Abstract / Summary
Background: Heart rate variability (HRV) reflects parasympathetic regulation and is typically associated with better health outcomes. However, minoritized populations, particularly African Americans, show a paradoxical pattern of higher resting HRV despite greater cardiovascular risk, a phenomenon known as the Cardiovascular Conundrum. Discrimination has been proposed as a key mechanism, but evidence remains fragmented.
Methods: The present meta-analysis quantified HRV in relation to discrimination across 3 domains: (1) resting HRV differences between minoritized and majority groups, (2) HRV reactivity to discrimination-related tasks, and (3) the association between perceived discrimination and resting HRV. A systematic search yielded 40 articles comprising 52 independent studies.
Results: Minoritized groups showed higher resting HRV than majority groups (g = .22, P < .001), as well as acute HRV reductions during discrimination-related tasks (g = -.17, P = .04), and lower resting HRV associated with greater perceived discrimination (g = -.19, P = .006). Evidence of publication bias emerged only for the latter meta-analysis. No significant moderators emerged to explain the substantial heterogeneity, with the exception of the type of HRV measure used.
Conclusions: These findings are consistent with the hypothesis that discrimination may become biologically embedded through acute vagal withdrawal during discriminatory events, a cumulative reduction in HRV associated with perceived discrimination, and a paradoxical elevation of resting HRV indicative of chronic compensatory regulation.