Discrimination and C-reactive protein across the life course: Findings from three national US cohorts.

Discrimination is increasingly recognized as a chronic social stressor that may contribute to physiological dysregulation. While cross-sectional research has linked discrimination exposure to elevated systemic inflammation (e.g., C-reactive protein [CRP]), less is known about how these associations unfold across the lifespan. To examine the relationship between systemic inflammation and repeated exposure to interpersonal discrimination among non-Hispanic White and Black adults, we analyzed harmonized data from three US population-based cohorts spanning young adulthood (National Longitudinal Study of Adolescent to Adult Health; Add Health), mid-adulthood (Midlife in the United States Study; MIDUS), and older adulthood (Health and Retirement Study; HRS). In each cohort, interpersonal discrimination was assessed at two time points using a self-reported item asking whether participants had been treated with less respect or courtesy than others. Based on responses across waves, we created a harmonized exposure variable with three categories: no exposure (discrimination not reported at either time point), intermittent exposure (reported at one time point only), and chronic exposure (reported at both baseline and follow-up). In adjusted models accounting for baseline CRP, sex, race, education, and change in body mass index, chronic exposure to discrimination was significantly associated with increases in CRP over time in the young adult cohort (Add Health). Specifically, individuals reporting chronic discrimination in Add Health showed greater increases in inflammation relative to those reporting no exposure (B = 0.87 mg/L, 95% CI: 0.19 to 1.54). No significant associations were observed in MIDUS or HRS. These findings suggest that chronic interpersonal discrimination may have a particularly strong impact on inflammatory processes during early adulthood, pointing to a potential sensitive period in which psychosocial stressors have long-term consequences for inflammatory homeostasis.