RESUMEN
In the present study, we investigated the association between non-suicidal self-injury (NSSI) and problems in identity formation among patients with eating disorder (ED). NSSI is highly prevalent in ED, and problems with identity formation are characteristic of both NSSI and ED. Few studies, however, have investigated identity formation in patients with ED with and without NSSI while taking into account comorbid psychopathology (e.g. anxiety and depression). Therefore, we investigated the relationships between NSSI characteristics, identity confusion/synthesis, and anxiety/depression in 99 female patients with ED by means of self-report questionnaires. The results showed that 58.6% of the patients with ED engaged in at least one type of NSSI (most frequently cutting), with no significant differences in rates of NSSI or identity problems among ED subtypes. Presence, versatility and automatic negative reinforcement functions of NSSI were each significantly and positively related to identity confusion and negatively related to identity synthesis. Even after controlling for age, anxiety, and depression, lack of identity synthesis remained a significant predictor of NSSI in patients with ED. Given that NSSI may constitute an effort to deal with identity confusion/synthesis in patients with ED, therapists should take this developmental task into account while treating patients with ED with NSSI.