Funding for this research was provided by:
Expenses for Research and Development of Geriatrics and Gerontology (26-12, 29-12)
Received: 22 August 2020
Accepted: 2 April 2021
First Online: 13 April 2021
: The study was conducted with the approval of the Ethical Review Board of the National Center for Geriatrics and Gerontology, Japan and all participants provided fully informed consent with written documents prior to participation.
: Not applicable.
: The authors declare that they have no competing interests.