Inclusion Criteria:  Age 50-100 years. Fulfill the criteria for PD, DLB, MSA, PSP or CBS. Alongside with these participants patients with duplications in the gene coding for a-synuclein will be included. Absence of cognitive symptoms or parkinsonism as assessed by a physician with special interest in cognitive disorders (Healthy controls). Speaks and understands Swedish to the extent that an interpreter was not necessary for the patient to fully understand the study information and cognitive tests.  Exclusion Criteria:  Significant unstable systemic illness or organ failure, such as terminal cancer, that makes it difficult to participate in the study. Current significant alcohol or substance misuse. Refusing MRI or PET.