Major Depressive Disorder Studies

Name:
Title:
Institution:
GABA (gamma-aminobutyric acid) is the principal inhibitory neurotransmitter in the brain and known to exert most of its function by activation of so-called GABA-A receptors. Abnormalities in the inhibitory amino acid neurotransmitter system of gama- aminobutyric acid (GABA) play a role in the pathophysiology of major depressive disorder (MDD). Proton magnetic resonance spectroscopy (1H MRS) studies that have investigated of these GABAergic abnormalities in vivo in patients with MDD have yielded mixed findings, due to differences in MRS methods used to measure GABA.
Increasing evidence points to an association between major depressive disorders (MDDs) and diverse types of GABAergic deficits. In this review, we summarize
It exhibits high comorbidity with anxiety disorders, with 50–60% of depressed patients reporting a lifetime history of anxiety disorders, and many anxiety disorder patients showing a history of treatment for depression . Antidepressant drug (AD) treatments currently in use for both anxiety and depressive disorders are designed to target monoaminergic neurotransmission, and they have set the foundation for the so-called catecholamine and serotonin hypotheses of affective disorders. Collectively, these hypotheses posit that antidepressants act by increasing the extracellular concentration and function of monoamine transmitters in the forebrain and, by extension, that mood disorders are caused by altered production, release, turnover, or function of monoamine transmitters or altered function of their receptors. There is, however, a growing consensus that altered monoaminergic transmission is insufficient to explain the etiology of depressive disorders and that currently used antidepressants instead are modulating other neurochemical systems that have a more fundamental role in
Notably, the observed GABAergic deficits in MDD were found to be more pronounced during major depressive episodes, which may indicate that the GABA levels reduction is state-dependent. This state-dependent GABA reduction in MDD could be a biomarker for disease and directly relate to symptom severity as suggested by meta-regression analysis. More attention should be paid on the MRI acquisition methods for GABA detection in future.
GABA is the principal neurotransmitter mediating neural inhibition in the brain. GABAergic neurons are present throughout all levels of the neuraxis, represent between 20 and 40% of all neurons depending on brain region, and are known to balance and fine tune excitatory neurotransmission of various neuronal systems including the monoaminergic and cholinergic projections to the