BREAKING UP WITH YOUR DRUG CAN BE HARD TO DO, BUT IS IT MAINLY BECAUSE COMPULSIVE BEHAVIOR INVOLVES SPECIFIC BRAIN REGIONS?

Abstract

Reading Lubman et al. (2004) stirred a memory. Years ago, The Royal Society of Canada convened a committee at the request of Health and Welfare Canada to consider whether nicotine in cigarettes was addictive (Kalant et al. 1989). Fortunately the chair of this committee was the distinguished Harold Kalant who had the experience of decades of working on prominent international committees (e.g. for the World Health Organization) concerned with the definition of drug dependence and addiction. (LTK also served on this RSC committee). The beginning of this report benefited especially from Kalant's experience with historical changes in terminology and definitions. It was judged that ‘Earlier definitions of drug addiction have evolved over the past 40 years, in the direction of diminishing emphasis on tolerance and physical dependence as defining features of addiction, and growing emphasis on the behavioural aspects of “compulsive” drug-seeking and drug-taking, reinforced by the psychoactive effects of the drug, and on the great difficulty in cessation of drug-taking and the high probability of relapse’ (p. v). The definition was: Drug addiction is a strongly established pattern of behaviour characterized by (1) The repeated self-administration of a drug in amounts which produce reinforcing psychoactive effects, and (2) great difficulty in achieving voluntary long-term cessation of such use, even when the user is strongly motivated to stop. (p. v) This definition might be shortened to: ‘a drug use that is difficult to stop.’ Part of our intent was to avoid terms like ‘withdrawal’, ‘psychological dependence’, and ‘physical dependence’ because of their unclear relationship to the underlying fact of difficulty in stopping. At the time we expressed reluctance to employ the ‘imprecise and mechanistically questionable term “compulsive.”’ Now, almost 15 years later, developments in brain imaging and neuroscience and progress in research on obsessive-compulsive disorder may have increased precision and have made it less questionable to explore what it means to say that addiction is a form of compulsive behavior, and there may be a promising idea of which brain regions are involved. In pursuing this program of research we would ask for more work to clarify what comes first—the addictive behavior or the brain dysfunction. We would also encourage a re-reading of an even older paper in addiction research. Did Lee Robins’ famous US soldiers who were addicted to heroin in Vietnam, but not when they returned home, have their brains (now their prefrontal cortexes) hi-jacked in South-East Asia, but freed in the US (Robins 1973)? Would longitudinal studies of changes in inhibitory brain dysfunction in these soldiers have helped explain this effect or were broader ecological issues more likely at play? Advancing our understanding of addiction will probably benefit from models that include measures of context as well as brain.