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Generalized Cognitive Deficits in Schizophrenia: A Study of First-Episode Patients
Journal article   Open access   Peer reviewed

Generalized Cognitive Deficits in Schizophrenia: A Study of First-Episode Patients

Somaia Mohamed, Jane S Paulsen, Daniel O'Leary, Stephen Arndt and Nancy Andreasen
Archives of general psychiatry, Vol.56(8), pp.749-754
08/01/1999
DOI: 10.1001/archpsyc.56.8.749
PMID: 10435610
url
https://doi.org/10.1001/archpsyc.56.8.749View
Published (Version of record) Open Access

Abstract

BACKGROUND Cognitive impairment is recognized as a core characteristic of schizophrenia. There has always been a debate about the nature, selectivity, and time of onset of these deficits in relationship to the onset of illness and treatment factors. To our knowledge, the present study represents the largest sample of mostly neuroleptic-naive patients with first-episode schizophrenia that has been reported to date. METHODS A group of 94 patients experiencing their first episode of schizophrenic illness and 305 normal comparison subjects were administered a comprehensive clinical and neuropsychological evaluation. Seventy-three patients were neuroleptic naive, 14 had received treatment for less than 1 week, and the remaining 7 had been medicated for less than 2 weeks. RESULTS Patients performed significantly worse than the comparison subjects on every neuropsychological variable except those assessing savings scores (ie, forgetting over time). Twenty-five of 30 tests had an effect size (ES) greater than 0.75 when the 2 groups were compared. An ES analysis within the schizophrenia group revealed that the greatest relative impairments were on the Wechsler Adult Intelligence Scale–Revised digit symbol (ES, −0.52) and comprehension (ES, −0.42) subscales. CONCLUSIONS Our findings are in concert with others demonstrating that significant cognitive impairment across multiple ability domains is a core characteristic of schizophrenia and is not caused by chronic illness, treatment, or institutionalization. The ES analysis emphasizes that patients with schizophrenia have a generalized deficit that is not easily explained by a single anatomical region or ability area.Arch Gen Psychiatry. 1999;56:749-754-->

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