Lack of tolerance to the disinhibiting effects of alcohol in heavy drinkers

Rationale: Alcohol tolerance is observed as a diminished response to a given dose as a function of repeated administrations of the drug. Research has consistently shown that heavier drinkers display reduced reactions to alcohol (i.e., tolerance) compared with lighter drinkers. However, the majority of this work has focused primarily on measures of motor performance, whereas the development of tolerance to alcohol's impairing effects on cognitive processes, such as inhibitory mechanisms of behavioral control, remains relatively unexplored. Objective: The purpose of the present study was to examine the relationship between drinking habits and the degree to which alcohol affects drinkers' inhibitory control and motor coordination. Methods: Fifty-two non-dependent drinkers reported their recent drinking patterns. Their inhibitory control and motor coordination were measured in response to placebo and 0.65 g/kg alcohol. Results: Alcohol significantly impaired inhibitory control and motor coordination compared with placebo. Moreover, greater quantity and frequency of recent consumption predicted less alcohol impairment of motor coordination. However, there was no relationship between recent drinking habits and the degree of impairment of inhibitory control. Conclusions: These findings suggest that tolerance to the disinhibiting effects of alcohol might not readily develop as a result of recent, heavy drinking.