What is the Enroll-HD Study for Huntington's Disease?

Enroll-HD is the largest observational study in the world dedicated to Huntington disease (HD) ^[1]. An observational study is very different from a clinical drug trial—if you participate in Enroll-HD, you will not be asked to take any experimental medications or change your current medical care ^[2]. Instead, researchers simply observe and track your health over time to better understand how HD progresses ^[3]. Participating in this study is a safe, impactful way to contribute to HD research and help scientists develop future treatments, even if you have no interest in testing new drugs yourself ^[4].

Who Can Join Enroll-HD?

You do not need to have active symptoms or even a positive genetic test to participate. The study is open to almost anyone connected to an HD family ^[1]. By comparing data from different groups, researchers can more easily identify what changes are truly caused by the HD gene ^[5]. Eligible participants include:

• Gene-positive individuals: People who have the HD gene expansion, whether they currently have symptoms (manifest) or are completely symptom-free (premanifest) ^[6].
• Gene-negative individuals: Blood relatives who have been tested and do not carry the HD gene ^[1].
• At-risk individuals: People who have a parent with HD but have chosen not to undergo predictive genetic testing. You will not be forced to learn your genetic status to join ^[7].
• Spouses and caregivers: Partners or non-blood family members who share a living environment with an HD patient. They act as a crucial “control group” for comparison ^[1].

What Does the Study Involve?

Participation typically involves a single clinical visit once a year ^[8]. The length of the visit can vary, but you can usually expect it to take 2 to 3 hours. During this visit, a research team will conduct a series of standard checks to measure your physical and mental health. These annual assessments usually include:

• Motor evaluations: Physical tests to check your movement, balance, and coordination ^[1].
• Cognitive assessments: Puzzles and memory tasks, such as matching symbols and numbers, to evaluate how your brain processes information ^[9].
• Behavioral and functional reviews: Questionnaires discussing your mood, emotional well-being, and ability to handle daily tasks ^[5].
• Biological samples: Providing a blood sample to help researchers study biomarkers (measurable biological signs of the disease) ^[1].

Is My Information Private?

A common and valid concern regarding research is the privacy of genetic and medical data. In Enroll-HD, your personal identity is rigorously protected. Before your health information is added to the global database, your name and other identifying details are removed and replaced with a unique, encrypted code ^[1][3]. This process (called de-identification) ensures that scientists worldwide can study the trends in your data, but they cannot trace the information back to you personally.

How Your Participation Helps

Because Huntington disease affects every person differently, scientists need massive amounts of data to map out the “natural history”—or typical progression over time—of the disease ^[3]. Enroll-HD creates a global database that allows scientists to track long-term symptom trajectories and understand what factors might speed up or slow down disease progression ^[8].

Furthermore, having this rich, long-term observational data is absolutely essential for designing safe and effective clinical drug trials ^[4]. Before researchers can test if a new drug works, they use Enroll-HD data to understand what symptoms to target and how to measure success ^[10]. Many participants report that joining the study gives them a better understanding of the disease, a strong relationship with a specialized care team, and a deep sense of purpose in the fight against HD ^[11].

Cost and How to Sign Up

Joining the study is completely voluntary and free of charge ^[12]. It will not be billed to your health insurance. To participate, you can search for a clinical site near you—often located at specialized HD clinics or academic medical centers—via the official Enroll-HD website or by speaking directly with your local neurologist ^[1]. Many local sites also provide small stipends or reimbursements for travel and parking to ensure that volunteering is not a financial burden.