that confer an increased susceptibility for developing nicotine dependence (Zhang et al., 2006b). As in the case with alcohol, studies examining differences in response to nicotine administration have revealed some interesting associations. For instance, female G118 allele-carriers report attenuated rewarding effects of nicotine (Ray et al., 2006). In a separate study, nicotine was administered following the induction of a positive or negative mood via pictures and music. Smoking was reported as more rewarding to A118 allele-carriers when in a negative mood than it was for those with the G118 allele, suggesting that the A118 allele-carriers may respond more to the mood-enhancing properties of nicotine (Perkins et al., 2008). Accordingly, increases in cerebral blood flow to brain regions associated with cigarette craving were detected in smokers with the A118 allele compared to the G118 allele (Wang et al., 2008).
