Depression at follow-up and associated social determinants among isiZulu-speaking South Africans: evidence from the National Income Dynamics Study

AI Summary

Among isiZulu-speaking adults not depressed at baseline, 14.0% met criteria for depression at Wave 5.
Employment and high income expectations were independently protective against depression at follow-up (aORs 0.55 and 0.50 respectively).
Findings emphasise the role of social determinants and support addressing socioeconomic factors in prevention and early intervention strategies.

BMC Public Health. 2026 Jun 5. doi: 10.1186/s12889-026-28007-7. Online ahead of print.

ABSTRACT

BACKGROUND: Depression is a major public health concern globally, with a disproportionate burden in low- and middle-income countries. While the prevalence of depression has been widely documented in South Africa, less is known about depression at follow-up among individuals without depression at baseline and the social determinants associated with it in population-based cohorts. Evidence on depression at follow-up is essential for informing prevention and early intervention strategies.

METHODS: This study used longitudinal data from the National Income Dynamics Study (NIDS). Baseline depression status was assessed at Wave 1 using the CES-D-10, and depression at Wave 5 was assessed among adults who were not depressed at baseline and were observed again at follow-up. Multivariable logistic regression was used to examine associations between selected social determinants of health and depression at follow-up. Multiple imputation was applied to address missing data in selected covariates. Missingness was generally low across most variables, with higher levels observed for income expectations and age category. The analysis reflects cumulative risk of depression status at follow-up rather than the timing of first onset across intermediate waves.

RESULTS: At baseline, 28.3% (95% CI: 26.2-30.3) of participants met criteria for depression. Among adults who were not depressed at baseline, 14.0% (95% CI: 12.7-15.3) met criteria for depression at Wave 5. Depression at follow-up was independently associated with selected social and economic factors, including employment (aOR 0.55, 95% CI 0.37-0.83) and high income expectations (aOR 0.50, 95% CI 0.36-0.70), while several other demographic and behavioural factors were not associated after adjustment.

CONCLUSIONS: This study demonstrates a substantial risk of depression at follow-up among isiZulu-speaking South Africans and highlights the socially patterned nature of depression at follow-up. Longitudinal evidence on depression at follow-up among baseline non-cases provides critical insights beyond prevalence estimates and underscores the importance of addressing social determinants as part of comprehensive mental health prevention strategies.

PMID:42249371 | DOI:10.1186/s12889-026-28007-7

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