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


METHODS
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.
Mathes
Birgit
B
Melbourne Neuropsychiatry Centre, Department of Psychiatry, The University of Melbourne and Sunshine Hospital, Melbourne, Australia.
Wood
Stephen J
SJ
Proffitt
Tina M
TM
Stuart
Geoffrey W
GW
Buchanan
Jo-Anne M
JA
Velakoulis
Dennis
D
Brewer
Warrick J
WJ
McGorry
Patrick D
PD
Pantelis
Christos
C
D000293:Adolescent; D000328:Adult; D001288:Attention; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008297:Male; D008569:Memory Disorders / Q000209:etiology* / Q000503:physiopathology*; D008606:Mental Processes; D008875:Middle Aged; D011618:Psychotic Disorders / Q000503:physiopathology*; D012559:Schizophrenia / Q000503:physiopathology*