Psychological, social, and neurobiological correlates of non-suicidal self-injury and suicidal behavior in adolescents: a narrative review.

Background: Non-suicidal self-injury (NSSI) is highly prevalent during adolescence and is consistently associated with suicidal ideation (SI) and suicide attempts (SA). Although numerous psychological, social, and neurobiological correlates of the NSSI-suicidal behavior relationship have been investigated, current evidence remains fragmented, and the extent to which these correlates are specific to NSSI rather than reflecting broader psychopathology remains unclear. This narrative review aimed to synthesize current evidence on the psychological, social, and neurobiological correlates of the NSSI-suicidal behavior relationship in adolescents, while highlighting methodological limitations and future research priorities. Methods: A structured literature search was conducted in PubMed, Web of Science, PsycINFO, and China National Knowledge Infrastructure (CNKI) to identify relevant studies published between January 2010 and June 2025. Studies involving adolescent populations that examined NSSI, suicidal ideation, suicide attempts, or their psychological, social, or neurobiological correlates were included. Consistent with the methodology of a narrative review, studies were selected based on conceptual relevance without formal risk-of-bias assessment. Results: Current evidence consistently identifies NSSI as a significant risk marker for suicidal ideation and suicide attempts, although the predominantly observational nature of the literature precludes causal inference. Psychological correlates include cognitive flexibility and acquired capability for suicide; social correlates include family functioning, peer influences, and sex differences; and neurobiological studies implicate alterations in the hypothalamic-pituitary-thyroid (HPT) axis, hypothalamic-pituitary-adrenal (HPA) axis, and endogenous opioid system. Dialectical behavior therapy (DBT) demonstrates the strongest evidence for reducing both NSSI and suicidal behaviors in adolescents. However, interpretation of the available evidence is limited by cross-sectional designs, inconsistent definitions and measurements, biological heterogeneity, and inadequate control for psychiatric comorbidity. Conclusion: The relationship between NSSI and suicidal behavior in adolescents is shaped by interacting psychological, social, and neurobiological factors rather than a single mechanism. Current evidence also highlights the importance of distinguishing factors associated with the emergence of suicidal ideation from those related to the transition from ideation to suicide attempts. Future prospective, multi-method studies integrating these domains while accounting for psychiatric comorbidity are needed to clarify developmental pathways and improve risk assessment and intervention strategies.