However, since both high and low activity of the striatal dopamine system can be associated with low EF as seen in studies investigating ADHD and schizophrenia (although the presumed underlying mechanisms differ) (Toplak et al. 2005; Wing et al. 2013), we did not assume a direct or linear association between DRD2 CGS and EF. The gene discussed is DRD2; the disease is attention deficit-hyperactivity disorder.