**Prevention-in-PD-Study** This study aims to see if a lifestyle program can help people with REM Sleep Behavior Disorder (RBD) or Parkinson’s Disease (PD). RBD is when people act out dreams during sleep and it can be a warning sign for PD, a brain disorder affecting movement and other functions. The study will last for **six months** and includes: **exercise**, **Mediterranean diet**, **sleep counseling**, and **cognitive training** (activities that improve brain power). The program is designed to be practical and motivating, with support like psychoeducation (learning about the mind) and skills training. **Eligibility**: Participants should be aged 30-85, able to consent, and willing to join group and online sessions. RBD participants need a confirmed diagnosis through a sleep study, while PD participants should be in early to moderate stages of the disease. **Key Points**: - **Program Length**: 6 months with various trainings and support. - **Participation**: Includes group sessions and online meetings. - **Exclusions**: Those with severe depression, dementia, or other serious brain diseases, and those in other trials cannot join. This study could help shape future Parkinson's care by showing if lifestyle changes can be maintained and improve health.