Content area
Full Text
Our understanding of schizoaffective disorder can be organized in five different models (see Sidebar, page 170). One approach holds that schizoaffective disorder is its own illness, separate from others, as appears to be the case superficially by its separate diagnostic criteria in the Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV).1 A second model holds that schizoaffective disorder represents a middle clinical picture on a psychotic continuum that extends from bipolar disorder to schizophrenia; in other words, this model rejects the Kraepelinian dichotomy of bipolar disorder and schizophrenia.2,3 A third model argues that schizoaffective disorder represents the comorbidity of affective disorders and schizophrenia, thereby maintaining the Kraepelinian dichotomy and explaining overlap symptoms as chance co-occurrence.4 A fourth theory views schizoaffective disorder as basically a variant of bipolar disorder,5 and a fifth sees schizoaffective disorder as a variant of schizophrenia.6
PHENOMENOLOGY OF SCHIZOAFFECTIVE DISORDER
This is the aspect of the schizoaffective category that receives the most attention from clinicians. From this perspective, the term "schizoaffective" simply applies to those individuals with continuous psychotic and mood symptoms. Unlike mood disorders, psychotic symptoms are not brief or confined to the severe stages of either mania or depression. Unlike schizophrenia, mood symptoms remain prominent. Clinically, many patients seem to fall into this overlap region. Indeed, Kraepelin himself observed that many patients had such overlap of manic-depressive and dementia praecox symptoms.7,8 Hence, the fact that such overlap occurs is almost universally accepted, even by Kraepelin, who originated the idea that mood and psychotic disorders differ.
By itself, the presence of overlap does not invalidate the diagnoses of schizophrenia and mood disorders. This is partly because phenomenology is only one of four diagnostic validators.9 This is also partly because a difference in symptoms is not an all-or-nothing phenomenon. In other words, to say that schizophrenia and mood disorders differ in symptoms is not to say that they never overlap.10 It only means that they usually do not overlap. Indeed, some well-conducted symptom prevalence studies4 have shown that patients with mood and psychotic symptoms tend to differentiate into two big groups, one with mainly mood symptoms and one with mainly psychotic symptoms, although there is some overlap.
It is sometimes argued that the mere existence of schizoaffective disorder is counter...