Real-Time Levodopa Level Monitoring in Parkinson Disease

Inclusion Criteria: 1. Participants must meet the Movement Disorders Society (MDS) diagnostic criteria for clinically established Parkinson disease. 2. Able to provide signed informed consent (in English or Spanish) 3. Mild, moderate, or severe Parkinson disease, able to ambulate (Hoehn and Yahr stages I-IV) 4. Taking instant release oral carbidopa/levodopa therapy 5. Either not taking, or on stable doses of any of the following antiparkinsonian medications: dopamine agonists, monoamine oxidase B (MAO-B) inhibitors or catecholamine O-methyl transferase (COMT) inhibitors Exclusion Criteria: 1. Other neurological conditions including but not limited to stroke, dementia (including Parkinson disease dementia), or traumatic brain injury 2. Co-existent major psychiatric disease 3. Uncontrolled, active medical conditions (e.g., heart, kidney, or liver failure, diabetes, etc.) 4. Status post deep brain stimulation (DBS) device placement 5. Any other condition, that in the opinion of the investigators, would place the participant at risk.