The association between trajectories of physical activity and depression among older adults in China: an empirical study based on CHARLS data

<title>Abstract</title> <p>Background Geriatric depression is a growing public health concern. Methods Using group-based trajectory models, we analysed data from five waves of the China Health and Retirement Longitudinal Study (CHARLS) from 2011 to 2020 to identify latent clusters and the characteristics of changes in physical activity over time during the follow-up period. Multivariable logistic regression models were employed to analyse the association between different physical activity trajectory types and depression, and sensitivity analyses were conducted. Subgroup analyses were conducted to explore differences in depression among older adults with distinct characteristics across different physical activity trajectories. Results A total of 4067 older adults were included in the study, and four physical activity trajectories were identified: the Sustained low group, the Initial low followed by rise group, the Initial high followed by decline group, and the Sustained high group.After adjusting for confounding factors, using the Sustained low group as the reference, the Initial low followed by rise group (OR = 0.585) and the Sustained high group (OR = 0.549) showed a significantly reduced risk of depression, while the Initial high followed by decline group did not demonstrate a significant protective effect; Subgroup analysis indicated that the protective effect was more pronounced among individuals aged ≥ 65 years and women, and the results were validated as robust through sensitivity analysis. Conclusion Both the initial low followed by rise and sustained high physical activity groups significantly reduce depression risk, with age and gender differences. Encouraging inactive older adults to increase physical activity may help prevent depression.</p>