Robert Milstein

Five-component model of schizophrenia: assessing the factorial invariance of the positive and negative syndrome scale.

A five-component model of schizophrenia has been presented by Kay and Sevy based upon an analysis of the Positive and Negative Syndrome Scale. Kay and Sevy found factorial validity for negative and positive syndromes, and they identified excitement, depressive, and cognitive components as well. They suggested that subtypes and syndromes can be mapped along dimensions presented in their model. The present study compares the five-component solution for a new sample of 146 subjects to a reanalysis of the Kay and Sevy data. Despite divergent demographic characteristics, the two samples produce similar dimensions. Correlations of component loadings and subject scores as well as confirmatory factor analysis are presented. Discussion focuses on points of agreement and important differences in the symptoms assigned to each component. How the dimensions relate to rationally derived models of positive and negative syndromes is reviewed, and implications for subtyping and other methods of examining the heterogeneity of schizophrenia are considered.

The positive and negative syndrome scale and the brief psychiatric rating scale : reliability, comparability, and predictive validity

In a psychiatric rehabilitation study, 154 concurrent ratings were performed using the 30-item Positive and Negative Syndrome Scale (PANSS) and the 18-item Brief Psychiatric Rating Scale (BPRS). Although both instruments had excellent interrater reliability, the PANSS was consistently better: on the 18 symptom items the two instruments share, the PANSS had higher intraclass rs on 14; for the syndromes, the PANSS was higher than the BPRS on positive, negative, and total. Weighted Kappas comparing shared items revealed that most were not interchangeable, with only three coefficients in the excellent range. However, syndrome scale scores were very highly correlated and resulted in similar classification for negative schizophrenia. Ten of the 12 items of the PANSS not included in the BPRS had low zero-order correlations with BPRS items, which suggests that they measure symptoms distinct from those measured by the BPRS and should add to clinical predictive power. This proved true in our study of rehabilitation of patients with schizophrenia PANSS symptom ratings explained up to 55% of the variance on seven measures of work performance, whereas the BPRS had lower predictive power on six of the seven measures. We concluded that the PANSS may be superior to the BPRS in clinical research on schizophrenia and that most BPRS items are not interchangeable with identically named PANSS items.

Concurrent validity of the cognitive component of schizophrenia: Relationship of PANSS scores to neuropsychological assessments

Cognitive symptoms of schizophrenia may represent a separate component of the disorder that is distinct from positive or negative syndromes. In a previous study, we reported a factor analysis of the Positive and Negative Syndrome Scale (PANSS) that revealed five components, one of which we labeled the Cognitive component. In the present study, we explored the validity of the PANSS Cognitive component by examining correlations between neuropsychological measures and the five factor-analytically derived PANSS scores for 147 subjects with diagnoses of schizophrenia or schizoaffective disorder. Higher scores on the PANSS Cognitive component were significantly correlated with poorer performance on all neuropsychological tests, including the Wisconsin Card Sorting Test (WCST), the Digit Symbol Substitution Task, the Slosson Intelligence Test, and the Gorham Proverbs Test. Multiple regression revealed that these test scores explained 37% of the variance in the Cognitive component score. Neuropsychological tests have very limited associations with the other PANSS components. These results suggest that the Cognitive component of the PANSS is a valid measure of cognitive deficits in schizophrenia, and they support the hypothesis that Cognitive impairment is a distinctive feature of schizophrenia independent of positive and negative syndromes.

Insight and psychosocial treatment compliance in schizophrenia.

Research has suggested that poor insight in patients with schizophrenia is associated with poorer medication compliance and heightened levels of psychopathology. This study examined the relationship of insight to compliance with a work rehabilitation program and with levels of psychopathology and psychosocial functioning. Poor insight was found to be positively associated with fewer weeks of participation and with poorer social skills and personal presentation in the fifth week of work. Poor insight was also associated with cognitive disorganization and a lower intelligence quotient, but not with heightened levels of psychopathology. Results suggest that poor insight may predict noncompliance with psychosocial treatment and may be related to a constellation of cognitive deficits.

Relationship of Positive and Negative Symptoms to Cocaine Abuse in Schizophrenia

The prevalence of cocaine abuse by patients with schizophrenia has led researchers to investigate features of the disorder correlated with abuse. Although abuse has been found to be more common among patients with a diagnosis of paranoid subtype and a history of earlier and more frequent hospitaliza