Funding for this research was provided by:
National Natural Science Foundation of China (71233001, 71490732, 81872707, and 81573247)
National Institute on Aging (2P01AG031719)
Claude D. Pepper Older Americans Independence Center (5P30 AG028716)
Text and Data Mining valid from 2019-11-17
Received: 25 August 2019
Accepted: 11 November 2019
First Online: 17 November 2019
Ethics approval and consent to participate
: The study was approved by the Ethics Committee of Peking University and Duke University. All participants signed written informed consent.
: All authors have given their consent for the publication of this study.
: The authors declare that they have no competing interests.