Abstract
Background
Spatial working memory impairments are among the neurocognitive deficits that may
mark genetic predisposition toward schizophrenia. We previously reported that impairment
on the spatial span subtask of the Wechsler Adult Intelligence Scale—Revised increased
in a dose-dependent manner with increasing genetic predisposition toward schizophrenia
in a sample of discordant twins; however, it remains to be determined whether these
deficits reflect difficulties with encoding, maintenance, manipulation, time-tagging
of visual spatial information, storage capacity, or complex motor response.
Methods
We developed a spatial delayed response task in which memory set size was parametrically
varied, holding constant manipulation and decision processes. We then reassessed 80
of the previously studied twins (17 probands with 8 monozygotic co-twins and 13 dizygotic
co-twins, and 42 healthy twins).
Results
The spatial delayed response task was sensitive to genetic loading for schizophrenia
but did not provide evidence for capacity limitations in probands or their co-twins.
Conclusions
The findings suggest that deficits in the encoding or storage aspects of short-term
spatial mnemonic processing may be an effective endophenotypic marker for schizophrenia.
Keywords
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Article info
Publication history
Accepted:
August 22,
2002
Received in revised form:
August 8,
2002
Received:
May 23,
2002
Identification
Copyright
© 2003 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.
