New research indicates moderate to intense exercise in the elderly may be effective at reducing dementia and strokes. In comparing MRIs of the brain in those who exercised more intensely, researchers identified considerably less brain damage caused by blocked arteries as compared with those who exercised far less intensely. Interestingly, there was no difference in the brains of those who exercised with light intensity as compared with those who did not exercise at all. Although this study did not directly evaluate exercise intensity to the rates of dementia and stroke, the findings of increased brain blood flow and less brain damage strongly suggests moderate to intense exercise should significantly lower the incidence of dementia and stroke suffered by the elderly. According to the American Heart Association, 150 minutes of moderate-intensity or 75 minutes of vigorous-intensity exercise is recommended each week.