1. Department of Neurology, Geriatrics Research Institute and Hospital, Maebashi, Gunma, Japan
2. Department of Social Medicine, Hirosaki University Graduate School of Medicine, Hirosaki, Aomori, Japan
3. Department of Neurology, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan
4. Department of Orthopaedic Surgery, Hirosaki University Graduate School of Medicine, Hirosaki, Aomori, Japan
5. Department of Neurology, Hirosaki National Hospital, Hirosaki, Aomori, Japan
6. Department of Speech and Hearing, Hirosaki University of Health and Welfare/JuniorCollege, Hirosaki, Aomori, Japan
7. Centre for Prions and Protein Folding Diseases, University of Alberta, Edmonton, AB, Canada
8. Tanz Centre for Research in Neurodegenerative Diseases and Departments of Medicine, Medical Biophysics, and Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada