Longitudinal associations of trajectories of physical activity and sitting time with depression during middle-to-older adulthood

OBJECTIVES: Vulnerability to depression symptoms often increases from late middle adulthood into older adulthood and can significantly impact daily functioning. Modifiable lifestyle behaviours may support mentally healthy ageing, but changes in physical activity, sitting time, and depression symptom trajectories across middle-to-older adulthood are not well understood. Understanding whether these trajectories change together may identify modifiable behavioural patterns linked with depression symptoms over time. METHOD: = 1190), assessed on three occasions spanning 11 years, this study examined associations between trajectories of physical activity, sitting time, and depression symptoms using latent growth modelling. RESULTS: Trajectories of increasing physical activity were associated with trajectories of decreasing depression symptoms over time. However, change in sitting time was not associated with change in depression symptoms. CONCLUSION: Findings contribute to the limited evidence on longitudinal associations between modifiable lifestyle behaviours and mental wellbeing among middle-aged and older adults and may inform research examining causal pathways linking physical activity and depression. If replicated in studies designed to test causal mechanisms, these findings may have implications for future physical activity guidance and clinical or public health approaches.