Poor Fitness in Middle Age May Lead to a Smaller Brain, Study Says

Boston Marathon photo by Christopher Penn via Flickr/Creative Commons

Need another reason to care about fitness? A new Boston University School of Medicine (BUSM) study has some pretty motivating advice: Keep exercising so that your brain doesn’t shrink.

Researchers from BUSM found that poor physical fitness during middle age may be linked to smaller brain size later in life. The study, published in Neurology, examined more than 1,500 people age 40 or older, none of whom had symptoms of dementia or heart disease.

The study began with all participants taking a treadmill fitness test. Two decades later, they took a second treadmill test, and had MRI brain scans. Researchers then analyzed the results in two ways: They looked at the total group’s results, then looked everyone except those who had developed heart disease or took medication to control blood pressure.

“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 in a statement.

BUSM reached that conclusion by measuring the VO2, or exercise capacity, that participants were able to reach in one minute, as well as their brain size. For every eight units lower a person performed on the initial exercise test, the researchers found, their brain volume was incrementally smaller two decades later. The difference was equivalent to two years of premature brain aging. The second group—excluding those who developed heart disease—had a decrease in brain volume equal to one year of accelerated brain aging.

The study also showed that people whose blood pressure and heart rate went up at a faster rate during the treadmill test were more likely to have smaller brain volumes later in life. “While not yet studied on a large scale, these results suggest that fitness in middle age may be particularly important for the many millions of people around the world who already have evidence of heart disease,” Partano said.

While the study is observational, and correlation does not mean causation, finding yet another reason to exercise is never a bad thing.