Reduced GABA Levels in the ACC of Actively Drinking High Risk Individuals Compared to Recently Detoxified Alcohol-Dependent Patients

Abstract

Background: Acute gamma-aminobutyric acid (GABAergic) effects of alcohol consumption are well-known, whereas prior research has yielded inconsistent findings regarding on adaptations of the GABAergic neurotransmitter system to chronic alcohol use. Previous studies indicate either elevated or reduced GABA levels in cortical regions such as the anterior cingulate cortex (ACC) in persons with alcohol use disorder (AUD). We tested the hypothesis that active alcohol consumption compared to abstinence contributes to GABA levels as observed in prior research on chronic alcohol use. Methods: We investigated GABA levels in the ACC of 31 healthy controls (low risk, LR), 38 high risk individuals providing an active drinking pattern (high risk, HR) and 27 recently detoxified alcohol-dependent (AD) subjects via proton magnetic resonance spectroscopy (1H-MRS). Results: GABA levels in the ACC were significantly lower in HR compared with AD, but did neither differ between LR and AD nor between LR and HR. Also, we observed a quadratic effect indicating a distribution of GABA levels in the ACC as follows: LR > HR < AD. GABA levels were not associated with abstinence duration in AD. Conclusions: This study suggests that the GABAergic neurotransmitter system is blunted in AUD. More precisely GABA levels in the ACC seem to be higher in recently detoxified AD patients than in individuals at high risk which might suggest that GABA levels may increase after abstinence. No correlation was found between GABA levels and abstinence duration. Longitudinal studies are required to investigate alterations in the GABAergic system throughout the development and maintenance of AUD. Clinical Trial Registration: No: NCT02094196. Registered 20 March 2014, https://clinicaltrials.gov/study/NCT02094196.