Impact of diversified social interaction on elderly health in China: a longitudinal analysis based on interaction type and frequency

Background Among the social determinants of health, social interaction is an important modifiable factor and an essential component of the global active ageing strategy. This study examines the impact of different types and frequencies of social interaction on the health outcomes of elderly adults in China, adjusting for simultaneity and heterogeneity biases. Methods This study used data from the Chinese Health and Retirement Longitudinal Study, a five-wave panel survey conducted in 2011, 2013, 2015, 2018, and 2020, with 38,420 observations from 7,864 individuals aged 60 and older. We classified activities into three types: leisure-based individual interaction, community-based organisational interaction, and responsibility-driven caregiving interaction to capture the diversity of social interaction. Generalised estimating equation regression models were used to examine the associations between one- or two-wave-lagged social interaction and health outcomes (self-rated health, mental health, cognitive function, and diagnosed diseases). Random-effects estimation addressed individual-level heterogeneity. The 2SLS model was applied to examine the mutual causality relationship between interaction frequency and health, followed by a robustness test. Results Social interaction had a positive impact on elderly health, particularly in the medium- to long-term. One-wave-lagged interaction showed improved self-rated health (b=0.014, P <0.05), reduced mental distress (b=-0.232, P <0.01), and enhanced cognitive function (b=0.233, P <0.001) , with no effect on disease status. Leisure and community-based interactions significantly benefited physical and mental health, while responsibility-driven interactions improved cognition but increased mental distress. Interaction frequency was positively associated with health, with better access to facilities and public transport boosting interaction frequency. Living with children or a spouse, employment status and income level are also protective factors for health. Conclusion Active social interaction, regular participation in leisure activities, organized social activities, and informal social interactions have beneficial effects on health of older adults. Policies should prioritize supportive environments and age-friendly community renovations, while families and society should strengthen internal and external support systems to foster active and healthy aging.