1. Department of Neurology, The Third Affiliated Hospital of Sun Yat-sen University , 600# Tianhe Road, Guangzhou, Guangdong 510630, PR China
2. Department of Neurology, The Affiliated Hospital of Hangzhou Normal University , Wenzhou Road 126, Hangzhou 310015, Zhejiang , China
3. Division of Public Health Sciences, Washington University School of Medicine in St. Louis , St Louis, MO 63110, USA
4. Department of Biostatistics, Epidemiology and Informatics, University of Pennsylvania , Philadelphia, PA 19104, USA