Bizarre delusions and first-rank symptoms in a first-admission sample: a preliminary analysis of prevalence and correlates.

This report examines the prevalence and correlates of bizarre delusions and Schneider's first-rank symptoms (FRS) in a first-admission sample with psychosis. A total of 196 patients were assessed with the Structured Clinical interview for DSM-III-R (SCID) and given a consensus diagnosis. Project psychiatrists blind to the consensus diagnoses coded each delusion and hallucination in the sample for both FRS and DSM-III-R bizarreness. Interrater reliability of bizarreness was lower than that of FRS (kappa = .681 v 861). The majority of symptoms (72%) were neither bizarre nor FRS, and of the remainder, bizarre delusions that were not also FRS were extremely uncommon. The prevalence of FRS was 70% in schizophrenia, 29% in psychotic bipolar disorder, and 18% in psychotic depression. For seven schizophrenic patients (7.45%), diagnosis of that disorder depended on the presence of a DSM-III-R bizarre delusion to meet criteria. There was a trend for FRS to be associated with poorer prognostic features in the schizophrenic sample. We concluded that although the constructs of bizarre delusions and FRS overlap, FRS were a more important feature in schizophrenia than bizarreness. The rarity of bizarre delusions that were not FRS, combined with the lower reliability of their assessment as compared with that of FRS, raises questions about the continued emphasis on this phenomenon in the definition of schizophrenia.