A comparison of delay discounting among smokers, substance abusers, and non-dependent controls

Abstract

Previous studies have shown that smokers and substance-dependent individuals discount rewards that are available after a delay more than individuals without a history of substance dependence. However, it is not clear whether delay discounting is similar among smokers and substance-dependent individuals. Further, the influence of the combination of smoking and other substance dependence on delay discounting remains unknown. The present study compared the performance of four groups of individuals on a delay discounting task. The groups were (a) heavy smokers with comorbid substance dependence, (b) heavy smokers with no history of substance dependence, (c) never smokers with comorbid substance dependence, and (d) never smokers with no history of substance dependence. Analysis revealed that individuals who smoked and/or were dependent on another substance discounted delayed rewards more than individuals with no history of smoking or other substance dependence. No differences in the task performance of heavy smokers and substance-dependent individuals were found. Notably, participants who were dependent on multiple substances did not discount delayed rewards more than those dependent on only one substance. Overall, findings indicate that smoking and other substance dependence are similarly related to delay discounting.

Figure 1

Median indifference points for each of the four groups. Best fit curves were drawn through these points using Mazur’s (1987) hyperbolic decay equation. SUD = Substance Use Disorder.