1 Beijing Rehabilitation Hospital, Capital Medical University, Beijing, China.
2 Department of Neurology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany.
3 Department of Neurology, University of Pittsburgh, Pittsburgh, PA, United States.
4 Geriatric Research Education and Clinical Center, US Department of Veterans Affairs (VA) Pittsburgh Healthcare System, Pittsburgh, PA, United States.
5 Department of Neurology, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China.