Non-suicidal self-injury in adolescents and young adults: an expert review

Non-suicidal self-injury (NSSI) is highly prevalent among community and clinical adolescent populations and is associated with substantial psychiatric comorbidity, psychosocial impairment, and elevated suicide risk. This review synthesizes key findings on the development and maintenance of adolescent NSSI and discusses the clinical implications of this transdiagnostic behavioural phenomenon. It examines the prevalence and developmental course of NSSI, environmental and biological risk factors, proximal mechanisms, its conceptualization as an independent diagnosis versus a transdiagnostic risk marker, and current treatment approaches including their limitations. Current evidence indicates that adolescent NSSI emerges from interacting environmental risk factors (e.g. adversity and interpersonal stress) and neurobiological mechanisms related to emotional dysregulation, stress responsivity, and altered pain processing. While NSSI prospectively predicts suicidal behaviour, associations with other psychiatric disorders remain probabilistic and diagnostically non-specific. Overall, findings support conceptualizing NSSI as a transdiagnostic risk marker and behavioural phenotype linked to emotion dysregulation rather than as a distinct diagnostic entity. Adolescent NSSI reflects a dynamic biopsychosocial process involving emotional, neurobiological, and interpersonal mechanisms. Early detection and accessible intervention are essential to reduce chronicity, relapse, and the escalation of suicidal behaviour. Future research should prioritize mechanism-informed and personalized treatment approaches, improved identification of at-risk adolescents, and integration of developmental, neurobiological, and digital methodologies to advance prevention and intervention.