This is an observational study in which data are collected and studied from Parkinson's disease patients who have movement symptoms despite taking standard Parkinson's medications. In observational studies, observations are made without any changes to the participant's healthcare or treatment plan. No investigational product will be administered in this study, as participants will be treated with the standard of care that medical experts currently consider most appropriate.

Parkinson's disease (PD) is a condition that affects the brain and causes problems with movement and other body functions. The symptoms of Parkinson's disease can worsen over time. People with Parkinson's disease may experience shaking (tremor), slow movements, stiff muscles, trouble walking, and problems with balance. They can also have other symptoms, such as difficulty thinking clearly, changes in mood, or difficulty sleeping. Parkinson's disease mostly affects older adults, but it can happen to younger people too. There is no cure, but treatments can help manage the symptoms and improve quality of life.

While doctors and researchers know that Parkinson's disease affects people in different ways and can worsen over time, there are still many things they don't fully understand-especially for people who experience movement symptoms despite taking their usual Parkinson's medicines. Earlier studies did not follow these patients long enough or collect all the important information needed. This study is being done to fill those gaps.

The main purpose of this study is to better understand how Parkinson's disease changes over time in patients who experience movement symptoms while taking standard oral Parkinson's medications, what challenges patients and their care partners face, and how their treatments are working in real life. To do this, researchers will collect data on:

• Sociodemographics (e.g. age, gender, race/ethnicity, insurance provider).
• Medical history and vital signs (e.g. comorbidities, family history of Parkinson's, height, weight, blood pressure).
• Medications and treatments (e.g. Parkinson's and non-Parkinson's medications and other treatments, rehabilitation therapy sessions, use of mobility assistance devices).
• Movement symptoms (e.g. tremor, slow movement, balance).
• Non-movement symptoms (e.g. cognition, mood, sleep, activities of daily living).
• Molecular data (e.g. genetics, α-synuclein).
• Burden of care (e.g. economic cost).

Data will come from questionnaires or rating scales conducted by the doctor with the patient during study visits, diaries and logs completed by the patient, medical records, health insurance claims records, blood samples and skin biopsies, a digital device that records movement/non-movement symptoms, and questionnaires completed by the care partner.

Data will be collected from December 2025 to December 2032. Each participant may be followed for up to 5 years.

Inclusion Criteria for Patient:

• Individual of any sex ≥45 to ≤75 years of age at informed consent (at least 30% ≤60 years of age).
• Diagnosis of clinically established Parkinson's disease (PD) as defined by the Movement Disorder Society (MDS) Clinical Diagnostic Criteria for PD ≥4 and <12 years from time of PD diagnosis at informed consent.
• Modified H&Y stage II-III in the practically defined OFF-medication state (≥12 hours from last dose of antiparkinsonian medications).
• Score of ≥30 on MDS-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) part III in the OFF-medication state.
• Presence of motor fluctuations with ≥1 hour of absolute time in the OFF state per day as assessed by clinician/patient at screening.
• Receiving stable antiparkinsonian medication regimen for ≥4 weeks prior to screening with a levodopa daily dose ≥300 mg or a dosing frequency of ≥3 times per day.
• Responsiveness to levodopa as determined by change in the following measures from the practically defined OFF state to ON state after taking typical first-daily dose of PD-medications: i. any degree of improvement (≥0.5 point) in modified H&Y stage OR. ii. ≥30% improvement in MDS-UPDRS part III score.
• Montreal Cognitive Assessment (MoCA) score of ≥24.
• Agree to participate and provide signed informed consent.

Exclusion Criteria for Patient:

• Known history or presence of conditions that may provide an alternative to a PD diagnosis including but not limited to: multiple system atrophy, progressive supranuclear palsy, striatonigral degeneration, corticobasal syndrome/degeneration, vascular Parkinsonism, drug-induced Parkinsonism, essential tremor, diffuse Lewy body disease, Lewy body dementia, Huntington's disease, Wilson's disease, Fahr's disease, Alzheimer's disease, cerebrovascular disease, brain tumor, trauma, and infection.
• Known history or presence of significant vascular and/or cardiovascular disease limited to: stroke, transient ischemic attacks, poorly controlled hypertension, poorly controlled diabetes, unstable angina pectoris, or unstable myocardial infarction.
• Known history or presence of significant psychosis or impulse control disorder, or untreated or sub optimally treated depression.
• Known history or presence of human immunodeficiency virus, hepatitis B virus, hepatitis C virus, syphilis, or tuberculosis.
• Current or previously active malignant disease within the past 5 years, except definitively treated cutaneous squamous cell carcinoma, basal cell carcinoma, or in situ uterine cervical carcinoma.
• Currently pregnant, nursing, lactating, breastfeeding, or plan to be during study duration.
• Known history or current use of percutaneous levodopa/carbidopa intestinal gel, subcutaneous levodopa, or apomorphine pump.
• Prior history of brain surgery, including but not limited to: deep brain stimulation (DBS), pallidotomy, focused ultrasound thalamotomy, or other experimental neurosurgical procedure.
• Known history or current participation in cell or gene therapy procedures.
• Current participation in any interventional clinical trial.

Inclusion Criteria for Care Partner:

• ≥18 years of age at informed consent.
• Identified by the PD patient as their primary care partner.
• Agree to participate and the ability to provide signed informed consent independently, without the need for a legal representative.

Exclusion Criteria for Care Partner:

• Not applicable.

Patients with Parkinson's disease experiencing motor complications while on antiparkinsonian medications

Currently, there is no established plan for the sharing of Individual Patient Data (IPD) from this study. The availability of this study's data will later be determined according to Bayer's commitment to the EFPIA/PhRMA 'Principles for responsible clinical trial data sharing.' This pertains to the scope, timepoint, and process of data access.

As such, Bayer commits to considering requests from qualified researchers for patient- / study-level clinical trial data, and documents from clinical trials involving medicines and indications approved in the US and EU. However, this commitment does not reflect an active IPD sharing plan. This applies to data on new medicines and indications that have been approved by the EU and US regulatory agencies on or after January 01, 2014.

Researchers can use www.vivli.org to request access to IPD and documents from clinical studies to conduct research. Information on Bayer's criteria for listing studies is provided in the member section of the portal.