This NYT article, which details research  published last week in Annals of Internal Medicine, reports that exercise can slow the effect of dementia.

“People who exercised more than three times a week developed dementia at a rate of 13 per 1,000 patient-years, compared with 19.7 per 1,000 patient-years for those who exercised less.”

One of the study's author characterized the results thusly:  “Low levels of exercise cause a 30 to 40 percent reduction in risk for dementia. If someone is starting to decline, it looks like exercise may significantly help.”