The researchers don't know if exercise in childhood directly leads to less dementia since other factors could be at play, such as diet. And exercising as kids -- playing outdoors, for example -- may set a pattern for physical activity later in life, Middleton said.
If there is a cause-and-effect link between early exercise and less mental decline, she said it may have something to do with the brain's ability to change and develop new circuitry. It's also possible that exercise leads to less clogging of blood vessels in the brain, she said.
It's not clear whether men might benefit in the same way. The study only looked at women, Middleton said, and previous research has suggested that women benefit more from exercise than men.
Greg Cole, a brain researcher who's familiar with the findings, said scientists are interested in the benefits of exercise when it comes to brain decline, but they're focusing on studying the elderly at risk instead of looking backward at childhood.
Cole said the study's reliance on the memory of the elderly "makes one wonder" about its reliability. But childhood habits could presumably lead to lifelong habits that might contribute to the benefits of adult exercise seen in other studies, said Cole, a professor of medicine and neurology at the University of California at Los Angeles.
Kidshealth.org has details on children and exercise.
SOURCES: Laura E. Middleton, Ph.D., postdoctoral fellow, Sunnybrook Health Sciences Center, Toronto; Greg Cole, professor, medicine and neurology, University of California at Los Angeles. Journal of the American Geriatrics Society
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