Impact of mentalization, identity diffusion and psychopathology on nonsuicidal self-injury among adolescents.

Introduction: Nonsuicidal self-injury (NSSI) has become a major public health issue in adolescents. This cross-sectional case-controlled study aims to assess the impact of identity diffusion, psychopathology, and mentalization on NSSI in adolescence.

Methods: The study sample consisted of 153 adolescents (76.5% girls; M_age = 15.6 years). The sample included 56 clinical cases of NSSI, 45 psychiatric cases without NSSI, and 52 healthy controls, all recruited in Ankara, Türkiye, from June 1, 2022, to August 31, 2022. Mentalization was assessed by "The Movie for the Assessment of Social Cognition" (MASC) which categorizes mentalizing as "correct mentalizing" "hypermentalizing" "undermentalizing" and "no-mentalizing". All participants filled in the Self-Injurious Behavior Screening Questionnaire, Assessment of Identity Development in Adolescence (AIDA), and Youth Self Report (YSR), and Inventory of Statements About Self-injury (ISAS).

Results: The NSSI group showed lower mentalizing capacity than the healthy control group (p = .011), and more no-mentalizing errors than the other two groups (p = .014). Identity diffusion scores were higher in the NSSI group than in the other two groups (p < .001). Multivariate logistic regression analysis showed that the presence of maternal psychiatric disorder (p = .019, OR = 5.21), identity diffusion (p = .007, OR = 1.02), no mentalizing (p = .049, OR = 1.28), and total psychopathology symptoms (p = .009, OR = 1.12) had a significant impact on NSSI.

Conclusions: Current findings suggest that transdiagnostic approaches, including mentalization and identity diffusion, may contribute to a more comprehensive understanding of NSSI and to the development of clinical interventions.