Few clinical trials have been conducted to evaluate the efficacy and safety of antipsychotic drugs among older people with schizophrenia (excluding this study group), using a heterogeneous criterion for the definition of “older person.” Olanzapine was superior to haloperidol in overall symptoms, negative symptoms and response, and was associated with fewer dropouts than risperidone. Risperidone and haloperidol produced a more increase in prolactin than olanzapine, and olanzapine was associated with lower use of antiparkinson medication than haloperidol. The gene discussed is PRL; the disease is schizophrenia.