Classification of schizoaffective disorder

Abstract

Two studies were conducted to examine the viability of the major alternative models of the classification of schizoaffective disorder: that it is a subtype of schizophrenia, a type of affective disorder, on a continuum between schizophrenia and affective disorder, a totally independent disorder, or a heterogeneous category. The methodologies, taken from the prototype view of classification in cognitive psychology, study the behavior of the classifiers, in this case, clinicians assigning psychiatric diagnoses. These paradigms are especially useful in the study of schizoaffective disorder since different definitions of this diagnosis have resulted in widely discrepant findings. Therefore, finding the concept of schizoaffective disorder with the highest consensus is a reasonable first step before conducting empirical studies of patients. The first study attempted to locate exemplars or typical schizoaffective cases based on high diagnostic agreement and fast diagnostic decision time. Twenty clinicians assigned diagnoses to 30 cases, including 15 schizoaffective cases from the literature. While 11 exemplars were found for other diagnoses, only one was found for schizoaffective disorder. Schizoaffective cases were most often diagnosed as schizophrenia, particularly by more experienced clinicians. In the second study, 20 clinicians listed the essential clinical features of schizoaffective disorder and other major psychoses. The schizoaffective list shared as many features with schizophrenia as did the schizophrenic subtypes, but shared only one feature with the affective disorders. Overall, the results suggested that these clinicians perceive schizoaffective disorder as a variant of schizophrenia; however, this view of schizoaffective disorder may be changing in newer clinicians. Implications for defining schizoaffective disorder, suggestions for diagnosis, the generalizability of these findings and directions for future research are discussed.