Addiction
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Addiction has been conceptualized as a shift from controlled experimentation to uncontrolled, compulsive patterns of use. Current neurobiological models of addiction emphasize changes within the brain's reward system, such that drugs of abuse 'hijack' this system and bias behaviour towards further drug use. While this model explains the involuntary nature of craving and the motivational drive to continue drug use, it does not explain fully why some addicted individuals are unable to control their drug use when faced with potentially disastrous consequences. In this review, we argue that such maladaptive and uncontrolled behaviour is underpinned by a failure of the brain's inhibitory control mechanisms. ⋯ We propose that in chronically addicted individuals, maladaptive behaviours and high relapse rates may be better conceptualized as being 'compulsive' in nature as a result of dysfunction within inhibitory brain circuitry, particularly during symptomatic states. This model may help to explain why some addicts lose control over their drug use, and engage in repetitive self-destructive patterns of drug-seeking and drug-taking that takes place at the expense of other important activities. This model may also have clinical utility, as it allows for the adoption of treatments effective in other disorders of inhibitory dysregulation.
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This paper reviews international issues in the supply of tobacco and tobacco products, including trade liberalization and globalization. The paper begins with a brief discussion of the theoretical foundations for trade and trade restrictions. ⋯ The implications of two recently proposed international agreements--the Multilateral Agreement on Investments and the Framework Convention for Tobacco Control--are then discussed. The paper concludes by summarizing the theoretical and empirical evidence that shows clearly that trade liberalization has significantly increased tobacco use, particularly in low and middle-income countries, and follows this with a discussion of the lessons learned from tobacco for controlling alcohol supply.
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The question of addiction specifically concerns (1), the process by which drug-taking behavior, in certain individuals, evolves into compulsive patterns of drug-seeking and drug-taking behavior that take place at the expense of most other activities and (2), the inability to cease drug-taking; the problem of relapse. In this paper current biopsychological views of addiction are critically evaluated in light of the "incentive-sensitization theory of addiction", which we first proposed in 1993, and new developments in research are incorporated. ⋯ These are: (1) Potentially addictive drugs share the ability to produce long-lasting adaptations in neural systems. (2) The brain systems that are changed include those normally involved in the process of incentive motivation and reward. (3) The critical neuroadaptations for addiction render these brain reward systems hypersensitive ("sensitized") to drugs and drug-associated stimuli. (4) The brain systems that are sensitized do not mediate the pleasurable or euphoric effects of drugs (drug "liking"), but instead they mediate a subcomponent of reward we have termed incentive salience (drug "wanting"). We also discuss the role that mesolimbic dopamine systems play in reward, evidence that neural sensitization happens in humans, and the implications of incentive-sensitization for the development of therapies in the treatment of addiction.
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Many modern theories of drug use and dependence assign central prominence to the role of craving in drug use and relapse. However, some continue to debate whether drug craving has any motivational significance in terms of drug-using behaviors. Cognitive social learning theory adds additional perspective by imbedding craving within a network of cognitive processes that, as they inter-relate, influence drug use and relapse. ⋯ In addition, cognitive social learning theory complements theories that emphasize more biological or information processing aspects of addictive behaviors. Studies of addiction that have assessed elements of social learning theory suggest the following: (1) there exists an inverse relationship between efficacy and craving; (2) there appears to be an association between affect and craving, but the precise nature and strength of this association is unclear; (3) the relationship between outcome expectations and craving is largely unknown; and (4) correspondingly little is known about relationships between coping and craving. More empirical study is needed to address the strengths and limitations of cognitive social learning theory as it relates to our understanding the motivational significance of drug craving.
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The other papers in this series on reduced smoking discuss interventions focused on individuals. This paper illustrates possible smoking reduction interventions focused on policies rather than individuals. ⋯ Interventions such as price increases, restricting availability, advertising bans and product control could all be used to achieve harm reduction. Research on reducing the harm of smoking needs to include policy as well as treatment research.