Funding for this research was provided by:
Grant-in Aid for Scientific Research (A) from the Ministry of Education, Culture, Sports, Science, and Technology, Japan.
Text and Data Mining valid from 2018-06-06
Received: 19 September 2017
Accepted: 21 May 2018
First Online: 6 June 2018
Ethics approval and consent to participate
: The study protocol was approved by the ethics committees of the Tokyo Metropolitan Institute of Gerontology and Waseda University.
: Written informed consent for publication was obtained from all participants.
: The authors declare that they have no competing interests.
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