Association of serotonin transporter genotype with selective processing of smoking-related stimuli in current smokers and ex-smokers

We sought to determine whether polymorphism in the serotonin transporter (5HTT) gene is associated with attentional bias toward smoking-related stimuli in current smokers and ex-smokers, using a modified Stroop task and an attentional blink task to measure selective processing of smoking-related stimuli. All participants attended a single testing session during which they completed the modified Stroop and attentional blink tasks to index attentional bias for smoking-related stimuli, in counterbalanced order. The experimental design included two between-subjects factors of smoking status (current smoker, ex-smoker) and 5HTT genotype (short, long). Smoking status x genotype interactions were significant on both the modified Stroop (p=.046) and the attentional blink (p=.006) tasks. On the modified Stroop task, we found a significant effect of 5HTT genotype on color-naming interference among ex-smokers (p=.018) but not current smokers (p=.989). On the attentional blink task, we found a significant effect of 5HTT genotype for current smokers (p=.028), whereas among ex-smokers this effect did not reach statistical significance, although it constituted a trend (p=.086). Our data provide tentative support for a moderating influence of 5HTT genotype on attentional bias for smoking-related stimuli in ex-smokers. This finding may account for inconsistent reports of attentional bias among ex-smokers.