Socioeconomic status gradients in inflammation in adolescence.

OBJECTIVE: To determine whether lower socioeconomic status (SES), broadly defined, is associated with increased inflammation in adolescence and whether adiposity mediates these relationships.
METHODS: Fasting blood samples from 941 non-Hispanic black and white adolescents enrolled in a suburban, Midwestern school district were assayed for proinflammatory biomarkers (interleukin-6 [IL-6], tumor necrosis factor α soluble receptor 2 fibrinogen). A parent reported objective SES (parent education [E1 ≤ high school, E2 = some college, E3 = college graduate, E4 = professional degree], household income), and youth perceived SES (PSES). Multivariable linear regressions assessed the relationship of SES measures to biomarkers adjusting for age, race, sex, and puberty status. In the final step, body mass index (BMI) z score (BMIz) was added to models, and Sobel tests were performed to assess mediation by adiposity.
RESULTS: Parent education was inversely associated with IL-6 (βE1 = .11, βE2 = .10, βE3 = .02; p < .001). This association was attenuated but remained significant after BMIz adjustment (p = .01). Sobel testing confirmed BMIz's partial mediating role (p < .001). Parent education was also inversely associated with sTNFR2 (βE1 = .03, βE2 = .02, βE3 = .001; p = .01); this relationship was mediated by BMIz. Although no main effect was noted for PSES, PSES by race interactions was observed for sTNFR2 (p = .02) and IL-6 (p = .06). High PSES was associated with lower sTNFR2 and IL-6 for white but not black youth. There were no associations with household income.
CONCLUSIONS: Social disadvantage, specifically low parent education, is associated with increased inflammation in adolescence. Adiposity explains some but not all associations, suggesting that other mechanisms link lower SES to inflammation. High PSES is associated with lower inflammation for white but not black youth.