1. Department of Neurology, Columbia University, New York, New York
2. Department of Epidemiology, Columbia University, New York, New York
3. Department of Biostatistics, Columbia University, New York, New York
4. Department of Biostatistics, Epidemiology, and Informatics, University of Pennsylvania, Philadelphia
5. Department of Medicine, University of Washington, Seattle
6. Kaiser Permanente Washington Health Research Institute, Seattle