Positive and negative symptoms in dissociative identity disorder and schizophrenia: a comparative analysis.

A substantial number of patients with dissociative identity disorder have had previous diagnoses of schizophrenia, due to the presence of positive symptoms of schizophrenia. The authors investigated the pattern of positive and negative symptoms in patients with dissociative identity disorder, and compared it with norms in schizophrenia. A total of 108 patients with a clinical diagnosis of dissociative identity disorder were administered the Positive and Negative Syndrome Scale. The positive symptom and general psychopathology scores were significantly more severe in the dissociative identity group than the norms for schizophrenia, while the negative symptoms were significantly more severe in schizophrenia. Since patients with dissociative identity disorder report more positive symptoms of schizophrenia than do schizophrenics, while schizophrenics report more negative symptoms, a primary emphasis on positive symptoms may result in false-positive diagnoses of schizophrenia and false-negative diagnoses of dissociative identity disorder.