Exploring the relative contributions of multiple modifiable physical attributes to executive function and episodic memory performance in older adults

Background: The majority of studies examining the relationship between fitness and cognition examine a single physical attribute. Here, we assessed the relative contributions of multiple modifiable physical attributes and demographic variables to cognition in healthy older adults.Methods: Older adults (N = 619; mean age = 74.9, SD = 6.9) completed multiple physical attribute assessments (walking speed, respiratory function, grip strength, BMI) and cognitive tasks as part of the Health and Retirement Study. Principal components analysis was used to create cognitive composite scores, which revealed two domains: executive functions/processing speed and episodic memory. Lindeman, Merenda, and Gold analysis was employed to assess the relative importance of demographic and modifiable physical attributes to each cognitive domain.Results: Age, education, walking speed, and respiratory function explained the greatest amount of variance in the relative importance analysis for both executive functions/processing speed and episodic memory. Modifiable variables, including walking speed and respiratory function, accounted for similar amounts of variance as age and education in predicting executive functions/processing speed performance. After controlling for demographic variables, modifiable physical performance variables of walking speed and respiratory function collectively accounted for an additional 9.9% and 3.3% variance in executive functions/processing speed and episodic memory, respectively.Conclusions: These results indicated that modifiable physical performance variables are differentially associated with cognitive performance. Fitness indicators can account for similar amounts of variance as age in executive functions/processing speed in healthy older adults.