Association between socioeconomic status and healthy lifestyle with depressive symptoms in older adults: Evidence from five prospective cohort studies.

Introduction: Depression is a common illness that may severely limit psychosocial functioning and diminish quality of life. The complex interplay between socioeconomic status (SES), lifestyle behaviors, and depression remains insufficiently elucidated. This study aimed to investigate whether healthy lifestyles mediate the relationship between SES and depression.

Methods: Data were drawn from five nationally representative cohort studies across 20 countries between 2008 and 2018: the Health and Retirement Study (HRS), the English Longitudinal Study of Ageing (ELSA), the Survey of Health, Ageing and Retirement in Europe (SHARE), the China Health and Retirement Longitudinal Study (CHARLS), and the Korean Longitudinal Study of Aging (KLoSA). SES was derived using latent class analysis of education, income, and wealth. A composite healthy lifestyle score, based on smoking, alcohol consumption, physical activity, and social participation, categorized participants into unfavorable, intermediate, or favorable lifestyle groups. Depression was assessed using CES-D or EURO-D scales. Cox proportional hazards models, with random-effects models for pooling, were used to examine the association between SES and depressive symptoms. Causal mediation analysis evaluated the mediating roles of intermediate and unfavorable lifestyles in the SES-depression relationship. Analyses were conducted in 2025.

Results: Of 48,760 participants, 14,320 developed depressive symptoms. Low SES was associated with higher depression risk (pooled HR 1.41, 95% CI 1.37-1.45). Unfavorable lifestyle mediated 62.8% of the SES-depression association, and intermediate lifestyle mediated 6.0%. The highest risk was observed in those with both low SES and unfavorable lifestyle (pooled HR 2.47, 95% CI 2.34-2.60).

Conclusions: Unfavorable lifestyle substantially mediated the association between low SES and depression, highlighting the importance of lifestyle interventions to reduce socioeconomic disparities. Country-level heterogeneity underscores the need for context-specific strategies.