Nicotine as an Addictive Substance: A Critical Examination of the Basic Concepts and Empirical Evidence

The present review is a critical analysis of the concepts behind and the empirical data supporting the view that tobacco use represents an addiction to nicotine. It deals with general aspects of the notion of addiction, while concentrating on specific problems associated with incorporating nicotine into current frameworks. The notion of addiction suffers from unprecedented definitional difficulties. The definitions offered by various authorities are very different, even contradictory. Definitions that reasonably include nicotine are so broad and vague that they allow many trivial things, such as salt, sugar, and watching television, to be considered addictive. Definitions that exclude the trivia also exclude nicotine. The addiction hypothesis, in general, is strongly shaped by views that certain drugs bring about a molecular level subversion of rationality. The main human evidence for this is verbal reports of smokers who say that they can't quit. On the other hand, the existence of many millions of successful quitters suggests that most people can quit. Some smokers don't quit, but whether they can't is another matter. The addiction hypothesis would be greatly strengthened by the demonstration that any drug of abuse produces special changes in the brain. It has yet to be shown that any drug produces changes in the brain different from those produced by many innocuous substances and events. The effects of nicotine on the brain are similar to those of sugar, salt, exercise, and other harmless substances and events. Apart from numerous conceptual and definitional inadequacies with the addiction concept in general, the notion that nicotine is addictive lacks reasonable empirical support. Nicotine does not have the properties of reference drugs of abuse. There are so many findings that conflict so starkly with the view that nicotine is addictive that it increasingly appears that adhering to the nicotine addiction thesis is only defensible on extra-scientific grounds.