Physical activity might reduce the risk of cardiovascular disease partly by decreasing activity in parts of the brain related to stress, a study in the Journal of the American College of Cardiology suggests. Researchers looked at data from more than 50 300 adults in Massachusetts who completed an exercise survey and more than 700 who underwent brain imaging. People who exercised more tended to have fewer cardiovascular disease events and lower activity in stress-related brain regions, the researchers reported.