But a new study shows that the working out as a young adult can offer improved mental capacity sooner. The 25-year study of 3,381 people is part of the ongoing Coronary Artery Risk Development in Young Adults Study; the results were published in the American Heart Association journal Circulation.
Over the course of the study, participants had their blood pressure, blood sugar and cholesterol levels measured every two to five years. At the end of the study, the participants took tests to measure memory, thinking speed and mental flexibility.
The people who had blood pressure, blood sugar and cholesterol levels slightly higher than recommended levels between the ages of 18 and 30 were found to score significantly lower on the thinking tests in their 40s and 50s.
It's unclear what biological mechanisms might explain this correlation, but one theory is that those three heart-health indicators are risk factors for artery-narrowing plaque buildup. So, less healthy people may have more plaque buildup in the arteries that connect the heart and the brain.
"Things that would be good for the heart are probably going to be good for the brain," researcher David Jacobs told NPR.
The authors of the study hope that a better understanding of health and exercise may help us learn how to reduce the risks of mental decline associated with old age.