Exercise may slow the atrophy of the brain brought on by Alzheimer's, suggests a new study.

Researchers at the University of Kansas School of Medicine found that study participants who had mild Alzheimer's and who worked out regularly had larger brains that those who did not exercise regularly.

They studied 121 people 60 and over, exposing them to fitness tests while measuring their white and grey brain matter and overall brain volume using MRI. Fifty-seven of the participants had early-stage Alzheimer's while the rest of the participants did not have dementia.

"People with early Alzheimer's disease who were less physically fit had four times more brain shrinkage when compared to normal older adults than those who were more physically fit, suggesting less brain shrinkage related to the Alzheimer's disease process in those with higher fitness levels," said study author Jeffrey Burns, of the University of Kansas School of Medicine in Kansas City, in a release.

A decreasing brain volume has been linked in previous research to poorer cognitive performance.

Conversely, exercise has the opposite effect. "Higher fitness through increased physical activity has been associated with enhanced neuronal survival to brain insults, increased vascularization, and elevations of growth factors in areas important for memory," reads the study.

The researchers believe that the onset of Alzheimer's may also reduce people's ability to work out, thereby reducing activity levels and leading to a lowered brain mass.

Burns says that people with early-stage Alzheimer's might be able to preserve their cognitive function longer if they exercise.

The study is published in July 15 issue of the journal Neurology.