Effectiveness of phase-oriented treatment for trauma-related dissociative disorders: a systematic review.

Dissociative disorders (DDs) are a group of mental health conditions characterised by disconnection from thoughts, feelings, memories, or sense of identity. It is believed that DDs, particularly dissociative identity disorder (DID) result from severe and chronic childhood trauma. Guidance from the International Society for the Study of Trauma & Dissociation (ISSTD) recommends trauma-informed phase-oriented treatment (PoT) to treat DDs. To date, there has been no systematic evaluation of treatment effectiveness of PoT in DDs. This review aimed to systematically assess published studies and evaluate the evidence and effectiveness of PoT for DDs relative to other treatments. The search included four databases from 1980-2025 and reference lists of core papers. Studies were included if (1) participants have a primary diagnosis of DID or other specified dissociative disorder (OSDD), (2) it examined PoT and/or other treatments in these populations, and (3) it used at least one outcome measure pre- and post-treatment. Study quality was assessed using the Effective Public Health Practice Project (EPHPP) tool. 6088 articles were screened and 19 articles met the inclusion criteria. All treatment types were associated with improvements in symptoms of dissociation, general mental health symptoms, psychopathology, and general functioning. When compared to one another, each treatment type has its strengths depending on the outcome of interest. This review demonstrates an emerging evidence base for using psychological interventions to treat DDs. High-powered controlled trials are needed to build upon these results to inform clinical practice.