Schizoaffective disorder: is the news of its nonexistence premature? Editor's introduction.

Because of the continued controversy about the nature of the schizoaffective disorders and their relationships to schizophrenia and the affective disorders, a thorough review of the concept, genetics, treatment, outcome, and biological aspects of the schizoaffective disorders in relationship to schizophrenia and the affective disorders appears timely. The use of explicit criteria for schizoaffective disorders, such as those provided by the Research Diagnostic Criteria, permits clinical investigators to continue the inquiry into these disorders. Current evidence appears most consistent with the idea that schizoaffective disorder is usually a variant of affective psychosis and sometimes a variant of schizophrenia. However, the possibility that an interacting group of biological vulnerabilities, environmental insults, and ensuing psychological reactions produces the spectrum of clinical states from "pure" schizophrenia to "pure" affective psychosis with schizoaffective disorder as a genuine mixed state needs further investigation. Dimensional diagnostic systems rather than categorical ones may be of value for many clinical and research purposes.