Schizoaffective disorder: concept and reality.

A wide variety of concepts have been proposed to account for schizoaffective psychoses. Presenting a mixture of schizophrenic and affective symptoms, these psychoses have long defied classification in the usual scheme of the two major diagnostic categories, schizophrenia and major affective disorder. Empirical findings are often contradictory, and have sometimes supported the classification of schizoaffective disorder with schizophrenia, and, more recently, with major affective disorders. An alternative hypothesis is that schizoaffective disorder is fundamentally heterogeneous, and that research efforts should be directed toward the identification of homogeneous subtypes. To illustrate the latter research strategy, we describe our current research program of long-term followup and family studies of patients with schizoaffective psychoses and other atypical psychoses. Extensive data have been obtained using blind, structured psychiatric interviews with probands after 30 to 40 years of followup, and with their first degree relatives. In the same way, followup and family data were obtained for patients who met research criteria for schizophrenia, mania, and depression, and for matched surgical controls. By comparing these groups of "typical" psychotic patients with the schizoaffective patients, we can select homogeneous subgroups of schizoaffective patients and analyze their characteristics to refine clinical and research criteria for the differential diagnosis of schizoaffective subtypes.