Schizoaffective disorder: a form of schizophrenia or affective disorder?

BACKGROUND: The diagnostic status of schizoaffective disorder continues to be controversial. Researchers have proposed that schizoaffective disorder represents a variant of schizophrenia or affective disorder, a combination of the 2, or an intermediate condition along a continuum between schizophrenia and affective disorder.
METHOD: We compared outpatients aged 45 to 77 years with DSM-III-R diagnosis of schizoaffective disorder (N = 29), schizophrenia (N = 154), or nonpsychotic mood disorder (N = 27) on standardized rating scales of psychopathology and a comprehensive neuropsychological test battery. A discriminant function analysis was used to classify the schizoaffective patients based on their neuropsychological profiles as being similar either to schizophrenia patients or to those with nonpsychotic mood disorder.
RESULTS: The schizoaffective and schizophrenia patients had more severe dyskinesia, had a weaker family history of mood disorder, had been hospitalized for psychiatric reasons more frequently, were more likely to be prescribed neuroleptic and anticholinergic medication, and had somewhat less severe depressive symptoms than the mood disorder patients. The schizophrenia patients had more severe positive symptoms than the schizoaffective and mood disorder patients. The neuropsychological performances of the 2 psychosis groups were more impaired than those of the nonpsychotic mood disorder patients. Finally, on the basis of a discriminant function analysis, the schizoaffective patients were more likely to be classified as having schizophrenia than a mood disorder.
CONCLUSION: These findings suggest that schizoaffective disorder may represent a variant of schizophrenia in clinical symptom profiles and cognitive impairment.