Background: Both chronic alcohol consumption and alcohol withdrawal lead to neural tissue damage which partly recovers during abstinence. This study investigated withdrawal-associated changes in glutamatergic compounds, markers of neuronal integrity, and gray matter volumes during acute alcohol withdrawal in the hippocampus, a key region in development and maintenance of alcohol dependence in humans and rats.
Methods: Alcohol-dependent patients (N = 39) underwent magnetic resonance imaging (MRI) and MR spectroscopy (MRS) measurements within 24 hours after the last drink and after 2 weeks of abstinence. MRI and MRS data of healthy controls (N = 34) were acquired once. Our thorough quality criteria resulted in N = 15 available spectra from the first and of N = 21 from the second measurement in patients, and of N = 19 from healthy controls. In a translational approach, chronic intermittent ethanol-exposed rats and respective controls (8/group) underwent 5 MRS measurements covering baseline, intoxication, 12 and 60 hours of withdrawal, and 3 weeks of abstinence.
Results: In both species, higher levels of markers of glutamatergic metabolism were associated with lower gray matter volumes in the hippocampus in early abstinence. Trends of reduced N-acetylaspartate levels during intoxication persisted in patients with severe alcohol withdrawal symptoms over 2 weeks of abstinence. We observed a higher ratio of glutamate to glutamine during alcohol withdrawal in our animal model.
Conclusions: Due to limited statistical power, we regard the results as preliminary and discuss them in the framework of the hypothesis of withdrawal-induced hyperglutamatergic neurotoxicity, alcohol-induced neural changes, and training-associated effects of abstinence on hippocampal tissue integrity.
Keywords: Alcohol Withdrawal; Glutamate; Gray Matter; Hippocampus; Magnetic Resonance Spectroscopy.
Copyright © 2017 by the Research Society on Alcoholism.