Verbal and performance IQ for discrimination among psychiatric diagnostic groups

WAIS Verbal and Performance IQ scores were obtained from medical records of 500 psychiatric inpatients recently admitted to a large university hospital. With a subsample of the original 500 patients for whom there was diagnostic agreement between two independent clinicians, a multivariate analysis of variance was carried out to determine the extent to which the Verbal and Performance scores discriminated among eight diagnostic categories into which patients were classified. In the multivariate ANOVA, statistical techniques were employed to control for concomitant background variation that otherwise might have been confounded with true diagnostic group differences in Verbal and Performance IQ. Although mentally retarded and organic brain syndrome patients could be distinguished significantly from other diagnostic groups on the basis of their lower total IQ scores, the data did not support the persistent clinical belief that functional psychiatric disorders differed in the WAIS measurement space.