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Abstract:
Abstract: Cognitive dysfunction has consistently been found
in patients with schizophrenia and also in their unaffected
siblings suggesting that these deficits are familial and may be
suitable for use as intermediate phenotypes in genetic studies. The
present study examined performance on tests of general
intelligence, executive functioning, motor functioning, lexical
access, and memory (verbal and visual) and hypothesized that (1)
siblings of patients with schizophrenia perform worse on the
neuropsychological battery compared to normal controls; (2)
subgroups of siblings of schizophrenic patients with impaired
cognition on specific tests would have a higher rate of impaired
performance compared to normal controls; and (3) relative risk for
impaired cognition would be moderate or higher. 147 patients with
schizophrenia, 193 of their siblings, and 47 healthy controls were
assessed using a neuropsychological test battery. Relative risk was
estimated using cutoff scores of one and two standard deviations
(SD) below the control mean. Schizophrenic patients performed
significantly worse than controls on all tests except for the Wide
Range Achievement Test. Relative risk to siblings was elevated on
the Wisconsin Card Sort Task, California Verbal Learning Test, and
Trails B, ranging from 2.2 to 3.8. These moderate relative risk
scores suggest that there may be a significant genetic component to
cognitive deficits associated with schizophrenia.
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