Adequate diagnosis of the cause of Parkinsonism and treatment in an elderly patient with schizophrenia: A case report.

Background: Parkinsonism is frequently observed in patients with schizophrenia, and most patients are diagnosed with drug-induced parkinsonism. However, comorbidity with idiopathic Parkinson's disease or Parkinson-plus syndrome is also possible. The pathophysiology and treatment for each of these are entirely different, thus an appropriate diagnosis is required. However, distinguishing them based on clinical symptoms alone is often difficult, and many cases are misdiagnosed. Additionally, Parkinsonism is frequently mistaken for negative symptoms. Case Description: We report a case of 68-year-old woman diagnosed with schizophrenia, who was admitted to a welfare center. At approximately age 60, the patient experienced motivation reduction, a loss of appetite, and pain in the extremities. In her mid-60s, tremor and muscle rigidity appeared; nuclear medicine testing was performed for a detailed examination, resulting in a diagnosis of levodopa-responsive Parkinson's syndrome. Notably, the patient's parkinsonism and emotional symptoms, which had been considered negative symptoms thus far, improved with levodopa treatment. Conclusion: This case report illustrates the importance of properly diagnosing the cause of parkinsonism in patients with schizophrenia.