1. Department of Neurology, Johns Hopkins School of Medicine, Baltimore, MD, USA
2. Department of Medicine, Division of Geriatrics, University of Mississippi Medical Center, Jackson, MS, USA
3. Department of Anesthesiology and Critical Care Medicine, Johns Hopkins School of Medicine, Baltimore, MD, USA
4. Department of Neurology, Mayo Clinic, Rochester, MN, USA
5. Department of Radiology, Mayo Clinic, Rochester, MN, USA
6. Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
7. Department of Radiology, Johns Hopkins School of Medicine, Baltimore, MD, USA
8. Department of Internal Medicine, Section on Gerontology and Geriatrics Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA