The explanation we offered in Musci et al. (2015a) with regard to the relationship found between Uhl’s polygenic quit success score and age of first cigarette smoked drew on 4 lines of evidence. The first centered on nicotine’s role in activating the brain’s reward system (Corrigal, Coen, & Adamson, 1994; Laviolette & Van de Kooy, 2004; Tapper, Nashmi, & Lester, 2006). The second is the finding that prolonged exposure to cigarette smoke among non-smokers may increase the likelihood of inhaling secondary smoke and experiencing the reinforcing effects of nicotine (Okoli, Kelly and Hahn, 2007). The third is that the age of 1st cigarette smoked is associated with the number of one’s friends who smoke tobacco cigarettes (Wang et al., 2009; 2012). The fourth is Wang et al. (2012)’s finding that the effect of our early elementary classroom-based preventive intervention on age of first cigarette smoked was via its effect on delaying the reported age a cigarette was first offered by a peer. Synthesizing these 4 lines of evidence, we contended that the quit success score may be an index of
