1. Department of Geriatric Neurology, Chinese PLA General Hospital, Beijing, P.R. China
2. Research Center of Clinical Epidemiology, Peking University Third Hospital, Beijing, P.R. China
3. Department of Neurology, Peking Union Medical College Hospital, Beijing, P.R. China
4. Department of Gerontology, Bethune International Peace Hospital, Shijiazhuang, P.R. China
5. Department of Neurology, Chinese PLA 201 Hospital, Dalian, P.R. China
6. Department of Gerontology, Changhai Hospital, Shanghai, P.R. China
7. Department of Neurology, Chinese PLA 401 Hospital, Qingdao, P.R. China
8. Department of Neurology, General Hospital of Chengdu Military Command, Chengdu, P.R. China
9. Department of Neurology, Chinese PLA 323 Hospital, Xi'an, P.R. China
10. Department of Neurology, General Hospital of Lanzhou Military Command, Lanzhou, P.R. China
11. Department of Neurology, Chinese PLA 107 Hospital, Yantai, P.R. China
12. First Cadre Department, Fuzhou General Hospital of Nanjing Military Command, Fuzhou, P.R. China
13. Forth Cadre Department, General Hospital of Guangzhou Military Command, Guangzhou, P.R. China