The Swedish BioFINDER Sleep Study

Inclusion Criteria: Idiopathic RBD: * Polysomnography verified RBD according to AASM criteria. * Does not fulfill diagnostic criteria for idiopathic Parkinson´s disease. * Age range 50-100. Women who are \<55 years of age will be required to take a pregnancy test before participation in the PET and scintigraphy part of the study if not post-menopausal. * Ability to give informed consent. * Speaks and understands Swedish to the extent that an interpreter is not necessary for the patient to fully understand the study information and cognitive tests. Early Parkinson´s disease: * Fulfills the diagnostic criteria for idiopathic Parkinson´s disease. * The PD patients will be de novo (yet without any PD treatment) or with treatment for a maximum of 3 years. * Age range 50-100. Women who are \<55 years of age will be required to take a pregnancy test before participation in the PET and scintigraphy part of the study if not post-menopausal. * Ability to give informed consent. * Speaks Swedish fluently as stated above. Healthy Controls * Age range 50-100. Women who are \<55 years of age will be required to take a pregnancy test before participation in the PET and scintigraphy part of the study if not post-menopausal. * No diagnosis of PD or another significant neurological disorder. * No diagnosis of RBD. * Ability to give informed consent. * Speaks Swedish fluently as stated above. Exclusion Criteria: For all groups: * Past history of severe or repeated concussive head injury or stroke or any significant systemic disease or unstable medical condition. * History of severe and unstable depression, schizophrenia, schizoaffective disorder or bipolar disorder. * Significant white matter microvascular disease. * Contraindication to MRI and PET. Exclusion criteria specific for early Parkinson´s disease: * Normal dopamine transporter (\[18F\]FE-PE2I) scan.