Reduced glutamate in the anterior cingulate cortex in depression: An in vivo proton magnetic resonance spectroscopy study

Background: Functional imaging studies suggest a specific role of the anter ior brain regions in the pathogenesis of major depression. The aim of this study was to evaluate possible neurochemical alterations in the frontomesia l cortex in patients with major depressive episode using in vivo proton mag netic resonance spectroscopy (H-1-MRS). Methods: Single voxel H-1-MRS was performed in 19 patients with major depre ssive episodes and 18 age-matched healthy controls within the anterior cing ulate cortex and the parietal white matter Absolute concentrations were est imated for N-acetyl-aspartate, choline-containing compounds, total creatine , myo-inositol, unresolved glutamate and glutamine (Glx) and glutamate alon e (Glu). Voxel composition tvas analyzed by image segmentation into cerebro spinal fluid (CSF), grey and white matter. Results: MANOVA test for Glx and Gill using age, percent CSF and percent gr ey matter contribution as covariates yielded a significant group effect wit hin the anterior cingulate due to decrease of Glx in patients (-10.4%, p =, 013). Considering only severely depressed patients, both Glx and Glu (-14.3 %, p =.03) showed a significant decrease. There was no significant group ef fect for the neuronal marker NAA, creatine, choline or myo-inositol in eith er localization. Conclusions: This study suggests a possible role of altered glutamatergic n eurotransmission within the anterior cingulate in the pathogenesis of mood disorders. The otherwise unremarkable findings of major brain metabolites c onfirms lack of neurodegenerative or membrane metabolic changes in major de pression, Biol Psychiatry 2000;47:305-313 (C) 2000 Society of Biological Ps ychiatry.