Huntington’s disease is a rare, inherited neurodegenerative condition that slowly and permanently robs a person’s physical and mental health. As the disease progresses, some of the physical symptoms can include involuntary movements like jerking and twisting. What’s more, friends and family may notice subtle mood changes, like increased irritability or apathy, when the disorder first begins to reveal itself. Every patient will experience the disease individually; some might even have drastic personality changes and become violent or paranoid, which can be frightening for the patient and loved ones to witness and live through.
Researchers know that Huntington’s disease is caused by mutations in a single gene (called HTT) that interferes with the body’s ability to produce a protein called huntingtin. (While scientists are unsure of huntingtin’s purpose, it is found in nerve cells [neurons] in the brain and appears to build up inside neurons, causing them to die or malfunction.) There is no cure for Huntington’s disease, and researchers haven’t yet found a way to stop the disease from progressing. However, certain medications can ease some symptoms.
Even though the genetic mutation is present at birth, symptoms do not typically appear until around age 40 (though they can start emerging a decade earlier or later). In extremely rare cases of juvenile Huntington’s disease, the disease begins causing problems during childhood or teenage years. People with Huntington’s disease live between 10 to 30 years after its initial onset and usually die from complications of infections, like pneumonia, or injuries related to falling.
More than 30,000 people in the U.S. have Huntington’s disease, according to the National Institute of Neurological Disorders and Stroke (NINDS).
At Yale Medicine, a team of neurologists and other specialists work together to provide a personalized treatment plan that addresses the particular symptoms a patient with the disease might have.
What causes Huntington’s disease?
Huntington’s disease is caused by a mutation in the single HTT gene, which is located on chromosome 4. Genes provide instructions to the body on how to make cells. When genes are mutated, the instructions they provide are changed, too, and this can create problems immediately or later in life. Researchers are unsure exactly why this mutation causes Huntington’s disease, but they have found that brain cells (neurons) located in the basal ganglia, a part of the brain responsible for coordinating movement, thought, memory, emotion and perception, begin dying as the symptoms appear.
What are the symptoms of Huntington’s disease?
The symptoms vary based on the disease’s progression. Early on, a person may experience mood swings and become angry, depressed, irritated, or passive in ways that do not fit their personality. Someone with a normally positive attitude might suddenly become extremely sad and moody. Difficulty with tasks involving organizing, prioritizing, learning new skills, making decisions, and driving a car may also emerge. Additional signs might include the following:
- Involuntary movements in the face, fingers, feet or torso (called chorea)
- Social withdrawal
As the disease progresses, the symptoms prevent a person from carrying out normal activities, like going to work or caring for themselves. Cognitive problems continue to intensify, and usually lead to dementia-like symptoms (but not always involving complete memory loss). As muscle problems worsen, speech can become difficult to understand and it may become difficult to swallow or eat. Other issues can include the following:
- Unwanted muscle contractions (known as dystonia)
- Extreme rigidness (called akinesia)
- Difficulty walking
- Changes in sleeping patterns and insomnia
- Weight loss
- Loss of bowel and bladder control
Who is at risk for Huntington’s disease?
A parent with the mutation has a 50 percent chance of passing it on to each child. In very rare cases, a person can develop the disease without a parent who has the mutation.
How is Huntington’s disease diagnosed?
A diagnosis of Huntington’s disease usually comes after a series of genetic, neurological, and psychological tests with specialists. A neurologist will not only investigate a person’s mental status, but also his or her ability to walk, hear, balance, move, and react with automatic reflexes. The patient will be asked to provide as many details about family medical history as possible. This can help determine the need for genetic testing, which confirms the diagnosis.
Before a genetic test is done for Huntington’s disease, the patient and loved ones should set up an appointment with a genetic counselor to discuss possible situations that might arise in light of a positive or negative result.
How is Huntington’s disease treated?
Though some of the mental and movement problems that come with the disease can be eased, Huntington’s disease cannot be cured.
To address mood swings related to depression, anxiety, and other mental distress caused by the disease, doctors may prescribe anti-depressants, including fluoxetine, sertraline, citalopram, or nortriptyline.
For involuntary movements, a physician may prescribe tetrabenazine or deutetrabenazine, both of which are approved by the Food and Drug Administration (FDA) to address symptoms of Huntington’s disease.
What research is being done to find treatments for Huntington’s disease?
Right now, researchers are studying how the huntingtin protein might play a role in causing neurons to die. Understanding this might reveal ways to prevent brain cells from dying. Studies are also using advanced imaging techniques, like optogenetics, which activate or silence neurons in the brains of living animals, to learn more about how the whole circuitry of the brain is affected by Huntington’s disease.
How is Yale Medicine unique in its approach for caring for patients with Huntington’s disease?
“People affected by Huntington's disease present with unique needs. Most need coordinated care from a movement disorders neurologist, a psychiatrist, and a memory disorders specialist,” says neurologist Anant Wadhwa, MD. “We strive to provide compassionate, individualized, evidence-based care, with the goal of helping people take control of their lives.”