1. Department of Community Health and Preventive Medicine, Hamamatsu University School of Medicine , Hamamatsu, Shizuoka , Japan
2. Center for Preventive Medical Sciences, Chiba University , Chiba , Japan
3. Department of Social Epidemiology, Graduate School of Medicine and School of Public Health, Kyoto University , Kyoto , Japan
4. Department of Gerontological Evaluation, Center for Gerontology and Social Science, Research Institute, National Center for Geriatrics and Gerontology , Oubo, Aichi , Japan