Growing evidence has shown that anomalies in the function of neurotransmitters and weakened energy metabolism can contribute to major depressive disorder. Chadi G. Abdallah, MD, ofthe Department of Psychiatry at Yale University School of Medicine in New Haven, Connecticut, and his team examined whether impairments in energetics and glutamate neurotransmitter cycling are present in major depression.
They used carbon-13 magnetic resonance spectroscopy (C-13 NMR) to measure these fluxes in individuals diagnosed with MDD relative to healthy comparison subjects. Data was collected from 23 people with MDD, who were not taking medication, and 17 healthy controls.
Mitochondrial energy production of glutamatergic neurons was 26% lower in the depression group. No difference was found in the rate of the glutamate/glutamine cycle (Vcyc). A significant correlation was observed between glutamate concentrations and Vcyc in the overall sample.
“The authors interpret the reduction in mitochondrial energy production as being due to either mitochondrial dysfunction or a reduction in proper neuronal input or synaptic strength,” the researchers concluded. “Future MRS studies could help distinguish these possibilities.”