title: Longitudinal assessment of premorbid cognitive functioning in patients with schizophrenia through examination of standardized scholastic test performance.
abstract: OBJECTIVE
  Studies suggest the presence of premorbid cognitive impairment in patients with schizophrenia, yet the onset and course of these deficits remain unclear. The purpose of this study was to investigate the longitudinal course of premorbid cognitive functioning in individuals with schizophrenia by using prospective data obtained from scholastic test results.
  
  
  METHODS
  Scores from grades 4, 8, and 11 on the Iowa Tests of Basic Skills and the Iowa Tests of Educational Development were obtained for 70 subjects who later developed schizophrenia. The mean percentile rank of the subjects' scores in the areas of vocabulary, reading comprehension, language, mathematics, sources of information, and an overall composite category were compared with state norms.
  
  
  RESULTS
  The subjects scored below the 50th percentile for each category in all three grades, but only language, reading, sources of information, and composite scores from grade 11 were significantly below state norms. With regard to longitudinal course, there was a significant linear decrease in language scores over time. Scores from grade 11 were positively correlated with WAIS-R IQ, verbal fluency, and Rey Auditory Verbal Learning scores at first illness episode. Scores from grade 11 were not significantly correlated with age at illness onset or ratings of disorganized, psychotic, or negative symptoms.
  
  
  CONCLUSIONS
  Scholastic test scores at grades 4 and 8 were nonsignificantly below average in this group of children who later developed schizophrenia. However, test scores dropped significantly between grades 8 and 11. This corresponds to ages 13-16 years, or the onset of puberty. Poor or declining scholastic performance may be a precursor to the cognitive impairment seen during the first episode of illness.
authors.affiliation: Department of Psychiatry, Mental Health Clinical Research Center, University of Iowa Hospitals and Clinics, 200 Hawkins Drive, Iowa City, IA 52240, USA. bfuller@mrpc.umaryland.edu
authors.forename: Rebecca
authors.initials: R
authors.lastname: Fuller
authors.forename: Peg
authors.initials: P
authors.lastname: Nopoulos
authors.forename: Stephan
authors.initials: S
authors.lastname: Arndt
authors.forename: Dan
authors.initials: D
authors.lastname: O'Leary
authors.forename: Beng-Choon
authors.initials: BC
authors.lastname: Ho
authors.forename: Nancy C
authors.initials: NC
authors.lastname: Andreasen
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D017668:Age of Onset; D002648:Child; D002657:Child Development; D003072:Cognition Disorders / Q000175:diagnosis* / Q000453:epidemiology; D015897:Comorbidity; D004522:Educational Status; D005260:Female; D006801:Humans; D007361:Intelligence Tests / Q000706:statistics & numerical data; D008137:Longitudinal Studies; D008297:Male; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D011446:Prospective Studies; D011581:Psychological Tests / Q000706:statistics & numerical data*; D012559:Schizophrenia / Q000175:diagnosis* / Q000453:epidemiology; D012565:Schizophrenic Psychology