1. Center for Networked Biomedical Research in Neurodegenerative Diseases (CIBERNED)Carlos III Institute of Health Madrid Spain
2. Department of Statistics, Center of Human and Social SciencesSpanish Council for Scientific Research Madrid Spain
3. Department of Psychiatry and Neurology, Perelman School of Medicine at the University of Pennsylvania; Parkinson's Disease Research, Education and Clinical CenterPhiladelphia Department of Veterans Affairs Philadelphia Pennsylvania USA
4. King's College London, Department of Neurosciences, Institute of Psychiatry, Psychology & Neuroscience and Parkinson's Foundation Centre of ExcellenceKing's College Hospital Denmark Hill London UK
5. National Center of Epidemiology and Center for Networked Biomedical Research in Neurodegenerative Diseases (CIBERNED)Carlos III Institute of Health Madrid Spain
6. Department of Clinical and Movement NeurosciencesUCL Queen Square Institute of Neurology London UK