The relationship between cognitive and physical performance: MacArthur Studies of Successful Aging.

BACKGROUND: The relationship between change in cognitive and physical performance has yet to be fully understood. Because aging decreases the ability to learn new information while preserving more established knowledge, this article examines whether the association between change in cognitive and physical performance depends on the nature of the physical task.
METHODS: Data from the MacArthur Research Network on Successful Aging Community Study--a longitudinal three-site, cohort study of high-functioning, disability-free Americans aged 70 to 79 in 1988 (reinterviewed in 1991 and 1995)--are used for this investigation. We examine the association between change in cognitive performance and two categories of physical performance: novel/attentional demanding physical tasks (e.g., standing on a single leg) or routine physical tasks (e.g., walking at a normal pace). Change in physical performance (over 7 years) is regressed on change in cognitive performance (over the same period) controlling for baseline cognitive ability, demographic factors, health status, and behavioral characteristics.
RESULTS: The findings suggest that declines in cognitive performance are associated with declines in both novel/attentional demanding and routine physical tasks. In addition to decline in cognition, gender, prevalent health conditions (e.g., cancer, high blood pressure, and the fracture of a hip), and smoking behavior are associated with decline in performance on some physical tasks.
CONCLUSIONS: The findings suggest that the successful execution of physical tasks demands cognitive processes regardless of the nature of the task. Researchers using performance-based measures of physical functioning should pay particular attention to the cognitive capacities of their subjects and how these might influence their assessment.