Cothcal-Striatal-Thalamic Circuits and Brain Glucose Metabolic Activity in 70 Unmedicated Male Schizophrenic Patients

Objective: The cortical-striatal-thalamic circuit modulates cognitive processing and thus may be involved in the cognitive dysfunction in schizophrenia. The imaging ofmetabolic rate in the structures making up this circuit could reveal the correlates ofschizophrenia and its main symp-toms. Method: Seventy male schizophrenic patients underwent [18F]-fluorodeoxyglucose posi-tron emission tomography after a period ofat least 4 weeks during which they had not received neuroleptic medication and were compared to 30 age-matched male normal comparison sub-jects. Results: Analyses revealed decreased metabolism in medial frontal cortex, cingulate gyrus, medial temporallobe, corpus callosum, and ventral caudate and increased metabolism in the left lateral temporal and occipital cortices in the schizophrenic cohort. Consistent with previous studies, the schizophrenic group had lower hypofrontality scores (ratios of lateral frontal to occipital metabolism) than did comparison subjects. The lateral frontal cortical metabolism of schizophrenic patients did not differ from that of comparison subjects, while occipital cortical metabolism was high, suggesting that lateral hypofrontality is due to abnormalities in occipital rather than lateral frontal activity. Hypofrontality was more prominent in medial than lateral frontal cortex. Brief Psychiatric Rating Scale (BPRS) scores, obtained for each schizophreni