As the course of Parkinson’s disease increases, the risk of some psychiatric symptoms (including visual hallucinations and confusion) increases. In this case, the options available include clozapine and quetiapine (Seroquel), because these drugs have a small risk of aggravating movement disorders such as bradykinesia and tremor while improving psychiatric symptoms. Other antipsychotic drugs such as haloperidol, fenetylline, risperidone (Vestrone), sulpiride, and chlorpromazine can also improve the psychiatric symptoms of Parkinson’s disease, but can aggravate movement disorders such as bradykinesia. In contrast, olanzapine (Reptil) has an inexact effect on improving such symptoms. In addition, other problems of Parkinson’s disease, including allodynia, tremor, and even pain, are indications for which clozapine can be used. However, psychiatrists and neurologists also have concerns about clozapine and some of its side effects, mainly granulocytopenia and myocardial damage. However, a recent study by Finnish scientists (Tiihonen, Lancet 2009), published in the prestigious international journal The Lancet, suggests that clozapine has the best safety profile compared to other atypical antipsychotics (Seroquel, Vestrone, Reptil). In the study, researchers at Kuopio University Hospital followed 67,000 Finnish patients with schizophrenia between 1996 and 2006, and showed a 26% reduction in premature death rates with clozapine compared to fenbutrazine. In contrast, the premature death rate was 41% higher for Seroquel, 34% higher for Vespertine, and 13% higher for Reptil, also using fenbutrazine as a comparator. Therefore, clozapine should be considered as a “first-line” drug for schizophrenia. The above studies were conducted in patients with schizophrenia, and although there are no direct studies of the psychiatric symptoms of Parkinson’s disease, there is reason to believe that it is relatively safer because the doses of antipsychotics required in patients with psychiatric symptoms of Parkinson’s disease are much lower than those required in anti-schizophrenia. An additional advantage of clozapine is its price advantage, which is so cheap as to be almost negligible.