Cyrus S H Ho1, Roger C M Ho2, Einar P Wilder-Smith3. 1. Department of Psychological Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore. Electronic address: su_hui_ho@nuhs.edu.sg. 2. Department of Psychological Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore. 3. Division of Neurology, National University Health System, Singapore.