The most fit middle-age adults are much less likely to develop dementia in their senior years than those who are the least fit at midlife, according to a new study by The Cooper Institute, Cooper Clinic and UT Southwestern Medical Center researchers.
The research was published in the current edition of Annals of Internal Medicine and released Tuesday.
The study followed more than 19,000 healthy men and women who completed a preventive medical exam at Cooper Clinic in Dallas at an average age of 49. The exam also included an assessment of other health risk factors such as body mass index (BMI), blood pressure, and cholesterol. Their health status was evaluated using Medicare data between 1999 and 2009, an average of 24 years after their Cooper Clinic examination.
The researchers divided the participants into those who were most and least fit, defined asthe amount of time people ran on a treadmill. The fittest subjects ran the equivalent of a seven-minute mile during the treadmill test, while the least fit jogged the equivalent of a 12-minute mile.
They followed the participants beyond age 65 years to see who would develop dementia, which is progressive loss of memory and thinking that usually affects older adults. The researchers then compared the number of people who had dementia among the most and least fit.
The researchers used the Cooper Center Longitudinal Study (CLSS) database that contains more than 250,000 records from almost 100,000 individuals representing more than 1,800,000 person-years of observation. The CCLS is one of the most highly referenced databases containing more than 3,000 variables and considered the world’s foremost repository of information on fitness. The data collection began with founder Dr. Kenneth Cooper’s first patient in December 1970.
They concluded that higher midlife fitness levels were associated with lower hazards of developing Alzheimer disease and other types of dementia in men and women older than 65 years.
The researchers said greater fitness might be associated with lower dementia because it also lower risk for diabetes and hypertension, which also are risk factors for dementia. Higher fitness levels have been associated with greater brain volume, which may increase cognitive function and lower the risk of dementia, they said.
The risk of dementia did not appear to be affected by whether participants had had a stroke during the follow-up period, and nor did educational attainment appear to alter the results.
Other studies have established that midlife health and behaviors can influence future outcomes. Middle-age depression, smoking, and high body mass index, as well as other cardiovascular risk factors, have been linked to the risk for dementia in later life.
The researchers cautioned that the findings might be influenced by other healthy behaviors, such as healthy eating, that are common among physically fit people. The research also does not recommend a specific level of physical fitness that people can achieve to prevent dementia.
They noted the study’s strengths included a large sample size, a long follow-up period and the detailed Cooper Clinic medical history on each subject at midlife.
This study also specifically addressed fitness levels, which is an objective measure rather than self-reported behavior. A 2011 study reported that less than 10 percent of adults achieve the 150-minutes-per-week guideline recommended by the federal government. Researchers in that study used accelerometry and found that self-reported estimates of physical activity were six times greater than the actual measured activity.
“We’ve known that exercise is beneficial to brain health in the short-term,” said Laura DeFina, MD, of The Cooper Institute, and first author on the study. “What’s unique about this study is that it demonstrates the long-term, positive effect of fitness on the brain.”
“The exercise we do in middle-age is relevant for not only how long we live, but also how well we live. This data provides insight into the value of lifelong exercise and its protection against dementia in older age,” said co-author Jarett Berry, MD, of UT Southwestern Medical Center, in a statement. “The fear of dementia in later life is real, and the possibility that exercise earlier in life can lower that risk is an important public health message.”
Alzheimer’s is the second most-feared disease among U.S. adults, behind only cancer, according to a 2011 survey by MetLife Foundation.
Besides DeFina and Berry, other Dallas-based authors included Benjamin Willis, MD, and David Leonard, PhD, of The Cooper Institute; Nina Radford, MD, of Cooper Clinic; and Myron Weiner, MD, and Ang Gao, MS, of UT Southwestern Medical Center.
Many of that same team used the CLSS in a study last fall in the Archives of Internal Medicine that suggested middle-age fitness had a greater impact on preventing chronic disease than overall survival.
DeFina said the research team has other studies about to be published on healthy aging.
“We know being fit is good for you. The next generation of research is: Why is it good for you? We’re trying to find the right message that gets the public off the couch. What is the driver that helps to get people to move?” she said.
The researchers recommended future studies should seek to determine the ideal amount of physical activity to prevent dementia.
The study was funded by the UT Southwestern, the National Heart, Lung and Blood Institute, and the American Heart Association.
Steve Jacob is editor of D Healthcare Daily and author of the new book Health Care in 2020: Where Uncertain Reform, Bad Habits, Too Few Doctors and Skyrocketing Costs Are Taking Us. He can be reached at firstname.lastname@example.org.