Schizophrenia symptoms comprise overactivity of the dopamine 2 (D2) receptor system, associated with positive psychotic symptoms such as delusions and hallucinations, as well as underactivity of the dopamine 1 (D1) receptor system, related to the so-called negative symptoms such as anhedonia, apathy and affective flattening.1 However, all available pharmacological schizophrenia treatments act mainly through blocking dopamine D2 receptors, which may induce parkinsonism that could mimic negative symptoms. This evidence concerns the gene DRD2 and schizophrenia.