Research Review: Sex differences in the clinical correlates of nonsuicidal self-injury in adolescents - a systematic review

Background: Nonsuicidal self-injury (NSSI), or 'the deliberate, self-inflicted destruction of body tissue…without suicidal intent and for purposes not culturally sanctioned', is a robust predictor of future suicide-related behavior and therefore a modifiable target for suicide prevention. The prevalence of NSSI is rising in adolescents, particularly among females; however, it is unknown whether sex differences also exist in the clinical and psychosocial factors associated with NSSI. Understanding how the correlates of NSSI differ by sex is important for developing tailored treatments. This study systematically reviews sex differences in the clinical and psychosocial correlates of NSSI among adolescents.

Methods: MEDLINE and PsycINFO were searched using the keywords 'adolescents', 'self-injury', and 'sex factors' and synonyms for English-language articles published between January 1, 2000 and May 10, 2022. We included studies that presented original data on NSSI, included adolescents ages 10-19, reported sex differences, and explicitly defined self-injury as that done without suicidal intent. Fifty-seven studies containing 54 unique samples were included. Data were summarized by sex and recorded by: (a) characteristics of NSSI, (b) clinical and psychosocial correlates of NSSI, and (c) associations with suicide.

Results: We used data on NSSI from 54 unique samples of adolescents worldwide. Males more commonly used violent methods of NSSI, such as burning, and were more likely to be physically aggressive and experience substance abuse. Females more commonly self-injured by cutting, and their NSSI was more likely to be repetitive and associated with emotional distress. In both sexes, NSSI was associated with adverse childhood experiences (ACEs) such as sexual abuse/violence and bullying. NSSI was predictive of suicide in females but not males.

Conclusions: Data from 22 countries and 352,516 participants suggest important sex differences in the clinical and psychosocial factors associated with NSSI among adolescents that future assessment and treatment strategies ought to consider.