1. Bumrungrad International Hospital, Bangkok 10110, Thailand
2. Division of Neurology, Department of Medicine, Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand
3. Department of Preventive and Social Medicine, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand
4. Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA