DRD2 and Cognitive impairment: Haloperidol, the typical antipsychotic that blocks dopamine D2 receptors, is considered to be poor improvement on cognitive impairment (Gallhofer et al., 2007; Saeedi, Remington, & Christensen, 2006), and it causes obvious extrapyramidal side effects that need anticholinergic which in turn damages cognitive function (Ogino, Miyamoto, Miyake, & Yamaguchi, 2014).