Evidence for phase-based psychotherapy as a treatment for dissociative identity disorder comorbid with major depressive disorder and alcohol dependence.

We report on the treatment and successful outcome of a 58-year-old Native American male with a history of complex trauma presenting with dissociative identity disorder (DID) and major depressive disorder. The treatment included a trauma-informed phase-based psychotherapy as recommended by the International Society for the Study of Trauma and Dissociation for treating DID. We assessed symptoms at baseline and at three additional time points over the course of 14 months. We utilized the Reliable Change Index to examine statistically significant change in symptoms over the course of treatment. Significant symptom improvements were realized posttreatment across all measured domains of functioning, including dissociative symptoms, alcohol abuse, depression, anxiety, and emotion regulation skills. Moreover, the client no longer met criteria for DID, major depressive disorder, or alcohol abuse. Results are discussed in terms of the effectiveness of trauma-focused, phase-based treatment for DID for cases of complex trauma with comorbid disorders.