Overview

Drug addiction is a progressive disorder characterized by a transition from controlled to uncontrolled and compulsive drug seeking that continues despite knowledge of adverse consequences (Hoffman and Goldfrank, 1990; Leshner, 1997; McGinnis and Foege, 1999). It is also a chronic relapse disorder. Periods of successful drug abstinence for many individuals end with relapse to compulsive drug use. Drug addiction is a devastating disorder that has severe health costs to both the individual and the public (McLellan et al., 2001). Although environmental variables can influence an individual’s risk for developing addiction, human and animal research show that addiction is fundamentally a disorder of the brain. Application of neuroscience approaches to the study of addiction is thus an integral part of efforts to understand and ultimately to treat the disorder. Two issues that are central to understanding the problem of drug abuse and addiction are 1) identification of drug actions that contribute to an initially positive drug experience and 2) elucidation of the neural mechanisms underlying the progression of addiction and the development of drug craving. Acute self-administration of addictive compounds produces a multitude of transient effects on the brain, only some of which contribute to a positive drug experience and the desire to repeat that experience in a social setting.