The mediating effects of depressive symptoms on the association between hobby engagement and functional disability: evidence from three cohort studies.

BACKGROUND: Functional disability is a critical public health challenge in aging populations. While lifestyle factors have been extensively studied, the protective role of hobby engagement against functional decline remains underexplored. Thus, this study aimed to examine the association between hobby engagement and functional disability, as well as the potential mediating effects of depressive symptoms across three large international longitudinal cohort studies.

METHODS: We analyzed data from the China Health and Retirement Longitudinal Study (CHARLS), the Survey of Health, Ageing and Retirement in Europe (SHARE), and the Mexican Health and Aging Study (MHAS). Hobby engagement and depressive symptoms were self-reported by participants. Functional disability was assessed using standardized Activities of Daily Living (ADL) and Instrumental Activities of Daily Living (IADL) measures. Cox proportional hazards models and General linear mixed models were employed to examine the associations between hobby engagement and functional disability incidence and progression. Mediation analysis was used to explore the role of depressive symptoms.

RESULTS: Across all three cohorts, hobby engagement demonstrated consistent negative associations with both ADL and IADL disability. In the fully adjusted models, hobby engagement was associated with a reduced risk of ADL disability (CHARLS: HR = 0.77, 95% CI: 0.70-0.84; SHARE: HR = 0.73, 95% CI: 0.67-0.80; MHAS: HR = 0.82, 95% CI: 0.73-0.92) and IADL disability (CHARLS: HR = 0.70, 95% CI: 0.63-0.77; SHARE: HR = 0.65, 95% CI: 0.60-0.72; MHAS: HR = 0.68, 95% CI: 0.60-0.78). The mixed-effects models showed that hobby engagement was associated with a significantly slower rate of annual functional decline (For ADL, β for Time × Hobby interaction: -0.019 in CHARLS, -0.029 in SHARE, and - 0.025 in MHAS; For IADL, β for Time × Hobby interaction: -0.014 in CHARLS, -0.032 in SHARE, and - 0.027 in MHAS). The protective effect of hobby engagement was partially mediated by depressive symptoms, with the mediation proportion of 25.20% in CHARLS, 21.05% in SHARE, 32.25% in MHAS for ADL disability and 14.52% in CHARLS, 13.80% in SHARE, and 12.53% in MHAS for IADL disability.

CONCLUSION: Hobby engagement may protect against functional disability across diverse populations and cultural contexts. This effect was partially explained by the alleviation of depressive symptoms.