People who are physically active appear to be at lower risk for cognitive impairment late in life, and for women, a new study suggests, physical activity during the teenage years may provide the greatest benefit.

The study used data about 9,395 women 65 and older, most of them white, who participated in a multicenter study of osteoporotic fractures. They were asked whether they had been physically active on a regular basis during their teenage years and at ages 30, 50 and later. Their cognitive function was also assessed.

Those who had been active regularly at any age were at lower risk for impairment in later life, but the greatest benefit was for those who had been active in their teens. Only 8.5 percent of those active during adolescence were cognitively impaired later on, compared with 16.7 percent of those who had been inactive teenagers. After adjusting for differences between the groups and risk factors like diabetes, researchers concluded that physical activity during the teenage years was associated with a 35 percent lower risk for cognitive impairment later in life.

The study was published in the Journal of the American Geriatrics Society.

“People often separate the body and mind, and forget that physical activity is actually controlled by the brain,” said Laura E. Middleton, the study’s lead author and a postdoctoral fellow at the Heart and Stroke Foundation Center for Stroke Recovery at Sunnybrook Health Sciences Center in Toronto. “A large portion of the brain is dedicated toward coordinating and controlling movement.”