Dependence on tobacco and nicotine products: a case for product-specific assessment.

The International Classification of Diseases and the Diagnostic and Statistical Manual for diagnosing tobacco/nicotine dependence emphasize the dependence-producing drug nicotine. These diagnostic tools have been challenged on grounds of poor predictive validity, and they do not differentiate across various forms of nicotine-containing products. In fact, nicotine-containing products (e.g., tobacco cigarettes, smokeless tobacco [ST], waterpipe, electronic cigarettes [ECIGs], and nicotine replacement [NR] products) have very different characteristics both in terms of sensory and behavioral involvement and also in pharmacokinetic and pharmacodynamic effects. For example, a cigarette and a nicotine patch are very different on almost every one of these dimensions. When ability to stop using a nicotine/tobacco product is used as a criterion for dependence, success rates vary considerably across products: Tobacco cigarette cessation is more difficult than ST cessation that in turn is more difficult than NR product cessation. Based on these results, we hypothesize that there is a continuum of dependence as much as there is a continuum of harm, with tobacco cigarettes and NR products on opposite ends of both continua and other products (waterpipe and ECIGs) somewhere in between. In order to capture more precisely the dependence produced by both nicotine and its administration forms, product-specific instruments may be required. The pros and cons of this approach are discussed.