The Self-Concept and Identity Measure in patients with personality disorders: A psychometric evaluation and associations with identity processes, core domains of self-functioning, and personality disorder symptoms

As developmental and clinical research on identity has largely developed in disconnect, scholars recommend adopting a developmental psychopathology perspective on identity, which considers adaptive and pathological identity functioning. Such a perspective has also been introduced in the Diagnostic and Statistical Manual of Mental Disorders (5th ed.; DSM-5) Alternative Model for Personality Disorders (AMPD), which suggests that all personality disorders (PDs) are marked by moderate to extreme deficits in self-functioning (i.e., identity and self-direction). The present study aims to validate the Dutch Self-Concept and Identity Measure (SCIM), a 27-item self-report questionnaire that assesses consolidated identity, disturbed identity, and lack of identity, in 153 psychiatric inpatients with PDs (75.2% female; M_age = 31.73). We investigated the factor structure and reliability of the SCIM, and examined associations of SCIM scales with typical identity processes, AMPD domains of self-functioning, and symptoms of all PDs. Results indicated that a 23-item Dutch SCIM produced valid and reliable scores among patients with PDs. Furthermore, SCIM scales were significantly and differentially related to identity commitment processes, ruminative identity exploration, domains of self-functioning, and symptoms of all PDs. Moreover, findings indicated that PDs varied regarding the severity of identity impairment.