Background It is clinically imperative to better understand the relationship between trauma, auditory hallucinations and dissociation. The personal narrative of trauma has enormous significance for each individual and is also important for the clinician, who must use this information to decide on a diagnosis and treatment approach. Aims To better understand whether dissociation contributes in a significant way to hallucinations in individuals with and without trauma histories. Method Three groups of participants with auditory hallucinations were recruited, with diagnoses of: schizophrenia (without trauma) (n = 18), post-traumatic stress disorder (PTSD, n = 27) and comorbid schizophrenia and PTSD (SCZ+PTSD), n = 26). Clinician-administered measures included the PTSD Symptoms Scale Interview (PSSI-5), the Clinician-Administered Dissociative States Scale (CADSS) and the Psychotic Symptom Rating Scales (PSYRATS). Results Dissociative symptoms were significantly higher in participants with trauma histories (PTSD and SCZ+PTSD groups) and significantly correlated with hallucinations in trauma-exposed participants, but not in participants with schizophrenia (without trauma history). Hallucination severity was correlated with the CADSS amnesia subscale score, but depersonalisation and derealisation were not. Conclusions Dissociation may be a mechanism in trauma-exposed individuals who hear voices, but it does not explain all hallucinatory experiences. The SCZ+PTSD group were in an intermediary position between schizophrenia and PTSD on dissociative and hallucination measures. The PTSD and SCZ+PTSD groups experienced dissociative phenomena much more frequently than the schizophrenia group, with a significant trend towards the amnesia subtype of dissociation.

Background Visual experiences such as hallucinations are commonly reported by people with psychosis, psychological trauma and dissociative states, although questions remain about their similarities and differences. For diagnostic and therapeutic purposes, clinical research must better delineate and compare the characteristics of these experiences in post-traumatic stress disorder (PTSD) and in schizophrenia. Aims To compare visual phenomena and dissociation in participants with a primary psychotic illness and those with a trauma diagnosis. Method A quantitative group design study comparing visual phenomena in three participant groups who also have a history of hearing voices: schizophrenia and no trauma history (n = 19), PTSD with dissociation (n = 17) and comorbid schizophrenia and PTSD (n = 20). Validated clinical measures included the North-East Visual Hallucination Interview, PTSD Symptoms Scale Interview, Clinician Administered Dissociative States Scale, Psychotic Symptoms Rating Scales and Positive and Negative Syndrome Scale. Results There was a remarkable similarity in visual experiences, including rates of complex visual hallucinations, between the three diagnostic groups. There were no significant differences in the severity or components of distress surrounding the visual experiences. Dissociation predicted visual hallucination severity for the comorbid schizophrenia and PTSD group, but not for PTSD or schizophrenia alone. Conclusions Visual experiences in PTSD can include visual hallucinations that are indistinguishable from those experienced in schizophrenia. Multimodal hallucinations are frequently observed in both schizophrenia and PTSD. A model for visual hallucinations in PTSD is suggested, following two separate neurobiological pathways based on distinct responses to trauma.

Objective This study compared voice characteristics and beliefs in participants diagnosed with post-traumatic stress disorder (PTSD) with dissociation, schizophrenia (SCZ) and both diagnoses of SCZ and PTSD. The relationship between dissociation and voice beliefs was also assessed. Method We identified 56 participants meeting the diagnostic criteria for PTSD with dissociation, SCZ or both diagnoses (PTSD + SCZ) who also experienced auditory hallucinations. Measures included PTSD Symptoms Scales Interview (PSSI-5), Psychotic Symptoms Rating Scale (PSYRAT), Clinician Administered Dissociative States Scale (CADSS), Beliefs about Voices Questionnaire (BAVQ) and Positive and Negative Syndrome Scale (PANSS). Results Beliefs about voices were similar across diagnostic groups. Participants with SCZ were more likely to attribute their voices to an external origin, and participants with dual diagnosis were less able to control their voices. The PTSD-only group scored higher in dissociation scores than either the SCZ-only or dual diagnosis group. Malevolent voice appraisals correlated with dissociation scores only in the dual diagnosis group. Conclusions This research supports the hypothesis that voice beliefs are similar across diagnoses of PTSD and SCZ. However, differences in voice characteristics, emotional responses and relationship to dissociation may need to be considered in the psychological management of voices.