Mechanisms of impact of mental health peer support in high-, middle- and low-income settings: mediation analysis of the UPSIDES randomised controlled trial.
AIMS: While there is growing evidence for the effectiveness of peer support (PS) in improving psychosocial outcomes among individuals with severe mental health conditions, the mechanisms through which these effects occur remain insufficiently understood. This study examines whether social inclusion, hope and empowerment mediate the relationship between PS, personal recovery and health and social functioning. METHODS: Data were collected from 565 adults with severe mental health conditions who participated in the multicentre UPSIDES randomised controlled trial across six sites in Germany, Uganda, Tanzania, India and Israel. Participants in the intervention group received structured PS from trained peer workers over a 6- to 8-month period. Standardised, self-report measures of social inclusion, hope, empowerment and personal recovery, as well as clinician-rated health and social functioning, were administered at baseline, 4 months, end of intervention (8 months) and 12-month follow-up. Cross-lagged panel modelling was used to explore longitudinal associations and mediating pathways. RESULTS: The cross-lagged models showed strong autoregressive effects across all variables, indicating high temporal stability. There were no significant direct effects of PS on recovery or health and social functioning. However, mediation analysis identified significant indirect effects of PS on personal recovery via social inclusion (β = 0.114, 95% confidence interval [CI] [0.049, 0.194], P < 0.05) and hope (β = 0.037, 95% CI [0.001, 0.086], P < 0.05). Similar indirect effects were observed for health and social functioning (via social inclusion: β = -0.035, 95% CI [-0.064, -0.013]; via hope: β = -0.026, 95% CI [-0.052, -0.006]; both P < 0.05). CONCLUSIONS: Findings suggest that PS affects recovery-related outcomes primarily through intermediate mechanisms of enhanced hope and social inclusion. These results support theoretical models positing indirect pathways of change in PS interventions and highlight the value of targeting social and psychological domains when designing and implementing PS in mental health services. Individuals with lower baseline levels of hope and social inclusion may particularly benefit from PS.