The primary objective of this study is to determine whether data acquired from a remote monitoring approach can reliably identify and track motor symptoms in prodromal PD and clinical PD. The study is a one-year longitudinal biomarker study recruiting idiopathic RBD patients, Parkinson's Disease patient and healthy controls. All participants receive a smartphone with the Roche PD Mobile Application, complete a number of active tests daily and their movements will be remotely monitored. Participants will undergo additional neurological exams and DaT-SPECT and MRI imaging in the study. A second objective of this study will be to validate an immunohistochemistry skin biopsy assay for the detection of pathological alpha-synuclein diagnostic of PD, in the peripheral nerves of the skin.