Physical activity and depression in older adults: the knowns and unknowns.

This study provides a comprehensive and updated review of the literature with respect to the relationship between physical activity and depression in older adults. The evidence from both observational studies and experimental studies are collected to present a discussion on the type and dose of physical activity, as well as the underlying mechanisms of physical activity and depression in older adults. Overall, the results from previous studies support a solid inverse relationship between physical activity and depression in older adults, while the dose-effect relationship between them, as well as different effects among different types of physical activities, remains largely unexplored. Depression in older adults is related to an array of negative health outcomes and is more chronic compared to that in younger adults. Physical activity has been regarded as a promising non-pharmaceutical method in treating and preventing depression in older adults. Further experimental work and research need to be done to develop theoretically grounded and evidence-based interventions to better advance our knowledge of this topic and effectively promote physical activity in older adults.