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Regional cerebral glucose metabolism in never-medicated patients with schizophrenia
1Department of Psychiatry, University of British Columbia, 2255 Wesbrook Mall, Vancouver, BC V6T 2A1. cmblclrk@interchange.ubc.ca
Objective:
The purpose of this study was to assess regional cerebral glucose metabolism in patients with schizophrenia who had never received antipsychotic medication and whose olfactory identification ability had been assessed. Two hypotheses were examined. First, the patients were compared with normal controls to determine whether differences in regional cerebral metabolism were apparent. Second, regional rates of metabolism were correlated with olfactory ability and the relation between them determined.
Methods:
The patient (n = 26) and control (n = 32) subjects were scanned at rest using positron emission tomography (PET) after administration of 18F-fluorodeoxyglucose (FDG). In addition, the University of Pennsylvania Smell Identification Test was administered to each patient.
Results:
Patients with schizophrenia had reduced rates of glucose metabolism in the right and left thalamus that reached significance if not corrected for multiple comparisons. However, if a Bonferroni correction was applied over the 27 regions of interest, the differences were not significant. Scores on the Smell Identification Test were negatively correlated with 8 regions of interest. When scores were analyzed using multiple regression, the left frontal cortex and the medial parietal cortex were significant predictors.
Conclusions:
The finding of reduced metabolism in the thalami is consistent with some of the previous literature, whereas the negative correlations between specific regions and olfactory function are not consistent with studies using activation paradigms.