Schizoaffective disorder has features of both schizophrenia and mood disorders.
The lifetime prevalence is in the range of 0.32% to 1.1%.
The depressive type of schizoaffective disorder is more common in older patients, whereas the bipolar type is more common in younger patients.
Patients have a better prognosis than patients with schizophrenia but a worse prognosis than patients with mood disorder.
Patients tend to have a non-deteriorating course and better response to mood stabiliser medications than patients with schizophrenia.
Patients with schizoaffective disorder are a heterogeneous group with a variable predominance of schizophrenia and affective disorder symptoms.
Schizoaffective disorder is an illness defined by a course that combines significant affective and psychotic symptoms. The DSM definition requires the presence of schizophrenia symptoms concurrent with the mood symptoms (depression or mania), and lasting for a considerable part of a 1-month period. Schizoaffective disorder is further classified as manic type (when manic symptoms are prominent) or depressive type (when only schizophrenia and major depressive symptoms have been present). 
The ICD-10 definition requires the presence of prominent affective and psychotic symptoms, either at the same time or within a few days of each other.  A schizoaffective episode is diagnosed only when the patient does not meet criteria for either schizophrenia or a depressive or manic episode. Schizoaffective disorder is further classified as manic type when manic or mixed symptoms are prominent; or a depressive type when only schizophrenia and depressive symptoms have been present.
Associate Clinical Professor of Psychiatry
University of California
RGB declares that he has no competing interests.
Health Sciences Professor
Department of Psychiatry and Human Behavior
University of California, Irvine School of Medicine
AP is on the advisory board of Boehringer Ingelheim.
Professor of Psychiatry
University of Missouri Kansas City
KS declares that he has no competing interests.
Associate Professor of Psychiatry
University of Maryland School of Medicine
WTR declares that he has no competing interests.
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