Multimorbidity, cognitive function, and physical activity.

Previous research demonstrates that both physical activity and multimorbidity are associated with cognitive function. However, the extent to which physical activity may moderate the relationship between multimorbidity and cognitive function has not been thoroughly evaluated. Data from the 1999-2002 NHANES were used (60+ years; N = 2157). A multimorbidity index variable was created based on physician diagnosis of a multitude of chronic diseases. Physical activity was self-reported and cognitive function was evaluated from the digit symbol substitution test. Multimorbidity was inversely associated with cognitive function for the unadjusted and adjusted models. However, generally, multimorbidity was no longer associated with cognitive function for the majority of older adults who achieved the minimum recommended physical activity level (≥2000 MET-min-month), as issued by the United States Department of Health and Human Services. In this national sample of older adults, there was some evidence to suggest that physical activity moderates the relationship between multimorbidity and cognitive function.