July 15, 2026
Staying physically active in your 30s and 40s may have brain benefits for decades to come, according to a new report. The study found that people who began an exercise program in their early-to-middle adult years had more robust brains than their inactive peers.
The study, in the Journal of Health and Sport Science, looked at 130 men and women who ranged in age from 26 to 58. Most were in their 30s and 40s. None were regular exercisers. All got thorough medical check-ups at the start of the study, including assessment of their aerobic fitness, blood pressure, body mass index and other health measures.
Participants also had MRI brain scans to assess their so-called brain age. Brain age refers to the biological age of the brain, which may be older or younger than someone’s actual, chronological age. By measuring brain features such as the volume of white matter and gray matter, the presence of brain lesions, and how well blood circulates in the brain, scientists can determine whether your brain appears to be older or younger than the brains of others your age.
Having a young brain age, especially one that is lower than your chronological age, is associated with better memory and thinking skills years down the road, and a lower risk of developing Alzheimer’s disease and other forms of dementia. Conversely, an older brain age is associated with worse cognitive function and a greater risk of Alzheimer’s.
The researchers, from the AdventHealth Research Institute in Orlando, Florida, then randomly divided the study volunteers into two groups.
Half were assigned to a supervised exercise program where they came to a lab twice a week for an hourlong aerobic exercise session using treadmills and stationary bikes. The exercise was moderate to vigorous in intensity, generally involving brisk walking, jogging or cycling. Volunteers in the exercise group supplemented the lab sessions with home exercise, so that they got at least 150 minutes per week of moderate to vigorous exercise.
The rest of the volunteers continued their customary routines, with no special exercise program, and served as controls.
After a year, the researchers again assessed their health. Not surprisingly, those in the exercise group showed improvements in their aerobic fitness, though there was little to no improvement in other health measures like blood pressure and body mass index. The exercisers, however, showed brain changes that surprised the researchers. Their brains appeared “younger” on brain scans. While the brains of those in the inactive control group showed modest increases in biological age, the exercise group had lowered their brain age by an average of about seven months.
Though the study was small and more research is needed, the findings suggest that the early and middle adult years may be a critical time to help build a more robust brain. Exercising early in life, the study suggests, may help fortify the brain against chronological aging and, years down the road, possibly protect against the ravages of a disease like Alzheimer’s, although this was not directly assessed in this study.
The findings add to growing evidence that regular exercise throughout life can help to keep the brain young. Most previous studies of the effects of exercise on brain health have involved older adults, in midlife or beyond. Earlier research from the same group, for example, found that adults in their 60s who undertook a yearlong program of walking increased the volume of their hippocampus, a brain region critical for memory. A more robust hippocampus is associated with a lower risk of developing Alzheimer’s.
This study looked at younger adults, and builds on earlier research showing that exercise, in many forms, is good for the aging brain. Maintaining a consistent exercise program throughout adulthood, the findings suggest, may produce a functionally “younger” brain that provides resilience against age-related brain changes, potentially lowering the risk of Alzheimer’s disease and other forms of dementia decades down the road.
By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by Eric Schmidt, PhD, of The Fisher Center lab at The Rockefeller University.
Source: Lu Wan, Cristina Molina-Hidalgo, Mary E. Crisafio, et al: “Fitness and exercise effects on brain age: A randomized clinical trial.” Journal of Sport and Health Science, December 2026
