Impulsivity and cigarette smoking: delay discounting in current, never, and ex-smokers

Rationale: Impulsivity is implicated in drug dependence. Recent studies sho w problems with alcohol and opioid dependence are associated with rapid dis counting of the value of delayed outcomes. Furthermore, discounting may be particularly steep for the drug of dependence. Objectives: We determined if these findings could he extended to the behavior of cigarette smokers. In particular, we compared the discounting of hypothetical monetary outcomes b y current, never, and ex-smokers of cigarettes. We also examined discountin g of delayed hypothetical cigarettes by current smokers. Methods: Current c igarette smokers (n=23), never-smokers (n=22) and ex-smokers (n=21) indicat ed preference for immediate versus delayed money in a titration procedure t hat determined indifference points at various delays. The titration procedu re was repeated with cigarettes for smokers. The degree to which the delaye d outcomes were discounted was estimated with two non-linear decay models: an exponential model and a hyperbolic model. Results: Current smokers disco unted the value of delayed money more than did the comparison groups. Never - and ex-smokers did not differ in their discounting of money. For current smokers, delayed cigarettes lost subjective value more rapidly than delayed money. The hyperbolic equation provided better fits to the data than did t he exponential equation for 74 out of 89 comparisons. Conclusions: Cigarett e smoking, like other forms of drug dependence, is characterized by rapid l oss of subjective value for delayed outcomes, particularly for the drug of dependence. Never- and ex-smokers could discount similarly because cigarett e smoking is associated with a reversible increase in discounting or due to selection bias.