Dissociative symptoms in schizophrenic patients with positive and negative symptoms.

Given the close historical relationship between schizophrenia and dissociative disorders, namely multiple personality disorder, we assessed 27 ICD-10 diagnosed schizophrenic inpatients for dissociative symptoms using the German version of the Dissociative Experience Scale and compared them to a nonclinical control group matched for gender and age. Other self-report instruments covering general psychopathology, and an expert rating on the predominance of positive or negative schizophrenic symptoms, were also administered. Schizophrenic patients have significantly more dissociative symptoms than controls. Moreover, patients with a plus type of schizophrenia show significantly higher levels of dissociation than patients mainly exhibiting less productive symptoms. However, dissociative phenomena are only significantly correlated with delusions and hallucinatory behavior, and do not show any correlation with other positive symptoms of schizophrenia. Severe dissociative psychopathology is also associated with impairment in other psychopathological dimensions. The implications of these findings are discussed with regard to the theory of dissociation, the differential diagnosis between schizophrenia and dissociative disorders and a possible contribution of dissociative phenomenology to the clinical heterogeneity of schizophrenia.