The effects of ECT on brain glucose: A pilot FDG PET study

Background: Regional brain activity was measured before and after electroconvulsive therapy (ECT) using [18F]fluorodeoxyglucose (FDG) positron emission tomography (PET). Methods: 6 patients (4 females) with major depression were free of psychotropic medications for at least 2 weeks prior to baseline FDG scans. Patients were treated with bifrontotemporal ECT, and posttreatment scans were obtained after the last treatment. Results: A region of interest (ROI) analysis of absolute metabolic rate showed a decrease in CMRglu after ECT in all 61 regions examined. In 17 of the 61 regions, the decrease was significant at the p < 0.05 level. In the right parietal lobe, and the right anterior and left posterior frontal lobes, the decrease in CMRglu significantly correlated with the decrease in Hamilton Depression Rating Scale (HDRS) scores (r = 0.83, 0.82, and 0.84, respectively). The analysis of CMRglu normalized to global metabolic rate showed significant increases in 8 of 61 regions, including basal ganglia, upper brainstem, and occipital lobe. Discussion: The decreases in global glucose metabolism and correlation of changes in frontal metabolism with decreases in HDRS are consistent with earlier brain imaging studies of ECT. The relative increases in CMRglu observed in regions with known dopaminergic innervation (caudate and upper brainstem) have not been previously reported.