Alcohol-induced impairment of central nervous system function: Behavioral skills involved in driving

Several points emerge from the large body of data on the effects of alcohol on CNS function. First, the degree of impairment is dose related, but not identical or strictly linear for all behaviors. Second, alcohol-related impairment of CNS functions cannot be demonstrated a low BALs. There is no consistent evidence that BALs below 50 mg/dl impair any behavior in most individuals. Third, for most behavioral skills, the decrement in performance after alcohol is slight, rarely exceeding 35-50% of the control period. In many studies, changes of only 8-10% are reported to be statistically significant. Fourth, previous findings suggest that tolerance to alcohol-related CNS impairment may develop in regular drinkers. Tolerance may not develop uniformly for all behavioral skills. Finally, studies of the effects of alcohol on integrated driving under closed-course conditions show evidence of 'excessive' use of control maneuvers and impaired performance at BALs beginning at 50-60 mg/dl. Again, the degree of impairment is small at these BALs but increases more rapidly as the BAL exceeds 100 mg/dl.