Brain alcohol detectability increase with repeated administration in humans: A proton spectroscopy study

Proton MRS was used to detect brain alcohol after repeated alcohol exposure in human subjects. MRS detectability measurements were made after administration of an alcoholic drink (0.6 g/kg alcohol) and after an identical drink administered 6 h later. Between‐drink differences in the methyl proton triplet resonance of ethyl alcohol were assessed at statistically equivalent and near‐peak blood alcohol concentrations (reflecting brain alcohol concentrations) and statistically equivalent internal standard N‐acetyl resonance areas after Drinks 1 and 2, respectively. Brain alcohol detectability was not altered in TE 30‐ms spectra but was increased in all five subjects after Drink 2 by an average of 70% in TE 270‐ms spectra (P < 0.01). This was accompanied by significant between‐drink differences in subjective ratings of alcohol's effects, suggestive of induction of acute alcohol tolerance. These findings suggest increased brain alcohol detectability in TE 270‐ms spectra after repeated alcohol exposure that may reflect acute alcohol tolerance.