Results of previous work assessing the relationship between impulsivity and inhibition provided mixed results. Although some studies found that higher self-reported impulsivity is associated with poor behavioral inhibition (i.e., higher stop RT; Gorlyn et al., 2005; Logan et al., 1997), others have shown no relationship (Cheung et al., 2004; Lijffijt et al., 2004). In our study, we found that the combined genotype T/C + C/C of rs4648317 and the combined genotype A/G + G/G of rs12364283, as well as the haplotype block consisting of these SNPs, were associated with lower self-reported impulsivity/sensation seeking, as well as lower stop RT (i.e., better behavioral inhibition performance). This finding is the first step in understanding the genetic basis of the neurobiological processes of the two phenotypes. However, the results need to be interpreted cautiously and replicated in future studies in light of the fact that self-reported measure of impulsivity/sensation seeking did not remain significant after adjusting for multiple comparisons.
