The psychosis of schizophrenia: Prevalence, response to atypical antipsychotics, and prediction of outcome

Background: Psychosis is a defining feature of schizophrenia consisting of formal thought disorder; delusions, and hallucinations. Although psychosis is present in the majority of patients with schizophrenia, the prevalence, responsiveness to atypical antipsychotic drug therapy, and prediction of ou tcome of individual psychotic symptoms in a population of well-diagnosed pa tients with schizophrenia have not been conclusively established. Methods: This paper examined the prevalence, responsiveness to the atypical antipsychotic olanzapine, and relationship to outcome of individual psycho tic symptoms using data from a previously reported large multicenter, doubl e-blind clinical trial of olanzapine (mean daily dose at endpoint = 13.6 +/ - 6.9 mg/day). Results: The most frequently reported psychotic symptoms at baseline were d elusions (65%), conceptual disorganization (50%), and hallucinations (52%), and the majority of patients (68%) experienced from one to three symptoms. Additionally with olanzapine treatment there were significant improvements (p < .001) in baseline to endpoint Positive and Negative Symptom Scale (PA NSS) psychotic item scores, with the largess effect sizes observed for hall ucinatory behavior, unusual thought content, suspiciousness/persecution, an d delusions. During the acute phase of the trial, quality of life was corre lated significantly with baseline conceptual disorganization (p = .038) and unusual thought content (p = .023), and time spent in the hospital was cor related with unusual thought content (p = .005). Conclusions: The implications of these for the clinical management of schiz ophrenia are discussed. Biol Psychiatry 1999;46:361-364 (C) 1999 Society of Biological Psychiatry.