1. Harvard T.H. Chan School of Public Health, Department of Social and Behavioral Sciences, Boston, Massachusetts
2. Tohoku University Graduate School of Dentistry, Department of International and Community Oral Health, Sendai, Japan
3. Chiba University, Center for Preventive Medical Sciences, Chiba, Japan
4. Department of Gerontological Evaluation, Center for Gerontology and Social Science, National Center for Geriatrics and Gerontology, Aichi, Japan