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Regular exercise, including walking at an easy pace, seems to protect the aging brain from erosion in thinking ability -- and even from Alzheimer's, according to two studies released today.
Previous studies have shown that exercise can ward off heart disease, diabetes and other killer diseases. But today's findings raise the hope that daily exercise might be able to stem the tide of Alzheimer's disease, which might affect up to 16 million Americans by 2050.
Jennifer Weuve of the Harvard School of Public Health and her colleagues found that older women who were physically active, including those who walked at a leisurely pace two to three hours a week, performed much better on tests of memory and thinking ability than inactive women.
And those who exercised more did even better: The team found that women who were the most active -- for example, those who walked at least six hours a week -- had a 20% reduced risk of doing poorly on the same tests of cognitive ability.
''You don't need to run a marathon to get this benefit,'' says Marilyn Albert, a spokeswoman for the Alzheimer's Association.
The study of 18,766 older women appears in The Journal of the American Medical Association.
This study fits with other evidence that suggests exercise triggers the release of naturally produced chemicals that protect brain cells and keep them performing at top speed, says David Bennett, director of the Alzheimer Disease Center at Rush University Medical Center in Chicago.
A second study in the same journal added to the evidence that exercise could offer protection against dementia and Alzheimer's.
Robert Abbott of the University of Virginia and his colleagues found that relatively sedentary older men -- those who walked less than one-quarter of a mile each day -- had nearly twice the risk of developing dementia as men who walked more than 2 miles each day.
These studies suggest that regular physical activity might do more than just keep the body in shape. ''Exercise really does seem to make a difference in terms of cognitive decline,'' Albert says.
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