Sensorimotor gating deficits are relevant in schizophrenia and can be measured using prepulse inhibition (PPI) of the startle reflex. It is conceivable that such deficits may hinder the cognitive functions in schizophrenia patients. In this study, using PPI and a neuropsychological battery, we studied this possibility in a group of 23 acute, neuroleptic-free schizophrenia patients and 16 controls. A non-significant decrease in PPI was found in the patients as compared to the controls, as well as significant differences in the performance of Trail A and B in Wisconsin Card Sorting and Digit/Symbol Tests. No statistically significant correlations between PPI and neuropsychological performance were found after the correction for multiple comparisons in any group. Our results suggest that PPI deficits in schizophrenia patients may not contribute to the cognitive deficits typical of that illness, at least in patients with a non-significant PPI decrease.
The caudate nucleus is involved in cognitive function. Schizophrenic patients showed cognitive dysfunction. It has been reported that volume reduction of the caudate nucleus was associated with cognitive impairment in schizophrenic patients. Because treatment with olanzapine improves cognitive dysfunction in schizophrenia, olanzapine may affect the caudate nucleus volume in patients with schizophrenia. We measured volumes of grey and white matter in the caudate nucleus of schizophrenic patients. Methods: Ten schizophrenic patients and ten healthy subjects were examined magnetic resonance imaging. Ten patients were scanned at the time of pre-treatment and post-treatment with olanzapine. MR data analysis was performed using BRAINS software in order to measure grey and white matter volume of the caudate nucleus. Results: Schizophrenic patients had reduced volume of grey and white matter of the caudate nucleus compared with healthy subjects. The average duration of treatment with olanzapine was 186 days in schizophrenic patients. The volume of grey and white matter in the caudate nucleus at the time of post-treatment was significant larger than that at the time of pre-treatment with olanzapine in patients with schizophrenia. There was no significant difference between the volume of grey matter of the caudate nucleus at the post-treatment with olanzapine and that of healthy subjects. Conclusion: Schizophrenic patients had reduced volume of the caudate nucleus. Treatment with olanzapine may improve volume reduction of grey matter of the caudate nucleus in schizophrenic patients.
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