Received: 23 September 2020
Accepted: 11 February 2021
First Online: 19 February 2021
Ethics approval and consent to participate
: The study protocol was approved by the Ethics Committee of the Tokyo Metropolitan Institute of Gerontology (No.1924). Written informed consent was obtained from all participants in the baseline survey.An overseeing mental health expert (T.O., a certified psychiatrist who met all the participants) determined that all participants were capable of ethically and medically consenting for their participation in the research.
: Not Applicable.
: The authors declare that they have no competing interests.