Acute tolerance to alcohol: changes in subjective effects among social drinkers.

The development of acute tolerance to the subjective effects of alcohol was examined in 32 social drinkers. Measures were made of self-reported level of intoxication and responses to questions from the alcohol scale of the Addiction Research Centre Inventory. The time to peak self-reported intoxication level was found to be 20 min earlier than the time to peak blood alcohol concentration. Changes from the ascending to the descending limb of the blood alcohol curve were found with five of the ARCI questions. In all cases the proportion of alcohol-typical responses was lower on the descending portion of the curve, even though blood alcohol levels were equivalent. Further analyses examined the effects of prior drinking history on the development of acute tolerance. Peak self-reported intoxication levels were significantly lower and occurred earlier for heavier drinkers. Furthermore, for four of the five ARCI questions heavier drinkers were less likely to give an alcohol-typical response than lighter drinkers on the ascending portion of the curve.