seniors

Cognitive decline is not simply a function of getting old

October, 2010
  • New research suggests that even “normal” cognitive decline with age reflects the type of brain damage that is (in greater amount) characteristic of dementia.

Findings from the long-running Religious Orders Study, from 354 Catholic nuns and priests who were given annual cognitive tests for up to 13 years before having their brains examined post-mortem, has revealed that even the very early cognitive impairments we regard as normal in aging are associated with dementia pathology. Although pathology in the form of neurofibrillary tangles, Lewy bodies, and cerebral infarctions were all associated with rapid decline, they were also associated with “normal” mild impairment. In the absence of any of these lesions, there was almost no cognitive decline.

Previous research has shown that white matter lesions are very common in older adults, and mild cognitive impairment is more likely in those with quickly growing white matter lesions; importantly, the crucial factor appears to be the rate of growth, not the amount of lesions. This new study extends the finding, suggesting that any age-related cognitive impairment reflects the sort of brain pathology that ultimately leads to dementia (if given enough time). It suggests that we should be more proactive in fighting such damage, instead of simply regarding it as normal.

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Factors linked to cognitive deficits in type 2 diabetes

October, 2010

Cognitive deficits and even dementia are more common in older diabetics. A new study points to three health issues that, if present, increase the risk that older diabetics will develop cognitive problems.

Type 2 diabetes is known to increase the risk of cognitive impairment in old age. Now analysis of data from 41 older diabetics (aged 55-81) and 458 matched controls in the Victoria Longitudinal Study has revealed that several other factors make it more likely that an older diabetic will develop cognitive impairment. These factors are: having higher (though still normal) blood pressure, having gait and balance problems, and/or reporting yourself to be in bad health regardless of actual problems.

Diabetes and hypertension often go together, and both are separately associated with greater cognitive impairment and dementia risk, so it is not surprising that higher blood pressure is one of the significant factors that increases risk. The other factors are less expected, although gait and balance problems have been linked to cognitive impairment in a recent study, and they may be connected to diabetes through diabetes’ effect on nerves. Negativity about one’s health may reflect emotional factors such as anxiety, stress, or depression, although depression and well-being measures were not themselves found to be mediating effects for cognitive impairment in diabetics (Do note that this study is not investigating which factors, in general, are associated with age-related cognitive impairment; it is trying to establish which factors are specifically sensitive to cognitive impairment in older diabetics).

In the U.S., type 2 diabetes occurs in over 23% of those over 60; in Canada (where this study took place) the rate is 19%. It should be noted that the participants in this study are not representative of the general population, in that they were fairly well-educated older Canadians, most of whom have benefited from a national health care system. Moreover, the study did not have longitudinal data on these various factors, meaning that we don’t know the order of events (which health problems come first? How long between the development of the different problems?). Nevertheless, the findings provide useful markers to alert diabetics and health providers.

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Memory problems more common in older men?

October, 2010

A large community study of older adults has found mild cognitive impairment was more prevalent in men.

A study involving 2,050 people aged 70 to 89 has found that mild cognitive impairment was 1.5 times more common in men than women. Among the 1,969 who did not have dementia, over 16% (329) had MCI — around 11% amnestic MCI (MCI-A) and 5% non-amnestic (MCI-MCD). A total of 19% of men had MCI, compared to 14% of women. MCI was also more common among the never-married, those with the APOEe4 (Alzheimer’s risk) gene, and those with less education.

This is the first study conducted among community-dwelling persons to find a higher prevalence of MCI in men. However, I note that some years ago I reported on a Dutch study involving some 600 85-year-olds, that found that significantly more women than men had a good memory (41% vs 29%; good mental speed on word and number recognition tests was also found in more women than men: 33% vs 28%). This was considered particularly surprising, given that significantly more of the women had limited formal education compared to the men.

The researchers suggested biological factors such as the relative absence of cardiovascular disease in the women might account for the difference. I would suggest another factor might be social, given that social stimulation has been shown to help prevent cognitive decline, and women are more likely than men to keep up social links in old age.

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New advice on how much cognitive abilities decline with age

October, 2010

A new study suggests that inconsistencies in rate of age-related cognitive decline may be partly due to practice effects, but though decline does occur it is slower than some have estimated.

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.

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Deep Brain Stimulation shows promise for patients with Alzheimer's

September, 2010

A safety trial has shown that Deep Brain Stimulation is safe for those with mild Alzheimer’s, and may slow cognitive decline.

A pilot study involving six patients with mild Alzheimer’s has shown using Deep Brain Stimulation (DBS) is safe and may help improve memory, or at least slow decline. Patients received continuous stimulation for 12 months, between 2005 and 2008. Impaired glucose utilization in the temporal and parietal lobes was dramatically reversed early in the treatment, and maintained after the year of continuous stimulation. Performance on cognitive tests showed possible improvement and/or slowing in the rate of cognitive decline at 6 and 12 months in three of the six patients.

The principal aim of this pilot study was to assess the safety of the procedure, and it is now hoped to move on to a larger study to assess its effectiveness. Anyone interested in more information about participating in the next phase should visit: http://www.uhn.on.ca/Focus_of_Care/KNC/Functional_Neurosurgery/research.asp.

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Link between gum disease and poorer cognition in older adults

September, 2010

A strong association between gum inflammation and poorer cognitive performance in 70-year-olds has been found in a small study.

Following on from indications that gum disease might be a risk factor for dementia, analysis of data from 152 subjects in the Danish Glostrop Aging Study has revealed that periodontal inflammation at age 70 was strongly associated with lower cognitive scores (on the Digit Symbol Test). Those with periodontal inflammation were nine times more likely to test in the lower range compared to those with little or no periodontal inflammation. A larger follow-up study, among a more ethnically diverse range of subjects, is planned. I hope they also plan to extend the cognitive testing.

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The findings were presented by Dr. Angela Kamer at the 2010 annual meeting of the International Association for Dental Research July 16, in Barcelona, Spain.

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Vitamin B supplements could delay onset of Alzheimer's

September, 2010
  • Vitamin B supplements markedly reduced brain atrophy in older adults with MCI, offering hope that they may be effective in delaying the development of Alzheimer’s.

A two-year study involving 271 older adults (70+) with mild cognitive impairment has found that the rate of brain atrophy in those taking folic acid (0.8 mg/d), vitamin B12 (0.5 mg/d) and vitamin B6 (20 mg/d), was significantly slower than in those taking a placebo, with those taking the supplements experiencing on average 30% less brain atrophy. Higher rates of atrophy were associated with lower cognitive performance. Moreover those who with the highest levels of homocysteine at the beginning of the trial benefited the most, with 50% less brain shrinkage. High levels of homocysteine are a risk factor for Alzheimer’s, and folate, B12 and B6 help regulate it.

The finding that atrophy can be slowed in those with MCI offers hope that the treatment could delay the development of Alzheimer’s, since MCI is a major risk factor for Alzheimer’s, and faster brain atrophy is typical of those who go on to develop Alzheimer’s.

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More reason to eat berries for a healthy brain

September, 2010

A new study adds to the evidence that berries and other foods rich in polyphenols help your brain fight age-related cognitive decline.

A number of studies have found evidence that fruits and vegetables help fight age-related cognitive decline, and this has been thought to be due to their antioxidant and anti-inflammatory effects. A new study shows there may be an additional reason why polyphenols benefit the aging brain. One reason why the brain works less effectively as it gets older is that the cells (microglia) that remove and recycle biochemical debris not only fail to do their housekeeping work, but they actually begin to damage healthy cells. Polyphenols restore normal housekeeping, by inhibiting the action of a protein that shuts down the housekeeping (autophagy) process.

While many fruits and vegetables are good sources of polyphenols, berries and walnuts, and fruit and vegetables with deep red, orange, or blue colors, are particularly good.

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Poulose, S. & Joseph, J. 2010. Paper presented at the 240th National Meeting of the American Chemical Society.

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Brain may age faster in people whose hearts pump less blood

September, 2010
  • A large study confirms that your cardiac health affects your brain, and provides evidence that the extent of this problem is greater than we think.

I have often spoken of the mantra: What’s good for your heart is good for your brain. The links between cardiovascular risk factors and cognitive decline gets more confirmation in this latest finding that people whose hearts pumped less blood had smaller brains than those whose hearts pumped more blood. The study involved 1,504 participants of the decades-long Framingham Offspring Cohort who did not have a history of stroke, transient ischemic attack or dementia. Participants were 34 to 84 years old.

Worryingly, it wasn’t simply those with the least amount of blood pumping from the heart who had significantly more brain atrophy (equivalent to almost two years more brain aging) than the people with the highest cardiac index. Those with levels at the bottom end of normal showed similar levels of brain atrophy. Moreover, although only 7% of the participants had heart disease, 30% had a low cardiac index.

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The problem of 'destination amnesia'

September, 2010

Two studies demonstrate why knowing whether you’ve told someone something is difficult for all of us, and that this is particularly so as you get older.

A number of studies have found that source memory (knowing where you heard/read/experienced something) is a particular problem for older adults. Destination memory (knowing who you’ve told) is an area that has been much less studied. Last year I reported on why destination memory is difficult for all of us (my report is repeated below). A follow-up study has found not only that destination memory is a particular problem for older adults, but that it is in fact a worse problem than source memory. Moreover, destination amnesia (falsely believing you've told someone something) is not only more common among older adults, but is associated with greater confidence in the false belief.

The study compared the performance of 40 students (aged 18-30) and 40 healthy older adults (aged 60-83). In the first task, the participant read out loud 50 interesting facts to 50 celebrities (whose faces appeared on a computer screen), and were then tested on their memory of which fact they told to which famous person. In the second task, they had to remember which famous person told them which particular fact. Older adults' performance was 21% worse than their younger counterparts on the destination memory test, but only 10% worse (50% vs 60%) on the source memory test. This latter difference was not statistically significant.

The 2009 study, involving 60 students, found good reason for destination memory to be so poor — apparently outgoing information is less integrated with context than incoming information is. In the study, 50 random facts were linked with the faces of 50 famous people; half the students then “told” each fact to one of the faces, reading it aloud to the celebrity’s picture. The other half read each fact silently and saw a different celebrity moments afterward. In the subsequent memory test, students who simulated telling the facts did 16% worse. In another experiment using personal facts, it was significantly worse.

However, the final experiment found that you could improve your destination memory by saying the name of the person you’re speaking to, as you tell them. The findings also suggest that self-focus is an important factor: increasing self-focus (e.g. by telling a personal story) worsened destination memory; reducing self-focus (e.g. by naming the listener) improved it.

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[1809] Gopie, N., Craik F. I. M., & Hasher L.
(2010).  Destination memory impairment in older people..
Psychology and Aging.

[396] Gopie, N., & MacLeod C. M.
(2009).  Destination Memory: Stop Me if I've Told You This Before.
Psychological Science. 20(12), 1492 - 1499.

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