something that can be taught, is still unknown.
Training can improve age-related memory decline in elderly
Older adults show two kinds of cognitive-processing deficits: under-recruitment, where appropriate areas of the brain are less likely to be utilized without specific instruction, and non-selective recruitment, where non-relevant regions of the brain are more likely to be used. A recent imaging study confirmed that older adults were less likely than younger ones to use the critical frontal regions when performing a memory task, and more likely to use cortical regions that are not as useful. However, when subjects were given specific strategy instructions, the older adults showed increased activity in the frontal regions, and their remembering improved. Even with this support however, older adults still showed a greater tendency to use brain regions that were not useful.
How aging brains compensate for cognitive decline
Evidence from a series of studies using functional positron emission tomography (PET) images suggests that one way older adults may compensate for age-related cognitive decline is by using additional regions of the brain to perform memory and information processing tasks. For example, simple short-term memory tasks involve the same brain regions in both older and younger adults, but older adults also activate a frontal cortex region that young adults use only when performing complex short-term memory tasks. This may explain why performance of older adults on complex memory tasks is usually significantly poorer than that of younger adults - the frontal cortex region that young adults will activate to help with complex short-term memory tasks is already preoccupied in older adults, and is less available to help when the task becomes more complex.
The research was conducted by University of Michigan researchers under the leadership of cognitive neuroscientist Patricia Reuter-Lorenz, and presented at the annual meeting of the American Psychological Association in San Francisco.