Gregory J. Madden

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

Abstract Rationale: 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. Objectives: 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.

Impulsive and Self-Control Choices in Opiate-Dependent Patients and Non-Drug-Using Control Participants: Drug and Monetary Rewards

Delay discounting was investigated in opioid-dependent and non-drug-using control participants. The latter participants were matched to the former on age, gender, education, and IQ. Participants in both groups chose between hypothetical monetary rewards available either immediately or after a delay. Delayed rewards were

Impulsivity : the behavioral and neurological science of discounting

1,000, and the immediate-reward amount was adjusted until choices reflected indifference. This procedure was repeated at each of 7 delays (1 week to 25 years). Opioid-dependent participants were given a second series of choices between immediate and delayed heroin, using the same procedures (i.e., the amount of delayed heroin was that which could be purchased with

Delay Discounting of Real and Hypothetical Rewards III: Steady-State Assessments, Forced-Choice Trials, and All Real Rewards

1,000). Opioid-dependent participants discounted delayed monetary rewards significantly more than did non-drug-using participants. Furthermore opioid-dependent participants discounted delayed heroin significantly more than delayed money.

Delay discounting of potentially real and hypothetical rewards: II. Between- and within-subject comparisons.

This volume is an approachable, comprehensive overview of the behavioural science and neuroscience of our impulsive choices and their relation to delay discounting - the tendency to devalue temporally distant rewards or punishments, even though they may greatly outbalance the immediate benefit of our choices. The cutting-edge researchers who contributed to this volume have documented cross-species similarities in impulsive decision making and pioneered the neuroscience of impulsive choice. In this text they provide insights into harmless impulsive acts as well as those that dominate and destory lives.

Discounting of delayed health gains and losses by current, never- and ex-smokers of cigarettes

Human research in delay discounting has omitted several procedures typical of animal studies: forced-choice trials, consequences following each response, and assessment of stable response patterns. The present study manipulated these procedures across two conditions in which real or hypothetical rewards were arranged. Six college students participated in daily sessions, in which steady-state discounting of hypothetical and real rewards was assessed. No systematic effects of repeated exposure to hypothetical rewards was detected when compared with first day assessments of discounting. Likewise, no systematic effect of reward type (real versus hypothetical) was detected. When combined with previous research failing to detect a difference between hypothetical and potentially real rewards, these findings suggest that assessing discounting of hypothetical rewards in single sessions is a practical and valid procedure in the study of delay discounting.

Needle sharing in opioid-dependent outpatients: psychological processes underlying risk

Prior studies comparing discounting of delayed hypothetical or potentially real rewards have reported no differences, but they used within-subjects designs. This raises the possibility that participants remembered their choices in one condition and repeated them in the other. In Experiment 1, between-subjects comparisons were made with an adjusting-amount procedure. No significant effect of reward type on delay discounting was detected. Experiment 2 increased the proportion of real rewards and made between- and within-subject comparisons. These comparisons also failed to reveal a significant effect of reward type. Although these findings are consistent with prior findings, caution is urged because choices involving hypothetical rewards have yet to be compared with choices involving real rewards (i.e., the consequences of every choice are obtained) in an experiment using forced-choice trials and steady-state methodology.

Pathological Gamblers Discount Probabilistic Rewards Less Steeply than Matched Controls

Recent evidence implicates steep discounting of delayed outcomes as an important feature of drug dependence. We determined discounting rates for health gains and health losses in current cigarette smokers (n = 23), never-smokers (n = 22) and ex-smokers (n = 21). Participants indicated preference for immediate vs. delayed hypothetical health gains and for immediate vs. delayed hypothetical health losses in a titration procedure that determined indifference points at a range of delays. The degree of discounting was estimated using two nonlinear decay models: an exponential model and a hyperbolic model. The hyperbolic equation generally provided better fits to the data than the exponential equation did. Current smokers discounted delayed health gains and health losses more steeply than never-smokers did. Discounting by ex-smokers was generally intermediate to that of current smokers and never-smokers, although not statistically different from either. Current smokers and ex-smokers discounted delayed health losses more steeply than they did health gains. Never-smokers did not discount gains and losses differently. Cigarette smokers show rapid loss of value for delayed health outcomes, emphasizing the need for smoking-cessation treatments that provide relatively immediate consequences for abstinence.

Comparing the reinforcing efficacy of nicotine containing and de-nicotinized cigarettes: a behavioral economic analysis.

Needle sharing contributes to the spread of the human immunodeficiency virus and other health concerns and remains a persistent problem among injection drug users. We determined whether needle sharing may be related to the discounting of the value of delayed outcomes. Outpatients in treatment for heroin dependence indicated preference for immediate versus delayed hypothetical monetary and heroin outcomes in a titration procedure that determined indifference points at various delays. The degree to which the delayed outcomes lost value was estimated with a nonlinear decay model. Participants who agreed to share a needle in a scenario (N=15) discounted delayed money more steeply than did the nonsharing group (N=17). Both groups discounted delayed heroin more steeply than delayed money. Persistent needle sharing may be related to the relative inability of delayed outcomes to impact current behavior. Training to mitigate the effect of delay on outcome value may offer reductions in needle sharing and drug abuse.

A Comparison of Measures of Relative Reinforcing Efficacy and Behavioral Economics: Cigarettes and Money in Smokers

Nineteen treatment-seeking men meeting Diagnostic and Statistical Manual for Mental Disorders (4th ed.) criteria for pathological gambling and 19 demographically matched controls participated. Participants provided demographic information, information about their recent drug use and gambling activities, and biological samples (to confirm drug abstinence). They also completed the Eysenck Personality Questionnaire, the South Oaks Gambling Screen (SOGS), and 2 questionnaires designed to separately quantify probability and delay discounting. Pathological gamblers discounted probabilistic rewards significantly less steeply than matched controls. A significant correlation revealed that more shallow probability discounting was associated with higher SOGS scores. Across groups, there was no significant difference in delay discounting, although this difference approached significance when education and ethnicity were included as covariates. These findings, collected for the 1st time with pathological gamblers, are consistent with previous reports that problem-gambling college students discount probabilistic rewards less steeply than controls. The nature of the relation between probability discounting and severity of problem gambling is deserving of further study.