Is residual impairment after alcohol an effect of repeated performance?

The study examines the residual impairment of performance due to alcohol on the descending limb of the blood alcohol curve. The occurrence of residual impairment at low or zero levels of blood alcohol is well established but its cause is uncertain. It is hypothesized that residual impairment may be due in part to the methodological procedure of repeated performance testing in the post-ingestion period.

There were 80 volunteers randomly allocated to one of four treatment conditions: a) alcohol and repeated performance (A-R) where psychomotor tasks were performed at 20-min interval for 2 h post ingestion; b) alcohol and double performance (A-D) where tasks were performed only at 1 h and 2 h from ingestion; c) placebo and repeated performance (P-R); and d) placebo and double performance (P-D). Alcohol was administered as vodka to achieve a peak blood-alcohol concentration (BAC) of approximately 80 mg per 100 ml. Performance effects were assessed by a dual task of primary pursuit tracking and secondary visual reaction time, and a visual sustained attention task.

Alcohol caused significant impairment of secondary reaction time, the effect being greatest at peak BAC. Sustained attention was also impaired by alcohol but the effect just missed significance. Repeated performance conditions were associated with significantly greater impairment of secondary reaction time and sustained attention when compared with double performance conditions. The factor of performance condition did not, however, interact with that of alcohol.

The monotony and boredom that may be associated with repeated performance do not contribute to residual alcohol impairment.