Dissociation : Vol. 9, No. 3, p. 190-196 : Prevalence of dissociative symptoms and disorders within an adult outpatient population with schizophrenia
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Objective: The objectives of this study were to determine the prevalence of dissociative symptoms and disorders in an adult outpatient population with schizophrenia and to study the relationship between dissociative symptoms and positive and negative symptoms of schizophrenia. Method: Consenting adult outpatients with schizophrenia from the Kingston Psychiatric Hospital in Kingston, Ontario, were administered the Dissociative Experiences Scale (DES). Patients scoring 25 or higher on the DES were interviewed with the Positive and Negative Syndrome Scale (PANSS), and two interviews for dissociative disorders: the Structured Clinical Interview for DSM-IV Dissociative Disorders (SLID-D) and the Dissociative Disorders Interview Schedule (DDIS). Results: 53 patients completed the DES, and 14 (26%) scored 25 or greater. The scores on the DES subscale of absorption and imaginative involvement were significantly higher than the scores of the two other DES subscales, for both the group scoring >25 and also for the study sample as a whole. The prevalence of dissociative disorders in this population was estimated to be 9%, with dissociative amnesia the only dissociative disorder diagnosed. The high DES scorers had a predominance of positive symptoms as evidenced by a composite index score (positive symptoms score minus negative symptoms score) of 4.1, placing these patients at the 80th percentile, when compared to a normative population of patients with schizophrenia. Conclusions: The finding of consistently elevated scores on the absorption and imaginative involvement subscale of the DES in this sample suggests that the DES may not be a valid instrument to screen for dissociative disorders among patients with schizophrenia. However, patients with schizophrenia who present with a predominance of positive symptoms should be assessed for the presence of a dissociative disorder.