BACKGROUND: In eastern and southern Africa, HIV and depression lead to substantial morbidity and mortality. Each condition affects the other: people living with HIV (PLHIV) have higher depression rates, while depression increases HIV acquisition and hinders treatment. The combined impact of HIV-depression interactions on HIV and mental health remains poorly understood.
METHODS: We adapted the EMOD-HIV simulation model to incorporate depression incidence, recovery and relapse. We modelled a bidirectional scenario between HIV and depression: HIV increased depression incidence; depression increased HIV incidence and reduced HIV care outcomes. In a counterfactual scenario, all HIV-depression interactions were removed. We estimated how interactions impacted depression episodes, HIV acquisitions, HIV-related deaths and HIV treatment benefits in a high-prevalence region of Western Kenya, 1985–2035.
RESULTS: Without interactions, the model projected 1.23 million (95% CI 1.21M to 1.24M) HIV acquisitions, 658 000 (95% CI 650 000 to 666 000) HIV deaths and 12.88 million (95% CI 12.87M to 12.89M) depression episodes. HIV-depression interactions increased depression episodes by 9.76% (95% CI 9.67% to 9.87%), HIV acquisitions by 12.3% (95% CI 12.0% to 12.6%) and HIV deaths by 12.5% (95% CI 12.2% to 12.9%). These interactions also diminished HIV treatment benefits, with 7.72% (95% CI 7.39% to 8.07%) fewer HIV acquisitions and 3.88% (95% CI 3.71% to 4.05%) fewer deaths averted per person-year on treatment. In secondary analyses, increased depression incidence among PLHIV had the greatest effect on HIV outcomes, contributing 7.26% of acquisitions and 7.55% of deaths.
CONCLUSION: HIV-depression interactions have worsened both epidemics. Depression’s effects on HIV incidence have been especially deleterious, while its effect on HIV care engagement is increasingly important.
How has mental health impacted the HIV epidemic and how has the HIV epidemic impacted mental health in Western Kenya? A mathematical modelling study
BMJ Global Health, 11 (8), e020217. doi: 10.1136/bmjgh-2025-020217. PMCID: PMC13504884.