Nicotine dependence is associated with decreased rates of initial cessation and a higher risk of transitioning from lapse to relapse (Japuntich et al. 2011). Although pre-quit level of nicotine dependence is related to relapse, it is not a consistent predictor of quit attempts and smoking cessation, and that association is highly dependent on which measurement is used (Etter 2005; Japuntich et al. 2011; Piper et al. 2006). For example, the widely used Fagerstrom Test for Nicotine Dependence (FTND) (Fagerstrom 1978; Heatherton et al. 1991) does not consistently and robustly predict withdrawal symptoms or quitting success (Borrelli et al. 2001; Piper et al. 2004; Silagy et al. 1994). The same is true for measures of smoking heaviness predicting cessation (Fidler et al. 2011). Together with evidence suggesting that nicotine dependence and smoking cessation each have some unique genetic contributions (Li et al. 2003; Xian et al. 2003), these data underscore the point that nicotine dependence and smoking cessation represent distinct phenotypes. While some genetic influences may be shared by these phenotypes, it cannot be assumed that genetic associations with nicotine dependence will translate to smoking cessation or vice versa.
