title: A comparison of reading and demographic-based estimates of premorbid intelligence in schizophrenia.
abstract: Estimating premorbid intelligence in schizophrenia is difficult because the illness affects aspects of premorbid and postmorbid functioning. We evaluated two qualitatively different estimates of premorbid intelligence 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. The Barona Index (BI, a demographically-based instrument) and the National Adult Reading Test (NART, a reading test of irregularly-spelled words) were utilized. Subjects (n = 40) were adult neuroleptic-medicated inpatients 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 significantly higher NART Performance IQs (t[35] = -3.34, p < 0.01). Correlational 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 association between NART estimates and cognitive deterioration. Results suggest BI may be a better estimate of premorbid intelligence in schizophrenia as it is less influenced by potential consequences of the disease.
authors.affiliation: Department of Psychiatry, Medical College of Pennsylvania/Eastern Pennsylvania Psychiatric Institute, Norristown State Hospital, Philadelphia, USA.
authors.forename: J I
authors.initials: JI
authors.lastname: Tracy
authors.forename: A C
authors.initials: AC
authors.lastname: McGrory
authors.forename: R C
authors.initials: RC
authors.lastname: Josiassen
authors.forename: C A
authors.initials: CA
authors.lastname: Monaco
mesh_terms: D000328:Adult; D002908:Chronic Disease; D003072:Cognition Disorders / Q000175:diagnosis / Q000523:psychology; D005260:Female; D006801:Humans; D007360:Intelligence; D008297:Male; D008609:Mental Status Schedule; D008875:Middle Aged; D011618:Psychotic Disorders / Q000175:diagnosis / Q000523:psychology; D011932:Reading; D012559:Schizophrenia / Q000175:diagnosis*; D012565:Schizophrenic Psychology; D012569:Schizotypal Personality Disorder / Q000175:diagnosis* / Q000523:psychology