Several studies with laboratory animals have linked measures of impulsivity to the initiation of alcohol self-administration or acute alcohol responses. One of the most widely cited studies used delay discounting as a predictor of alcohol self-administration (Poulos, Le, & Parker, 1995). These authors reported that male rats showing steeper discounting of delayed rewards subsequently self-administered more alcohol in a test of consumption. Mitchell, Reeves, Li, & Phillips (2006) examined the extent to which discounting predicted the degree of locomotor stimulation after alcohol in mice; locomotor stimulation is considered an indicator of rewarding effects. The mice that discounted more steeply exhibited less locomotor stimulation upon initial exposure to ethanol. However, after repeated exposure to alcohol, these same animals exhibited greater alcohol-induced locomotor activity. Thus, in rats, impulsive discounting showed a more general link to alcohol use, whereas with mice, more impulsive discounting was only related in the expected direction after repeated exposure to alcohol.
