Studies have found that older people are less likely to develop Alzheimer's disease and other forms of dementia if they engage in vigorous exercise, such as jogging, swimming, or brisk walking.

But according to a new study, even mundane, low-key tasks like gardening, cooking and washing dishes can lower the risk of Alzheimer's if they're performed often enough.

The study, published in the journal Neurology, included 716 dementia-free men and women in their 70s and 80s. Compared to the most active people, those with the lowest levels of overall physical activity had more than double the risk of going on to develop Alzheimer's disease. Greater physical activity was also associated with a slower rate of aging-related memory and cognitive decline.

"This suggests that people in their 80s who can't participate in formal exercise still get a benefit by leading a more active lifestyle," says lead author Dr. Aron S. Buchman, associate professor of neurological sciences at Rush University Medical Center, in Chicago. "You don't have to get a membership in the local YMCA. If you walk up some more steps, stand up and do the dishes more, you stand to benefit because it's incremental and adds up over the course of a full day."

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