Drug Abuse and Impulsivity: Tests of Animal Models

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This project investigates “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. We believe that processes related to impulsivity may be as important as reward processes in determining whether an individual will use drugs. One reason for the lack of attention to “impulsivity related” factors may be the lack of adequate laboratory models. The primary objective of the proposed research is to develop and use laboratory-based, behavioral measures of impulsivity to study the relationship between impulsive processes and drug abuse. Our own research as well as other recent findings indicates that “impulsivity” does not refer to a single process or trait. Instead, several distinct behavioral processes appear to underlie the broad category of “impulsive behaviors”. One process that can result in impulsive behaviors is the preference for smaller, more immediate rewards over larger delayed rewards, and it is measured using the delay discounting task. A second process corresponds to the inability to inhibit (stop) a prepotent response. This is referred to as behavioral inhibition and is measured using the Stop Task. We have identified a new, third process, which relates to attention. Impairments in attention have not been studied extensively in relation to drug abuse; sustained attention is likely to be important for self-control, particularly during periods of abstinence from drug taking behaviors. The proposed project will use non-human laboratory models of impulsivity to determine the strength of association between cocaine self-administration and impulsivity as measured by delay discounting and sustained attention tasks. A self-administration (SA) procedure which includes acquisition of drug taking, escalation of drug intake, extinction of drug taking, and finally cue-induced reinstatement of drug taking, which models important features of human drug use will be used. We have previously accumulated promising data on these tasks, and the proposed studies will provide important information validating the role of specific types of impulsive behaviors in drug abuse. The proposed studies will provide important new information concerning putative animal models of impulsivity, and the ability of these models to predict cocaine self-administration.