1. National Centre of Epidemiology Carlos III Institute of Health Madrid Spain
2. Center for Networked Biomedical Research in Neurodegenerative Diseases (CIBERNED) Carlos III Institute of Health Madrid Spain
3. UCL Queen Square Institute of Neurology University College London London UK
4. King's College London, Department of Neurosciences, Institute of Psychiatry, Psychology & Neuroscience and Parkinson's Foundation Centre of Excellence King's College Hospital London UK
5. Department of Psychiatry and Neurology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia Department of Veterans Affairs Parkinson's Disease Research, Education and Clinical Center (PADRECC) Philadelphia Pennsylvania USA