Childhood Socioeconomic Status and the Occurrence of Recent Negative Life Events as Predictors of Circulating and Stimulated Levels of Interleukin-6.

Abstract

Evidence supports an inverse association of childhood socioeconomic status (SES) with systemic inflammation in adulthood. However, it remains to be determined whether this association is dependent on exposure to stressful life experiences. We predicted that the combination of a high number of recent negative life events and low childhood SES would be associated with the highest levels of both circulating interleukin (IL)-6 and lipopolysaccharide-stimulated production of IL-6. We tested this prediction among a community sample of 459 adults (47% male, mean [standard deviation] age = 42.8 [7.3] years). Inverse associations were found between childhood and adult SES indices with circulating IL-6 levels (r values between -0.07 and -0.16, p < .05) but not stimulated IL-6 levels (r values between -0.007 and 0.07, p > .05). The number of recent negative life events (mean [standard deviation] = 2.43 [2.34]) was not significantly related to subjective childhood SES and other SES indices (r values < 0.06, p > .10). Multivariate linear regression analyses revealed a significant association between the interaction of subjective childhood SES and recent negative life events and circulating IL-6 (β = -0.09, t(404) = -1.98, p = .049) and a marginally significant association with stimulated levels of IL-6 (β = -0.10, t(365) = -1.94, p = .054), whereas these covariate-adjusted models revealed no main effects for subjective SES or recent negative life events. The relationship between childhood SES and IL-6 seems to be moderated by recent life events, such that individuals with a relatively low childhood SES exhibit an inflammatory phenotype in the context of a high number of recent negative life events.