1. Department of Geriatric Medicine, Tokyo Medical University, Tokyo, Japan
2. Department of Diabetes, Endocrinology and Metabolism, Tokyo Medical University, Tokyo, Japan
3. Research Team for Neuroimaging, Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan
4. Department of Functional Brain Imaging Research, Clinical Research Cluster, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba-shi, Chiba, Japan