Tuesday, December 18, 2007

"Mental reserves" as antidote to Alzheimer's disease

A fascinating aspect of various kinds of debilitation (back pain, heart attacks, dementia) is that degenerative changes in anatomy commonly associated with them (disk and vertebral degeneration, cardiac vessel blockage, brain lesion and beta-amyloid plaques-shown in figure) are often observed on autopsy in physically and mental robust people, who have shown no symptoms of debilitation. What is different about them? Apparently their bodies were able to do a more effective 'work around' or compensation for the damage. A relevant article by Jane Brody in the December 11 New York Times deals with evidence that cognitive reserves, the brain’s ability to develop and maintain extra neurons and connections between them may later in life help compensate for the rise in dementia-related brain pathology that accompanies normal aging. Some edited clips:
Cognitive reserve is greater in people who complete higher levels of education. The more intellectual challenges to the brain early in life, the more neurons and connections the brain is likely to develop and perhaps maintain into later years... brain stimulation does not have to stop with the diploma. Better-educated people may go on to choose more intellectually demanding occupations and pursue brain-stimulating hobbies, resulting in a form of lifelong learning...novelty is crucial to providing stimulation for the aging brain...as with muscles, it’s “use it or lose it.” The brain requires continued stresses to maintain or enhance its strength...In 2001, ... a long-term study of cognitively healthy elderly New Yorkers....found, on average, those who pursued the most leisure activities of an intellectual or social nature had a 38 percent lower risk of developing dementia. The more activities, the lower the risk...the most direct route to a fit mind is through a fit body...physical exercise “improves what scientists call ‘executive function,’ the set of abilities that allows you to select behavior that’s appropriate to the situation, inhibit inappropriate behavior and focus on the job at hand in spite of distractions. Executive function includes basic functions like processing speed, response speed and working memory.
This point about exercise and executive function was the subject of my Nov. 15 post.

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