Drug Abuse and Impulsivity: Tests of Animal Models

This project investigated impulsivity as a predisposing factor for drug abuse. Drug abuse researchers have extensively studied “reward-related” factors that facilitate drug-seeking behaviors, including both unconditioned and conditioned positive affective responses to drugs while ignoring “impulsivity-related” processes that normally inhibit or limit the use of drugs. Dr. Richards believes that processes related to impulsivity may be as important as reward processes in determining whether an individual will use drugs. One reason for the failure to consider “impulsivity-related” factors has been the lack of adequate laboratory models. Although there are a variety of laboratory models designed to investigate the rewarding effects of drugs, there are few models designed to investigate processes that may cause an individual not to take drugs. The primary objective of the research is to develop and use laboratory-based, behavioral measures of impulsivity to study the relationship between impulsive processes and drug abuse. Dr. Richards’ team has identified three distinct behavioral processes that may underlie the occurrence of maladaptive “impulsive behaviors” such as using drugs of abuse. First, preference for the immediate small rewards associated with drug taking over the delayed but larger rewards associated with abstaining may result in drug taking. Second, the inability to inhibit or stop a pre-potent response may result in occurrence of drug taking. And third, lapses of attention may be associated with relapse to drug abuse. This study examined the strength of the association between cocaine self-administration and the three behavioral processes identified as underlying the occurrence of impulsive behaviors by investigating acquisition of drug-taking, escalation of drug intake, extinction of drug-taking, and cue-induced reinstatement of drug-taking. This research will provide important new information concerning putative animal models of impulsivity and the ability of these models to predict cocaine self-administration in humans. Funded by a grant of $554,750 from NIDA. This project is supported through funds provided by the American Recovery and Reinvestment Act (ARRA), 2009-2012.