Magnetic resonance imaging of the brain during alcohol absorption and elimination--a study of the "rising tide phenomenon".

The absorption phase of alcohol is typically accompanied by more marked behavioral effects than the elimination phase. The mechanism behind this so-called "rising tide phenomenon" has not been fully elucidated. We hypothesized that the rising tide of alcohol during the absorption phase increases the permeability of the blood-brain barrier (BBB), thus elevating the free water content with consequent edema. The resulting increase in intracranial pressure, combined with alcohol's direct toxic effects, results in a synergetic reinforcement of the symptoms of intoxication. To test this hypothesis we performed proton magnetic resonance imaging (MRI) on the human brain during the alcohol absorption and elimination phases. Our results indicate that the alcohol-induced transient opening of the BBB is a possible factor behind the rising tide phenomenon.