Aging - rate of cognitive decline

White matter appears to decrease faster than grey matter, but doesn't begin to decline until the forties. Presumably this relates to the decline in processing speed that is the most evident characteristic of age-related decline.

Grey matter, on the other hand, declines at a fairly constant rate from adolescence, mirroring a decline in processing ability that seems to start as early as the twenties.

Cognitive decline seems to be faster in women than men. This presumably reflects apparent gender differences in brain activity. For example, while women seem to have a greater density of brain cells in the prefrontal cortex, they also show a steeper rate of decline so that, in old age, the density is similar between the genders.

There is some evidence that individual differences in processing speed and memory are more important than age, and that personality attributes affect the rate of cognitive decline and brain atrophy.

Some gene variants, including the so-called Alzheimer’s gene, are associated with a faster rate of decline, or an earlier start. These may be triggered by activity in early adulthood. Head size in adulthood also seems to affect rate of decline. Head size in adulthood reflects not only head size at birth, but growth in the early years — pointing to the importance of providing both proper nourishment and intellectual stimulation in these early years.

A review of 34 longitudinal studies, involving 71,244 older adults, has concluded that depression is associated with greater cognitive decline.

The study included people who presented with symptoms of depression as well as those that were diagnosed as clinically depressed, but excluded any who were diagnosed with dementia at the start of study.

Previous research has found that depression is associated with an increased dementia risk.

The researchers recommend that preventative measures such as exercising, practicing mindfulness, and undertaking recommended therapeutic treatments, such as Cognitive Behaviour Therapy, might help protect cognitive health.

While the review included some studies into anxiety, the numbers were insufficient to draw a conclusion.

https://www.eurekalert.org/pub_releases/2018-05/uos-dsu052318.php

Data from 23,572 Americans from the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study has revealed that those who survived a stroke went on to have significantly faster rates of cognitive decline as they aged.

Participants, who were aged 45 years or older, had no history of cognitive impairment at the beginning of the population-based study. Over the next five to seven years, 515 of them (2%) had a stroke.

Stroke was associated with an acute decline in global cognition, new learning, and verbal memory. Those who had a stroke showed faster declines in global cognition and executive function (but not new learning nor verbal memory) over the next years.

Global cognition was assessed using the Six-Item Screener [SIS]; new learning by the Consortium to Establish a Registry for Alzheimer Disease Word-List Learning; verbal memory by the Word-List Delayed Recall; executive function by the Animal Fluency Test.

The findings suggest a need for better long-term follow-up care for stroke survivors, including therapy to retain or even regain cognitive ability.

http://www.eurekalert.org/pub_releases/2015-07/uomh-mt070715.php

A study involving 382 older adults (average age 75) followed for around five years, has found that those who don’t get enough vitamin D may experience cognitive decline at a much faster rate than people who have adequate vitamin D.

Participants included 17.5% with dementia at the beginning of the study, 32.7% with MCI, and 49.5% cognitively healthy.

Those with dementia had lower levels of vitamin D than the other two groups.

While some people with low vitamin D didn’t show any cognitive decline and some with adequate vitamin D declined quickly, people with low vitamin D on average declined two to three times as fast as those with adequate vitamin D, in two crucial cognitive domains: episodic memory and executive function. Semantic memory and visuospatial ability were not significantly affected.

Factors such as age, gender, education, BMI, season of blood draw, vascular risk, and presence of the 'Alzheimer's gene', ApoE4, were controlled for.

Unlike previous studies of vitamin D and dementia, the participants were racially and ethnically diverse and included whites (41%), African Americans (30%), and Hispanics (25%). Nearly two-thirds (61%) had low vitamin D levels in their blood, including 54% of the whites and 70% of the African-Americans and Hispanics.

Vitamin D is primarily obtained through sun exposure. Accordingly, people with darker skin are more likely to have low levels of vitamin D because melanin blocks ultra-violet rays.

It remains to be seen whether Vitamin D supplements could slow cognitive decline.

http://www.futurity.org/vitamin-d-cognitive-decline-1003932/

 

The issue of the effect of menopause on women’s cognition, and whether hormone therapy helps older women fight cognitive decline and dementia, has been a murky one. Increasing evidence suggests that the timing and type of therapy is critical. A new study makes clear that we also need to distinguish between women who experience early surgical menopause and those who experience natural menopause.

The study involved 1,837 women (aged 53-100), of whom 33% had undergone surgical menopause (removal of both ovaries before natural menopause). For these women, earlier age of the procedure was associated with a faster decline in semantic and episodic memory, as well as overall cognition. The results stayed the same after factors such as age, education and smoking were taken into consideration.

There was also a significant association between age at surgical menopause and the plaques characteristic of Alzheimer's disease. However, there was no significant association with Alzheimer’s itself.

On the positive side, hormone replacement therapy was found to help protect those who had surgical menopause, with duration of therapy linked to a significantly slower decline in overall cognition.

Also positively, age at natural menopause was not found to be associated with rate of cognitive decline.

Bove, R. et al. 2013. Early Surgical Menopause Is Associated with a Spectrum of Cognitive Decline. To be presented at the American Academy of Neurology's 65th Annual Meeting in San Diego, March 21, 2013.

I’ve written before about the gathering evidence that sensory impairment, visual impairment and hearing loss in particular, is a risk factor for age-related cognitive decline and dementia. Now a large long-running study provides more support for the association between hearing loss and age-related cognitive decline.

The study involved 1,984 older adults (aged 75-84) whose hearing and cognition was tested at the start of the study, with cognitive performance again assessed three, five, and six years later.

Those with hearing loss showed significantly faster cognitive decline than those with normal hearing — some 30-40% faster (41% on the MMSE; 32% on the Digit Symbol Substitution Test), with rate directly related to the amount of hearing loss.

On average, older adults with hearing loss developed significant cognitive impairment 3.2 years sooner than those with normal hearing — a very significant difference indeed.

It has been suggested that increasing social isolation and loneliness may underlie some, if not all, of this association. It may also be that difficulties in hearing force the brain to devote too much of its resources to processing sound, leaving less for cognition. A third possibility is that some common factor underlies both hearing loss and cognitive decline — however, the obvious risk factors, such as high blood pressure, diabetes and stroke, were taken account of in the analysis.

The findings emphasize the importance of getting help for hearing difficulties, rather than regarding them as ‘natural’ in old age.

[3293] Lin, F. R., Yaffe K., Xia J., & et al
(2013).  Hearing loss and cognitive decline in older adults.
JAMA Internal Medicine. 1 - 7.

I’ve reported before on the growing evidence that metabolic syndrome in middle and old age is linked to greater risk of cognitive impairment in old age and faster decline. A new study shows at least part of the reason.

The study involved 71 middle-aged people recruited from the Wisconsin Registry for Alzheimer's Prevention (WRAP), of whom 29 met the criteria for metabolic syndrome (multiple cardiovascular and diabetes risk factors including abdominal obesity, high blood pressure, high blood sugar and high cholesterol).

Those with metabolic syndrome averaged 15% less blood flow to the brain than those without the syndrome.

One tried and true method of increasing blood flow to the brain is of course through exercise.

The study was presented at the Alzheimer's Association International Conference in Vancouver, Canada by Barbara Bendlin.

The latest finding from the large, long-running Health, Aging, and Body Composition (Health ABC) Study adds to the evidence that preventing or controlling diabetes helps prevent age-related cognitive decline.

The study involves 3,069 older adults (70+), of whom 717 (23%) had diabetes at the beginning of the study in 1997. Over the course of the study, a further 159 developed diabetes. Those with diabetes at the beginning had lower cognitive scores, and showed faster decline. Those who developed diabetes showed a rate of decline that was between that faster rate and the slower rate of those who never developed diabetes.

Among those with diabetes, those who had higher levels of a blood marker called glycosylated hemoglobin had greater cognitive impairment. Higher levels of this blood marker reflect poorer control of blood sugar.

In other words, both duration and severity of diabetes are important factors in determining rate of cognitive decline in old age.

Data from the Nurses' Health Study Cognitive Cohort, involving 19,409 older women (70-81), has found that higher levels of long-term exposure to air pollution were associated with faster rates of cognitive decline over a four-year period.

For each 10 micrograms per cubic meter of air increase in pollutants, cognitive decline was comparable to two years of age-related decline.

Pollution exposure was estimated from geography. Cognition was tested by three telephone interviews, administered at roughly two-year intervals.

Air pollution linked to heart attack risk

Given the association between cardiovascular risk factors and cognitive decline (“What’s good for the heart is good for the brain”), it’s worth noting that a review of 34 studies has found that every main air pollutant, with the exception of ozone, was significantly associated with greater risk of heart attack. For most of the pollutants, an increase in concentration of 10 micrograms per cubic meter of air – barely noticeable – was associated with a 1-3% increase in the chance of having a heart attack in the next week.

The size of the risk is small compared with traditional risk factors such as smoking status or hypertension or diabetes, but is something that those with other cardiovascular risk factors may want to consider. There’s also growing evidence that high levels of pollution increase stroke risk.

For more about the effects of air pollution on cognition

A ten-year study following 12,412 middle-aged and older adults (50+) has found that those who died after stroke had more severe memory loss in the years before stroke compared to those who survived stroke and those who didn't have a stroke.

Participants were tested every two years, using a standard word-recall list to measure memory loss (or caregiver assessment for those whose memory loss was too severe). During the decade of the study, 1,027 participants (8.3%) survived a stroke, 499 (4%) died after stroke, and 10,886 (87.7%) remained stroke-free over the study period.

Before having a stroke, those who later survived a stroke had worse average memory than similar individuals who never had a stroke, however their rate of memory decline was similar (0.034 and 0.028 points per year, respectively). Those who later died after a stroke, on the other hand, showed significantly faster memory decline (0.118 points per year).

Whether this is because those who die after stroke have a more compromised brain prior to the stroke, or because greater memory impairment makes people more vulnerable in the wake of a stroke, cannot be told from this data (and indeed, both factors may be involved).

Among survivors, stroke had a significant effect on memory decline, with memory scores dropping an average of 0.157 points at the time of the stroke — an amount equivalent to around 5.6 years of memory decline in similarly-aged stroke-free adults. However, in subsequent years, decline was only a little greater than it had been prior to the stroke (0.038 points per year).

(You can see a nice graph of these points here.)

Wang, Q., Capistrant, B.D., Ehntholt, A. & Glymour, M.M. 2012. Abstract 31: Rate of Change in Memory Functioning Before and After Stroke Onset. Presented at the American Stroke Association's International Stroke Conference 2012. http://stroke.ahajournals.org/cgi/content/meeting_abstract/43/2_MeetingAbstracts/A31?sid=960f2015-06d1-478f-8c03-c00994d35f2c

Comparison of 99 chimpanzee brains ranging from 10-51 years of age with 87 human brains ranging from 22-88 years of age has revealed that, unlike the humans, chimpanzee brains showed no sign of shrinkage with age. But the answer may be simple: we live much longer. In the wild, chimps rarely live past 45, and although human brains start shrinking as early as 25 (as soon as they reach maturity, basically!), it doesn’t become significant until around 50.

The answer suggests one reason why humans are uniquely vulnerable to Alzheimer’s disease — it’s all down to our combination of large brain and long life. There are other animals that experience some cognitive impairment and brain atrophy as they age, but nothing as extreme as that found in humans (a 10-15% decline in volume over the life-span). (Elephants and whales have the same two attributes as humans — large brains and long lives — but we lack information on how their brains change with age.)

The problem may lie in the fact that our brains use so much more energy than chimps’ (being more than three times larger than theirs) and thus produce a great deal more damaging oxidation. Over a longer life-span, this accumulates until it significantly damages the brain.

If that’s true, it reinforces the value of a diet high in antioxidants.

[2500] Sherwood, C. C., Gordon A. D., Allen J. S., Phillips K. A., Erwin J. M., Hof P. R., et al.
(2011).  Aging of the cerebral cortex differs between humans and chimpanzees.
Proceedings of the National Academy of Sciences. 108(32), 13029 - 13034.

Growing evidence has pointed to the benefits of social and mental stimulation in preventing dementia, but until now no one has looked at the role of physical environment.

A study involving 1294 healthy older adults found that those whose life-space narrowed to their immediate home were almost twice as likely to develop the condition as those with the largest life-space (out-of-town). The homebound also had an increased risk of MCI and a faster rate of global cognitive decline.

By the end of the eight-year study (average follow-up of 4.4 years), 180 people (13.9%) had developed Alzheimer’s. The association remained after physical function, disability, depressive symptoms, social network size, vascular disease burden, and vascular risk factors, were taken into account.

It may be that life-space is an indicator of how engaged we are with the world, with the associated cognitive stimulation that offers.

A six-year study involving over 1200 older women (70+) has found that low amounts of albumin in the urine, at levels not traditionally considered clinically significant, strongly predict faster cognitive decline in older women. Participants with a urinary albumin-to-creatinine ratio of >5 mcg/mg at the start of the study experienced cognitive decline at a rate 2 to 7 times faster in all cognitive measures than that attributed to aging alone over an average 6 years of follow-up. The ability most affected was verbal fluency. Albuminuria may be an early marker of diffuse vascular disease.

Data from 19,399 individuals participating in the Renal Reasons for Geographic and Racial Differences in Stroke (REGARDS) study, of whom 1,184 (6.1%) developed cognitive impairment over an average follow-up of 3.8 years, has found that those with albuminuria were 1.31-1.57 times more likely to develop cognitive impairment compared to individuals without albuminuria. This association was strongest for individuals with normal kidney function. Conversely, low kidney function was associated with a higher risk for developing cognitive impairment only among individuals without albuminuria. Surprisingly, individuals with albuminuria and normal kidney function had a higher probability for developing cognitive impairment as compared to individuals with moderate reductions in kidney function in the absence of albuminuria.

Both albuminuria and low kidney function are characteristics of kidney disease.

Lin, J., Grodstein, F., Kang, J.H. & Curhan, G. 2010. A Prospective Study of Albuminuria and Cognitive Decline in Women. Presented at ASN Renal Week 2010 on November 20 in Denver, CO.

Tamura, M.K. et al. 2010. Albuminuria, Kidney Function and the Incidence of Cognitive Impairment in US Adults. Presented at ASN Renal Week 2010 on November 20 in Denver, CO.

More evidence that vascular disease plays a crucial role in age-related cognitive impairment and Alzheimer’s comes from data from participants in the Alzheimer's Disease Neuroimaging Initiative.

The study involved more than 800 older adults (55-90), including around 200 cognitively normal individuals, around 400 people with mild cognitive impairment, and 200 people with Alzheimer's disease. The first two groups were followed for 3 years, and the Alzheimer’s patients for two. The study found that the extent of white matter hyperintensities (areas of damaged brain tissue typically caused by cardiovascular disease) was an important predictor of cognitive decline.

Participants whose white matter hyperintensities were significantly above average at the beginning of the study lost more points each year in cognitive testing than those whose white matter hyperintensities were average at baseline. Those with mild cognitive impairment or Alzheimer's disease at baseline had additional declines on their cognitive testing each year, meaning that the presence of white matter hyperintensities and MCI or Alzheimer's disease together added up to even faster and steeper cognitive decline.

The crucial point is that this was happening in the absence of major cardiovascular events such as heart attacks, indicating that it’s not enough to just reduce your cardiovascular risk factors to a moderate level — every little bit of vascular damage counts.

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.

Reports on cognitive decline with age have, over the years, come out with two general findings: older adults do significantly worse than younger adults; older adults are just as good as younger adults. Part of the problem is that there are two different approaches to studying this, each with their own specific bias. You can keep testing the same group of people as they get older — the problem with this is that they get more and more practiced, which mitigates the effects of age. Or you can test different groups of people, comparing older with younger — but cohort differences (e.g., educational background) may disadvantage the older generations. There is also argument about when it starts. Some studies suggest we start declining in our 20s, others in our 60s.

One of my favorite cognitive aging researchers has now tried to find the true story using data from the Virginia Cognitive Aging Project involving nearly 3800 adults aged 18 to 97 tested on reasoning, spatial visualization, episodic memory, perceptual speed and vocabulary, with 1616 tested at least twice. This gave a nice pool for both cross-sectional and longitudinal comparison (retesting ranged from 1 to 8 years and averaged 2.5 years).

From this data, Salthouse has estimated the size of practice effects and found them to be as large as or larger than the annual cross-sectional differences, although they varied depending on the task and the participant’s age. In general the practice effect was greater for younger adults, possibly because younger people learn better.

Once the practice-related "bonus points" were removed, age trends were flattened, with much less positive changes occurring at younger ages, and slightly less negative changes occurring at older ages. This suggests that change in cognitive ability over an adult lifetime (ignoring the effects of experience) is smaller than we thought.

Subjective cognitive impairment (SCI), marked by situations such as when a person recognizes they can't remember a name like they used to or where they recently placed important objects the way they used to, is experienced by between one-quarter and one-half of the population over the age of 65. A seven-year study involving 213 adults (mean age 67) has found that healthy older adults reporting SCI are dramatically more likely to progress to MCI or dementia than those free of SCI (54% vs 15%). Moreover, those who had SCI declined significantly faster.

Reisberg, B. et al. 2010. Outcome over seven years of healthy adults with and without subjective cognitive impairment. Alzheimer's & Dementia, 6 (1), 11-24.

More data from the National Survey of Midlife Development in the United States has revealed that cognitive abilities reflect to a greater extent how old you feel, not how old you actually are. Of course that may be because cognitive ability contributes to a person’s wellness and energy. But it also may reflect benefits of trying to maintain a sense of youthfulness by keeping up with new trends and activities that feel invigorating.

[171] Schafer, M. H., & Shippee T. P.
(2009).  Age Identity, Gender, and Perceptions of Decline: Does Feeling Older Lead to Pessimistic Dispositions About Cognitive Aging?.
The Journals of Gerontology Series B: Psychological Sciences and Social Sciences. 65B(1), 91 - 96.

An imaging study involving 79 volunteers aged 44 to 88 has found lower volumes of gray matter and faster rates of decline in the frontal and medial temporal lobes of those who ranked high in neuroticism traits, compared with those who ranked high in conscientious traits. These are brain regions particularly affected by aging. The idea that this might occur derived from the well-established effects of chronic stress on the brain. This is the first study to investigate whether the rate and extent of cognitive decline with age is influenced by personality variables. Extraversion, also investigated, had no effect. The study does not, however, rule out the possibility that it is reduction in brain tissue in these areas that is affecting personality. There is increasing evidence that people tend to become more neurotic and less conscientious in early-stage Alzheimer's.

[174] Jackson, J., Balota D. A., & Head D.
(Submitted).  Exploring the relationship between personality and regional brain volume in healthy aging.
Neurobiology of Aging. In Press, Corrected Proof,

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

Marital status and gender affects rate of age-related cognitive decline; education doesn’t

Analysis of data from 6,476 adults born prior to 1924 (taken from the AHEAD study), who were given five rounds of cognitive testing between 1993 and 2002, has found marital status is a significant factor in rate of cognitive decline, with widows and widowers and those who never married declining faster than married individuals. This is consistent with findings of the benefits of social stimulation and support for aging cognition. Confirming earlier indications, it was also found that women declined faster than men. Level of education did not affect rate of decline. There was an effect of socioeconomic status, in that those in the bottom quintile declined more slowly than those in the highest quintile, and non-Hispanic blacks declined more slowly than non-Hispanic whites, but the chief difference was at baseline — that is, socioeconomic status and race were a far more significant factor in the level of cognitive performance at the start of the study, compared to the rate of decline with age.

[628] Karlamangla, A. S., Miller-Martinez D., Aneshensel C. S., Seeman T. E., Wight R. G., & Chodosh J.
(2009).  Trajectories of Cognitive Function in Late Life in the United States: Demographic and Socioeconomic Predictors.
Am. J. Epidemiol.. 170(3), 331 - 342.

http://www.eurekalert.org/pub_releases/2009-08/uoc--sfn080709.php

Evidence cognitive decline begins in late 20s

A seven-year study involving 2,000 healthy participants between the ages of 18 and 60 has revealed that in 9 of 12 tests the average age at which the top scores were achieved was 22. A notable decline in certain measures of abstract reasoning, processing speed and spatial visualization became apparent at 27. Average memory declines could be detected by about age 37. However, accumulated knowledge skills, such as improvement of vocabulary and general knowledge, actually increase at least until the age of 60. It must be remembered however that there is considerable variance from person to person.

[239] Salthouse, T. A.
(2009).  When does age-related cognitive decline begin?.
Neurobiology of Aging. 30(4), 507 - 514.

http://www.eurekalert.org/pub_releases/2009-03/uov-cdb031909.php
http://news.bbc.co.uk/2/hi/health/7945569.stm

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.

[362] Wilson, R. S., Hebert L. E., Scherr P. A., Barnes L. L., Mendes de Leon C. F., & Evans D. A.
(2009).  Educational attainment and cognitive decline in old age.
Neurology. 72(5), 460 - 465.

http://www.eurekalert.org/pub_releases/2009-02/aaon-emn012709.php

Brain slows at 40, starts body decline

We get slower as we age, we all know that. This slowness reflects damage to the myelin sheathing (“white matter”) that coats nerve fibers and is vital for speedy conduction of electrical impulses. A study involving 72 healthy men aged 23 to 80 has found that the speed with which they could tap an index finger, and the health of the myelin in the region that orders the finger to tap, both peaked at age 39, then gradually declined with increasing age. This explains why you don’t get many world-class athletes after 40. Luckily, it probably takes a little longer before the myelin in cognitive areas starts to fray (a decade or so, it’s thought). The finding is consistent with a recent report that the system that’s supposed to repair myelin becomes less efficient with age. More research is looking at what you can do to help your myelin, but in the meantime, it’s suggested that mental and physical activity may help stimulate myelin repair, and stress may damage it.

[468] Villablanca, P., Bartzokis G., Lu P. H., Tingus K., Mendez M. F., Richard A., et al.
(2008).  Lifespan trajectory of myelin integrity and maximum motor speed.
Neurobiology of Aging.

http://www.physorg.com/news144948216.html
http://www.eurekalert.org/pub_releases/2008-10/uoc--pdc101708.php

Memory loss becoming less common in older Americans

A new nationally representative study involving 11,000 people shows a downward trend in the rate of cognitive impairment among people aged 70 and older, from 12.2% to 8.7% between 1993 and 2002. It’s speculated that factors behind this decline may be that today’s older people are much likelier to have had more formal education, higher economic status, and better care for risk factors such as high blood pressure, high cholesterol and smoking that can jeopardize their brains. In fact the data suggest that about 40% of the decrease in cognitive impairment over the decade was likely due to the increase in education levels and personal wealth between the two groups of seniors studied at the two time points. The trend is consistent with a dramatic decline in chronic disability among older Americans over the past two decades.

[1307] Langa, K. M., Larson E. B., Karlawish J. H., Cutler D. M., Kabeto M. U., Kim S. Y., et al.
(2008).  Trends in the Prevalence and Mortality of Cognitive Impairment in the United States: Is There Evidence of a Compression of Cognitive Morbidity?.
Alzheimer's & dementia : the journal of the Alzheimer's Association. 4(2), 134 - 144.

http://www.eurekalert.org/pub_releases/2008-02/uomh-mla021808.php

People at genetic risk for Alzheimer's age mentally just like noncarriers

A long-running study involving 6,560 people has found that carriers of the so-called ‘Alzheimer’s gene’— the APOE4 allele — does not contribute to cognitive change during most of adulthood. There was no difference in cognitive performance between carriers and non-carriers prior to the development of dementia symptoms.

[1189] Jorm, A. F., Mather K. A., Butterworth P., Anstey K. J., Christensen H., & Easteal S.
(2007).  APOE genotype and cognitive functioning in a large age-stratified population sample.
Neuropsychology. 21(1), 1 - 8.

http://www.eurekalert.org/pub_releases/2007-01/apa-pag010307.php

Longevity gene also helps retain cognitive function

The Longevity Genes Project has studied 158 people of Ashkenazi, or Eastern European Jewish, descent who were 95 years of age or older. Those who passed a common test of mental function were two to three times more likely to have a common variant of a gene associated with longevity (the CETP gene) than those who did not. When the researchers studied another 124 Ashkenazi Jews between 75 and 85 years of age, those subjects who passed the test of mental function were five times more likely to have this gene variant than their counterparts. The gene variant makes cholesterol particles in the blood larger than normal.

[916] Barzilai, N., Atzmon G., Derby C. A., Bauman J. M., & Lipton R. B.
(2006).  A genotype of exceptional longevity is associated with preservation of cognitive function.
Neurology. 67(12), 2170 - 2175.

http://tinyurl.com/yrf5s4
http://www.eurekalert.org/pub_releases/2006-12/aaon-lga121906.php

Risk of mild cognitive impairment increases with less education

A study of 3,957 people from the general population of Olmsted County, Minnesota is currently in train to find how many of those who did not have dementia might have mild cognitive impairment. A report on the findings so far suggests 9% of those aged 70 to 79 and nearly 18% of those 80 to 89 have MCI. Prevalence varied not only with age but also years of education: 25% in those with up to eight years of education, 14% in those with nine to 12 years, 9% in those with 13 to 16 years, and 8.5% in those with greater than 16 years.

Findings from this study were presented April 4 at the American Academy of Neurology meeting in San Diego.

http://www.eurekalert.org/pub_releases/2006-04/mc-mci033006.htm

Human cerebellum and cortex age in very different ways

Analysis of gene expression in five different regions of the brain's cortex has found that brain changes with aging were pronounced and consistent across the cortex, but changes in gene expression in the cerebellum were smaller and less coordinated. Researchers were surprised both by the homogeneity of aging within the cortex and by the dramatic differences between cortex and cerebellum. They also found that chimpanzees' brains age very differently from human brains; the findings cast doubt on the effectiveness of using rodents to model various types of neurodegenerative disease.

[951] Fraser, H. B., Khaitovich P., Plotkin J. B., Pääbo S., & Eisen M. B.
(2005).  Aging and Gene Expression in the Primate Brain.
PLoS Biol. 3(9), e274 - e274.

http://www.eurekalert.org/pub_releases/2005-08/hu-hca072805.php

Childhood environment important in staving off cognitive decline

Confirming earlier studies, a British study of 215 men and women aged between 66 and 75, has found that the larger a person's head, the less likely their cognitive abilities are to decline in later years. Those with the smallest heads had a fivefold increased risk of suffering cognitive decline compared with those with the largest heads. Encouragingly, however, this doesn’t mean you’re doomed at birth — the researchers found that it wasn’t head circumference at birth that was important, but head size in adulthood. During the first year of life, babies' brains double in size, and by the time they are six, their brain weight has tripled. These, it appears, are the crucial years for laying down brain cells and neural connections — pointing to the importance of providing both proper nourishment and intellectual stimulation in these early years.

[1208] Gale, C. R., Walton S., & Martyn C. N.
(2003).  Foetal and postnatal head growth and risk of cognitive decline in old age.
Brain. 126(10), 2273 - 2278.

http://observer.guardian.co.uk/uk_news/story/0,6903,1051264,00.html

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

How aging brains compensate for cognitive decline

Many of the cognitive deficits associated with advancing age are related to functions of the prefrontal cortex such as working memory, decision-making, planning and judgment. Postmortem examination of 20 brains ranging in age from 25 to 83 years, confirm that prefrontal regions may be particularly sensitive to the effects of aging. It also appears that white matter decreases at a faster rate than grey matter with age.

Kigar, D.L., Walter, A.L., Stoner-Beresh, H.J. & Witelson, S.F. 2001. Age and volume of the human prefrontal cortex: a postmortem study. Paper presented to the annual Society for Neuroscience meeting in San Diego, US.

Memory starts to decline in our mid-twenties

Studies of more than 350 men and women between the ages of 20 and 90 have found that cognitive decline starts as early as the twenties, and this decline in cognitive processing power appears to be constant - that is, the rate of decline is the same when you are in your twenties as when you are in your sixties. However young adults don't notice this decline because the loss hasn't yet become great enough to affect everyday activities.

Denise Park, who directs the Center for Aging and Cognition at the University of Michigan Institute for Social Research (ISR) presented a paper on these studies on Aug. 24 in San Francisco at the annual meeting of the American Psychological Association.

http://www.umich.edu/~newsinfo/Releases/2001/Aug01/r081301a.html

Gray matter may decline from adolescence, but white matter keeps growing until our late forties

Brain scans of 70 men, ages 19 to 76 confirms that the brain's gray matter, the cell bodies of nerve cells, declines steadily from adolescence. But surprisingly, the white matter, the fatty material that insulates the long extending branches of the nerve cells and makes nerve signals move faster, in the frontal parts of the brain appears to grow at least until the late 40's, before beginning to decline. The growth of white matter may improve the brain's ability to process information.

[1246] Bartzokis, G., Beckson M., Lu P. H., Nuechterlein K. H., Edwards N., & Mintz J.
(2001).  Age-Related Changes in Frontal and Temporal Lobe Volumes in Men: A Magnetic Resonance Imaging Study.
Arch Gen Psychiatry. 58(5), 461 - 465.

http://www.nytimes.com/2001/05/22/health/22VITA-3.html

Mental faculties unchanged until the mid-40s

A large-scale study of mental abilities in adults found that mental faculties were unchanged until the mid-40s, when a marked decline began and continued at a constant rate. The ability to remember words after a delay was especially affected. Accuracy did not seem to be affected, only speed.

The paper was presented to a British Psychological Society conference in London.

http://www.guardian.co.uk/Archive/Article/0,4273,4108165,00.html

Gender differences in frontal lobe neuron density

A recent study has found that women have up to 15% more brain cell density in the frontal lobe, which controls so-called higher mental processes, such as judgement, personality, planning and working memory. However, as they get older, women appear to shed cells more rapidly from this area than men. By old age, the density is similar for both sexes. It is not yet clear what impact, if any, this difference has on performance.

Witelson, S.F., Kigar, D.L. & Stoner-Beresh, H.J. 2001. Sex difference in the numerical density of neurons in the pyramidal layers of human prefrontal cortex: a stereologic study. Paper presented to the annual Society for Neuroscience meeting in San Diego, US.

http://news.bbc.co.uk/hi/english/health/newsid_1653000/1653687.stm

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