Addicts tend to respond impulsively in the sense of choosing small immediate rewards over larger but delayed rewards. One approach that appears to be useful in understanding impulsive choices is the study of delay discounting, or how the subjective value of a reward such as cash or drugs is modulated by delay to the reward. Research shows that addicts are characterized by higher delay-discounting rates and impulsivity scores than non addicts. However, it is still unknown if such scores correlate with the severity of drug addiction, if they predict rates of addiction treatment success, or if effective drug addiction treatment modifies delay-discounting rates or impulsivity.
The aim of this project is to compare untreated, and successfully treated opiate addicts in terms of delay-discounting rates and impulsivity scores. Thirty untreated opiate addicts, thirty patients who have been in methadone maintenance treatment and drug-free for at least two years, and 20 matched non substance abusers serving as controls will be enrolled in the study. All subjects will provide a urine sample that will be tested for drugs of abuse. Data collection will be done during a single 2-hour session. Delay-discounting rates will be assessed with a choice procedure between a fixed delayed monetary reward, and various smaller amounts of cash to be had immediately. All choices will be between hypothetical rewards. Two magnitudes of the delayed monetary reward and 8 delay intervals will be investigated. Impulsivity will be assessed with the Eysenck Personality Questionnaire. The obtained results will address the possibility that in methadone patients: a) delay-discounting and impulsivity might be fixed personality traits , b) delay-discounting rates and/or impulsivity scores might be differentially affected by drug abuse, and c) that delay-discounting rates and/or impulsivity scores might be modifiable by treatment. The results obtained from this study will shed light on the relationships between delay-discounting rates, impulsivity, and addiction treatment, and will be useful in determining the need for further research.
| Robles, Elias; Huang, B Emma; Simpson, Pippa M et al. (2011) Delay discounting, impulsiveness, and addiction severity in opioid-dependent patients. J Subst Abuse Treat 41:354-62 |
