Socioeconomic Status Interacts with Conscientiousness and Neuroticism to Predict Circulating Concentrations of Inflammatory Markers

BACKGROUND: Socioeconomic health disparities research may benefit from further consideration of dispositional factors potentially modifying risk associated with low socioeconomic status, including that indexed by systemic inflammation. PURPOSE: This study was conducted to investigate interactions of SES and the Five-Factor Model (FFM) personality traits in predicting circulating concentrations of the inflammatory markers interleukin-6 (IL-6) and C-reactive protein (CRP). METHOD: Using a sample of middle-aged and older adults from the Midlife in the United States Survey (MIDUS) biomarker project (N = 978), linear regression models tested interactions of each FFM trait with a composite measure of SES in predicting IL-6 and CRP, as well as the explanatory role of medical morbidity, measures of adiposity, and health behaviors. RESULTS: SES interacted with conscientiousness to predict levels of IL-6 (interaction b = .03, p = .002) and CRP (interaction b = .04, p = .014) and with neuroticism to predict IL-6 (interaction b = -.03, p = .004). Socioeconomic gradients in both markers were smaller at higher levels of conscientiousness. Conversely, the socioeconomic gradient in IL-6 was larger at higher levels of neuroticism. Viewed from the perspective of SES as the moderator, neuroticism was positively related to IL-6 at low levels of SES but negatively related at high SES. Interactions of SES with both conscientiousness and neuroticism were attenuated upon adjustment for measures of adiposity. CONCLUSIONS: Conscientiousness may buffer, and neuroticism amplify, excess inflammatory risk associated with low SES, in part through relationships with adiposity. Neuroticism may be associated with lower levels of inflammation at high levels of SES.