Mass General - Division of Clinical Research

for RBD Group 1. Polysomnogram-confirmed RBD by ICSD-3 criteria 2. Capable of providing informed consent at time of study enrollment 3. Age > 18 years

for RBD Group 1. Diagnosis of PD, dementia of any type, or MSA unless previous participant in NAPS1. 2. Narcolepsy-associated RBD 3. RBD secondary to any known cause except prodromal synucleinopathy. 4. Participation in a clinical trial, except by specific permission by the Executive Committee 5. In the opinion of the investigator, the individual has a clinically significant uncontrolled medical condition that would impede safe completion of the study protocol Inclusion Criteria for Control Group 1. Ability to provide written consent 2. Age > 18 years 3. Must meet age, sex, and race matching criteria per the Data Management and Statistical core recommendations for the site 4. Must be willing to undergo all testing procedures, including neuroimaging and lumbar puncture. 5. Normal capacity to perform complex activities of daily living independently based on informant or physician report Exclusion Criteria for Control Group 1. History of dream enactment behavior to suggest RBD 2. Parkinsonism, MSA, dementia, or mild cognitive impairment 3. Active central nervous system, systemic, psychiatric condition or use of psychoactive medication that would adversely affect cognitive, neuropsychiatric, motor, or autonomic functioning. 4. Contraindications to complete MRI. 5. Contraindications to lumbar puncture. 6. Participation in a clinical trial, except by specific permission by the Executive Committee 7. In the opinion of the investigator, the individual has a clinically significant uncontrolled medical condition that would impede safe completion of the study protocol