Psychosocial factors and inflammation in the multi-ethnic study of atherosclerosis

Background: Psychosocial factors are associated with the development and progress of cardiovascular disease, but the pathological mechanisms remain unclear. We examined the associations of psychosocial risk factors for cardiovascular disease with concentrations of inflammatory markers among healthy adults and assessed the extent to which these associations are mediated by behaviors, body mass index (BMI), and diabetes mellitus. Methods: This cross-sectional study used data from the baseline examination of the Multi-Ethnic Study of Atherosclerosis, a multisite study of 6814 men and women aged 45 to 84 years. Regression analyses were used to estimate associations of cynical distrust, chronic stress, and depression with serum levels of C-reactive protein, IL-6, and fibrinogen before and after adjustment for socioeconomic position, behaviors, BMI, and diabetes. Results: Higher levels of cynical distrust were associated with higher levels of inflammatory markers. The percentage differences (95% confidence intervals [CIs]) comparing the 80th and 20th percentiles of the scale were 7% (3%-11%) for IL-6; 9% (2%-16%) for C-reactive protein; and 1.3% (0.1%-2.4%) for fibrinogen. Higher levels of chronic stress were associated with higher concentrations of IL-6 and C-reactive protein. The percentage differences (95% CIs) comparing 2 and 0 ongoing stressful circumstances were 4% (1%-8%) for IL-6 and 5% (1%-11%) for C-reactive protein. Depression was positively associated with the level of IL-6 (percentage difference [95% CI] comparing the Center for Epidemiologic Studies -Depression Scale scores of >= 21 vs < 21 was 7% [1%-14%]). Associations of psychosocial factors with inflammatory markers were reduced by 20% to 55% after adjustment for behavioral factors and by 45% to 100% after adjustment for BMI and diabetes, mostly owing to the effect of BMI. No associations remained after controlling for socioeconomic position, behaviors, BMI, and diabetes. Conclusions: Psychosocial factors are associated with higher levels of inflammatory markers, most consistently for cynical distrust. Results are compatible with a mediating role of BMI, behaviors, and diabetes.