1. Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health , Baltimore, Maryland , USA
2. Cochlear Center for Hearing and Public Health, Johns Hopkins Bloomberg School of Public Health , Baltimore, Maryland , USA
3. Kaiser Permanente Center for Health Research , Portland, Oregon , USA
4. Department of Neurology, Mayo Clinic , Rochester, Minnesota , USA
5. The MIND Center, University of Mississippi Medical Center , Jackson, Mississippi , USA
6. Millinckrodt Institute of Radiology, Washington University School of St. Louis , St. Louis, Missouri , USA
7. Department of Radiology, Section of High Resolution Brain PET Imaging, Johns Hopkins School of Medicine , Baltimore, Maryland , USA
8. Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins School of Medicine , Bethesda, Maryland , USA
9. Stroke Branch, National Institute of Neurological Disorders and Stroke Intramural Research Program, National Institute of Health , Bethesda, Maryland , USA