1. Department of Geriatric Medicine; Kanazawa Medical University; Kahoku-gun; Ishikawa
2. Department of Geriatric Medicine; University of Tokyo; Bunkyo-ku; Tokyo
3. Department of Community Healthcare and Geriatrics; Graduate School of Medicine; Nagoya University; Nagoya; Aichi
4. Department of Psychiatry; National Center for Geriatrics and Gerontology; Obu; Aichi
5. Department of Internal and Geriatric Medicine; Graduate School of Medicine; Kobe University; Kobe; Hyogo
6. Laboratory of Infectious Diseases; Graduate School of Infection Control Sciences; Kitasato University; Minato-ku; Tokyo; Japan