Social and digital engagement associated with reduced depressive symptoms in adults aged 50 and older: a multi-country cohort study

BACKGROUND: Social participation and digital use are associated with reduced depression risk among older adults, but most supporting evidence does not consider both time-invariant and time-varying confounders and is inconsistent. We aimed to evaluate the impact of social participation and digital use on the incidence of depressive symptoms among older adults by a multi-country cohort considering both time-invariant and time-varying counfounders. METHODS: We used data from four nationally representative observational studies across 18 countries (2008-2021): the Health and Retirement Study (HRS), the Survey of Health, Aging and Retirement in Europe (SHARE), the China Health and Retirement Longitudinal Study (CHARLS), and the Mexican Health and Aging Study (MHAS). Participants aged 50 years or older without depressive symptoms at baseline and without related behaviors pre-baseline were included. Interested exposure social participation and digital use were measured by specific questions. Depressive symptoms were assessed using the Center for Epidemiologic Studies Depression Scale (CES-D) and the European Depression Scale (EURO-D). Targeted maximum likelihood estimation method was applied to estimate adjusted relative risks (RRs) and 95% confidence intervals (CIs) for the long-term impact of exposure on depressive symptoms onset. RESULTS: A total of 69,186 eligible participants were included. At baseline, 77.0%, 44.0%, 34.2%, and 49.8% of participants were exposed to social participation in HRS, SHARE, CHARLS, and MHAS, respectively, and these proportions were 55.7%, 55.9%, 4.5%, and 69.9% for digital use exposure. During follow-up, a total of 18,245 (26.4%) individuals developed depressive symptoms. The RRs (95% CI) of depression risk under social participation versus no social participation were 0.80 (0.68-0.93) in HRS, 0.80 (0.74-0.87) in SHARE, 0.86 (0.77-0.96) in CHARLS, and 0.93 (0.85-1.02) in MHAS. Compared with no digital use, the RRs (95% CI) of depression risk under digital use were 0.88 (0.72-1.08) in HRS, 0.85 (0.77-0.93) in SHARE, 0.75 (0.60-0.92) in CHARLS, and 0.88 (0.79-0.98) in MHAS. CONCLUSIONS: Engagement in social participation and digital use are associated with a reduced incidence of depressive symptoms in older adults. In the digital world, besides social participation, promoting digital use for social connection may be an effective strategy for depression prevention in ageing populations.