A new large-scale study suggests that even a small amount of weekly exercise may increase brain volume and slow age-related memory decline.

Researchers analyzed more than 10,000 brain scans from adults aged 18 to 97 and compared the images with participants' reported levels of physical activity.

They discovered that people who engaged in moderate exercise — such as walking, cycling, or swimming — for just 25 minutes a week had noticeably larger brain volume than those who did not exercise at all.

The differences were especially significant in regions involved in thinking and memory, including the hippocampus, which usually shrinks as we age and is linked to cognitive decline and dementia.

Exercisers also showed greater grey and white matter volume, suggesting healthier communication between brain cells.

Although the study was correlational rather than experimental, researchers believe exercise likely plays a direct role by reducing inflammation and stimulating chemicals that encourage the growth of new neurons and blood vessels.

This process may create what they call a "structural brain reserve", meaning the brain starts aging from a stronger baseline.

Notably, moderate exercise appeared more beneficial than vigorous workouts, though any physical movement provided advantages. As one researcher concluded, it is never too early — or too late — to start, and even minimal activity may meaningfully support long-term brain health.