This study is for people with Parkinson's Disease (PD) who have motor problems. Parkinson's is a brain disorder that affects movement. "Motor" refers to muscles and movement. The study uses a medication called CVN424 to see if it helps with these issues. Participants will take either CVN424 or a placebo (a pill with no medicine) once a day for 12 weeks. A placebo helps researchers compare results. **Eligibility:** - Must have Parkinson's Disease and specific physical criteria. - Need to be taking stable PD medications. - Must be able to identify different states of movement and keep a diary. **Key Points:** - **Duration:** The study lasts 12 weeks. - **Visits:** Participants will need to attend scheduled visits and follow instructions. - **Compensation:** There may be compensation for time and travel, but details are not specified. This study could offer a new treatment option, but there are specific health criteria to join. Participants should be comfortable with keeping detailed records and attending visits.