However, in another study, adult 7-R allele carriers with ADHD performed better in a working memory task as compared to those without the 7-R allele (Boonstra et al., 2008) suggesting that the effects of DRD4 48 bp might depend on age and ADHD status (Altink et al., 2012). This evidence concerns the gene DRD4 and attention deficit-hyperactivity disorder.