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Huntington’s Disease

What is it?

Huntington’s Disease (HD) is an inherited brain disorder and neurodegenerative illness. As the condition progresses, symptoms worsen, and people need more care.

Symptoms appear most often between 30 and 50 years old. Early signs can include irritability, depression, involuntary movements, poor coordination, and trouble making decisions.

What causes it?

We all carry a gene called the HTT gene, located on chromosome 4, which makes a protein called Huntingtin. Mutations in this gene are responsible for HD.

Long strands of building blocks of DNA make up genes. HD’s genetic mutation causes a “genetic stutter” in the code that makes up the gene’s instructions. In other words, in those DNA strands, specific genetic code repeats – appearing more times than is normal.

If it’s hard to imagine, picture this: You’re on your computer doing your taxes – and in one of your calculations, you unknowingly lean on a number key for several seconds. You wind up with a bunch of extra digits in that field, which affects all the rest of your calculations.

A genetic stutter is similar – repeating bits of genetic code, often many times more often than it should. The longer those building blocks of DNA in the genetic code repeat, the earlier the onset of symptoms.

While people with the genetic mutation can live without symptoms for years, symptoms will likely develop at some point. We do not yet know what triggers the onset of symptoms, and there is no way of knowing when symptoms will start.

What is the prognosis?

Since HD causes nerve cell loss in the brain’s basal ganglia, HD affects an individual’s ability to move, think, and process thoughts and feelings.

As HD progresses over time, neurons in the brain deteriorate, leading to further physical, cognitive, and psychological decline. Clinicians often divide the progression of HD into the early, middle and late stages. Each stage marks a loss in ability.

Today, there is no cure for HD, and there is no medication available to stop, reverse, or slow the disease’s course. Once symptoms begin, life expectancy usually ranges from 10 to 15 years. Because it is a progressive disease, the time will come when a person with HD needs others to care for them. Common causes of death with HD include infections (often aspiration pneumonia), fall-related injuries, and heart failure.

This condition also affects family and friends who care for people with HD. It’s important for these people to get information and support for themselves, as well as practice self care.

How common is it?

Though once considered rare, HD is one of the more frequently encountered hereditary diseases. It affects both women and men and all ethnic groups. In the United States, an estimated 30,000 people have Huntington’s Disease. Approximately 200,000 Americans are at risk of inheriting the disease from an affected parent. Other key facts regarding the genetics of HD:

  • Those who have a parent with HD have a 50 percent (i.e., one in two) chance of inheriting the defective gene.
  • When a parent has HD, each child has an equal chance of inheriting the illness.
  • If one child inherits the gene, it does not necessarily mean the others will also.
  • HD does not skip generations; if a child does not inherit the gene, they cannot pass the gene on to future generations.

What are the symptoms?

An individual with Huntington’s disease often has problems in three areas: control of body movement, cognitive (or mental) functioning, and psychological issues. The intensity and number of symptoms vary case by case. Symptoms experienced by those with HD may include:

  • Movement: Quick, dance-like, uncontrollable movements of the limbs are typical of those with HD and are commonly called chorea by health professionals. Movements of the torso and face are the most obvious. All movement disorders tend to progress over time, both in frequency and severity. Movements may be grossly exaggerated, causing what was intended to be a small movement to be uncoordinated and dramatic. For example, an intended small shift in bed may cause the individual to instead vault out of bed. Eventually rigidity or muscle stiffness may occur. Walk may become unsteady, or even appear as if the person is drunk. Speech may be slurred, and it may be difficult to pronounce words. In later stages of the disease, swallowing becomes increasingly difficult (dysphagia), and choking is a major concern.
     
  • Cognitive: Huntington’s disease causes changes in the brain that slow processing of information and hamper organizational ability. The person you care for may find it increasingly difficult to plan and carry out normal household tasks or projects, cope with new situations, or switch from task to task (multi-tasking). Because individuals with HD have difficulty processing information, they may have difficulty remembering words, and the act of speaking may become challenging. Individuals with HD may exhibit poor judgment and problems with short-term memory. Declining cognitive function is common as the disease progresses, although those with HD continue to recognize their caregivers, are aware of what is happening around them, and can give feedback about their condition and care.
     
  • Psychological: Some people with HD may have difficulty controlling impulses and emotions, resulting in outbursts or aggression. Mild to severe depression, common in most individuals with chronic, long-term conditions, is one of the primary complaints of HD. Other psychological symptoms include irritability and anxiety. Some individuals may exhibit schizophrenic-like behavior, such as hallucinations, mania, anxiety, and psychosis.

How is HD diagnosed?

Physicians usually diagnose HD through a full medical history, laboratory and neurological tests, brain imaging and a genetic test.

A thorough neurological exam that uses the Unified Huntington’s Disease Rating Scale (UHDRS), as well as an extensive patient and family medical history, can confirm the presence of HD. A physician or neurologist familiar with HD can make this determination.

Genetic testing is the most conclusive and definitive way to determine if your friend or family member will develop, or has developed, Huntington’s disease.

How does genetic testing work with HD?

In 1993, the discovery of the gene that causes Huntington’s disease led to the development of a direct gene test for HD. A blood test can predict Huntington’s disease before symptoms develop but cannot identify when symptoms will appear.

In addition to a thorough neurological exam, it is recommended that a person obtain genetic counseling before being tested so that they can have support as they go through the testing process, as well as a chance to explore the ramifications of a positive or negative result. A post-test follow-up appointment with the genetic counselor is also recommended.

Testing after onset of symptoms

A second blood test, called a confirmatory test, confirms the presence of the HD gene. The procedure for this test is the same as the pre-symptomatic test, but the test is given after symptoms of the disease appear.

HD, testing, and kids

Prenatal testing is available to determine if a fetus carries the HD gene. Most health professionals recommend not testing children and instead waiting until they are at least 18 years old. Most children don’t yet have the emotional development and tools to manage that kind of news. Imagine being a child or teen and knowing that you will have that disease at some point in your future, but not knowing when. It’s a heavy burden. In the absence of a cure, many at-risk individuals choose to live with uncertainty, rather than take the test. It’s an intensely personal and potentially life-changing decision which is best discussed with a professional genetics counselor and loved ones.

Finding a testing center that follows the Huntington’s Disease Society of America (HDSA) guidelines for genetic testing is very important. HDSA regularly updates its list of testing centers, and it can be found on their website.

What kind of HD-related research is underway?

Robust research continues in search of strategies to fight and cure HD.

While efforts to develop a cure are underway, researchers are also focusing on how to delay the onset of HD or to slow – even stop – the progression. Other research efforts with animal models are identifying the effects of HD, how it manifests, and if or how successful animal trials can be translated to treatments that work in humans. Both basic (laboratory) and clinical (testing of medications and treatments) research continue to help new drug testing.

To stay informed of, or take part in, ongoing clinical trials, contact HD Trailfinder (https://hdsa.org/hd-research/hd-trial-finder/), HD Buzz (https://en.hdbuzz.net/) or Hopes (https://hopes.stanford.edu/clinical-trials-on-huntingtons-disease/).

How is HD treated?

Although no medications exist yet that halt or slow the progression of HD, much can be done to manage the symptoms of it:

  • To reduce involuntary movements, physicians often prescribe neuroleptic drugs.
  • For psychological symptoms or emotional disorders, anti-depressants or anti-psychotic medications are often recommended.

Families should proceed with caution when using new medications, as some individuals with HD may be more sensitive to side effects than others. It is important to document side effects of new medications or changes in behavior after a medication has been added to the routine of the person you care for.

Beyond medication

Many other non-medical treatments can assist those with HD and the individuals caring for them.

  • Exercise is the number one treatment to combat depression and other mood disorders, as well as agitation and fatigue. Research has shown it can also help slow down the progression of HD.
  • Physical therapy can address early balance and walking problems and provide exercises to build strength. Occupational therapy can provide strategies to help people with HD do tasks and hobbies, as well as make the home safer and more livable, improve communication, and suggest ideas to offset cognitive decline. A few organizational techniques that have been found to be helpful include:
    • labeling items around the house (e.g., identifying the contents of drawers and cabinets in the kitchen and bathroom)
    • using a whiteboard, lists and notes
    • communicating with short, direct instructions
  • Because HD affects metabolism, people with HD may burn calories at a much higher than average rate, so maintaining a high-calorie diet is necessary. A registered dietitian can assist with diet changes and meal planning.
  • Support from a speech therapist is helpful across all stages of the disease, as the ability to communicate becomes impaired. A speech therapist can also evaluate swallowing problems and make necessary recommendations to ease these difficulties.

Are there any tips for managing appointments with health professionals and tracking important information from those visits?

It can be overwhelming to coordinate care and to find appropriate resources and professionals who are trained in HD care. However, these professionals do exist and HDSA is a good referral sources as they have information for providers across the United States. People with HD often interact with multiple providers such as physicians, social workers, physical therapists, occupational therapists, speech therapists, nutritionists, and other health care providers. By seeking early intervention from these professionals, people with HD can have more control over their disease progression and ultimately over their well-being.

Keeping a notebook or “health journal” of interactions with health care providers, procedures, and medication regimens, will help to keep appointments organized and provide a personal record of care.

What should we expect with this diagnosis? What kind of support will be important?

Due to the strong emotional impact of the diagnosis of this chronic, hereditary condition, and the stress of knowing that others in the family may be at risk, participation in support groups can be very helpful. Support groups provide a safe, confidential and caring environment in which to share information about individual experiences and challenges of HD with others in similar situations. Topics discussed include, providing care throughout the disease course, coping strategies, family dynamics, sharing frustrations, as well as practical information regarding navigating insurance, medication, and more. Both online and in-person support groups are available for individuals with HD, their family caregivers, and for those living at risk. Counseling also may be helpful for individuals, couples, or families who are learning to cope with chronic illness or periodic health crises.

Important: Caring for the Caregiver

Individuals who help a friend or family member with HD may be at increased risk of poor health, depression, and isolation. It is important for the health of the family caregiver, as well as the health of the person with HD, for their caregivers to take some time off from caregiving (known as respite), get enough sleep, and have a support system of their own. Respite can be obtained with the help of family members, friends, volunteer services, home care agencies, adult day health centers, social service organizations, or assisted living communities. Caregivers who make time for themselves can give better care to their friends and family members. For more information, see Family Caregiver Alliance’s Fact Sheet, Taking Care of YOU: Self-Care for Family Caregivers.

Finally, it is critical that people with HD know there is hope. Research is moving us closer every day toward new treatments and a potential cure. With what we have learned about strategies for coping with the effects of HD, a growing number of individuals with Huntington’s Disease are living meaningful lives and remain productive well into the later stages of the disease.

This is overwhelming. Where can we get help?

Family Caregiver Alliance
National Center on Caregiving 

(415) 434-3388 | (800) 445-8106
Website: www.caregiver.org
Email: info@caregiver.org
FCA CareNav: https://www.caregiver.org/connecting-caregivers/fca-carenav/

Family Caregiver Services by State: https://www.caregiver.org/connecting-caregivers/services-by-state/

Family Caregiver Alliance (FCA) seeks to improve the quality of life for caregivers through education, services, research, and advocacy. Through its National Center on Caregiving, FCA offers information on current social, public policy, and caregiving issues and provides assistance in the development of public and private programs for caregivers. For residents of the greater San Francisco Bay Area, FCA provides direct family support services for caregivers of those with Alzheimer’s disease, stroke, MS, ALS, head injury, Parkinson’s, and other debilitating brain disorders that strike adults.

Other Organizations and Links

Huntington’s Disease Society of America
www.hdsa.org

International Huntington Association
www.huntington-assoc.com

HOPES: Huntington’s Outreach Project for Education, at Stanford
www.stanford.edu/group/hopes

Caregiver Action Network
www.caregiveraction.org

Clinical Trials, NIH’s U.S. National Library of Medicine
www.clinical trials.gov : (https://clinicaltrials.gov/search/term=Huntington’s%20Disease)

Clinical Trials, NIH’s National Institute of Neurological Disorders and Stroke
www.nih.gov (https://www.ninds.nih.gov/Disorders/Clinical-Trials/Find-Ninds-Clinical-Trials?province=All&field_disorders_taxonomy_tags_tid=Huntington%27s+Disease)

Family Caregiver Alliance curated the information in this fact sheet, and Natasha Boissier, LSCSW of University of California, provided a medical review. Sources for this information include Huntington’s Disease Society of America (www.hdsa.org), International Huntington Association (www.huntington-assoc.com), Huntington’s Outreach Project for Education at Stanford (www.stanford.edu/group/hopes), NIH’s National Institute of Neurological Disorders and Stroke (https://www.ninds.nih.gov), Hereditary Disease Foundation (www.hdfoundation.org), and National Organization for Rare Disorders (https://rarediseases.org/rare-diseases/huntingtons-disease/). Edited for readability and user experience by Trish Doherty (http://trishdoherty.net). Revised September 2021. © Family Caregiver Alliance. All rights reserved.