Time Dimension of the Link Between Income Inequality and Health: The Immediate, Cumulative, and Comparative Effects

The income inequality hypothesis (IIH) posits that greater income dispersion harms indi-vidual health through psychosocial pathways. Yet decades of empirical re-search—especially in cross-national settings—have yielded inconsistent findings. This study revisits the IIH by distinguishing three temporal dimensions of inequality: immedi-ate (current levels), cumulative (long-run averages), and comparative (recent change). Us-ing harmonized Gini series linked to repeated cross-sections of the World Values Survey (1981-2016) across more than 90 countries and regions, we estimate multilevel models that adjust for individual and national covariates. Results reveal a consistent negative as-sociation between worsening inequality over the prior decade and self-rated health—supporting a comparative, time-sensitive specification of the IIH. In contrast, im-mediate and cumulative inequality often show null or even positive associations, particu-larly in less developed contexts and under random-effects estimation. These patterns suggest that inequality’s health consequences are temporally contingent, and that long-run deterioration in distributional conditions poses a particular threat to population health and should be closely monitored in future research and policy.