Temporal lobe metabolic differences in medication-free outpatients with schizophrenia via the PET-600

Regional cerebral glucose metabolic rates (rCMRglc) were compared in 18 unmedicated outpatients with schizophrenia and 11 normal controls using high resolution positron emission tomography (PET) and the tracer [F-18]-2-fluoro-2D-deoxyglucose (FDG). From previous work we expected to see abnormal hippocampal rCMRglc in the patients, but no striatal abnormalities. Trial-by-trial Stroop cognitive task, which has been shown to activate the anterior cingulate, was performed within a day of the PET study. As our patients performed abnormally on the Stroop we tested for a correlation between the anterior cingulate rCMRglc and Stroop performance. We found no whole slice cortical average glucose metabolic abnormalities. As, predicted we found abnormally decreased left hippocampal rCMRglc in the patients. No striatal or cingulate rCMRglc abnormalities were noted in patients, but they demonstrated a highly positive correlation between anterior and cingulate rCMRglc and Stroop facilitation. Patients with higher Stroop interference had more prominent hippocampal metabolic decreases. These localized temporal lobe abnormalities could account for some of the patient's positive symptoms and are consistent with recent findings in the literature.