A major new study suggests that people who stay physically active in midlife and beyond may dramatically reduce their risk of developing dementia, even if they are already in their 40s, 50s, or older. The research, published in JAMA Network Open, found that adults with the highest levels of physical activity between ages 45 and 64 had a 41% lower risk of dementia, while those who were most active between ages 65 and 88 experienced a 45% lower risk.
Researchers say the findings change how people should think about exercise and brain health. Instead of seeing physical activity as a general benefit, the data suggests that midlife and late life may be particularly critical windows for protecting the brain, especially as risk factors for stroke, heart disease, diabetes, and other conditions rise during these decades. Experts emphasize that movement supports vascular health and may help prevent damage that leads to cognitive decline.
The study involved more than 4,400 adults of different age groups who were part of the long-running Framingham Heart Study. Results showed no significant dementia risk reduction from activity during young adulthood. However, the protective effect in midlife and later years remained strong, even among those with genetic risk factors. Participants carrying the APOE ε4 gene, which increases the likelihood of developing Alzheimer’s disease, still saw a 66% reduction in dementia risk when they maintained high levels of physical activity.
Researchers assessed activity levels using a composite measure that factored in sleep, sedentary time, and different intensities of movement. While this approach limited the ability to recommend exact weekly exercise targets, earlier studies have suggested more specific guidelines. For instance, previous research shows that walking 3,800 steps a day can reduce dementia risk, and cycling as transportation has been linked with lower rates of Alzheimer’s.
Guidelines from the World Health Organization recommend that adults aim for 150 to 300 minutes of moderate exercise per week, or 75 to 150 minutes of vigorous activity. That could include brisk walking, running, cycling, and strength training. Experts urge beginners to start slowly to avoid injury and focus on building consistent daily habits, such as short walks before work or movement breaks during the day.
While the new study supports the protective role of exercise, researchers acknowledge limitations. Participants self-reported activity levels, which can be unreliable, and scientists lacked data on how habits changed across decades. Health specialists say studies using wearable trackers may provide clearer evidence in the future.
Experts believe exercise lowers dementia risk through several biological mechanisms. Movement strengthens blood vessels, reduces inflammation, supports healthier metabolism, and may slow the buildup of beta-amyloid proteins in the brain. These proteins are closely associated with Alzheimer’s disease.
The authors caution that people who exercise regularly may also engage in other healthy behaviors, so the relationship between movement and lower dementia risk is complex. Still, the results add to growing evidence that lifestyle choices can meaningfully influence brain health long before symptoms begin.
With dementia affecting roughly 57 million people globally and projected to triple by 2050, scientists say actionable behaviors are essential. For adults reconsidering their habits, experts recommend focusing on balance, gradual progress, and conversations with healthcare providers about individual risk.
