Couch Potatoes Have Shrinking Brains

Use it or lose it, couch potatoes! We often hear about the importance of maintaining muscle mass and bone strength in middle age, but a new study suggests that exercise may be equally important in keeping our brains robust.

The research, published in the medical journal of the American Academy of Neurology, showed that poor physical fitness in middle age may be linked to smaller brain size 20 years later. “We found a direct correlation in our study between poor fitness and brain volume decades later, which indicates accelerated brain aging,” said study author Nicole Spartano, PhD, of the Boston University School of Medicine in Boston.

The study looked at 1,583 participants in the Framingham Heart Study. Their average age was 40, and they did not have dementia or heart disease. Their initial treadmill test results were compared with one they took 20 years later, along with MRI scans of their brains. The researchers estimated each person’s exercise capacity by seeing how long they could exercise on the treadmill before their heart rate reached a certain level.

The less fit a person was in middle age—the people whose blood pressure and heart rate went up most during that initial exercise test—where the same folks who were likely to have smaller brain volumes in the MRI tests 20 years later. For every eight units lower a person performed on the treadmill test, their brain volume two decades later was smaller, equivalent to two years of accelerated brain aging.

Researcher Spartano noted that the study is observational. The means poor fitness doesn’t necessarily cause the lack of brain volume, but shows an association. These results, do, however, suggest that midlife fitness can be an important step to ensure your brain will age in a healthy way. One more reason to get up off that couch and do something good for your body—and your noggin.