Income inequality widens the existing income-related disparity in depression risk in post-apartheid South Africa: Evidence from a nationally representative panel study.

Aim: Income inequality (II) and poverty are major challenges in South Africa (SA) yet little is known about their interaction on population mental health. We explored relationships between district II, household income (HHI) and depressive symptoms in national panel data.

Method: We used 3 waves (2008, 2010, 2012) of the SA National Income Dynamics Study (n=25936) in adjusted mixed effects logistic regression to assess if the relationship between HHI and depressive symptoms is dependent on level of II. Depressive symptoms were assessed with Centre for Epidemiologic Studies Depression scale, and District inequality ratios (P10P90) derived from HHI distributions in 53 districts.

Results: Lower HHI and increasing II were associated with depressive symptoms. The interaction term between HHI and II on depressive symptoms was significant (β=0.01, 95% CI: <0.01-0.01); with increasing II and decreasing HHI, depression risk increased.

Conclusion: II widens income-related disparities in depression risk in SA, with policy implications for understanding socioeconomic determinants of mental health and informing global efforts to reduce disparities in high poverty and inequality contexts.