Non-suicidal self-injury in female adolescents and psychiatric patients: A replication and extension of the role of identity formation

• We assessed 348 female adolescents and 131 psychiatric patients on NSSI and identity.
• Anxiety, depression, personality were accounted for in predicting NSSI by identity.
• In adolescents, identity confusion uniquely and positively predicted NSSI.
• In patients, identity synthesis uniquely and negatively predicted NSSI.
• Clinicians should focus on identity issues in dealing with NSSI.

Non-suicidal self-injury (NSSI) refers to the direct destruction of one’s body tissue without suicidal intent and constitutes an important health issue in community adolescents and especially in patients with an eating disorder (ED) or borderline personality disorder (BPD). Given that identity formation constitutes a core developmental task during adolescence and is strongly affected in ED and BPD, the present study examined the incremental predictive power of identity formation towards NSSI above and beyond well-established predictors such as demographic variables, anxiety, depression, Big Five personality traits, perfectionism, and effortful control. A total of 348 female adolescents and 131 psychiatric patients completed self-report questionnaires. Although correlational analyses demonstrated that both identity confusion and synthesis were significantly (positively and negatively, respectively) related to NSSI, logistic regression analyses indicated that identity confusion in adolescents (positively) and identity synthesis in patients (negatively) predicted NSSI. Further, important associations between identity and different functions underlying NSSI were uncovered. Hence, therapists are encouraged to focus on issues of identity formation when developing prevention and intervention efforts.