Latest Research News
As we all know, people are living longer and obesity is at appalling levels. For both these (completely separate!) reasons, we expect to see growing rates of dementia. A new analysis using data from the long-running Framingham Heart Study offers some hope to individuals, however.
Looking at the rate of dementia during four distinct periods in the late 1970s, late 1980s, 1990s, and 2000s, using data from 5205 older adults (60+), the researchers found that there was a progressive decline in the incidence of dementia at a given age, with an average reduction of 20% per decade since the 1970s (22%, 38%, and 44% during the second, third, and fourth epochs, respectively).
There are two important things to note about this finding:
- the decline occurred only in people with a high school education and above
- the decline was more pronounced with dementia caused by vascular diseases, such as stroke.
The cumulative risk over five years, adjusted for age and gender, were:
- 3.6 per 100 persons during the first period (late 1970s and early 1980s)
- 2.8 per 100 persons during the second period (late 1980s and early 1990s)
- 2.2 per 100 persons during the third period (late 1990s and early 2000s)
- 2.0 per 100 persons during the fourth period (late 2000s and early 2010s).
Part of the reason for the decline is put down to the decrease in vascular risk factors other than obesity and diabetes, and better management of cardiovascular diseases and stroke. But this doesn't completely explain the decrease. I would speculate that other reasons might include:
- increased mental stimulation
- improvements in lifestyle factors such as diet and exercise
- better health care for infectious and inflammatory conditions.
The finding is not completely unexpected. Recent epidemiological studies in the U.S., Canada, England, the Netherlands, Sweden and Denmark have all suggested that “a 75- to 85-year-old has a lower risk of having Alzheimer’s today than 15 or 20 years ago.” Which actually cuts to the heart of the issue: individual risk of dementia has gone down (for those taking care of their brain and body), but because more and more people are living longer, the numbers of people with dementia are increasing.
(2016). Incidence of Dementia over Three Decades in the Framingham Heart Study.
New England Journal of Medicine. 374(6), 523 - 532.
A French study involving 36 healthy older adults (60-80), prescreened for amyloid deposits in the brain to exclude people who might have preclinical Alzheimer’s disease, has found a linear increase in gray matter volume in proportion to the number of years of education (7-20 years). Specifically, increases were seen in the right superior temporal gyrus, anterior cingulate gyrus, and left insular cortex, and metabolism also increased proportionately with years of education in the anterior cingulate gyrus, as did functional connectivity between anterior cingulate gyrus and the right hippocampus, left angular gyrus, right posterior cingulate, and left inferior frontal gyrus. This increased connectivity was associated with improved cognitive performance.
The conclusion is that both the structure of the brain and its function in old age are increased in proportion to the number of years of education.
(2013). Relationships between years of education and gray matter volume, metabolism and functional connectivity in healthy elders.
NeuroImage. 83, 450 - 457.
An Indian study involving 648 dementia patients, of whom 391 were bilingual, has found that, overall, bilingual patients developed dementia 4.5 years later than the monolingual ones. There was no additional advantage to speaking more than two languages.
The effect remained after factors such as education, sex, occupation, and urban vs. rural dwelling, had been accounted for. The finding is consistent with previous research, and is not only the largest study so far on the subject, but the first to show the effect also applies to illiterate people who had not attended school. Moreover, the effect was found in three different types of dementia: frontotemporal, vascular, and Alzheimer’s disease.
(2013). Bilingualism delays age at onset of dementia, independent of education and immigration status.
Neurology. 81(22), 1938 - 1944.
A large Danish study comparing two groups of nonagenarians born 10 years apart has found that not only were people born in 1915 nearly a third (32%) more likely to reach the age of 95 than those in the 1905 cohort, but members of the group born in 1915 performed significantly better on tests of cognitive ability and activities of daily living. Additionally, significantly more members of the later cohort scored maximally on the MMSE (23% vs 13% of the earlier cohort). All this even though the later cohort were on average two years older than the first cohort when tested (94-5 vs 92-3 years)
The difference doesn’t appear to be due to education (educational achievement was slightly higher in the 1915 cohort, but only in women, who had overall very low educational attainment in both groups). It’s suggested that factors such as better diet and general living conditions, improved health care, and greater intellectual stimulation have helped the younger cohort improve their cognitive functioning.
(2013). Physical and cognitive functioning of people older than 90 years: a comparison of two Danish cohorts born 10 years apart.
The Lancet. 382(9903), 1507 - 1513.
Here’s a different aspect to cognitive reserve. I have earlier reported on the first tranche of results from this study. Now new results, involving 246 older adults from the Rush Memory and Aging Project, have confirmed earlier findings that having a greater purpose in life may help protect against the brain damage wrought by Alzheimer’s disease.
Participants received an annual clinical evaluation for up to 10 years, which included detailed cognitive testing and neurological exams. They were also interviewed about their purpose in life, that is, the degree to which they derived meaning from life's experiences and were focused and intentional. After death (average age 88), their brains were examined for Alzheimer’s pathology.
Cognitive function, unsurprisingly, declined progressively with increased Alzheimer’s pathology (such as amyloid plaque and tau tangles). But ‘purpose in life’ modified this association, with higher levels of purposiveness reducing the effect of pathology on cognition. The effect was strongest for those with the greatest damage (especially tangles).
The analysis took into account depression, APOE gene status, and other relevant medical factors.
(2012). Effect of Purpose in Life on the Relation Between Alzheimer Disease Pathologic Changes on Cognitive Function in Advanced Age.
Archives of General Psychiatry. 69(5), 499 - 504.
A review of 15 randomized controlled trials in which people with mild to moderate dementia were offered mental stimulation has concluded that such stimulation does indeed help slow down cognitive decline.
In total, 718 people with mild to moderate dementia, of whom 407 received cognitive stimulation, were included in the meta-analysis. The studies included in the review were identified from a search of the Cochrane Dementia and Cognitive Improvement Group Specialized Register, and included all randomized controlled trials of cognitive stimulation for dementia which incorporated a measure of cognitive change.
Participants were generally treated in small groups and activities ranged from discussions and word games to music and baking. Treatment was compared to those seen without treatment, with "standard treatments" (such as medicine, day care or visits from community mental health workers), or with alternative activities such as watching TV and physical therapy.
There was a “clear, consistent benefit” on cognitive function for those receiving cognitive stimulation, and these benefits were still seen one to three months after the treatment. Benefits were also seen for social interaction, communication and quality of life and well-being.
While no evidence was found for improvements in the mood of participants, or their ability to care for themselves or function independently, or in problem behaviors, this is not to say that lengthier or more frequent interventions might not be beneficial in these areas (that’s purely my own suggestion).
In one study, family members were trained to deliver cognitive stimulation on a one-to-one basis, and the reviewers suggested that this was an approach deserving of further attention.
The reviewers did note that the quality of the studies was variable, with small sample sizes. It should also be noted that this review builds on an earlier review, involving a subset of these studies, in which the opposite conclusion was drawn — that is, at that time, there was insufficient evidence that such interventions helped people with dementia. There is no doubt that larger and lengthier trials are needed, but these new results are very promising.
(Submitted). Cognitive stimulation to improve cognitive functioning in people with dementia.
The Cochrane Library.
I’ve spoken before about the association between hearing loss in old age and dementia risk. Although we don’t currently understand that association, it may be that preventing hearing loss also helps prevent cognitive decline and dementia. I have previously reported on how music training in childhood can help older adults’ ability to hear speech in a noisy environment. A new study adds to this evidence.
The study looked at a specific aspect of understanding speech: auditory brainstem timing. Aging disrupts this timing, degrading the ability to precisely encode sound.
In this study, automatic brain responses to speech sounds were measured in 87 younger and older normal-hearing adults as they watched a captioned video. It was found that older adults who had begun musical training before age 9 and engaged consistently in musical activities through their lives (“musicians”) not only significantly outperformed older adults who had no more than three years of musical training (“non-musicians”), but encoded the sounds as quickly and accurately as the younger non-musicians.
The researchers qualify this finding by saying that it shows only that musical experience selectively affects the timing of sound elements that are important in distinguishing one consonant from another, not necessarily all sound elements. However, it seems probable that it extends more widely, and in any case the ability to understand speech is crucial to social interaction, which may well underlie at least part of the association between hearing loss and dementia.
The burning question for many will be whether the benefits of music training can be accrued later in life. We will have to wait for more research to answer that, but, as music training and enjoyment fit the definition of ‘mentally stimulating activities’, this certainly adds another reason to pursue such a course.
(Submitted). Musical experience offsets age-related delays in neural timing.
Neurobiology of Aging.
We know that physical exercise greatly helps you prevent cognitive decline with aging. We know that mental stimulation also helps you prevent age-related cognitive decline. So it was only a matter of time before someone came up with a way of combining the two. A new study found that older adults improved executive function more by participating in virtual reality-enhanced exercise ("exergames") that combine physical exercise with computer-simulated environments and interactive videogame features, compared to the same exercise without the enhancements.
The Cybercycle Study involved 79 older adults (aged 58-99) from independent living facilities with indoor access to a stationary exercise bike. Of the 79, 63 participants completed the three-month study, meaning that they achieved at least 25 rides during the three months.
Unfortunately, randomization was not as good as it should have been — although the researchers planned to randomize on an individual basis, various technical problems led them to randomize on a site basis (there were eight sites), with the result that the cybercycle group and the control bike group were significantly different in age and education. Although the researchers took this into account in the analysis, that is not the same as having groups that match in these all-important variables. However, at least the variables went in opposite directions: while the cybercycle group was significantly younger (average 75.7 vs 81.6 years), it was significantly less educated (average 12.6 vs 14.8 years).
Perhaps also partly off-setting the age advantage, the cybercycle group was in poorer shape than the control group (higher BMI, glucose levels, lower physical activity level, etc), although these differences weren’t statistically significant. IQ was also lower for the cybercycle group, if not significantly so (but note the high averages for both groups: 117.6 vs 120.6). One of the three tests of executive function, Color Trails, also showed a marked group difference, but the large variability in scores meant that this difference was not statistically significant.
Although participants were screened for disorders such as Alzheimer’s and Parkinson’s, and functional disability, many of both groups were assessed as having MCI — 16 of the 38 in the cybercycle group and 14 of the 41 in the control bike group.
Participants were given cognitive tests at enrolment, one month later (before the intervention began), and after the intervention ended. The stationary bikes were identical for both groups, except the experimental bike was equipped with a virtual reality display. Cybercycle participants experienced 3D tours and raced against a "ghost rider," an avatar based on their last best ride.
The hypothesis was that cybercycling would particularly benefit executive function, and this was borne out. Executive function (measured by the Color Trails, Stroop test, and Digits Backward) improved significantly more in the cybercycle condition, and indeed was the only cognitive task to do so (other cognitive tests included verbal fluency, verbal memory, visuospatial skill, motor function). Indeed, the control group, despite getting the same amount of exercise, got worse at the Digits Backward test, and failed to show any improvement on the Stroop test.
Moreover, significantly fewer cybercyclists progressed to MCI compared to the control group (three vs nine).
There were no differences in exercise quantity or quality between the two groups — which does argue against the idea that cyber-enhanced physical activity would be more motivating. However, the cybercycling group did tend to comment on their enjoyment of the exercise. While the enjoyment may not have translated into increased activity in this situation, it may well do so in a longer, less directed intervention — i.e. real life.
It should also be remembered that the intervention was relatively short, and that other cognitive tasks might take longer to show improvement than the more sensitive executive function. This is supported by the fact that levels of the brain growth factor BDNF, assessed in 30 participants, showed a significantly greater increase of BDNF in cybercyclists.
I should also emphasize that the level of physical exercise really wasn't that great, but nevertheless the size of the cybercycle's effect on executive function was greater than usually produced by aerobic exercise (a medium effect rather than a small one).
The idea that activities that combine physical and mental exercise are of greater cognitive benefit than the sum of benefits from each type of exercise on its own is not inconsistent with previous research, and in keeping with evidence from animal studies that physical exercise and mental stimulation help the brain via different mechanisms. Moreover, I have an idea that enjoyment (in itself, not as a proxy for motivation) may be a factor in the cognitive benefits derived from activities, whether physical or mental. Mere speculation, derived from two quite separate areas of research: the idea of “flow” / “being in the zone”, and the idea that humor has physiological benefits.
Of course, as discussed, this study has a number of methodological issues that limit its findings, but hopefully it will be the beginning of an interesting line of research.
(2012). Exergaming and Older Adult Cognition.
American Journal of Preventive Medicine. 42(2), 109 - 119.
Growing evidence points to greater education and mentally stimulating occupations and activities providing a cognitive reserve that enables people with developing Alzheimer's to function normally for longer. Cognitive reserve means that your brain can take more damage before it has noticeable effects. A 2006 review found that some 30% of older adults found to have Alzheimer’s when autopsied had shown no signs of it when alive.
There are two relevant concepts behind the protection some brains have: cognitive reserve (which I have mentioned on a number of occasions), and brain reserve, which is more structural. ‘Brain reserve’ encapsulates the idea that certain characteristics, such as a greater brain size, help protect the brain from damage. Longitudinal studies have provided evidence, for example, that a larger head size in childhood helps reduce the risk of developing Alzheimer’s.
While cognitive reserve has been most often associated with education, it has also been associated with occupation, bilingualism, and music. A new study provides physical evidence for how effective bilingualism is.
The Toronto study involved 40 patients with a diagnosis of probable Alzheimer’s, of whom half were bilingual (fluent in a second language, and consistent users of both languages throughout their lives). Bilingual and monolingual patients were matched on a test of cognitive function (the Behavioral Neurology Assessment). The two groups were similar in education levels, gender, and performance on the MMSE and the clock drawing test. The groups did differ significantly in occupational status, with the monolinguals having higher job status than the bilinguals.
Notwithstanding this similarity in cognitive performance, brain scans revealed that the bilingual group had substantially greater atrophy in the medial temporal lobe and the temporal lobe. The two groups did not differ in measures of central and frontal atrophy, however — these regions are not associated with Alzheimer’s.
In other words, bilingualism seems to specifically help protect those areas implicated in Alzheimers, and the bilinguals could take much greater damage to the brain before it impacted their cognitive performance. It is suggested that the act of constantly switching between languages, or suppressing one language in favor of other, may help train the brain to be more flexible when the need comes to compensate for damaged areas.
The findings are consistent with previous observational studies suggesting that bilingualism delays the onset of Alzheimer's symptoms by up to five years.
Valenzuela MJ and Sachdev P. 2006. Brain reserve and dementia: A systematic review. Psychological Medicine, 36(4): 441e454.
Adding to the growing evidence that social activity helps prevent age-related cognitive decline, a longitudinal study involving 1,138 older adults (mean age 80) has found that those who had the highest levels of social activity (top 10%) experienced only a quarter of the rate of cognitive decline experienced by the least socially active individuals (bottom 10%). The participants were followed for up to 12 years (mean of 5 years).
Social activity was measured using a questionnaire that asked participants whether, and how often, in the previous year they had engaged in activities that involve social interaction—for example, whether they went to restaurants, sporting events or the teletract (off-track betting) or played bingo; went on day trips or overnight trips; did volunteer work; visited relatives or friends; participated in groups such as the Knights of Columbus; or attended religious services.
Analysis adjusted for age, sex, education, race, social network size, depression, chronic conditions, disability, neuroticism, extraversion, cognitive activity, and physical activity.
There has been debate over whether the association between social activity and cognitive decline is because inactivity leads to impairment, or because impairment leads to inactivity. This study attempted to solve this riddle. Participants were evaluated yearly, and analysis indicates that the inactivity precedes decline, rather than the other way around. Of course, it’s still possible that there are factors common to both that affect social engagement before showing up in a cognitive test. But even in such a case, it seems likely that social inactivity increases the rate of cognitive decline.
(2011). Late-Life Social Activity and Cognitive Decline in Old Age.
Journal of the International Neuropsychological Society. FirstView, 1 - 8.
Clinical records of 211 patients diagnosed with probable Alzheimer's disease have revealed that those who have spoken two or more languages consistently over many years experienced a delay in the onset of their symptoms by as much as five years. It’s thought that lifelong bilingualism may contribute to cognitive reserve in the brain, enabling it to compensate for memory loss, confusion, and difficulties with problem-solving and planning.
Of the 211 patients of the Sam and Ida Ross Memory Clinic at Baycrest, 102 patients were classified as bilingual and 109 as monolingual. Bilingual patients had been diagnosed with Alzheimer's 4.3 years later than the monolingual patients on average, and had reported the onset of symptoms 5.1 years later. The groups were equivalent on measures of cognitive and occupational level, there was no apparent effect of immigration status, and there were no gender differences.
The findings confirm an earlier study from the same researchers, from the clinical records of 184 patients diagnosed with probable Alzheimer's and other forms of dementia.
(2010). Delaying the onset of Alzheimer disease.
Neurology. 75(19), 1726 - 1729.
A long-running study involving 1,157 healthy older adults (65+) who were scored on a 5-point scale according to how often they participated in mental activities such as listening to the radio, watching television, reading, playing games and going to a museum, has found that this score is correlated to the rate of cognitive decline in later years.
Some 5 ½ years after this initial evaluation, 395 (34%) were found to have mild cognitive impairment and 148 (13%) to have Alzheimer’s. Participants were then tested at 3-yearly intervals for the next 6 years. The rate of cognitive decline in those without cognitive impairment was reduced by 52% for each point on the cognitive activity scale, but for those with Alzheimer's disease, the average rate of decline per year increased by 42% for each point on the cognitive activity scale. Rate of decline was unrelated to earlier cognitive activity in those with MCI (presumably they were at the balance point).
This is not terribly surprising when you think of it, if you assume that the benefit of mental stimulation is to improve your brain function so that it can better cope with the damage happening to it. But eventually it reaches the point where it can no longer compensate for that damage because it is so overwhelming.
(2010). Cognitive activity and the cognitive morbidity of Alzheimer disease.
Neurology. 75(11), 990 - 996.
Confirming previous research, a study involving 270 Alzheimer’s patients has found that larger head size was associated with better performance on memory and thinking tests, even when there was an equivalent degree of brain damage. The findings are consistent with the theory of cognitive reserve. They also point to the importance of brain development early in life, since the brain reaches 93% of its final size at age six, and while partly determined by genes, brain growth is also influenced by nutrition, infections, and brain injuries.
(2010). Head circumference, atrophy, and cognition: Implications for brain reserve in Alzheimer disease.
Neurology. 75(2), 137 - 142.
Older news items (pre-2010) brought over from the old website
Mental & Social Stimulation
Cognitive activities may delay memory decline in dementia
A 5-year study involving 488 people age 75 to 85 found that, for the 101 people who developed dementia, the more stimulating activities they engaged in, the longer rapid memory loss was delayed. Participants reported at the beginning of the study how often they participated in six activities: reading, writing, doing crossword puzzles, playing board or card games, having group discussions, and playing music. For each activity, daily participation was rated at seven points, several days a week was rated at four points, and weekly participation was rated at one point. The average was seven points total for those who later developed dementia, meaning they took part in one of the six activities each day, on average. Ten people reported no activities, and 11 reported only one activity per week. Accelerated decline was delayed by more than two months for each activity, so for example a person participating in 11 activities per week put off rapid decline by 1.29 years compared to a person participating in only four activities per week.
Hall, C.B. et al. 2009. Cognitive activities delay onset of memory decline in persons who develop dementia. Neurology, 73, 356-361.
Some activities associated with less memory loss
A study involving 1321 randomly selected people aged 70 to 89, of whom 197 had mild cognitive impairment, has found that reading books, playing games, participating in computer activities or doing craft activities such as pottery or quilting was associated with a 30 to 50% decrease in the risk of developing memory loss compared to people who did not do those activities. Also, those who watched television for less than seven hours a day were 50% less likely to develop memory loss than people who watched for more than that. Other activities in later age were not significantly associated with a reduced chance of having MCI. Only two activities during middle age (50-65) were significantly associated with a reduced chance of later memory loss: participation in social activities and reading magazines.
Geda, Y.E. et al. 2009. Cognitive Activities Are Associated with Decreased Risk of Mild Cognitive Impairment: The Mayo Clinic Population-Based Study of Aging. Presented April 28 at the American Academy of Neurology's 61st Annual Meeting in Seattle.
No support for 'brain exercise' software for healthy elderly
A review of research on the impact of cognitive training on the healthy elderly (not those with mild cognitive impairment or Alzheimer's disease), has found no evidence that structured cognitive intervention programs affects the progression of dementia in the healthy elderly population. This is not to say that it doesn’t; the fault lies in the quality of the research. The researchers found only a very small number of studies that met their criteria. Those that did meet the criteria were mostly found to be limited in their methodologies or lacking in follow-up. They concluded that more random clinical trials in cognitive training need to be conducted with sufficient follow-up time that can actually measure changes in daily functioning.
Papp, K.V., Walsh, S.J. & Snyder, P.J. 2009. Immediate and delayed effects of cognitive interventions in healthy elderly: A review of current literature and future directions. Alzheimer's & Dementia, 5 (1), 50-60.
Mental and physical exercise delays dementia
A study using genetically engineered mice has found providing the mice with an enriched environment that enhanced their mental and physical stimulation improved performance on memory tests at an early stage of Huntington's disease, when memory impairment has begun. Specific molecular changes were also observed at the synapses in the hippocampus. Those without increased mental and physical activity showed decreased levels of specific proteins that are expressed at the synapse, but those exposed to stimulation didn’t. The finding offers hope for slowing the progression of the disease, as well as other dementias.
Nithianantharajah, J., Barkus, C., Murphy, M. & Hannan, A.J. Gene–environment interactions modulating cognitive function and molecular correlates of synaptic plasticity in Huntington’s disease transgenic mice. Neurobiology of Disease, Published online ahead of print 24 November 2007
Mental stimulation in old age reduces Alzheimer's risk
Post-mortem analysis of participants in a large, long-running study has provided more support for the idea that mental stimulation protects against Alzheimer’s. The study found a cognitively active person in old age was 2.6 times less likely to develop dementia and Alzheimer’s disease than a cognitively inactive person in old age. This association remained after controlling for past cognitive activity, lifetime socioeconomic status, and current social and physical activity. Frequent cognitive activity during old age was also associated with reduced risk of mild cognitive impairment.
Wilson, R.S., Scherr, P.A., Schneider, J.A., Tang, Y. & Bennett, D.A. 2007. The relation of cognitive activity to risk of developing Alzheimer’s disease. Neurology, published online ahead of print June 27
Enhanced environment restores memory in mice with neurodegeneration
Research involving genetically engineered mice has found that mice whose brains had lost a large number of neurons due to neurodegeneration regained long-term memories and the ability to learn after their surroundings were enriched with toys and other sensory stimuli. The same effect was also achieved through the use of a drug that encourages neuronal growth. The findings suggest not only new approaches to treatment for those with Alzheimer's or other neurodegenerative diseases, but also supports recent suggestions that "memory loss" may be an inaccurate description of the kinds of mental deficits associated with neurodegenerative diseases. The memories are still there; they are simply inaccessible.
Fischer, A., Sananbenesi, F., Wang, X., Dobbin, M. & Tsai, L-H. 2007. Recovery of learning and memory is associated with chromatin remodelling. Nature, 447, 178-182.
Learning slows physical progression of Alzheimer's disease
A mouse study has found that short but repeated learning sessions can slow the development of two brain lesions that are the hallmarks of Alzheimer's disease —beta amyloid plaques, and tau tangles. The researchers are now investigating whether more frequent and vigorous learning will have bigger and longer benefits.
Billings, L.M., Green, K.N., McGaugh, J.L. & LaFerla, F.M. 2007. Learning Decreases Aß*56 and Tau Pathology and Ameliorates Behavioral Decline in 3xTg-AD Mice. Journal of Neuroscience, 27, 751-761.
How mental and physical stimulation slows Alzheimer's
A new study reveals how mental and physical activity slows the cognitive decline seen in Alzheimer’s. In the study, genetically engineered mice were housed in either standard cages or ones with access to an enriched environment. After five months, the mice housed in the enriched environment had fewer Ab plaques, smaller plaque size, and reduced amyloid angiopathy compared to mice housed in standard cages. However there were no differences in the levels of soluble Ab peptide or the expression levels of its precursor protein (APP). Further investigation revealed differences suggesting that an enriched environment elicits protection via pathways that prevent Ab accumulation and enhance its clearance. The data confirm that an environment rich in mental and physical stimulation slows the progression of Alzheimer-like brain pathology.
Ambrée, O. et al. 2006. Reduction of amyloid angiopathy and A² plaque burden after enriched housing in TgCRND8 mice: involvement of multiple pathways. American Journal of Pathology, 169, 544-552.
Social networks protect against Alzheimer's
Previous studies have found that older people with more extensive social networks are less likely to suffer cognitive impairment. Now a new study provides evidence that social networks, like education, offers a 'protective reserve' capacity that spares them the clinical manifestations of Alzheimer's disease. 89 elderly people without known dementia participating in the Rush Memory and Aging Project underwent annual clinical evaluation and cognitive tests. To determine social network, participants were asked about the number of children they have and see monthly; about the number of relatives, excluding spouse and children, and friends to whom they feel close and with whom they felt at ease and could talk to about private matters and could call upon for help, and how many of these people they see monthly. Their social network was the number of these individuals seen at least once per month. Brain autopsy was done at the time of death. It was found that, as the size of the social network increased, the same amount of Alzheimer’s pathology in the brain (i.e., extent of plaques and tangles) had less effect on cognitive test scores. In other words, for persons without much pathology, social network size had little effect on cognition. However, as the amount of pathology increased, the apparent protective effect on cognition also increased.
Bennett, D.A., Schneider,J.A., Tang,Y., Arnold,S.E. & Wilson,R.S. 2006. The effect of social networks on the relation between Alzheimer's disease pathology and level of cognitive function in old people: a longitudinal cohort study. Lancet Neurology,5, 406-412.
Use your brain, halve your risk of dementia
In the first comprehensive review of the research into 'cognitive reserve', which looks at the role of education, occupational complexity and mentally stimulating activities in preventing cognitive decline, researchers concluded that complex mental activity across people’s lives almost halves the risk of dementia. All the studies also agreed that it was never too late to build cognitive reserve. The review covered 29,000 individuals across 22 studies.
Valenzuela, M.J. & Sachdev, P. 2006. Brain reserve and dementia: a systematic review. Psychological Medicine, In press
Enriched environment delays onset of Alzheimer's in mice
A study of genetically engineered mice has found that an enriched environment, with more opportunities to exercise, explore and interact with others, can dramatically reduce levels of beta-amyloid peptides, hallmarks of Alzheimer's disease. The mice also showed greater activity for several genes involved in memory and learning, the growth of new nerve cells, cell survival, and the growth of new blood vessels within the brain. As with humans, mice in the enriched environment showed varying levels of activity. The most active were found to have the least beta-amyloid. Researchers suggested the reason may simply be a matter of blood flow; physical and mental activity can stimulate growth of new blood vessels and keep existing vessels open and functional.
Lazarov, O.et al. 2005. Environmental Enrichment Reduces Aβ Levels and Amyloid Deposition in Transgenic Mice. Cell, 120(5), 701-713.
More evidence that mental exercise helps prevent or postpone dementia
Another study provides support for the idea that mentally demanding activities can help stave off dementia. The study involved 469 people aged 75 and older. Over the course of the study, dementia developed in 124 of the participants (Alzheimer's disease in 61, vascular dementia in 30, mixed dementia in 25, and other types of dementia in 8). Those who participated at least twice weekly in reading, playing games (chess, checkers, backgammon or cards), playing musical instruments, and dancing were significantly less likely to develop dementia. Although the evidence on crossword puzzles was not quite statistically significant, those who did crossword puzzles four days a week had a much lower risk of dementia than those who did one puzzle a week. Most physical activities, like group exercise or team games, had no significant impact. The only exception - ballroom dancing - possibly occurred because of the mental demands of remembering dance steps, responding to music and coordinating with a partner. Although the study was careful to include only those who showed no signs of dementia at the start, it cannot be ruled out that people in very early, pre-clinical stages of dementia may be less likely to participate in mentally demanding activities.
Verghese, J., Lipton, R.B., Hall, C.B., Kuslansky, G. & Katz, M.J. 2003. Low blood pressure and the risk of dementia in very old individuals. Neurology, 61, 1667-1672.
Mentally stimulating activities may reduce Alzheimer's risk
A study of 700 seniors over several years found that more frequent participation in cognitively stimulating activities, such as reading books, newspapers or magazines, engaging in crosswords or card games, was significantly associated with a reduced risk of Alzheimer’s disease (AD). Over the period, 111 participants developed AD. In comparing levels of cognitive activity with the risk of developing AD, it was found that a one-point increase in cognitive activity (on a 5-point scale) corresponded with a 33% reduction in the risk of AD. On average, compared with someone with the lowest activity level, the risk of disease was 47% lower for those whose frequency of activity was highest. General cognitive decline was also less among people who did more cognitively stimulating activities.
Wilson, R.S., de Leon, C.F.M., Barnes, L.L., Schneider, J.S., Bienias, J.L., Evans, D.A. & Bennett, D.A. 2002. Participation in Cognitively Stimulating Activities and Risk of Incident Alzheimer Disease. JAMA, 287,742-748.
Language skills in your 20s may predict risk of dementia decades later
Confirming earlier indications, autopsies of the brains of 38 Catholic nuns in the Nun Study has found that those who had no memory problems, whether or not their brains showed Alzheimer’s disease hallmarks, had higher early language scores compared to those who showed symptoms of Alzheimer’s or mild cognitive impairment. Early language was assessed in terms of the number of ideas produced every 10 words in the essays they wrote in their late teens or early 20s when they entered the Order. There was no effect in terms of grammatical complexity. Those with Alzheimer's disease hallmarks and no memory problems also had enlarged neurons in the CA1 region of the hippocampus.
Iacono, D. et al. 2009. The Nun Study. Clinically silent AD, neuronal hypertrophy, and linguistic skills in early life. Neurology, first published on July 8, 2009 as doi: doi:10.1212/WNL.0b013e3181b01077
Education may not affect how fast you will lose your memory
A study involving some 6,500 older Chicago residents being interviewed 3-yearly for up to 14 years (average 6.5 years), has found that while at the beginning of the study, those with more education had better memory and thinking skills than those with less education, education was not related to how rapidly these skills declined during the course of the study. The result suggests that the benefit of more education in reducing dementia risk results simply from the difference in level of cognitive function.
Wilson, R.S., Hebert, L.E., Scherr, P.A., Barnes, L.L., de Leon, C.F.M. & Evans, D.A. 2009. Educational attainment and cognitive decline in old age. Neurology, 72, 460-465.
Education protects against pre-Alzheimer's memory loss
Another study has come out supporting the view that people with more education and more mentally demanding occupations may have protection against the memory loss that precedes Alzheimer's disease, providing more evidence for the idea of cognitive reserve. The 14-month study followed 242 people with Alzheimer's disease, 72 people with mild cognitive impairment, and 144 people with no memory problems. During the study period, 21 of the people with MCI developed Alzheimer's. The metabolic changes in those with MCI who developed Alzheimer’s indicate the cognitive reserve is already in play in the pre-dementia stage.
Garibotto, V. et al. 2008. Education and occupation as proxies for reserve in aMCI converters and AD: FDG-PET evidence. Neurology, 71, 1342-1349.
Connection between Alzheimer's, education & head size
Earlier findings from the Nun Study have found associations with smaller head size and Alzheimer’s disease, and lower educational achievement and Alzheimer’s disease. The latest analysis clarifies these associations. It appears that a smaller head size is associated with lower educational achievement only in those who carry the “Alzheimer’s” APOE-4 gene, and those who later developed Alzheimer’s or Alzheimer’s pathology.
Mortimer, J,A., Snowdon, D.A. & Markesbery, W.R. 2008. Small Head Circumference is Associated With Less Education in Persons at Risk for Alzheimer Disease in Later Life. Alzheimer Disease & Associated Disorders, 22(3), 249-254.
Low childhood IQ linked to vascular dementia
A study of 173 people from the Scottish Mental Survey of 1932 who have developed dementia has found that, compared to matched controls, those with vascular dementia were 40% more likely to have low IQ scores when they were children than the people who did not develop dementia. This difference was not true for those with Alzheimer's disease. The findings suggest that low childhood IQ may act as a risk factor for vascular dementia through vascular risks rather than the "cognitive reserve" theory.
McGurn, B., Deary, I.J. & Starr, J.M. 2008. Childhood cognitive ability and risk of late-onset Alzheimer and vascular dementia. Neurology, first published on June 25, 2008 as doi: doi:10.1212/01.wnl.0000319692.20283.10
Effect of cognitive reserve on dementia confirmed
Another study has come out confirming that people with more years of education begin to lose their memory later than those with less education, but decline faster once it begins. Researchers note that since the participants were born between 1894 and 1908, their life experiences and education may not represent that of people entering the study age range today.
Hall, C.B., Derby, C., LeValley, A., Katz, M.J., Verghese, J. & Lipton, R.B. 2007. Education delays accelerated decline on a memory test in persons who develop dementia. Neurology, 69, 1657-1664.
Not finishing high school may lead to memory problems
A long-running Finnish study has found that compared with people with five or less years of education, those with six to eight years had a 40% lower risk of developing dementia and those with nine or more years had an 80% lower risk. Generally speaking, people with low education levels seemed to lead unhealthier lifestyles, but the association remained after lifestyle choices and characteristics such as income, occupation, physical activity and smoking had been taken into account.
Ngandu, T. et al. 2007. Education and dementia: What lies behind the association? Neurology, 69, 1442-1450.
Brain network associated with cognitive reserve identified
An imaging study involving young (18-30) and older (65-80) adults has identified a brain network within the frontal lobe that is associated with cognitive reserve, the process that allows individuals to resist cognitive decline due to aging or Alzheimer’s disease. Those with higher levels of cognitive reserve were able to activate this network in the brain while working on more difficult tasks, while participants with lower levels of reserve were not able to tap into this particular network. The network was found more often in younger participants, suggesting the network may degrade during aging.
Bilingualism has protective effect in delaying onset of dementia
An analysis of 184 people with dementia (132 were diagnosed with Alzheimer’s; the remaining 52 with other dementias) found that the mean age of onset of dementia symptoms in the 91 monolingual patients was 71.4 years, while for the 93 bilingual patients it was 75.5 years — a very significant difference. This difference remained even after considering the possible effect of cultural differences, immigration, formal education, employment and even gender as influencers in the results.
Bialystok, E., Craik, F.I.M. & Freedman, M. 2007. Bilingualism as a protection against the onset of symptoms of dementia. Neuropsychologia, 45 (2), 459-464.
Alzheimer's progresses more rapidly in highly educated people
A study of 312 New Yorkers aged 65 and older, who were diagnosed with Alzheimer's disease and monitored for over 5 years, found that overall mental agility declined faster for each additional year of education, particularly in the speed of thought processes and memory, and was independent of age, mental ability at diagnosis, or other factors likely to affect brain function, such as depression and vascular disease. It’s suggested this may reflect the greater ability of brains with a higher cognitive reserve to tolerate damage, meaning the damage is greater by the time it becomes observable in behavior. The finding confirms earlier findings from some epidemiological studies.
Scarmeas, N., Albert, S.M., Manly, J.J. & Stern, Y. 2006. Education and rates of cognitive decline in incident Alzheimer’s disease. Journal of Neurology Neurosurgery and Psychiatry, 77, 308-316.
Study links adolescent IQ/activity levels with risk of dementia
An analysis of high school records and yearbooks from the mid-1940s, and interviews with some 400 of these graduates, now in their 70s, and their family members, has found that those who were more active in high school and who had higher IQ scores, were less likely to have mild memory and thinking problems and dementia as older adults.
Fritsch, T., Smyth, K.A., McClendon, M.J., Ogrocki, P.K., Santillan, C., Larsen, J.D. & Strauss, M.E. 2005. Associations Between Dementia/Mild Cognitive Impairment and Cognitive Performance and Activity Levels in Youth. Journal of the American Geriatrics Society, 53(7), 1191.
Higher education or larger brain size may protect against dementia
More findings from the Nun Study, a longitudinal study of aging and Alzheimer's disease. It was found that nuns who completed 16 or more years of formal education or whose head circumference was in the upper two-thirds were four times less likely to be demented than those with both smaller head circumferences and lower education. (Head circumference is a good indicator of the volume or size of the brain.) It was not that these nuns were less likely to have the brain abnormalities characteristic of Alzheimer's disease, but that the larger brain size and more education provided extra reserve, allowing them to function normally in the presence of such brain abnormalities.
Mortimer, J.A., Snowdon, D.A. & Markesbery, W.R. 2003. Head Circumference, Education and Risk of Dementia: Findings from the Nun Study. Journal of Clinical and Experimental Neuropsychology, 25 (5), 671-679.
Effects of Alzheimer's disease may be influenced by education
New findings from the Religious Orders Study (ROS), a long-running prospective study of aging and cognitive function in Catholic clergy, provides evidence that formal education may provide a cognitive reserve or a "neuroplasticity" that can reduce the effect of AD brain abnormalities on cognitive function in later life. A post-mortem study of the brains of 130 participants who had all undergone cognitive testing some months before death, found that the relationship between cognitive performance and the number of amyloid plaques in the brain (characteristic of Alzheimer’s) changed with level of formal education. The more years education you had, the less effect the same number of plaques had on actual cognitive performance. For example, an 84-year-old woman in the most highly educated group (postgraduate work after college) might score 98.1 (on a scale where the average participant scores 100) in the absence of any plaques. The same age woman with the least education (some college attendance) would score 96.8. In the presence of about 18 plaques (more than the number required for a diagnosis of Alzheimer’s), the more highly educated woman's score would drop about two points, to 96.2, while the score of the woman with less formal education would drop more than 14 points, to 82. It’s worth noting that this considerable difference was observed in a population where even the least educated had some college attendance; presumably the difference would be even more marked in the general population.
Bennett, D.A., Wilson, R.S., Schneider, J.A., Evans, D.A., de Leon, M.C.F., Arnold, S.E., Barnes, L.L. & Bienias, J.L. 2003. Education modifies the relation of AD pathology to level of cognitive function in older persons. Neurology, 60, 1909-1915.
Early language ability may be linked to lower risk of Alzheimer's
The " Nun Study" has followed 678 Catholic nuns from 7 convents of the School Sisters of Notre Dame for 15 years. The stability and similarity of their lives makes them wonderful subjects, and the duration of the project means that it began when many were too young to manifest Alzheimer's or other diseases related to aging. Particularly helpful in this regard is that the sisters were required to write autobiographical essays when they took their vows in their 20's.
The research has shown that folic acid may help stave off Alzheimer's disease; that small, barely perceptible strokes may trigger some dementia; and, in an especially striking finding, that early language ability may be linked to lower risk of Alzheimer's because nuns who packed more ideas into the sentences of their early autobiographies were less likely to get Alzheimer's disease six decades later.
The latest report says nuns who expressed more positive emotions in their autobiographies lived significantly longer — in some cases 10 years longer — than those expressing fewer positive emotions.
The report was published in the Journal of Personality and Social Psychology.