CYP2D6 and delusional disorder: On the other hand, a study on 136 patients, aged 37 ± 13 years, diagnosed with schizophrenia, schizoaffective disorders, delusional disorder, or brief psychotic disorder and treated with a single regimen of risperidone showed no association between CYP2D6 polymorphisms (*1/*1, *1/*10, and *10/*10) and clinical improvement outcomes based on PANSS.