1 Morton and Gloria Shulman Movement Disorders Clinic and the Edmond J. Safra Program in Parkinson's Disease, Faculty of Medicine, Toronto Western Hospital, University of Toronto, Toronto, ON, Canada.
2 Department of Neurology, Centro Hospitalar Universitário de São João, Porto, Portugal.
3 Department of Clinical Neurosciences and Mental Health, Faculty of Medicine of University of Porto, Porto, Portugal.
4 Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, UK.
5 Donders Institute for Brain, Cognition and Behaviour, Department of Neurology, Centre of Expertise for Parkinson & Movement Disorders, Radboud University Medical Centre, Nijmegen, The Netherlands.