Contrary to what we found in response to CT, where the presence of DRD3 Ser9Gly seems to be advantageous, a large number of studies (but not all) have linked the presence of the Gly allele with a high risk for schizophrenia, ADHD, substance abuse as well as the development of attention and working memory deficits [64]. This evidence concerns the gene DRD3 and substance abuse.