Targeting depression before it starts: An updated systematic review and meta-analysis of preventive interventions in young adults from randomized controlled trials.
INTRODUCTION: Young adulthood is a high-risk period for major depressive disorder (MDD) onset yet is underrepresented in prevention research. This systematic review and meta-analysis examined the effectiveness of psychosocial preventive interventions in adults aged 18-25 years, focusing on symptom reduction, medium- and long-term effects, and MDD onset. METHODS: We conducted a PRISMA-compliant systematic review and meta-analysis (PROSPERO: CRD42024625481) of randomized controlled trials (RCTs) of psychosocial preventive interventions for depression in young adults (18-25) published up to April 15, 2025. Between-group symptom reduction was quantified using Hedges' g and pooled with random-effects models. Outcomes were analyzed at post-intervention, 6-, and 12-month follow-up. Effects on MDD onset were assessed via risk ratio (RR). Risk of bias was assessed with the RoB-2 tool. RESULTS: We included 65 interventions from 58 RCTs (N = 11,333; mean age 20.4; 61.6% female), with 92.8% rated high risk of bias. Interventions at post-test reduced depressive symptoms vs. controls (k = 65; g = -0.52; 95%CI:-0.70;-0.33; p < 0.01), with significant heterogeneity (I2 = 93.0%). Indicated, guided, and face-to-face interventions outperformed universal, selective, self-guided, and online interventions. Effects on symptomatology were highly heterogeneous and non-significant at 6- (k = 8) and 12-month (k = 4) follow-up. Four RCTs were identified evaluating MDD onset risk; pooled effects suggested a reduction in MDD onset (RR = 0.77; 95%CI:0.61;0.97; p < 0.01) though risk of bias was high and samples were highly selective. INTERPRETATION: Psychosocial preventive interventions modestly reduce depressive symptoms at post-test and may lower onset risk in highly selective populations. However, findings remain limited by high risk of bias, scarce data on the long-term sustainability of effects, and unclear mechanisms.