"We found that older adults who were sedentary throughout the study had the lowest levels of cognitive function at the beginning and experienced the fastest rate of cognitive decline," Barnes said. "Cognitive decline also was faster in those whose physical activity levels consistently declined during the study period."
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Maintaining or Increasing Activity Levels May Slow Cognitive Decline in Elderly
Studies have found that older adults who are physically active may experience slower rates of cognitive decline. Less is known about the impact of changes in physical activity levels on rate of cognitive decline.
Deborah E. Barnes, PhD, MPH, Assistant Professor of Psychiatry at the University of California, San Francisco, and a geriatrics researcher at the San Francisco VA Medical Center, and colleagues studied changes in levels of both physical activity and cognitive function over seven years in 3,075 white and black elders aged 70-79 years in the Health, Aging and Body Composition Study. Physical activity was assessed based on self-reported number of minutes walked per week at the beginning of the study and after two, four, and seven years of follow-up. Participants were classified at each time point as sedentary (0 minutes per week), low (less than 150 minutes per week) or high (150 minutes per week or more). Changes over time were classified as consistently sedentary, maintaining (low or high), decreasing, or increasing/fluctuating. Cognitive function was assessed using the 3MS.
The researchers found that 21% of study participants were consistently sedentary, 12% maintained their activity levels, 26% had declining levels, and 41% had increasing or fluctuating levels. After adjustment for age, sex, race, education, study site, diabetes, hypertension, smoking, alcohol consumption and baseline 3MS score, they found that the mean rate of decline in 3MS scores was 0.62 points/year in those who were consistently sedentary, 0.54 points/year (p=0.30) in those with declining activity levels, 0.44 points/year (p=0.01) in those with increasing/fluctuating activity levels, and 0.40 points/year (p=0.04) in those who maintained their activity levels.
"We found that older adults who were sedentary throughout the study had the lowest levels of cognitive function at the beginning and experienced the fastest rate of cognitive decline," Barnes said. "Cognitive decline also was faster in those whose physical activity levels consistently declined during the study period."
According to the researchers, sedentary elders who began new aerobic exercise programs experienced improvements in cognitive function, especially the ability to process complex information quickly. "Sedentary individuals should be encouraged to engage in physical activity at least occasionally," Barnes said. "People who are currently active should be encouraged to maintain or increase their activity levels."
Deborah Barnes, et al – The impact of changes in physical activity levels on rate of cognitive decline in a biracial cohort of non-demented elders (Funder: National Institutes of Health)
Bob DeMarco is an Alzheimer's caregiver and editor of the Alzheimer's Reading Room. The Alzheimer's Reading Room is the number one website on the Internet for advice and insight into Alzheimer's disease. Bob taught at the University of Georgia, was an executive at Bear Stearns, the CEO of IP Group, and is a mentor. He has written more than 700 articles with more than 18,000 links on the Internet. Bob resides in Delray Beach, FL.
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