A COMPARISON OF READING AND DEMOGRAPHIC-BASED ESTIMATES OF PREMORBID INTELLIGENCE IN SCHIZOPHRENIA

Estimating premorbid intelligence in schizophrenia is difficult becaus e the illness affects aspects of premorbid and postmorbid functioning. We evaluated two qualitatively different estimates of premorbid intel ligence in a sample of schizophrenia patients and tested whether: (1) the two indices were related and produced similar IQ estimates, and (2 ) either index was related to a measure of cognitive deterioration. Th e Barona Index (BI, a demographically-based instrument) and the Nation al Adult Reading Test (NART, a reading test of irregularly-spelled wor ds) were utilized. Subjects (n=40) were adult neuroleptic-medicated in patients with a DSM-III-R diagnosis of chronic schizophrenia (n=35) or schizoaffective disorder (n=5). Paired t-tests revealed statistically equivalent BI and NART estimates for Full Scale and Verbal IQs, but s ignificantly higher NART Performance IQs (t[35]= -3.34, p<0.01). Corre lational analyses suggested the two indices were associated but shared modest variance. BI correlations revealed expected associations with education and social position. NART IQs were related to education and a measure of cognitive status. Regression analyses supported the assoc iation between NART estimates and cognitive deterioration. Results sug gest BI may be a better estimate of premorbid intelligence in schizoph renia as it is less influenced by potential consequences of the diseas e.