Magnetic resonance spectroscopic studies of alcoholism: from heavy drinking to alcohol dependence and back again.

Background: The International Conference on Applications of Neuroimaging to Alcoholism was convened at Yale University in New Haven, Connecticut. One session featured six speakers who discussed magnetic resonance spectroscopy (MRS) applications in alcoholism, with topics ranging from multimodality imaging to measurements of neurotransmitter synthesis in the human brain in vivo. Methods: This session covered methodological topics related to 1 H and 13 C MRS, both theory and examples. The primary features of the 1 H MR spectra were described, including resonances from creatine-and choline-choline-containing compounds, N-acetylaspartate, myo-inositol, glutamate, glutamine, GABA, and macromolecules. Methods reviewed also included MRS imaging, in which numerous MRS voxels are observed simultaneously. Other methods described J-editing of GABA and 13 C MRS detection of oxidative metabolism and neurotransmitter synthesis. Results: Across studies, region-specific neurochemical changes were associated with alcohol dependence. With sobriety, many of the neurochemical alterations associated with alcohol dependence partially or fully abated, in association with partial recovery of brain structure and cognitive functions. The utility of 1 H MRS to measure brain ethanol was discussed. This work highlighted the need to consider method- and analysis-dependent mechanisms that can affect the quantification of ethanol using 1 H MRS. The utility of MRS as a tool to study alcohol dependence-related neurotoxicity was reviewed. In particular, the possibility that MRS may provide a noninvasive tool for studying glutamatergic activation associated with acute alcohol withdrawal may prove to be an important approach for mechanistic human studies related to neuropsychiatric complications of ethanol dependence and withdrawal, including dementia and hepatic encephalopathy. Conclusions: The International Conference on Applications of Neuroimaging to Alcoholism provided one of the first opportunities to convene a large group of investigators who used MRS techniques in the study of alcohol dependence. The range of data presented highlighted the growing range of insights related to the acute and chronic effects of ethanol on human brain chemistry. The ability to measure directly glutamate-glutamine cycling using 13 C-MRS presents new and exciting opportunities to probe excitatory neurotransmission.