An advantage of the clamping procedure used in this study is the ability to observe changes in subjective response over time that are not due to rate of BAL change or rate of alcohol elimination. An interesting additional finding was that after the rise in stimulant response during the first half of clamped ethanol infusion, stimulant response began to decline between the +30 and +60 timepoints among the most impulsive participants while steady state levels of ethanol were maintained. This pattern was most readily observable in the high dose condition and to a lesser extent in the low dose condition. These results are indicative of acute tolerance (O’Connor et al. 1998) to stimulant effects among the most impulsive individuals, even in the absence of declining BALs. Acute tolerance could represent an additional risk factor for impulsive individuals that could lead to heavy drinking in order to obtain higher BALs in the hopes of maintaining their initial stimulant response.
