1. Department of Neurology, Kaiser Permanente Walnut Creek Medical Center, Walnut Creek, California
2. Division of Research, Kaiser Permanente Northern California, Oakland
3. Department of Medicine, Kaiser Permanente Oakland Medical Center, Oakland, California
4. Department of Neurology, University of California, San Francisco
5. Department of Health Systems Science, Kaiser Permanente Bernard J. Tyson School of Medicine, Pasadena, California
6. Department of Epidemiology, Biostatistics and Medicine, University of California, San Francisco