A new study by scientists from the University of Edinburgh in Scotland suggests exercise may protect the aging brain better than mental or leisure activity. It finds that volunteers in their 70s who exercised more had less brain shrinkage and fewer signs of decline in memory and thinking skills when they underwent brain scans a few years later.

First author Alan Gow, from Edinburgh’s Centre for Cognitive Ageing and Cognitive Epidemiology, and colleagues, write about their findings in the 23 October online issue of Neurology.

The study covered 691 research volunteers from the Lothian Birth Cohort 1936, which means they were all born in 1936, and had been undergoing tests of their cognitive performance, such as memory and thinking ability, as they aged.

From responses to questionnaires the participants filled in at the age of 70, the researchers assessed their levels of physical activity, how often they took part in leisure activities, and their intellectual pursuits.

Then three years later, the participants underwent MRI brain scans from which the team could see if there were any structural features that are normally associated with cognitive decline.

The results showed less brain shrinkage in those participants who reported higher levels of physical activity three years earlier. (To assess brain shrinkage, the researchers compared the scans they took with estimates of the volunteers’ brain sizes when they were younger).

The brain scans of the higher exercisers also showed fewer structural features normally associated with reduced memory and thinking skills.

The structural features the researchers examined included white matter integrity (for which they measured “fractional anisotropy (FA) and mean diffusivity” in a dozen places); plus atrophy, gray and normal-appearing white matter (NAWM) volumes, and white matter lesion ( WML) load.

“A higher level of physical activity was associated with higher FA, larger gray and NAWM volumes, less atrophy, and lower WML load. The physical activity associations with atrophy, gray matter, and WML remained significant after adjustment for covariates, including age, social class, and health status,” they write.

Another interesting result was there appeared to be no significant link between mental or leisure activity and signs of aging on the brain scans.

The researchers conclude:

“In this large, narrow-age sample of adults in their 70s, physical activity was associated with less atrophy and WML. Its role as a potential neuroprotective factor is supported; however, the direction of causation is unclear from this observational study.

” Simon Ridley, Head of Research at Alzheimer’s Research UK, says in a statement:

“This study links physical exercise to fewer signs of ageing in the brain, suggesting that it may be a way of protecting our cognitive health. While we can’t say that exercise is the causal factor in this study, we do know that exercise in middle age can lower the risk of dementia later in life.”

He emphasizes the importance of following the volunteers to see if these structural features are tied to greater cognitive decline over the coming years.

Ridley also calls for more studies to take a detailed look at how physical activity might slow cognitive decline.

“We need to understand more about the risk factors of cognitive decline, but this knowledge can only come through research. We must continue to support dementia scientists to provide the answers,” he urges.

Written by Catharine Paddock PhD