large population of smokers [36]. This suggests that the upcoming DSM-V should retain those criteria that appear to be more characteristic of other forms of drug dependence. Note, however, that the current results do not address the question of whether dependence manifests itself similarly across substances. In fact, recent research indicates that the DSM-IV criteria measure different levels of dependence across different types of illicit drugs [37]. Thus, as suggested by Hughes [9], tobacco dependence may manifest itself differently than other forms of substance dependence.
