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

OBJECTIVES: 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. METHOD: 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. RESULTS: 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. CONCLUSION: While tentative, metaphysical interpretations of voices, incoherent thoughts and word substitution may reflect more psychotic processes.

Dissociation as a Mediator Between Childhood Abuse and Hallucinations: An Exploratory Investigation Using Dissociative Identity Disorder and Schizophrenia Spectrum Disorders.

Previous research has shown that the relationship between childhood abuse and the presence of auditory hallucinations is mediated by dissociation, specifically depersonalization and absorption. The current study assessed dissociation as a mediator of the relationship between childhood abuse and auditory hallucination frequency, characteristics and associated distress in those with dissociative identity disorder (DID; n = 50) and schizophrenia spectrum disorders (SSD; n = 49). It also tested whether dissociation mediated the relationship between childhood abuse and the presence of non-auditory hallucinations. Participants completed measures of childhood abuse, dissociation, auditory hallucination frequency, characteristics, distress, and non-auditory hallucinations. With distress associated with auditory hallucinations as the outcome, depersonalization was a mediator in the DID group. For non-auditory hallucinations, in the DID group depersonalization and amnesia were mediators between childhood abuse and the presence of visual, tactile and olfactory hallucinations. In the SSD group absorption mediated between childhood abuse and visual, olfactory and gustatory hallucinations. Results suggest that the presence of non-auditory hallucinations in DID and SSD are associated with different dissociative experiences.

Delusional beliefs and their characteristics: A comparative study between dissociative identity disorder and schizophrenia spectrum disorders.

Firmly held beliefs that have a delusional quality are commonly experienced in those with schizophrenia spectrum disorders (SSD) and have been reported in those with dissociative identity disorder (DID). However, no study to date has compared delusional belief content and characteristics between these diagnostic groups. This study examined delusional content, and the degree of conviction, preoccupation and distress associated with them in 50 participants with DID and 50 with an SSD exploring also dissociation and childhood trauma as predictors of delusional beliefs. Multivariate analysis of variance and linear regressions were conducted to explore differences between beliefs and characteristics and to examine their association with dissociation and childhood trauma. The SSD sample presented more self-referential delusional beliefs and characteristics compared to the DID group. Yet, the DID group had more mistrust delusional beliefs and characteristics in comparison to SSD participants. Mistrust beliefs were predicted by depersonalization/derealization in the DID sample, but did not predict any delusional belief in the SSD sample. The content of fixed beliefs differs between DID and SSD samples and in this study depersonalization/derealization experiences were related to mistrust beliefs but not to other delusional forms, and only in the DID sample.