Abstract
Background: A category of disorders frequently associated with a history of trauma are the dissociative disorders, of which Dissociative Identity Disorder (DID) is the most severe and chronic form. DID is associated with high levels of impairment, treatment utilization, and treatment costs, yet systematic research into treatment effects is scarce. Practice-based clinical guidelines advise a phase-based approach which is lengthy and has rather high reported dropout rates. Therefore, in the current proposal the efficacy of an alternative treatment for DID (i.e. schema therapy) is tested. Objective: The aim of this study is to critically test the effectiveness of schema therapy for DID patients, for whom at present no evidence-based treatment is available. Method: In light of the low prevalence of DID, and the proposed treatment length of three years, a case series experimental approach is used (non-concurrent multiple baseline design). Ten outpatients are included, who are diagnosed with DID by an independent rater using the Structured Clinical Interview for DSM-IV Dissociative Disorders (SCID-D-R), which is double-checked by another independent expert. Primary outcomes are a (bi)weekly assessed state measure of dissociative symptoms, a pre-, post- and follow-up measure of the presence of the DID diagnosis, and drop-out rate. Secondary outcomes include various measures of trait dissociative symptoms, comorbid symptomatology, and global symptomatic distress. Trial registration: Netherlands Trial Register (NTR): NTR4496.