Aging

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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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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Have I done it?

October, 2010

Watching another person do something can leave you with the memory of having done it yourself.

I’m not at all sure why the researcher says they were “stunned” by these findings, since it doesn’t surprise me in the least, but a series of experiments into the role of imagination in creating false memories has revealed that people who had watched a video of someone else doing a simple action often remembered doing the action themselves two weeks later. In fact in my book on remembering intentions, which includes a chapter on remembering whether you’ve done something, I mention the risk of imagining yourself doing something (that you then go on to believe you have actually done it), and given all the research on mirror neurons, it’s no big step to go from watching someone doing something to remembering that you did it. Nevertheless, it’s nice to get the confirmation.

The experiments involved participants performing several simple actions, such as shaking a bottle or shuffling a deck of cards. Then they watched videos of someone else doing simple actions—some of which they had performed themselves and some of which they hadn’t. Two weeks later, they were asked which actions they had done. They were much more likely to falsely remember doing an action if they had watched someone else do it — even when they had been warned about the effect.

It seems likely that this is an unfortunate side-effect of a very useful ability — namely our ability to learn motor skills by observing others (using the aforesaid mirror neurons) — and there’s probably not a great deal we can do to prevent it happening. It’s just a reminder of how easy it is to form false memories.

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[1839] Lindner, I., Echterhoff G., Davidson P. S. R., & Brand M.
(2010).  Observation Inflation.
Psychological Science. 21(9), 1291 - 1299.

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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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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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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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Common medications increase risk of mild cognitive impairment

August, 2010

A large study of older African-Americans has found taking common medications with anticholinergic effects was correlated with an increased risk of developing mild cognitive impairment.

Anticholinergics are widely used for a variety of common medical conditions including insomnia, allergies, or incontinence, and many are sold over the counter. Now a large six-year study of older African-Americans has found that taking one anticholinergic significantly increased an individual's risk of developing mild cognitive impairment and taking two of these drugs doubled this risk. The risk was greater for those who didn’t have the ‘Alzheimer’s gene’, APOE-e4.

This class of drugs includes Benadryl®, Dramamine®, Excedrin PM®, Nytol®, Sominex®, Tylenol PM®, Unisom®, Paxil®, Detrol®, Demerol® and Elavil® (for a more complete list of medications with anticholinergic effects, go to http://www.indydiscoverynetwork.org/AnticholienrgicCognitiveBurdenScale....).

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Adults recall negative events less accurately than children

August, 2010

A word experiment shows that unpleasant or traumatic events are likely to be inaccurately remembered, and this memory distortion increases with age. The findings have implications for eyewitness testimony.

Findings that children are less likely than adults to distort memories when negative emotions are evoked has significant implications for the criminal justice system. Experiments involving children aged seven and 11, and young adults (18-23) found that when they were shown lists of closely related emotional words (e.g. pain, cut, ouch, cry, injury), they would tend to mistakenly remember a related word (e.g. hurt) although it had not been present. Despite the prevailing theory that being involved in a very negative experience focuses your mind and helps you notice and remember details, words that had negative emotional content produced the highest levels of false memory. With arousal (such as would be evoked in a traumatic experience), memory was distorted more. These tendencies increased with age.

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[1670] Brainerd, C. J., Holliday R. E., Reyna V. F., Yang Y., & Toglia M. P.
(2010).  Developmental reversals in false memory: Effects of emotional valence and arousal.
Journal of Experimental Child Psychology. 107(2), 137 - 154.

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Low vitamin D levels associated with cognitive decline

August, 2010

Another study shows that older adults with low levels of vitamin D have higher levels of cognitive decline, particularly in executive function (but not attention).

Another study has come out showing that older adults with low levels of vitamin D are more likely to have cognitive problems. The six-year study followed 858 adults who were age 65 or older at the beginning of the study. Those who were severely deficient in vitamin D were 60% more likely to have substantial cognitive decline, and 31% more likely to have specific declines in executive function, although there was no association with attention. Vitamin D deficiency is common in older adults in the United States and Europe (levels estimated from 40% to 100%!), and has been implicated in a wide variety of physical disease.

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