The primary weakness of this study was its modest sample size, and our lack of a sample in which to examine replication of our findings. However, our sample was demographically diverse, with an overrepresentation of individuals meeting criteria for alcohol dependence, a disorder where sensation seeking may be a particularly relevant risk factor. Our genotypic data provided more thorough coverage of genetic variation in the candidate genes examined here than in previous association studies related to sensation seeking (Beaver, 2009; Ebstein, 2006; Heck et al., 2009), and we made use of our additional genomic data by taking a systems approach and considering the aggregate effect of numerous SNPs in multiple genes associated with dopamine. This approach resulted in significant improvement in our ability to predict sensation seeking scores, beyond the prediction afforded by covariates, with an overall non-trivial aggregate effect (Cohen, 1992) of SNPs on sensation seeking.
