My husband, at 74, is the baby of his bridge group, which includes a woman who is 85 and a man who is 89. This challenging game demands an excellent memory (for bids, cards played, rules and so on) and an ability to think strategically and read subtle psychological cues. Never having had a head for cards, I continue to be amazed by the mental agility of these septuagenarians and octogenarians.
The brain, like every other part of the body, changes with age, and those changes can impede clear thinking and memory. Yet many older people seem to remain sharp as a tack well into their 80s and beyond. Although their pace may have slowed, they continue to work, travel, attend plays and concerts, play cards and board games, study foreign languages, design buildings, work with computers, write books, do puzzles, knit or perform other mentally challenging tasks that can befuddle people much younger.
But when these sharp old folks die, autopsy studies often reveal extensive brain abnormalities like those in patients with Alzheimer's. Nikolaos Scarmeas and Yaakov Stern at Columbia-Presbyterian Medical Center recall that in 1988, a study of "cognitively normal elderly women" showed that they had "advanced Alzheimer's disease pathology in their brains at death." Later studies indicated that up to two-thirds of people with autopsy findings of Alzheimer's disease were cognitively intact when they died.
"Something must account for the disjunction between the degree of brain damage and its outcome," the Columbia scientists deduced. And that something, they and others suggest, is "cognitive reserve."
MENTAL EXERCISE
Cognitive reserve, in this theory, refers to the brain's ability to develop and maintain extra neurons and connections between them via axons and dendrites. Later in life, these connections may help compensate for the rise in dementia-related brain pathology that accompanies normal aging.
As Cathryn Jakobson Ramin relates in her new book, Carved in Sand: When Attention Fails and Memory Fades in Midlife, the brains of animals exposed to greater physical and mental stimulation appear to have a greater number of healthy nerve cells and connections between them. Scientists theorize that this excess of working neurons and interconnections compensates for damaged ones to ward off dementia.
Observing this, Stern, a neuropsychologist, and others set out to determine how people can develop cognitive reserve. They have learned thus far that there is no "quick fix" for the aging brain, and little evidence that any one supplement or program or piece of equipment can protect or enhance brain function - despite advertisements for products like ginkgo biloba to the contrary.
Nonetheless, well-designed studies suggest several ways to improve the brain's viability. Though best to start early to build up cognitive reserve, there is evidence that this account can be replenished even late in life.
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. Several studies of normal aging have found that higher levels of educational attainment were associated with slower cognitive and functional decline.
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