1. Department of NeurologyWashington University School of Medicine St Louis MO
2. Departments of Neurology and of Biostatistics, Epidemiology, and InformaticsUniversity of Pennsylvania Perelman School of Medicine Philadelphia PA
3. Center for Pharmacoepidemiology Research and TrainingUniversity of Pennsylvania Perelman School of Medicine Philadelphia PA
4. School of Public Health, Faculty of Health SciencesUniversity of the Witwatersrand Parktown South Africa