**Artificial Intelligence in Molecular Imaging Study** This study is looking at people with REM sleep behavior disorder (RBD), which is when you act out your dreams during sleep. They want to see if these people might develop Parkinson's disease (PD), dementia with Lewy bodies (DLB), or multiple system atrophy (MSA) in the future. **Artificial intelligence (AI)** will be used to check brain images and see who might be at risk. **Key Points:** - You will need to visit for clinical evaluation and have 2 imaging tests done. - You must have RBD but not already have Parkinson's or other brain disorders. - No signs of parkinsonism, narcolepsy, or moderate to severe sleep apnea are allowed. The study requires you to give written consent and you must not have any existing neurological issues. This research helps find ways to predict and possibly prevent these serious diseases using advanced technology.