My mom, now 64, does crossword puzzles to help ward off Alzheimer's disease. Now a study from Scandinavia suggests that her physical exercises might help, too.

The study was carried out in eastern Finland, in the provinces of North Karelia and Kuopio. Participants were surveyed once in the 1970s or 1980s, when they were 39 to 64 years old, then again in 1998, when they were 65 to 79. The midlife survey included a question about exercise – specifically about "leisure-time physical activity that lasts at least 20-30 minutes and causes breathlessness and sweating." The 1998 survey included an assessment for dementia. Of the 2,000 people in the study, 76 had Alzheimer's disease in 1998.

People who had been physically active in midlife were less likely to have Alzheimer's and other dementia when they were reexamined in 1998.

The study didn't look at why physical activity would decrease the risk of Alzheimer's, but the researchers speculate in their article, published online today in The Lancet Neurology, that exercise's benefits for the cardiovascular system might carry over to dementia. Exercise might help the brain remain flexible, or people who exercise might also have other lifestyle factors that decrease their risk for dementia.

To find out more: Read information on exercise and fitness from the National Institutes of Health.

The Washington Post puts its daily crossword online.

Go to the U.S. News guide on Alzheimer's disease to get in-depth information about symptoms, tests, treatment, and prevention.