The Role of Executive Functions in Cocaine Abuse

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DESCRIPTION: (provided by applicant) Cocaine abuse continues to be a substantial medical and social problem in the USA and elsewhere. Despite increasing knowledge of the pharmacological basis of cocaine's effects and of the environmental and socioeconomic factors in drug abuse, relatively little attention has been given to the cognitive factors that are involved in addiction. It is proposed that a substantial cognitive component of human addiction is a dysexecutive loss of control, that is, an inability to control one's own behavior in light of the strong motivation to consume drug. It is hypothesized that these executive processes are compromised in cocaine users which facilitates the continuation of the drug habit and are also compromised acutely following cocaine administration, which facilitates the duration of a particular drug binge. To address these issues, a series of studies are proposed that will examine those aspects of the executive control of behavior that are considered most germane to drug addiction using tasks that selectively isolate the executive function of interest to minimize the contribution of non-executive processes to task performance. As well as addressing the basic cognitive phenomena, these studies will also address the neuroanatomical substrates of these (dys)functions using functional MRI. Aims of this research include determining if cocaine users are impaired in executive control of behavior relative to drug-naive controls and if cocaine users are acutely impaired following a cocaine administration relative to their own baseline. Aspects of executive control will include the ability to (a) switch focal attention from one item of thought (i.e., a currently active working memory representation) to another item; (b) exercise control over strong prepotent urges; and (c) maintain endogenously driven attention. A further aim is to understand the neurobiological changes that occur in the onset of automaticity and how this may relate to drug addiction. Habit based behavior can be described as the loss of executive control as certain behaviors become automatized and fall under exogenously cued control. The neuroanatomy of this transition from controlled to automatic behavior and how it features in the onset of drug addiction is not well understood and has implications for how drug use tends to evolve into habitual behavior over which the drug user may feel and appear powerless. It is proposed to characterize the basic mechanisms of this transition and to assess the cocaine user's ability to re-establish executive control over what have become automatic processes.