August 28, 2013
Need more motivation to exercise? Being physically fit in middle age may lower your risk for Alzheimer’s disease later in life, a new study reports. The findings add to a large and growing body of evidence about the long-term benefits of physical activity on the brain.
The study involved more than 19,000 men and women who had visited a health clinic in Dallas, Texas, for routine health check-ups. All were in generally good health, and their heart and respiratory fitness was assessed using exercise treadmill tests. They were followed, on average, for more than 25 years.
The researchers used Medicare reports to determine whether someone was diagnosed with dementia in old age. They found that compared to those who were the least fit in middle age, the fittest patients were much less likely to develop Alzheimer’s or other forms of dementia in their 70s and 80s. Better fitness correlated with a lowered dementia risk, independent of illnesses like high blood pressure, diabetes and high cholesterol, which have also been linked to an increased dementia risk.
The results are consistent with some earlier reports that people who are healthier and fitter at midlife tend to be less likely to develop Alzheimer’s disease after age 65. One Canadian study involving 4,615 people, for example, found that those who are active are less likely to develop Alzheimer’s than those who are sedentary. Other reports have linked a lower dementia risk to specific activities like dancing.
The current study had several strengths, including a large pool of study participants. It also assessed physical fitness using exercise stress tests, a more reliable measure than relying on surveys that ask people how often they exercise.
The researchers say that exercise may benefit the brain through several pathways. Being more fit is associated with a lower risk of high blood pressure and diabetes, both of which may damage blood vessels in the brain. Physical fitness is also linked to a greater brain volume, which may help to protect against dementia. Exercise has also been linked to proteins produced in the brain that enhance the growth of new brain cells.
An accompanying editorial notes that despite ample evidence that physical activity is associated with many health benefits, it can be difficult to get patients to stick with exercise. Getting out the message that exercise may reduce the risk of Alzheimer’s, the second most feared disease after cancer, the author writes, may motivate people to get moving.
Source: Mary Sano, Ph.D.: “Never Too Fit for Body and Mind” (editorial). Laura F. DeFina, M.D.; Benjamin L. Willis, M.D., M.P.H.; Nina B. Radford, M.D. et al: “The Association Between Midlife Cardiorespiratory Fitness Levels and Later-Life Dementia.” Annals of Internal Medicine. Feb. 4, 2013.