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Now that you've got your body running along smoothly, are there any mental gymnastics you can do to keep dementia at bay? The evidence is provocative but not terribly compelling. There's no question that you can improve your ability to remember names or other bits of information by practicing memory tasks, just as practice will help you learn a new instrument or another language. A number of researchers have proposed that a lifetime of such efforts could allow you to build up a healthy cognitive reserve to offset the declines of old age, though the idea remains theoretical.
Several studies have found that folks who regularly engage in mentally challenging activities—like reading, doing crossword puzzles or playing chess—seem less likely to develop dementia later in life. The difficulty comes in figuring out whether their good fortune is a direct result of their leisure activities or whether their continuing pursuit of those pleasures merely reflects good genes for cognitive function.
A 20-year survey of 469 elderly people living in the Bronx, N.Y., tried to get to the bottom of this chicken-or-egg question by following subjects who had no signs of dementia in the first seven years of the study. The results, which were published in 2003, showed that reading and playing board games or a musical instrument was associated with a decreased risk of Alzheimer's disease or other forms of dementia. Intriguingly, those with the strongest habits demonstrated the greatest benefits. Participants who solved crossword puzzles four days a week, for instance, had a 47% lower risk of dementia than those who do the puzzles once a week.
By the same token, several studies have suggested that older folks who are socially active—who, for example, do volunteer work or attend religious services—have a reduced risk of dementia. There are, of course, plenty of caveats that go along with those observations, including the same old chicken-or-egg problem that haunts all observational studies: In this case, is withdrawal from society a cause or result of Alzheimer's disease?
So where does this leave us? "I use a thermostat analogy with my patients," says Dr. Laurel Coleman, a geriatrician who sits on the board of the Alzheimer's Association. "Let's say you're dialed in to get Alzheimer's disease at 82. You may be able to push that back until maybe you're 92." Depending on where their personal thermostat is set, some people will do everything right and still develop dementia in their 50s. Others will do everything wrong and be perfectly lucid at 101. Most of the rest of us will fall somewhere between those two extremes. For now, at least, preventing dementia is still a numbers game, but one in which we're starting to grasp the variables.