Classification

The coexistence of symptoms that characterize schizophrenia with those that characterize affective disorder poses a number of knotty questions. Schizoaffective disorder is the most enduring of the various labels used for this overlap but the definitions of this term have varied and have identified groups that have not overlapped well (Brockington and Leff, 1979). Most have specified either the presence of schizophrenia-like psychotic features within an affective syndrome, or the occurrence of psychotic features when affective symptoms are quiescent.

Much of the research over the past several decades has employed the definition contained in the Research Diagnostic Criteria (RDC) (Spitzer et al., 1978). In this system the presence within a major depressive or manic syndrome of a Schneiderian first-rank symptom such as a delusion of passivity or thought broadcasting, persistent non-affective hallucinations, or definite instances of formal thought disorder, warrants a diagnosis of schizoaffective disorder. The presence of any clear psychotic feature when affective symptoms are absent also suffices and this defines the mainly schizophrenic subtype of schizoaffective disorder. In contrast, the DSM-IV definition is much narrower and encompasses only those who would meet the RDC for the mainly schizophrenic subtype of schizoaffective disorder.

Competing views

Schizoaffective disorder may be considered in one of three or more ways. According to a dichotomous view, the diagnosis applies to individuals who, in fact, have either schizophrenia or an affective disorder.