1. Northwestern University Feinberg School of Medicine Chicago Illinois USA
2. Department of Otolaryngology—Head and Neck Surgery Columbia University Vagelos College of Physicians and Surgeons New York New York USA
3. Department of Epidemiology and Biostatistics College of Human Medicine Michigan State University East Lansing Michigan USA
4. Laboratory of Epidemiology and Population Science Intramural Research Program of the National Institutes of Health National Institute on Aging Baltimore Maryland USA
5. Department of Psychiatry and Neurology Columbia University Irving Medical Center New York New York USA