Tardive dyskinesia (TD) is a movement disorder that can arise as a side effect of treatment with dopamine receptor-blocking agents (DRBAs), including antipsychotic drugs (APDs) used to manage psychotic illnesses. Second-generation APDs (SGAs) are often preferred to first-generation drugs due to their lower propensity to cause TD, however many SGAs-treated patients still develop the condition. Although TD is a global health concern, evidence regarding the occurrence of TD and how it is managed in Asian countries is currently limited. This article reports the results of a systematic review of the published literature on TD focusing on its prevalence, types of patients, knowledge of the condition, causative factors, and usual treatment pathways in clinical practice in Asian countries. Epidemiological data suggest that the prevalence of TD is increasing globally due to an overall rise in APD use, contributing factors being polypharmacy with multiple APDs, the use of higher than necessary doses, and off-label use for non-psychotic indications. Although exact prevalence figures for TD in Asian countries are difficult to define, there is a similar pattern of rising APD use which will result in increasing numbers of TD patients in this region. These issues need to be addressed and strategies developed to minimize TD risk and manage this disabling condition which impacts patients' quality of life and daily functioning. To date, both research into TD has been predominantly psychiatry focused and the perspectives from neurologists regarding the clinical management of this challenging condition are scarce. However, neurologists have an essential role in managing the movement disorders manifestations that characterize TD. Optimum management of TD, therefore, should ideally involve collaboration between psychiatrists and neurologists in joint care pathways, wherever practical. Collaborative pathways are proposed in this article, and the challenges that will need to be addressed in Asian countries to improve the care of people with TD are highlighted, with a focus on the neurologist's viewpoint and the implications for the management of TD globally.
1·8 billion people of diverse ethnicities and cultures live in the Western Pacific Region. The increasing longevity of populations in this region is a major contributor to the exponential increase in Parkinson's disease prevalence worldwide. Differences exist between Parkinson's disease in the Western Pacific Region and in Europe and North America that might provide important insights into our understanding of the disease and approaches to management. For example, some genetic factors (such as LRRK2 mutations or variants) differ, environmental exposures might play differential roles in modulating the risk of Parkinson's disease, and fewer dyskinesias are reported, with some differences in the profile of non-motor symptoms and comorbidities. Gaps in awareness of the disease and inequitable access to treatments pose challenges. Further improvements in infrastructure, clinical governance, and services, and concerted collaborative efforts in training and research, including greater representation of the Western Pacific Region in clinical trials, will improve care of patients with Parkinson's disease in this region and beyond.
Nongenetic movement disorders are common throughout the world. The movement disorders encountered may vary depending on the prevalence of certain disorders across various geographical regions. In this paper, we review historical and more common nongenetic movement disorders in Asia. The underlying causes of these movement disorders are diverse and include, among others, nutritional deficiencies, toxic and metabolic causes, and cultural Latah syndrome, contributed by geographical, economic, and cultural differences across Asia. The industrial revolution in Japan and Korea has led to diseases related to environmental toxin poisoning, such as Minamata disease and β-fluoroethyl acetate-associated cerebellar degeneration, respectively, while religious dietary restriction in the Indian subcontinent has led to infantile tremor syndrome related to vitamin B12 deficiency. In this review, we identify the salient features and key contributing factors in the development of these disorders.
The increasing availability of molecular genetic testing has changed the landscape of both genetic research and clinical practice. Not only is the pace of discovery of novel disease-causing genes accelerating but also the phenotypic spectra associated with previously known genes are expanding. These advancements lead to the awareness that some genetic movement disorders may cluster in certain ethnic populations and genetic pleiotropy may result in unique clinical presentations in specific ethnic groups. Thus, the characteristics, genetics and risk factors of movement disorders may differ between populations. Recognition of a particular clinical phenotype, combined with information about the ethnic origin of patients could lead to early and correct diagnosis and assist the development of future personalized medicine for patients with these disorders. Here, the Movement Disorders in Asia Task Force sought to review genetic movement disorders that are commonly seen in Asia, including Wilson's disease, spinocerebellar ataxias (SCA) types 12, 31, and 36, Gerstmann-Sträussler-Scheinker disease, PLA2G6-related parkinsonism, adult-onset neuronal intranuclear inclusion disease (NIID), and paroxysmal kinesigenic dyskinesia. We also review common disorders seen worldwide with specific mutations or presentations that occur frequently in Asians.
Clinical case studies and reporting are important to the discovery of new disorders and the advancement of medical sciences. Both clinicians and basic scientists play equally important roles leading to treatment discoveries for both cures and symptoms. In the field of movement disorders, exceptional observation of patients from clinicians is imperative, not just for phenomenology but also for the variable occurrences of these disorders, along with other signs and symptoms, throughout the day and the disease course. The Movement Disorders in Asia Task Force (TF) was formed to help enhance and promote collaboration and research on movement disorders within the region. As a start, the TF has reviewed the original studies of the movement disorders that were preliminarily described in the region. These include nine disorders that were first described in Asia: Segawa disease, PARK-Parkin, X-linked dystonia-parkinsonism, dentatorubral-pallidoluysian atrophy, Woodhouse-Sakati syndrome, benign adult familial myoclonic epilepsy, Kufor-Rakeb disease, tremulous dystonia associated with mutation of the calmodulin-binding transcription activator 2 gene, and paroxysmal kinesigenic dyskinesia. We hope that the information provided will honor the original researchers and help us learn and understand how earlier neurologists and basic scientists together discovered new disorders and made advances in the field, which impact us all to this day.