Effectiveness of Single-Session Interventions (SSIs) for Anxiety and Depression in Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

ABSTRACTObjective: Single-session interventions (SSIs) have been proposed as a scalable approach to reduce anxiety and depressive symptoms; however, evidence for adults remains limited. This systematic review and meta-analysis synthesized randomized controlled trials (RCTs) evaluating SSIs relative to inactive or minimal-control conditions.Method: A systematic search identified adult RCTs. Outcomes were analyzed separately for anxiety and depression using three-level random-effects meta-analytic models. Effects were pooled across 1–13 weeks and within short-term (1–3 weeks) and medium-term (4–13 weeks) follow-up windows.Results: Twenty-one RCTs (N = 7,035) contributed 53 outcome-level effect sizes. Across 1–13 weeks, SSIs were associated with significant reductions in anxiety symptoms (g = −0.66, 95% CI [−0.98, −0.34]) and depressive symptoms (g = −0.49, 95% CI [−0.84, −0.13]). At 1–3 weeks, effects were significant for anxiety symptoms (g = −0.80, 95% CI [−1.24, −0.36]), but not depressive symptoms (g = −0.78, 95% CI [−1.78, 0.22]). At 4–13 weeks, effects were significant for both depressive symptoms (g = −0.29, 95% CI [−0.55, −0.02]) and anxiety symptoms (g = −0.48, 95% CI [−0.93, −0.02]). Heterogeneity was high, prediction intervals were wide, publication bias was detected for anxiety outcomes at 1–13 and 1–3 weeks and for depression at 1–13 weeks, and most studies had some concerns or high risk of bias.Conclusions: SSIs may reduce anxiety and depressive symptoms over the short-to-medium term in adults. Substantial heterogeneity, limited trial availability, publication bias, and risk of bias constrain confidence in the magnitude and generalizability of these effects. Rigorous trials with extended follow-up are needed to clarify effect durability and further inform the role within routine care.Keywords: anxiety, depression, meta-analysis, single-session interventions, systematic review