Adults with more social ties have slightly lower inflammation across 50 studies

Social role participation is theorized to relate to physical health through systemic inflammation. We conducted a meta-analysis quantifying the association between social role participation and systemic inflammatory markers. Specifically, we synthesized studies assessing social integration (the degree of participation in a variety of social relationships) and social isolation (having few to no social ties), two indicators of social role participation. We further evaluated whether the association between social participation and inflammation followed graded or threshold patterns and whether its magnitude varied across adult development. A systematic search identified 50 articles, contributing 77 effect sizes. Meta-analyses were conducted using random effects models with robust variance estimation and controlled for study quality and effect size conversion confidence. Results indicated that greater social role participation was associated with lower inflammation (age-unadjusted r = -.054, p < .001; age-adjusted r = -.037, p < .001). Moreover, we found evidence for a graded pattern, such that compared to the most isolated group, increasingly integrated groups showed progressively stronger inverse effect sizes with inflammation (b = -.04, p = .017). We found weak evidence that the magnitude of the social role participation-inflammation link was moderated by age. In a subset of the analyses, this link was stronger for older (vs. younger) samples. However, this only emerged in the model that also adjusted for other study characteristics (e.g., inflammatory marker, study design). This review is the first to synthesize evidence across social integration and isolation, showing that greater social role participation is associated with progressively lower levels of inflammation.