Huntington's Disease
Overview
What is Huntington's disease (HD)?
Huntington's disease (HD) is a genetic disease that’s passed from parent to child. It attacks the brain, causing unsteady and uncontrollable movements (chorea) in the hands, feet and face. Symptoms get worse over time. They eventually affect walking, talking and swallowing. It’s also common to have changes in emotion (feelings) and thinking, such as mood swings and memory problems.
Who does Huntington's disease (HD) affect?
Although anyone can develop HD, it tends to run in people of European descent (having family members who came from Europe). But the main factor is whether you have a parent with HD. If you do, you have a 50% chance of also having the disease.
What is juvenile Huntington’s disease (HD)?
Typically, HD symptoms appear in middle age. But with juvenile Huntington’s disease (JHD), symptoms begin in childhood. In addition to the symptoms of the adult disease, early signs in children may include seizures and stiffness. Children with JHD most often inherit the disease from their fathers.
How common is Huntington’s disease (HD)?
HD is rare, affecting about 30,000 Americans. In North America, the prevalence of HD was 5.7 per 100,000 people. Juvenile Huntington’s disease is even less common — children make up 5% to 10% of HD cases.
Symptoms and Causes
How is Huntington's disease (HD) inherited?
To understand how HD is inherited, you have to know a little bit about genetics — the study of physical characteristics passed down from generation to generation.
Every cell in your body has DNA (deoxyribonucleic acid). DNA is your body’s instruction manual. It provides the information you need to repair and rebuild cells. Your DNA dictates everything from your hair color and height to how your organs function.
Genes are like “chapters” within the DNA instruction manual. Here’s how genes affect Huntington’s disease:
- The huntingtin gene (HTT or HD gene) tells your body how to build the huntingtin protein. You get one HTT gene from each parent.
- If you have Huntington’s disease, one of your parents passed on an HTT gene with a mutation (like a misprint in a book). It tells your body to create an unusually long protein. Researchers believe this long protein damages and kills brain cells.
- Anyone who inherits the gene will eventually develop HD symptoms. The exact age when symptoms appear varies. Often, HD symptoms start earlier in each new generation than in the previous generation.
How does Huntington’s disease (HD) affect the brain?
Huntington’s disease develops when misshapen proteins destroy neurons (brain cells). First, they usually attack the basal ganglia, an area in the brain that oversees the body movements you control. The disease also impacts the brain’s cortex (surface of the brain). This part of the brain helps with thinking, decision-making and memory.
What are the symptoms of Huntington's disease (HD)?
HD affects a person both physically and mentally. Physical problems may start in small ways — for example, clumsiness or losing balance — and then get worse over time. If you have HD, you may develop:
- Uncontrolled movements (chorea).
- Emotional changes like mood swings, depression and irritability.
- Problems with memory, focus and multitasking.
- Slowed movements and speech.
- Slurred speech.
- Loss of hand coordination, such as being unable to hold a pencil.
- Difficulty swallowing.
What is Huntington’s disease chorea?
One of the first physical symptoms of HD is chorea, unintended jerks or twisting movements. Chorea usually affects hands, fingers and face muscles first. Later, it also makes your arms, legs and torso move uncontrollably. Chorea can make speaking, eating and walking more difficult. It may also affect your ability to perform everyday activities such as driving.
Can Huntington’s disease (HD) cause dementia?
In its later stages, HD can cause dementia. The loss of brain function leads to memory loss and personality changes.
Earlier in the disease, the impact on your brain is different. You might have problems multitasking or doing something that involves multiple steps. It could also be hard to plan or problem-solve soon after the onset of Huntington’s disease.
Diagnosis and Tests
How is Huntington's disease (HD) diagnosed?
A neurologist (a doctor specializing in the brain and nerves) will perform a physical exam. They will look for twitches and jerking as well as problems with your balance, reflexes and coordination. Your neurologist will also want to know if anyone else in your family has the disease.
You will have tests to rule out other conditions that cause similar symptoms and to confirm an HD diagnosis. Tests include:
- Blood test.
- Genetic testing.
- Imaging tests such as magnetic resonance imaging (MRI) and computed tomography (CT) scan.
What is genetic testing like?
Your healthcare provider draws your blood and sends it off to a laboratory to look at your DNA. The test determines if you have a mutation on the HTT gene. A genetic counselor (someone who specializes in genetic testing) will discuss the process and results with you.
Occasionally, genetic testing doesn’t provide a clear answer. Your HTT gene may be somewhere in the middle — creating longer-than-normal proteins but not providing a definite answer. In that case, imaging tests may help. They can show whether your brain has had any HD-related changes. Your provider may also ask if your family members can come in for genetic testing, too.
Can you find out if you have Huntington’s disease (HD) before symptoms appear?
If one of your parents or siblings has HD, your risk of having it is high. Predictive genetic testing — testing for genetic diseases before symptoms start — can tell if you have the gene mutation.
People have different responses to learning about a disease they’ll get someday. Knowing about the gene could help you make family plans and financial decisions. But it could also be emotionally difficult, especially since you can’t prevent the disease. It is essential to discuss testing with your genetic counselor to see whether finding out is the best decision for you.
Management and Treatment
Is there a cure for Huntington’s disease (HD)?
There is no cure for HD. However, clinical trials (tests in people) are looking at therapies that lower abnormal huntingtin protein to see if they’re safe and effective.
How is Huntington's disease (HD) treated?
Because HD affects you in various ways — physical, emotional and mental — you may need several types of treatment. Physical therapy, counseling and medications can work together to reduce your symptoms. A multi-disciplinary approach utilizing a neurologist, psychiatrist, genetic counseling, physical therapy, occupational therapy, speech therapy and other specialized fields can formulate a plan and address a patient’s individual needs.
To control chorea, doctors commonly prescribe:
- Tetrabenazine (Xenazine®).
- Deutetrabenazine (Austedo®).
- Haloperidol (Haldol®).
To help with emotional symptoms, your doctor may recommend:
- Antidepressants: Drugs that relieve depression include fluoxetine (Prozac®, Sarafem®) and sertraline (Zoloft®).
- Antipsychotic drugs: To reduce angry outbursts, agitation and hallucinations, your doctor may recommend drugs such as risperidone (Risperdal®) and olanzapine (Zyprexa®).
- Mood-stabilizing drugs: Medications like lithium (Eskalith®) decrease anxiety and prevent severe mood swings.
Prevention
Can you prevent Huntington’s disease (HD)?
HD is caused by having a mutation on the HTT gene. You can’t change your genes or prevent the disease from developing. Currently, there isn’t a treatment that can slow or stop the progression of HD.
Outlook / Prognosis
How does Huntington’s disease (HD) typically progress?
Huntington’s disease can start at different ages in different people. It gets worse over time.
Early stage
Symptoms are easier to handle early in the disease. You might feel moody or clumsy and struggle with complex thinking. You may also have small uncontrollable movements, but typically, you can continue your everyday activities.
Middle stage
Physical and mental changes during the middle stage make working, driving and household upkeep impossible. You may begin to have trouble with swallowing, and you might lose weight. Your balance may be off, increasing your risk of falling.
You can still manage your personal care. Typically, you can handle bathing, getting dressed and eating on your own or with some help.
End stage
During the final stage of HD, you’ll need help with everything. You’re usually unable to leave bed. This is when most people receive care day and night.
Will Huntington’s disease (HD) kill you?
Huntington’s disease makes everyday activities more difficult to do over time. How fast it progresses varies from person to person. But the average lifespan after diagnosis is 10 to 30 years. HD itself is not fatal. But you can die from its complications, such as infections like pneumonia or injuries related to falls.
Living With
How can I take care of myself if I have Huntington's disease (HD)?
You can take several steps to have the best quality of life as the disease progresses, including:
- Get regular exercise: Research shows exercise helps reduce symptoms.
- Eat a healthy diet: You may need extra nutrition. People can burn up to 5,000 calories a day through unintended movements.
- Drink plenty of water: When swallowing becomes difficult, you can easily become dehydrated.
- Find a support group: Ask your doctor for community resources where you can connect with others affected by the disease.
- Research care services: At some point, you’ll need a high level of care from either home care services or a nursing home.
- Appoint a trusted advisor: As the disease progresses, you’ll have to pass financial duties and important decision-making to someone else.
Remember, although you can’t prevent Huntington’s disease, you can plan for it. Symptoms take years to worsen. That gives you time to find healthcare providers you trust and get the support you need for the future. If you or someone in your family has Huntington’s disease, talk with a genetic counselor about what you need to know.
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