Posted: Feb 5, 2013 8:24 PM
"We already know exercise has cardiovascular and many other benefits, but this may give people more incentive to get moving," says researcher Laura F. DeFina, MD, from The Cooper Institute in Dallas, Texas. "Dementia is the second most feared disease after cancer, and our research suggests you can lower your risk by keeping fit."
The study is published in the Feb. 5 issue of the Annals of Internal Medicine.
The study included nearly 20,000 people. They received standardized fitness testing around the age of 50, and were then followed for an average of 25 years.
There were 1,659 cases of dementia reported. After taking other factors into account, people with the highest fitness level at midlife had a 36% lower risk of developing dementia than those in the lowest fitness category.
"The long follow-up time in our study is essential, as there is evidence that changes on the brain may begin up to 20 years before dementia starts to become evident," DeFina says.
While this was a study of fitness -- rather than how much someone exercised -- the results were consistent with U.S. physical activity guidelines, DeFina says. Those guidelines recommend 150 minutes of moderate exercise or 75 minutes of vigorous activity per week.
The researchers say while it is best to get fit early in life and keep it up throughout life, people who start later may still benefit.
"It is never too late to improve fitness. If you're not 49, there are still functional benefits of being active in your later years," DeFina says.
Adds researcher Benjamin L. Willis, MD, MPH: "The best time to plant a tree is 20 years ago, but the second best time is today."