Dependence on Nicotine Chewing Gum

To the Editor.— We would like to comment on the interesting article by Hughes and colleagues¹ entitled "Physical Dependence on Nicotine in Gum." The results largely replicate those of our earlier study,² but their interpretation and conclusions differ and could, in our view, seriously mislead physicians and the public about the risks of developing long-term dependence on the gum.

In a highly selected sample of former smokers who were still using nicotine chewing gum five months after quitting smoking, they showed that substitution of placebo gum was followed by mood changes and other subjective symptoms characteristic of tobacco withdrawal. In contrast to our study, they found no change in heart rate— the only "physical" effect they examined.

Having claimed that our study² "demonstrated that nicotine gum can induce physical dependence," Hughes and colleagues go on to suggest that their own results indicate that "exsmokers who use nicotine