DRD4 and attention deficit-hyperactivity disorder: Lastly, more recent neuroimaging studies showed that the presence of some DRD2 and DRD4 might, respectively, modulate the gyrification and the functional activity of cortical areas involved in cognitive processes that are impaired in ADHD and other psychiatric disorders (Palaniyappan et al., 2019; Overs et al., 2021).