Delay discounting in college cigarette chippers

Abstract

Individuals who smoke cigarettes regularly but do not become dependent on them provide a unique opportunity for studying the factors that inhibit drug dependence. Previous research on this population, sometimes referred to as 'cigarette chippers', showed that they did not differ from regular smokers in terms of smoking topography (e.g. puff number and duration) and circulating nicotine levels, but that they did show more self-control according to answers on a questionnaire. We evaluated the generality of this finding using a behavioral choice procedure. The participants were undergraduate students (n=71), who were regular smokers, chippers, or nonsmokers. In the choice procedure, one option was a smaller but sooner amount of money, and the other option was a larger but delayed amount of money. Under these conditions, preference for the sooner smaller amount implies that the later larger monetary amounts were discounted. It is widely assumed that the rate of discounting provides an operational definition of impulsivity. In one version of the procedure, the money was hypothetical. In a second version, each choice had a chance of producing an actual monetary outcome. When there was an actual monetary outcome, regular smokers were more likely to choose the sooner but smaller monetary option than chippers and nonsmokers. For all participants, the rate of discounting decreased as the magnitude of the monetary outcomes increased, and for smokers and chippers the differences in discount rates in the two versions of the delayed outcome procedure were the same. These findings are consistent with the view that chippers are less impulsive than smokers. Quantitative aspects of these findings led to the hypothesis that discount rates decrease as a negative power function of the monetary value of the options. This result establishes an analogy between delay discounting experiments and psychophysical experiments. Results from two earlier studies support the analogy.

Cigarette smokers discount past and future rewards symmetrically and more than controls: Is discounting a measure of impulsivity?

“…We replicate a substantial number of studies that have demonstrated that adult cigarette smokers discount future gains more than controls (e.g., Baker et al, 2003;Heyman and Gibb, 2006;Mitchell, 1999;Ohmura et al, 2005;Reynolds et al, 2004). We also provide the first demonstration that nicotine-dependent individuals discount past gains more than controls.…”

The role of impulsive behavior in drug abuse

“…Similarly, heavy social drinkers (Vuchinich and Simpson 1998) and alcoholics (Petry 2001, but see Kirby and Petry 2004) discounted monetary reinforcers more than light social drinkers and nonalcoholics, respectively. Cocaine abusers (Coffey et al 2003;Heil et al 2006;Kirby and Petry 2004), methamphetamine abusers (Hoffman et al 2006;Monterosso et al 2007), and cigarette smokers (Baker et al 2003;Bickel et al 1999;Heyman and Gibb 2006;Mitchell 1999;Reynolds et al 2004b, but see Johnson et al 2007;Ohmura et al 2005) also discounted future monetary rewards to a greater extent than nonusers. To address H2 in humans, that drug ingestion elevated impulsive behavior, it would be necessary to show that elevated impulsivity during use returned to and remained at lower levels (equivalent to nonusers) in ex-users (e.g., Bickel et al 1999).…”

Impulsive choice and environmental enrichment: Effects of d-amphetamine and methylphenidate

“…Subjects who consistently choose the smaller immediate reinforcer are said to discount the value of the delayed reinforcer, and it is possible that drug abuse may occur, at least in part, because the beneficial value of drug abstinence is discounted compared to the immediate effects of a drug [21,48]. Accordingly, compared to nonusers, delayed rewards are discounted to a greater extent in users of opioids [40,41,48], alcohol [89], cocaine [17,34,40], methamphetamine [37,56], and cigarettes [4,11,36,55,58,72, but see 47]. It is likely that the increased discounting in drug abusers compared with nonabusers arises from a combination of factors, including higher baseline levels of impulsivity in drug abusers, increases in impulsivity due to acute or chronic drug effects, and common genetic and environmental factors that predispose individuals to both drug abuse and impulsive choice.…”