Delay discounting of money and alcohol in actively using alcoholics, currently abstinent alcoholics, and controls

Rationale: Impulsivity is implicated in alcohol dependence, and discounting of delayed rewards may be an objective indicator of impulsiveness. Objectives: This study evaluated delay discounting functions in alcoholics and controls. It compared discounting rates between different magnitudes ($1000 and $100) and different types (money and alcohol) of rewards. Methods: Active alcoholics (n=19), currently abstinent alcoholics (n=12) and controls (n=15) indicated preferences for immediate versus delayed rewards using a titration procedure that determined indifference points at various delays. Four conditions were presented, and the delayed rewards in the four conditions were $1000, $100, 150 bottles of an alcoholic beverage, and 15 bottles of an alcoholic beverage. Results: In all three groups across all four conditions, hyperbolic discounting functions provided a good fit of the data. Linear contrasts, predicting the most rapid discounting rates in active alcoholics, intermediary rates in currently abstinent alcoholics, and the least rapid rates in controls, were significant for three of the four conditions. Alcohol was discounted more rapidly than money. Conclusions: These data provide further evidence of more rapid discounting of delayed rewards in alcohol abusers compared to controls, and especially steep discounting among current users. Rapid discounting of delayed rewards may be a feature related to addictive disorders. A better understanding of how delaying rewards in time impacts their value may have implications for treatment.