Evaluating the buffering vs. direct effects hypotheses of emotional social support on inflammatory markers: the multi-ethnic study of atherosclerosis.

Social support is associated with cardiovascular disease mortality, however, the physiologic mechanisms underlying this relationship remains unspecified. This study evaluated the association of social support with inflammatory markers associated with cardiovascular risk: C-reactive protein (CRP), interleukin-6 (IL-6), and fibrinogen. We evaluated two competing models of the support-inflammation relationship: first, that low social support is directly associated with inflammation, and second, that high support acts to buffer the effect of stress on inflammation. Using data from the baseline interview of the Multi-Ethnic Study of Atherosclerosis (N = 6814, 53% female, age 45-84 years) we assessed the independent and interacting associations of social support and stress with inflammation. Social support was measured by the emotional social support index. Stressors in multiple domains (work, family, finances, interpersonal) were assessed. Serum CRP, IL-6, and fibrinogen were analyzed from fasting samples using high-sensitivity assays. Multivariate linear regression, including models stratified by gender and age group (45-64 and 65-84 years), was used to assess the direct and buffering relationships between social support, stress, and inflammation. In bivariate analyses low social support was associated with higher levels of all three markers. In adjusted models, low support was associated with higher lnCRP (B: 0.15, 95% CI: 0.01, 0.30) among men but not women. High social support buffered the relationship between stress and CRP among middle-aged women only (P for interaction 0.042). Overall, social support was only modestly associated with inflammation in this relatively healthy sample, and these relationships varied by age and gender.