Brief ReportGeneral and Specific Cognitive Deficits in Schizophrenia: Goliath Defeats David?
Section snippets
Participants
Patients and control subjects were assessed and followed by the Schizophrenia Research Center at the University of Pennsylvania. Data for the present analyses were collected from January 1993 to May 1998, as described previously (6). Patients had DSM-III-R diagnoses of schizophrenia established by clinical examination and structured clinical interview but were free of other psychiatric conditions. Control subjects were free of psychiatric disorders in themselves and their first-degree
Sample Characteristics
Patients were significantly older than control subjects, more likely to be male, and less likely to be Caucasian. Patients also had fewer years of education, although parental education was statistically equivalent between groups (Table 2). To reduce the impact of demographic differences, all analyses covaried age, sex, race/ethnicity, and mother's/father's education.
The schizophrenia deficit was significant for every neuropsychological variable (all ps < .01). Wechsler Adult Intelligence Scale
Discussion
Results indicate that the deficit in schizophrenia neuropsychological performance relative to healthy control subjects is largely mediated through a common ability factor. Using a hierarchical model of cognitive structure, large samples of patients and control subjects, and a comprehensive neuropsychological battery, this factor accounted for 63% of the diagnosis-related variance in overall cognitive performance, consistent with our earlier report (5). Analyses revealed direct diagnosis effects
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