title: Impulsivity and cigarette smoking: delay discounting in current, never, and ex-smokers.
abstract: BACKGROUND
  Impulsivity is implicated in drug dependence. Recent studies show problems with alcohol and opioid dependence are associated with rapid discounting of the value of delayed outcomes. Furthermore, discounting may be particularly steep for the drug of dependence.
  
  
  OBJECTIVE
  We determined if these findings could be extended to the behavior of cigarette smokers. In particular, we compared the discounting of hypothetical monetary outcomes by current, never, and ex-smokers of cigarettes. We also examined discounting of delayed hypothetical cigarettes by current smokers.
  
  
  METHODS
  Current cigarette smokers (n=23), never-smokers (n=22) and ex-smokers (n=21) indicated preference for immediate versus delayed money in a titration procedure that determined indifference points at various delays. The titration procedure was repeated with cigarettes for smokers. The degree to which the delayed outcomes were discounted was estimated with two non-linear decay models: an exponential model and a hyperbolic model.
  
  
  RESULTS
  Current smokers discounted 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 the exponential equation for 74 out of 89 comparisons.
  
  
  CONCLUSIONS
  Cigarette smoking, like other forms of drug dependence, is characterized by rapid loss of subjective value for delayed outcomes, particularly for the drug of dependence. Never- and ex-smokers could discount similarly because cigarette smoking is associated with a reversible increase in discounting or due to selection bias.
authors.affiliation: Human Behavioral Pharmacology Laboratory, Department of Psychiatry, 38 Fletcher Place, University of Vermont, Burlington, VT 05401, USA. Warren.Bickel@uvm.edu
authors.forename: W K
authors.initials: WK
authors.lastname: Bickel
authors.forename: A L
authors.initials: AL
authors.lastname: Odum
authors.forename: G J
authors.initials: GJ
authors.lastname: Madden
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D005260:Female; D006801:Humans; D007175:Impulsive Behavior / Q000523:psychology*; D008297:Male; D008875:Middle Aged; D012201:Reward; D012907:Smoking / Q000523:psychology*; D016540:Smoking Cessation / Q000523:psychology*; D019966:Substance-Related Disorders / Q000523:psychology; D011795:Surveys and Questionnaires