Negative, positive, and disorganized symptom dimensions in schizophrenia, major depression, and bipolar disorder

We compared the factor structure of positive and negative symptoms in schizophrenia (N = 214), major depression (N = 97), and bipolar disorder (N = 58) to determine whether schizophrenia factors would generalize to mood disorders. A study of schizophrenia and mood disorders identified patients whose symptoms were evaluated with the Scale for the Assessment of Negative Symptoms and the Scale for the Assessment of Positive Symptoms. We conducted principal component analyses with orthogonal rotation on the global ratings. The factor structure replicated earlier findings of three factors (negative, positive, and disorganization) in groups with schizophrenia, combined mood disorders, and psychotic symptoms, regardless of diagnosis. An additional negative symptom factor was found in the major depression group. The bipolar group did not have a disorganization factor. Similar symptom factors in schizophrenia and mood disorders suggest a continuity in the major affective and psychotic disorders that appears to reflect the underlying dimension of a psychotic process.