Middle-aged people can reduce their risk of developing dementia and Alzheimer’s disease later in life by remaining physically active, according to a new study. Researchers found people who exercised at least twice a week in sessions lasting 20 minutes or more reduced their risk of developing Alzheimer’s disease by 60%, compared with those who did a small amount of training. The active group also lowered their odds of having dementia by 50%, reported the Lancet Neurology.