1. National Center of Epidemiology and CIBERNED; Carlos III Institute of Health; Madrid Spain
2. Department of Psychiatry; Maastricht University Medical Center; Maastricht The Netherlands
3. National Parkinson Foundation International Centre of Excellence; King's College London; London United Kingdom
4. National Institute for Health Research (NIHR) Mental Health Biomedical Research Centre and Dementia Unit at South London and Maudsley NHS Foundation Trust and King's College London; London United Kingdom
5. UCL Institute of Neurology; University College London, London; Royal Free Campus London United Kingdom
6. Department of Psychiatry and Departments of Neurology; Perelman School of Medicine at the University of Pennsylvania; Philadelphia Pennsylvania USA
7. Philadelphia Veterans Affairs Medical Center; Philadelphia Pennsylvania USA