al., 1998; Piasecki et al., 2003). The degree of nicotine withdrawal-related dysphoria experienced during nicotine abstinence appears similar to the levels reported by psychiatric out-patients (Hughes, 2006). While a third of U.S. smokers try to quit each year, only 3-5% stay quit over a year (CDC, 2002), which may partially be accounted for by over 50 % of smokers experiencing symptoms of nicotine withdrawal after they quit or cut-down (Breslau et al., 1992; Pergadia et al., 2006a). Uncovering both the environmental and genetic factors associated with nicotine withdrawal could broaden our etiologic models of nicotine dependence, and ultimately inform smoking cessation treatment.
