Prospective Neuroimaging Investigation of Idiopathic REM Sleep Behavior Disorder

This study will include 3 groups in relation with RBD: idiopathic RBD (iRBD), PD- RBD, normal controls without RBD. In all groups, neurological examinations, olfactory testings, nonmotor symptoms evaluations, neuropsychological evaluations (detailed outcomes are in the outcome section) will be performed at baseline evaluation after enrollment. Image data will be obtained on following modalities: brain magnetic resonance imaging (MRI), 18F-N-ω-fluoropropyl- 2β-carbomethoxy- 3β-(4-iodophenyl) nortropane ([18F]FP-CIT) positron emission tomography (PET), and 18F-fludeoxyglucose([18F]FDG) PET.

To assess progression toward Lewy body disorders, patients in iRBD group will be evaluated at 2, and 4 years of follow-up visit. Clinical, neuropsychological tests, brain MRI, and two PET scans will be administered. After 4 years, patients who are willing to participate will be additionally followed-up yearly as a routine clinical visit with clinical and neurological examinations until obvious signs of Lewy body diseases will develop.

In PD-RBD group, patients will be evaluated at 3-year follow-up period amongst days of routine clinic visits with administering clinical and neuropsychological tests.

Inclusion criteria

iRBD group:

• A diagnosis of RBD according to the international classification of sleep disorders-2 (ICSD-2) criteria
• No current neurological diseases related with RBD
• Male or female aged from 30 to 80 years old at screening
• Subject enrolled voluntarily and understood the contents of the study

PD group:

• A diagnosis of PD according to the UK Brain Bank Diagnostic Criteria
• A diagnosis of RBD according to the international classification of sleep disorders-2 (ICSD-2) criteria
• Male or female aged from 30 to 80 years old at screening
• Subject enrolled voluntarily and understood the contents of the study

Control group:

• No current neurological or psychiatric diseases related with RBD
• Male or female aged from 30 to 80 years old at screening
• Age and sex matched with those of subjects in iRBD group
• Subject enrolled voluntarily and understood the contents of the study

Exclusion criteria

• Clinically significant cognitive decline unable to follow the study (Mini-mental state examination [MMSE] score less than 20)
• History of psychiatric illnesses (ex. depression)
• Unable to walk and cooperate to the examination
• Unable to take magnetic resonance imaging or positron emission tomography
• Existence of illness or problems which makes difficult to be enrolled to the study judged by clinicians