Again, and in detail: We assumed that a high DRD2 CGS is associated with high self-reported impulsivity based on previous studies in healthy individuals (Buckholtz et al. 2010; Lee et al. 2009) and the aforementioned association between low levels of striatal dopamine and symptoms of ADHD (Moreno et al. 2010; Volkow et al. 2007). This evidence concerns the gene DRD2 and attention deficit-hyperactivity disorder.