Does physical activity moderate the association between depressive symptoms and disability in older adults?

OBJECTIVE: Depressive symptoms and disability are closely associated and known to have reciprocal relationships. This study examines whether physical activity moderates the association between depressive symptoms and disability in community-dwelling older adults.
METHODS: Baseline and 1-year follow-up data of 645 persons aged 65 years or older from the Suwon Longitudinal Aging Study were analyzed. A 15-item Geriatric Depression Scale, Physical Functioning scale, and physical performance tests were used to assess the individual's depressive symptoms and functional disability. Physical activity was defined as the recommended level of exercise based on its frequency and intensity. Multiple regression analysis with generalized estimating equations was conducted to examine the physical activity's role as an effect modifier in the association between depressive symptoms and disability.
RESULTS: Physical activity was a significant effect modifier in the 'depressive symptoms-disability' association, controlling for sociodemographic characteristics and health-related covariates. Moderate-intensity activity was as effective as vigorous activity in moderating the relationship. The moderating effect was notable among those displaying severe depressive symptoms and functional disability. Over time the strength of the association between depressive symptoms and disability tended to diminish for those engaging in physical activity.
CONCLUSION: The association between depressive symptoms and disability is moderated by physical activity in older persons. The findings suggest that healthcare professionals need to promote moderate amount of physical activity as a potential intervention tool in attenuating the depression-disability connection in later life, especially among those with high levels of physical and mental impairments.