Association Between Psychosocial Factors and C-Reactive Protein Across Income, Race, and Sex

Objective: A health disparity is a health difference that adversely affects disadvantaged populations, and thus could plausibly be due to social factors. Biopsychosocial processes that contribute to health disparities are not well-understood. Establishing whether candidate biomarkers are similarly associated with biologically relevant psychosocial constructs across health disparity groups is a current gap in our understanding. Method: This study examined associations between perceived stress, depressive symptoms, and social support with C-reactive protein (CRP) and whether associations varied by race, sex, or income in 24,395 Black and White adults aged 45 years or older from the REGARDS population-based national cohort. Results: The association between depressive symptoms and CRP was slightly larger at higher (vs. lower) income levels and larger for men (vs. women) but did not vary by race. Associations between stress and CRP and social support and CRP were not moderated by income, race, or sex. An interaction between race and income, evidenced that higher income was more strongly associated with lower CRP in White participants compared to Black participants, consistent with the idea of "diminishing returns" of income for the health of Black Americans. Conclusions: Basic associations between these psychosocial factors and CRP are small and generally similar across income, race, and sex. Black and lower-income Americans likely evidence higher CRP due to greater exposure to psychosocial risk factors rather than increased biological vulnerability to these exposures. Additionally, given small associations, CRP should not be used as a proxy for the construct of psychosocial stress.