1. Department of Neurology
2. Department of Epidemiology and Social Medicine, Albert Einstein College of Medicine, Bronx, New York, NY, USA
3. Center for Work and Health, Center for Healthier Ageing and IMR, Advance PCS, Hunt-Valley, MD, USA
4. The New England Center for Headache, Stamford, CT, USA
5. King's Headache Service, King's College Hospital, London, UK
6. Department of Epidemiology, The Johns Hopkins University, Baltimore, MD