Treatment dilemma in comorbidity of schizophrenia and idiopathic Parkinson's disease.

Extrapyramidal symptoms are frequently found in patients with schizophrenia. Most are attributed as drug-induced parkinsonism, but comorbidity of idiopathic Parkinson's disease is also possible. We report a 59-year-old male with a diagnosis of schizophrenia for 32 years. Progressive hand tremor was noted from age 53; and then masked face, bradykinesia, dysphagia, sialorrhea; and unsteady shuffling gait became markedly exacerbated, even after discontinuing all antipsychotics for 6 months. The diagnosis of idiopathic Parkinson's disease was confirmed by Tc99m TRODAT SPECT. The dilemma of psychopharmacological treatment to control both disorders was encountered. Based on the review of treatment for Parkinson's disease psychosis (PDP), the recommended treatments suggest the utilization of quetiapine, clozapine, or aripiprazole. However, monotherapy with each of the three atypical antipsychotics failed due to poor efficacy or worsening of parkinsonism symptoms. After a 2-month cautious titration, a combination of quetiapine 50 mg/day and clozapine 37.5 mg/day finally achieved satisfactory efficacy. This case report illustrates the dilemma of treating a patient with schizophrenia and comorbid idiopathic Parkinson's disease, which differed from PDP and required more clinical data for a proper treatment recommendation.