Long-term associations between the stability of physical activity trajectories and depressive symptom trajectories among middle-aged and older adults: A multi-trajectory modeling analysis using China Health and Retirement Longitudinal Study data

BACKGROUND: Although the positive effects of physical activity on depressive symptoms are well established, research on the dynamic relationship between long-term physical activity patterns and depressive symptom trajectories remains limited. OBJECTIVE: This study examines the long-term associations between physical activity and depressive symptom trajectories in adults aged 50 and older and explores potential gender differences. METHODS: Data were drawn from the China Health and Retirement Longitudinal Study (2011-2020), comprising 4103 participants aged 50 and older. Physical activity and depressive symptoms were assessed using the International Physical Activity Questionnaire and the 10-item Center for Epidemiologic Studies Depression Scale, respectively. Group-based trajectory modeling was employed to identify long-term patterns of physical activity and depressive symptoms. Multinomial logistic regression was performed to examine associations between trajectory groups, including interaction terms and gender-stratified analyses. RESULTS: The moderate-stable-increasing and moderate-stable-decreasing trajectories were significantly associated with a reduced risk of high depressive symptom trajectories (OR = 0.58, CI: 0.46-0.73; OR = 0.50, CI: 0.37-0.66). In contrast, the low-fluctuating-increasing trajectory was significantly associated with an elevated risk (OR = 2.48, CI: 1.74-3.52). Gender-stratified analyses revealed that the low-fluctuating-increasing trajectory was associated with a higher risk of high depressive symptoms in both men and women, whereas the moderate-stable-decreasing trajectory was linked to a lower risk across both sexes. Importantly, the moderate-stable-increasing trajectory was associated with reduced risk only in women. CONCLUSION: Moderate and stable physical activity trajectories are associated with reduced high depressive symptom risk, with stronger associations observed in women.