First, the phenotypic pattern of psychiatric comorbidity with nicotine dependence was what we expected. We found that nicotine dependent smokers, when compared with non-dependent smokers, had a two-to-three fold increase in risk for other psychiatric disorders, which is consistent with findings from the National Epidemiologic Survey of Alcohol Related Conditions (NESARC) and the National Comorbidity Survey (NCS). The development of nicotine dependence is clearly associated with other mental disorders (Dierker and Donny, 2008; Goodwin et al., 2008; Hasin et al., 2011; Swendsen et al., 2010).
