Deborah Barnes, PhD, MPH
July 13, 2009
Elders who maintained or increased their level of physical activity showed significantly less cognitive decline over seven years than those who were not active or whose activity levels declined during that time, according to a study led by researchers at the San Francisco VA Medical Center and the University of California, San Francisco.
Elders whose activity rates fluctuated at times but who ultimately stayed physically active over the course of the study also showed less decline.
The results were reported at the 2009 Alzheimer’s Association International Conference on Alzheimer’s Disease in Vienna, Austria by lead author Deborah E. Barnes, PhD, MPH, a geriatric researcher at SFVAMC and an assistant professor of psychiatry at UCSF.
The study looked at the self-reported activity levels of 3,075 white and African-American non-demented elders, age 70 to 79, living in Memphis, Tenn. or Pittsburgh, Pa. Half were women, and one fourth had not graduated from high school. Study participants reported the number of minutes they typically walked per week at the beginning of the study and then at intervals of two, four, and seven years.
At each time point, the participants were classified as sedentary (zero minutes per week), low activity (less than 150 minutes per week), or high activity (150 minutes per week or more), based on the Surgeon General’s exercise guidelines. Their level of cognitive function was also measured at each time point using the Modified Mini-Mental State Exam, a standard test with a maximum score of 100.
After seven years, the adjusted scores of the participants who were consistently sedentary declined by an average of .62 points per year, while the scores of those whose activity level decreased over seven years declined by an average of .54 points per year.
In contrast, participants whose activity levels increased either consistently or in a fluctuating pattern over time showed a decline of only .44 points per year. The scores of those who were consistently active declined only .40 points annually.
The results indicate that overall activity level is not as important as a long-term commitment to being active, according to Barnes. “If you follow the Surgeon General’s guidelines of exercising 30 minutes a day, five days a week some of the time but not all of the time, you’re probably OK as long as you resume being active, preferably as soon as possible,” she says. “The fact that people in the fluctuating activity group ranked with the increasingly active and consistently active groups was something of a surprise to us, albeit a pleasant one.”
Barnes says that the physical benefits of exercise and activity are well known, and notes a growing body evidence showing that physical activity also improves mental function. “However, until now, little was known about the impact of changes in physical activity levels on rates of cognitive decline,” she says. “This tells us that it’s important to maintain or increase your activity level in order to better sustain cognitive function as you age.”
Co-authors of the study were Eleanor M. Simonsick, PhD, and Tamara B. Harris, MD, MS, of the National Institute on Aging; Jennifer Brach, PhD, of the University of Pittsburgh; and Sandra K. Pope, PhD, MPH, of the University of Arkansas for Medical Sciences. The senior author was Kristine Yaffe, MD, of SFVAMC and UCSF.
SFVAMC has the largest medical research program in the national VA system, with more than 200 research scientists, all of whom are faculty members at UCSF.
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