title: Factor analysis of neurocognitive tests in a large sample of schizophrenic probands, their siblings, and healthy controls.
abstract: Large batteries of neuropsychological tests are typically necessary to identify cognitive deficits in schizophrenia and routinely examine multiple cognitive processes, with many tests often yielding more than one measure of interest. This study investigates the feasibility of a partial solution to the problem of multiple comparisons: the use of factor analysis to reduce the number of phenotypic variables and to better understand the underlying cognitive architecture in schizophrenia. Using a principle components analysis followed by a varimax rotation, we identified factor structures for schizophrenic patients (n=99), their unaffected siblings (n=167), and control subjects (n=131), both separately and as a composite group. Exploratory factor analysis of the full sample yielded a 7-factor model that included verbal memory, working memory, visual memory, IQ/speed/fluency, executive function, attention and digit span. A confirmatory factor analysis (CFA) with maximum likelihood estimation revealed that the 7-factor model fit observed data from the three groups adequately. Since we identified a factor structure representative of all groups that reduced 24 original variables to 7 variables of interest, factor analysis was useful in reducing the complexity of large batteries of cognitive measures to more manageable numbers of phenotypic variables. Furthermore, these findings provide the first confirmation that cognitive structure is comparable in family members of schizophrenia patients, as well as in patients themselves and controls.
authors.affiliation: Clinical Brain Disorders Branch, Genes, Cognition and Psychosis Program, National Institute of Mental Health, NIH, 10 Center Drive, CRC 7-5342, Bethesda, MD 20892, United States.
authors.forename: Margo R
authors.initials: MR
authors.lastname: Genderson
authors.forename: Dwight
authors.initials: D
authors.lastname: Dickinson
authors.forename: Catherine M
authors.initials: CM
authors.lastname: Diaz-Asper
authors.forename: Michael F
authors.initials: MF
authors.lastname: Egan
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Weinberger
authors.forename: Terry E
authors.initials: TE
authors.lastname: Goldberg
mesh_terms: D000293:Adolescent; D000328:Adult; D003072:Cognition Disorders / Q000175:diagnosis* / Q000209:etiology*; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D008297:Male; D008569:Memory Disorders / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology; D008570:Memory, Short-Term; D008875:Middle Aged; D009483:Neuropsychological Tests; D012559:Schizophrenia / Q000150:complications*; D012720:Severity of Illness Index; D035781:Siblings