1 Department of Neurology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi 371-8511, Japan. Electronic address: takumi.n@gunma-u.ac.jp.
2 Department of Neuropathology, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki 036-8562, Japan.
3 Geriatrics Research Institute and Hospital, 3-26-8 Otomo-machi, Maebashi 371-0847, Japan.
4 Department of Neurology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi 371-8511, Japan.