A comparison between auditory hallucinations, interpretation of voices, and formal thought disorder in dissociative identity disorder and schizophrenia spectrum disorders.

People with dissociative identity disorder (DID) and schizophrenia-spectrum disorders (SSD) both hear voices, but the experiences differ in key ways. DID participants reported voices as more internally located and generated, louder, and less controllable, and they endorsed more thought disorder symptoms. After accounting for sex, depersonalization, and childhood maltreatment, differences in voice loudness and controllability disappeared, but the DID group still reported more internal origin and derailment. The SSD group reported more distress, metaphysical beliefs about voices, incoherent thoughts, and word substitution. These latter features may reflect more psychotic processes.

Study at a glance

Abstract

Dissociative identity disorder (DID) and schizophrenia-spectrum disorders (SSD) share some overlapping phenomenological features making accurate diagnosis more difficult. Childhood abuse and depersonalization have been associated with psychotic symptoms across psychological disorders but their relationship to psychotic phenomenology remains understudied. The present study used quantitative measures to examine (1) similarities and differences in phenomenological voice hearing experiences, interpretations of voices, and thought disorder symptoms in individuals with DID (n = 44) or SSD (n = 45), and (2) whether depersonalization and childhood maltreatment influenced the initial pattern of findings. DID participants perceived their voices as being more internally located and generated, louder, and uncontrollable than SSD participants. Furthermore, the DID participants endorsed a greater frequency of thought disorder symptoms. Adding the covariates (sex, depersonalization, and child maltreatment) did not change the findings associated with location and origin of voices, and derailment, but there were now no differences in loudness or controllability. However, the schizophrenia sample reported more distress and metaphysical beliefs associated with voices, as well as more thought disorder incoherence and word substitution with the covariates controlled. While tentative, metaphysical interpretations of voices, incoherent thoughts and word substitution may reflect more psychotic processes.