Low Levels of Blood Alcohol Produce Measurable Physiological and Subjective Effects in Social Drinkers

Newswise — Subtle physiological changes involving the cardiovascular and autonomic nervous systems after exposure to alcohol are difficult to perceive in humans, particularly at lower alcohol levels. Researchers sought to determine the effect of acute intravenous alcohol infusion on skin blood flow (SBF) response and associated subjective responses in 24 social drinkers who participated in an alcohol self-administration study. SBF was measured at the fingertip and earlobe at four timepoints: at baseline, and 0 minutes, 10 minutes, and 20 minutes after beginning an intravenous form of alcohol self-administration.  The exposure produced relatively low breath alcohol levels of approximately 30 mg% (0.03%, compared with a reading of 0.08%, at which point an individual is considered legally intoxicated). Subjective responses were measured using questionnaires previously developed for studies such as this. 

The results showed that men had a higher overall SBF at baseline and at 0 minutes than women.  SBF in both sexes dropped significantly at 0 minutes and subsequently increased significantly during alcohol self-administration. Self-reported ratings of “liking” and “wanting more” alcohol were significantly associated with SBF recordings collected at fingertip at 10 and 20 minutes after beginning alcohol self-administration.

The researchers concluded that changes in SBF following acute intravenous alcohol self-administration are consistent with the sympathetic cardiovascular response previously associated with alcohol.  Furthermore, the cardiovascular effect is sensitive to relatively low levels of acute alcohol exposure, as are the associated subjective effects.  These findings may enhance our understanding of the physiological correlates of the subjective response to alcohol, and help to establish skin blood flow as a marker of the acute effects of alcohol, which can be used as a tool for understanding factors affecting the risk of chronic or heavy alcohol consumption.