COGNITION. The brain’s decline.
Treating cognitive problems common in elderly people requires a deeper understanding of how a healthy brain ages.
Nature, Vol 492, 6 December 2012: S4-5
normal cognitive ageing
about healthy brain ageing. There are only a few things that researchers can agree on. First, after the age of 60, nearly everyone will start to experience some decline in cognitive skills, most noticeably in memory, and this decline will be accompanied by a change in brain structure. Second, aerobic exercise slows or delays this mental slippage.
“Nearly a third of old people who are cognitively normal have enough amyloid and tau in their brains to meet the criteria for Alzheimer’s disease.”
There are fewer receptors and other proteins too, but the most dramatic fall is in the amount of dopamine (see ‘Ages of dopamine’) — a neurotransmitter whose many functions include movement control, general motivation and learning.
From early adulthood onwards, dopamine levels drop by about 10% per decade, making it a powerful marker for brain ageing.
The brain maintenance theory is consistent with evidence that aerobic exercise can slow cognitive decline by stimulating production of brain-derived neurotrophic factor, which helps the growth of new blood vessels, not only in the muscles being exercised but in the brain as well.
But it’s a rare octogenarian who can take a long run or play a heart-pounding game of squash, so scientists hope that studies such as COBRA will lead to alternative strategies.
One idea is to develop drugs that improve particular types of neurotransmission, but this might have limited value against a background of brain tissue shrinkage.
Another strategy could be to use computer-based cognitive training programmes designed to sharpen mental processing speed or working memory.
Several studies have shown that people of all ages can improve their performance on specific computer tasks in which they train.
Neuroscientist Adam Gazzaley at UCSF is so confident in the potential of this approach that he is developing commercial software for use at home. But even he admits there is no evidence that the improvements seen in computer-based tasks can help with life-related activities — such as helping you remember why you went to the fridge.
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So, she concludes, “some degree of worrying actually is good.” And, in fact, adds Friedman, “the prudent, persistent, planful people — both in childhood … and then in young adulthood we measured that — that was the strongest individual difference, or personality predictor, of long life.”
And it’s not just about risk aversion. The study found that conscientious people developed better social relationships and accomplished more at work. Think all that responsibility sounds boring? Not so, says Martin. “Because of those qualities, they tended to get nice opportunities in life, and so they went on to live some of the most exciting and interesting lives of anyone in the study.”
Ruline: I’m doing all right so far