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Early processing deficits in object working memory in first-episode schizophreniform psychosis and established schizophrenia

Published online by Cambridge University Press:  14 March 2005

BIRGIT MATHES
Affiliation:
Melbourne Neuropsychiatry Centre, Department of Psychiatry, The University of Melbourne and Sunshine Hospital, Melbourne, Australia
STEPHEN J. WOOD
Affiliation:
Melbourne Neuropsychiatry Centre, Department of Psychiatry, The University of Melbourne and Sunshine Hospital, Melbourne, Australia Brain Research Institute, Victoria, Australia
TINA M. PROFFITT
Affiliation:
ORYGEN Research Centre (incorporating the Early Psychosis Prevention and Intervention Centre (EPPIC)), Department of Psychiatry, The University of Melbourne, Australia
GEOFFREY W. STUART
Affiliation:
Melbourne Neuropsychiatry Centre, Department of Psychiatry, The University of Melbourne and Sunshine Hospital, Melbourne, Australia Centre for Neuroscience, The University of Melbourne, Melbourne, Australia
JO-ANNE M. BUCHANAN
Affiliation:
Melbourne Neuropsychiatry Centre, Department of Psychiatry, The University of Melbourne and Sunshine Hospital, Melbourne, Australia
DENNIS VELAKOULIS
Affiliation:
Melbourne Neuropsychiatry Centre, Department of Psychiatry, The University of Melbourne and Sunshine Hospital, Melbourne, Australia
WARRICK J. BREWER
Affiliation:
ORYGEN Research Centre (incorporating the Early Psychosis Prevention and Intervention Centre (EPPIC)), Department of Psychiatry, The University of Melbourne, Australia
PATRICK D. McGORRY
Affiliation:
ORYGEN Research Centre (incorporating the Early Psychosis Prevention and Intervention Centre (EPPIC)), Department of Psychiatry, The University of Melbourne, Australia
CHRISTOS PANTELIS
Affiliation:
Melbourne Neuropsychiatry Centre, Department of Psychiatry, The University of Melbourne and Sunshine Hospital, Melbourne, Australia Centre for Neuroscience, The University of Melbourne, Melbourne, Australia

Abstract

Background. While there are many studies showing working-memory deficits in schizophrenia there are only a few that disentangle impairments for working-memory subprocesses such as perceptual, attentional, mnemonic and executive function.

Method. In this study of delay-dependent memory, 55 patients with schizophreniform psychosis, 50 with established schizophrenia and 56 healthy controls were investigated. Using the delayed matching-to-sample task from the Cambridge Neuropsychological Test Automated Battery (CANTAB), performance deficits were found in both patient groups after controlling for age and pre-morbid IQ.

Results. Even after controlling for simultaneous matching-to-sample ability (i.e. perceptual matching), impaired performance in both patient groups was found as soon as the stimuli were no longer present. Impaired performance was not due to different types of errors in patients versus controls. Performance in both patient groups was comparable, except for a slight decrease of overall task performance. This suggests that the deficit is relatively stable during the course of the illness.

Conclusions. Our results suggest a deficit in patients with psychotic illness in the initial processes necessary to actively maintain information, such as the ability to form an internal representation of complex objects.

Type
Research Article
Copyright
2005 Cambridge University Press

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Footnotes

The study has been presented in part at the 2003 Meeting of the International Congress on Schizophrenia Research, Colorado Springs, CO, USA.