Age differences in the longitudinal associations of leisure-time physical activity and depressive symptoms with cognitive decline in older Taiwanese

Objectives: The associations of physical activity and depressive symptoms with cognitive decline are likely age dependent. The study was therefore aimed to investigate the age differences in the associations of leisure-time physical activity (LTPA) and depressive symptoms with cognitive decline in older Taiwanese. Method: A total of 3545 participants, age >= 50, from 2003 (baseline) and 2007 (end-point) survey datasets were analyzed. Cognitive decline was defined as a decrease of two or more points on the Short Portable Mental Status Questionnaire. The long-term LTPA and depressive symptoms were the change of status between the two time-points. Multivariable logistic regression was conducted to evaluate the longitudinal associations, stratified by age. Results: Significant associations between all levels of long-term LTPA status and cognitive decline were observed for the older group (age >= 70), but not any for the younger group (age 50-69). Significant associations between long-term depressive symptoms status and cognitive decline were also found in all levels for the older group, but only in one level for the younger group. The two odds ratios of cognitive decline between the age groups were further found to be significantly different for those with active LTPA in both time-points (p=.005) and for those with depressive symptoms decreased (p=.014). Conclusion: The findings suggest that there are age differences in the longitudinal associations of LTPA and depressive symptoms with cognitive decline in older Taiwanese. Understanding the pattern of age differences could be helpful in preventing cognitive decline of the elderly.