Decomposing the within-person and between-person sources of variation in physical activity-cognition associations for low-active older adults.

OBJECTIVES

To examine within-person and between-person sources of variation in the relationship between physical activity and cognition in older adults participating in a walking program. To explore whether demographic, health and fitness variables, and their interactions with activity, are significant predictors of cognition.

DESIGN

Brief longitudinal burst design.

PARTICIPANTS

118 participants (91 females, mean age = 72.81 + 5.24 years).

MAIN OUTCOME MEASURES

Cognition, self-reported moderate-to-vigorous walking and self-reported moderate-to-vigorous physical activity were assessed at baseline and 6, 9, 12 and 16 weeks follow-up. Attendance at weekly walks was also recorded.

RESULTS

Within-persons, changes in physical activity were related to select measures of executive functioning, with increased activity predictive of better cognition (three of four cognitive functions, p<.05). Between-persons, activity was also associated with cognition (two of four cognitive functions, p<.05). Younger age and higher education were related to better cognition. Interactions of demographic, health, and fitness variables with changes in within-person activity were generally non-significant.

CONCLUSION

The results highlight the importance of distinguishing within- from between-person effects in longitudinal analyses of the association between physical activity and cognition. This stringent within-person test of association underscores the potential value of simple physical activity interventions for improving cognitive function.