Study Reveals Mid-Life Exercise Cuts Dementia Risk Nearly Half

Published in The Journal of the American Medical Association (JAMA), the findings underscore the critical power of exercise in maintaining brain health as we age.

The study grouped participants into young adults, mid-life (45-64 years), and late-life (65 and older) categories, recording 567 cases of dementia by the study’s end. Physical activity was measured using a Physical Activity Index that counted hours spent in different intensities, from sedentary to vigorous.

Those with the highest activity levels in mid-life experienced a 41% lower risk of all-cause dementia, while late-life high activity was associated with a 45% reduced risk. Even moderate activity conferred significant protection, reducing dementia risk by 35-38%.

Crucially, the study also explored genetic risks related to the APOE e4 variant, a strong predictor of Alzheimer's. Non-carriers who exercised the most during mid-life achieved nearly 50-60% lower dementia risk, and late-life high activity led to a 46% risk drop. For APOE e4 carriers, late-life physical activity reduced dementia risk by an impressive 66% compared to inactive peers.

Researchers explained that exercise may slow amyloid protein accumulation—a hallmark of Alzheimer’s—while promoting growth and connectivity of neurons in the hippocampus, the memory center of the brain.

Given the rising global burden of dementia and limited pharmaceutical options, this study provides powerful evidence that regular physical activity during critical adult life stages is a practical, low-cost strategy to protect cognition and delay dementia onset.

REFERENCE: Marino FR, Lyu C, Li Y, Liu T, Au R, Hwang PH. Physical Activity Over the Adult Life Course and Risk of Dementia in the Framingham Heart Study. JAMA Netw Open. 2025;8(11):e2544439. doi:10.1001/jamanetworkopen.2025.44439