Researchers have also shown that exercise can stimulate the human brain’s ability to maintain old network connections and make new ones that are vital to healthy cognition. In a year-long study, 65 older people exercised daily, doing either an aerobic exercise program of walking for 40 minutes or a nonaerobic program of stretching and toning exercises. At the end of the trial, the walking group showed improved connectivity in the part of the brain engaged in daydreaming, envisioning the future, and recalling the past. The walking group also improved on execu­tive function, the ability to plan and organise tasks such as cooking a meal.

Several other clinical trials are exploring further the effect of physical activity on the risk of Alzheimer’s and cognitive decline. Other NIA-supported research is examining whether exercise can delay the development of Alzheimer’s disease in people with MCI. Findings from these and other clinical trials will show more definitively whether exercise helps protect our brains from cognitive impairment.