1. Neurology Department, Beijing Hospital, National Center of Gerontology, Beijing 100730, P. R. China
2. Graduate School, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100730, P. R. China
3. Anesthesiology Department, Beijing Hospital, National Center of Gerontology, Beijing 100730, P. R. China
4. The MOH Key Laboratory of Geriatrics, Beijing Hospital, National Center of Gerontology, Beijing 100730, P. R. China
5. Department of Neurology, Peking University First Hospital, Beijing 100034, P. R. China
6. Department of Orthopedics, The Fourth Hospital of Hebei Medical University, Shijiazhuang Development Zone, Hebei 050011, P.R. China
7. School of Basic Medicine, Peking University, Beijing 100191, P. R. China