Parkinson’s disease is a neurodegenerative disease that develops because of relatively selective damage to dopamine neurons in the substantia nigra and is characterized by motor symptoms centered on bradykinesia, tremors, and muscle rigidity. Furthermore, its prevalence in Japan is estimated to be 0.1%–0.18%, and aging contributes to its onset [
1]. In contrast, antipsychotics have dopamine receptor-blocking effects and cause drug-induced parkinsonism [
2]. Parkinsonism is defined as a pathological condition characterized by various symptoms similar to those observed in Parkinson’s disease. Among these disorders, types in which Parkinson’s disease symptoms manifest as side effects of medications were classified as drug-induced parkinsonism. Moreover, conditions that exhibited Parkinson-like symptoms but were not categorized as Parkinson’s disease were referred to as Parkinson’s syndrome. Drug-induced movement disorders could be associated with therapies that involve levodopa or dopamine agonists or to drugs possessing central dopamine receptor antagonist properties, anticholinergics, certain anticonvulsants, and amphetamines. These disorders typically arise from lesions or dysfunction within the extrapyramidal motor system, leading to impairments in motor function. The manifestations of these disorders can closely mimic those of idiopathic Parkinson’s disease, featuring the classic triad of resting tremors, rigidity, and bradykinesia. Additional Parkinson-like symptoms may include bradykinesia (reduced speed of movement), hypersalivation, drooling, shuffling gait, micrographia, dysphonia, and diminished postural reflexes [
3]. Approximately 30% of patients with schizophrenia have been reported to have a poor response to antipsychotic drugs. Seeking to improve positive symptoms, clinicians may resort to prescribing higher doses or combinations of multiple drugs, which can increase the likelihood of side effects and treatment resistance. Maintaining the optimum dosage of antipsychotic drugs and balancing the therapeutic effects and side effects are important. In drug-induced parkinsonism (DIP), Parkinson’s disease symptoms appear when approximately 80% of dopamine receptors 2 (D2-R) are blocked [
4]. The Manual for Handling Serious Side Effects and Diseases of the Ministry of Health, Labour and Welfare lists drugs with many side effects. However, clozapine and quetiapine have a blocking effect of approximately 60%; therefore, side effects are unlikely to occur [
5]. When DIP occurs, the only option is to reduce the dose of the causative drug and, in severe cases, temporarily discontinue it. However, many patients with DIP may continue to have parkinsonian symptoms long after discontinuation of the causative drug, suggesting potential neurodegeneration [
6]. Parkinson-like events have a wide-ranging impact on patients’ quality of life. Although these symptoms themselves are rarely a direct cause of death, they increase the risk of various complications, which can be life-threatening. Therefore, DIP is considered a significant side effect and is extremely important for comprehensively analyzing the relationship between Parkinson-like side effects and the drugs that induce them. The Japanese Adverse Drug Event Reporting (JADER) database, which is published by the Pharmaceuticals and Medical Devices Agency (PMDA), reports various side effects of drugs, including parkinsonism, bradykinesia, tremors, and muscle rigidity. It has been reported as a “Parkinson-like event.” Although this disease was induced by various drugs, the mechanisms underlying its various symptoms have not been fully elucidated. Therefore, in this study, we comprehensively analyzed the relationship between Parkinson-like events and the drugs that induce them using the JADER database.