Metabolic changes within the left dorsolateral prefrontal cortex occurring with electroconvulsive therapy in patients with treatment resistant unipolar depression

Background. The dorsolateral prefrontal cortex (DLPFC) is involved in the pathophysiology of major depression. In particular, metabolic (functional hypometabolism) and structural alterations have been described. In this study metabolic changes within the DLPFC of severely depressed patients before and after electroconvulsive therapy (ECT) were evaluated by proton STEAM spectroscopy (H-1-MRS). Method. Twelve severely depressed patients with a diagnosis of major depressive episode, unipolar with melancholic features (DSM-IV), were enrolled, and the left dorsolateral prefrontal cortex (DLPFC) was investigated before and after unilateral ECT by H-1-MRS. Three of the four non-responding patients were remeasured a third time after a combined ECT/antidepressant pharmacotherapy. The results were compared with 12 age- and gender-matched controls. Results. In depressed patients reduced glutamate/glutamine (Glx) levels were measured pre-ECT; Glx concentrations correlated negatively with severity of depression. After successful treatment, Glx increased significantly and levels no longer differed from those of age-matched controls. Conclusions. Our results indicate that major depressive disorder is accompanied by state-dependent metabolic alterations, especially in glutamate/glutamine metabolism, which can be reversed by successful ECT.