Timing of daily physical activity and onset of depressive symptoms: A longitudinal cohort study of community-dwelling older adults

BACKGROUND: Late-life depression is a major public-health concern. Although physical activity is protective, the longitudinal association of physical-activity timing on depressive-symptom onset in older adults remains unclear. We examined the association of physical activity timing with depressive symptoms in older adults. METHODS: This study included 2542 community-dwelling adults aged ≥60 years from the NCGG-SGS cohort who were free of depressive symptoms at baseline. Physical activity was measured using an accelerometer and summarized in three-hour intervals. Functional principal component analysis classified participants into early and late active groups. Depressive symptoms (GDS score ≥5) were assessed after 26.4 months. Risk differences were estimated using inverse probability and overlap weighting, adjusting for demographic, health, and lifestyle factors. RESULTS: Depressive symptoms developed in 14.7% of participants. The late active group (activity peak in the afternoon) had a lower incidence (10.1%) than the early active group (16.1%). After inverse probability weighting, the risk difference was -3.9% (95% CI: -7.0% to -0.8%, P= 0.009). After overlap weighting, the risk difference was -3.5% (95% CI: -6.6% to -0.4%, P= 0.011). Subgroup analyses showed consistent results across age, sex, and activity levels. CONCLUSIONS: A late active pattern was associated with a reduced risk of depressive symptoms in older adults. Timing of daily activity should be considered in depression-prevention strategies.