Understanding Adolescent Non-Suicidal Self-Injury: A Narrative Review of Theoretical Models and Evidence-Based Psychotherapies.

Objectives: Adolescent non-suicidal self-injury (NSSI) is a marker of severe emotional distress and a significant public health concern. This narrative review aimed to synthesize major theoretical models explaining the psychopathology of NSSI and critically evaluate the efficacy of evidence-based psychotherapies using the most recent high-level evidence. Methods: We searched articles in major academic databases published from January 2000 up to June 2025. We prioritized studies on adolescents, including efficacy studies (randomized controlled trials and meta-analyses) addressing NSSI as a primary outcome, and key theoretical papers. Results: NSSI was understood through integrated models, prominently featuring emotion dysregulation (biosocial theory), experiential avoidance (cognitive-behavioral models), impaired mentalization (attachment theory), and operant conditioning (functional model). The synthesis of high-level evidence, including a 2021 review from Cochrane, indicated that dialectical behavior therapy (DBT) had the strongest empirical support (high-certainty evidence) for reducing adolescent NSSI. However, while mentalization-based treatment, acceptance and commitment therapy, and attachment-based family therapy offered promising mechanism-specific approaches, evidence for their effectiveness for NSSI was preliminary or uncertain. Conclusion: DBT is currently the first-line treatment for NSSIs in adolescents. However, the field must move toward personalized care. Future research should focus on validating alternative therapies through head-to-head randomized controlled trials, identifying the core change mechanisms across treatments, and implementing stepwise care models to improve accessibility.