How might a Universal Basic Income influence UK mental health? A microsimulation modelling study

BACKGROUND: Universal Basic Income (UBI) may improve mental health (MH), but no studies have trialled or modelled UBI in whole populations. We simulated the MH effects of UBI on UK working-age adults. METHODS: Adults aged 25-64 were simulated from 2022-26 with the SimPaths microsimulation model, using data from the UK Household Longitudinal Study. SimPaths models short-term MH effects of UK tax/benefit policies via income, poverty and employment transitions. Three counterfactual UBI scenarios were modelled from 2023: ‘Partial’ (value equivalent to existing benefits), ‘Full’ (equivalent to the UK Minimum Income Standard) and ‘Full+’ (retained some means-tested benefits). Likely common mental disorder (CMD) was measured using the General Health Questionnaire (GHQ-12, score ≥4) and stratified by gender, education, and household structure. Simulations were run 1,000 times to generate 95% uncertainty intervals. Sensitivity analyses relaxed SimPaths assumptions about reduced employment resulting from Full/Full+ UBI. RESULTS: Partial UBI had little impact on poverty, employment or MH. Full UBI scenarios practically eradicated poverty, but decreased employment. Full+ UBI increased CMD prevalence by 0.38% points (0.13-0.69), equivalent to 157,951 additional CMD cases (54,036-286,805); effects were largest for men (0.63% [0.31-1.01]) and those with children (0.64% [0.18-1.14]). In our sensitivity analysis assuming minimal UBI-related employment impacts, CMD prevalence instead fell by 0.27% (-0.49, -0.05), a reduction of 112,228 cases (20,783-203,673); effects were largest for women (-0.32% [-0.65, 0.00]), those without children (-0.40 [-0.68, -0.15]) and those with least education (-0.42% [-0.97, 0.15]). MH effects waned by 2026 in all modelled scenarios. CONCLUSIONS: UBI has potential to improve short-term population MH by reducing poverty, but impacts may be highly contingent on whether individuals choose to remain in employment following its introduction. KEY MESSAGES: • A UBI meeting living costs may slightly improve population mental health if people continue working after receiving the benefit, especially for women, the least educated, and those without children. • In a ‘worst-case scenario’, where the increased income led to maximal reductions in employment, UBI might instead worsen short-term mental health, especially for men and those with children.