1. Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland
2. Department of Epidemiology, Johns Hopkins School of Public Health, Baltimore, Maryland
3. Department of Neurology, Yale University School of Medicine, New Haven, Connecticut
4. Department of Epidemiology, University of North Carolina at Chapel Hill
5. Department of Neurology, University of Mississippi Medical Center, Jackson
6. Department of Epidemiology, Emory University, Atlanta, Georgia