Defining and assessing nicotine dependence in humans

摘要

'Addiction' and 'dependence1 are used synonymously by most researchers and defined as a reward-seeking (usually drug taking) behaviour that has become out of control. The diagnosis has been based on the alcohol dependence syndrome identified 30 years ago by Edwards and Gross and includes tolerance, craving, withdrawal symptoms, difficulty controlling use, important activities given up, and continuation despite harmful consequences. A substantial proportion of smokers are addicted by reference to these criteria. However, it is possible to improve on both the definition and its assessment. This paper proposes that addiction is more usefully regarded as a symptom of potentially a range of underlying pathologies involving the 'motivational system'. Even among smokers there is heterogeneity in the pathology that makes it difficult for them to abstain voluntarily and this has important implications for treatment. For example, there will be smokers for whom the pathology involves a largely reversible effect of nicotine in creating an 'acquired drive', odiers for whom nicotine has induced long-term changes that make life less comfortable in its absence, and others whose smoking is more situationally driven. Assessment of addiction should first quantify the degree to which the behaviour dominates the individual's repertoire and then assess the underlying pathology in the motivational system. A framework for doing this is discussed.