1. From the Departments of Neurology, Epidemiology, and Social Medicine, Albert Einstein College of Medicine, Bronx, NY
2. Innovative Medical Research, Stamford, Conn and Hunt Valley, Md
3. Diamond Headache Clinic, Chicago, Ill
4. Strategic Insights, Inc, Chapel Hill, NC
5. Department of Epidemiology, Johns Hopkins School of Public Health, Baltimore, Md