The associations of socioeconomic status, social activities, and loneliness with depressive symptoms in adults aged 50 years and older across 24 countries: findings from five prospective cohort studies

Depression is the leading cause of mortality among mental health disorders. Evidence about the associations of socioeconomic status, social activities, and loneliness with depression is scarce. We aimed to identify whether social activities and loneliness mediate the association between socioeconomic status and depression, and the extent of interactive or joint relationships between social activities, loneliness, and socioeconomic status on depression.

In this population-based, cross-national cohort study we used data from five nationally representative surveys across 24 countries between Feb 15, 2008, and Feb 27, 2019: 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 Mexican Health and Ageing Study (MHAS). We included participants who were aged 50 years and older with reported information on socioeconomic status, social activities, and loneliness at baseline, and who had been assessed at least twice. We excluded participants with depressive symptoms at baseline; those with missing data on depressive symptoms and covariates; and those lost to follow-up. We defined socioeconomic status as high and low using latent class analysis based on family income, education, and employment status. Depression was assessed using the Center for Epidemiological Studies Depression Scale (CES-D) or EURO-D. We applied Cox proportional hazard models to estimate the association of socioeconomic status with depression. We used random-effects models to obtain pooled results. Joint and interactive effects of socioeconomic status, social activities, and loneliness on depression were explored, and the mediating roles of social activities and loneliness in the association between socioeconomic status and depression were explored using causal mediation analysis.