Effectiveness of acceptance and commitment therapy for suicidal ideation: a systematic review and meta-analysis

Introduction

Suicide remains a major global health concern, accounting for over 703,000 deaths annually. Suicidal ideation is a key clinical target across mood-related conditions, yet effective and scalable psychotherapeutic interventions remain limited. Acceptance and commitment therapy (ACT), a third-wave behavioural intervention, targets maladaptive responses to psychological distress by enhancing psychological flexibility. Unlike traditional cognitive approaches that aim to modify thought content, ACT focuses on altering the relationship with distressing internal experiences, offering a potentially mechanistically distinct approach. This study aimed to evaluate the effectiveness of ACT in reducing suicidal ideation.

Methods

This systematic review and meta-analysis was conducted in accordance with PRISMA guidelines. Electronic databases including PubMed, Embase, Scopus and the Cochrane Library were searched from inception to 31 January 2024. Randomised controlled trials investigating ACT as a primary intervention for suicidality were included if they used validated outcome measures such as the Beck Scale for Suicide Ideation or the Columbia Suicide-Severity Rating Scale. Studies involving mixed interventions or lacking appropriate control groups were excluded. Two independent reviewers conducted study selection, data extraction and quality assessment. Risk of bias was assessed using the Cochrane Risk of Bias 2.0 tool. A random-effects model was applied to calculate pooled standardised mean differences and 95% confidence intervals. Publication bias was assessed using Egger’s regression test where applicable. Heterogeneity was assessed using the I2 statistic.

Results

Eight studies met the inclusion criteria for the systematic review, including participants from multiple geographical regions. Four randomised controlled trials were eligible for meta-analysis. ACT was associated with a clinically meaningful reduction in suicidal ideation compared with control conditions (standardised mean difference = 1.12, 95% confidence interval 0.26 to 1.98). Substantial heterogeneity was observed (I2 = 88.2), reflecting variability in study populations, intervention formats and outcome measures. Outcome measures most commonly included the Beck Scale for Suicide Ideation and the Columbia Suicide-Severity Rating Scale. Interventions were delivered in individual, group and digital formats. All included studies were assessed as having a high overall risk of bias, primarily due to concerns in outcome measurement and reporting of randomisation procedures. Most interventions were delivered over short durations of one to three months, limiting conclusions regarding long-term effects.

Conclusions

These findings suggest that ACT may represent a clinically relevant and mechanistically informed approach for reducing suicidal ideation. By targeting experiential avoidance and promoting adaptive responses to distress, ACT may address processes central to suicidal thinking across mood-related conditions. However, the current evidence base remains limited by methodological concerns and short follow-up periods. Further well-designed and adequately powered trials are required to confirm these findings, examine durability of effects and clarify underlying mechanisms, including the role of psychological flexibility in mediating treatment outcomes. The scalability of ACT, including group-based and digital delivery formats, may further enhance its applicability in real-world clinical and suicide prevention settings.

This abstract represents an encore presentation of work previously published in Acta Neuropsychiatrica (2025).

References

No references