Clinical Research Directory

Inclusion Criteria: 1. Age-and sex-matched with the groups; 2. Being capable of giving informed consent for participation of the study; 3. Without a personal history or a family history of PD or RBD; 4. A total score on REM Sleep Behavior Questionnaire (RBDQ-HK) less than 19, which is the suggestive cut-off of a diagnosis of RBD; 5. Absence of self-report dream enactment behaviors and RSWA as measured by v-PSG Exclusion Criteria: 1. Having a history of ICD diagnosis or ICD symptom(s) assessed with Questionnaire for Impulsive-Compulsive Disorders in Parkinson's Disease-Rating Scale (QUIP-RS); 2. Presence of narcolepsy or other neurodegenerative diseases (except for PD group) that may give rise to RBD; 3. Presence of mood disorder which may have great impact on impulsivity; 4. A total score of the Montreal Cognitive Assessment (MOCA) ≤ 22 and the Clinical Dementia Rating (CDR) ≥ 1, indicating dementia; 5. Except for early medicated PD patients, if subjects from other groups who are on medication that may induce impulsivity, such as dopaminergic medication, will be excluded; 6. Contraindication to MRI (e.g., presence of implants or claustrophobia).