Huntington's Disease Guide

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The following guide is designed to be a primer for individuals seeking information about Huntington’s Disease (HD). We have tried to be as objective as possible in presenting the most accurate information available, but it is the responsibility of each individual to conduct their own research beyond this guide. If there is information that we have missed out or are as yet unaware of, please let us know by emailing contact@junomedical.com.

What is Huntington’s Disease?

Huntington’s Disease (HD), previously known as Huntington’s chorea, is an inherited genetic disorder which causes the deterioration of nerve cells in the brain. Over time the degeneration of the brain affects movement, behavior, and cognition. HD symptoms are often described as a combination of ALS, Parkinson’s and Alzheimer’s. Symptoms can appear at any age but typically become noticeable between 30 and 50 years of age.

What causes Huntington’s Disease?

Huntington’s Disease is caused by a defective gene inherited from a parent, with only 5% to 10% of cases resulting from a new genetic mutation. HD is an autosomal dominant disorder, which means that only one copy of the defective gene, inherited from one parent, is necessary to produce the disease. Therefore if one parent has the disease each child has a 50% chance of inheriting the defective gene.

Males and females are at equal risk of acquiring HD, but the disease occurs in certain races and ethnicities more than others, with people of European descent being at the greatest risk of acquiring it. Poor documentation and inconclusive evidence could contribute to the fact that a low frequency of HD among people of African origin has been recorded. It has been hypothesized that the HD mutations in Europe, Africa, and Asia are separate, which would account for the statistics.

Per million people, Huntington’s Disease affects:

  • 40-120 people in Europe of European descent
  • 100 people in the U.S.A.
  • 1-7 people in Asia
  • 0.6 people of African descent

Source: http://web.stanford.edu/group/hopes/cgi-bin/hopes_test/population-genetics-and-hd/

What are the symptoms of Huntington’s Disease?

There are many symptoms which indicate Huntington’s Disease, however, not everyone with the disorder will experience all of them to the same degree. Symptoms can appear at any age, however they usually become noticeable in a person’s 30s or 40s. The movement, cognitive, and psychiatric disorders associated with HD generally occur at different stages, and as the disease progresses some become more dominant and severely impede the individual’s ability to function normally. Evidence suggests also that the average age of onset is later for individuals who inherited the gene from their mother; this means that, typically, onset occurs earlier when the gene is inherited from one's father.

During the early stages of HD, people can function quite well at work and at home. As the disease progresses they may find it increasingly difficulty to work or manage a household, but are still able to deal with most day-to-day activities. In the advanced stages of Huntington’s involuntary movements give way to rigidity (dystonia), communication and swallowing become severely impaired, and affected individuals will become completely dependent, requiring full-time professional nursing care. The lifespan of someone with HD can vary, however, death typically occurs 15 to 25 years after the onset of the disease. This is due to complications such as heart failure, choking, infections or pneumonia, and not from HD itself. In about 9% of cases, suicide is the cause of death. Symptoms can be divided into physical changes, cognitive impairments, and psychiatric disorders:

Physical changes

The movement disorders associated with HD can include both involuntary movements and impaired voluntary movements:

  • Involuntary movements which may initially consist of fidgeting, twitching of the hands or feet, or excessive restlessness, will gradually develop into more obvious uncontrollable jerking and twitching of the head, neck, arms, and legs. This is also known as chorea which is derived from the Greek word “χορεία” meaning “dance”, as the movements are comparable to dancing.

  • Impaired voluntary movements may impact an affected person’s ability to perform daily activities, communicate, and remain independent, more than involuntary movements.

  • Diminished coordination initially affecting things like handwriting and driving, becomes increasingly pronounced. Gait, posture, and balance become impaired and, as a result, in later stages of the disease people stagger when they walk. Eventually they will be unable to walk and control their movements.

  • Weight loss can occur at different stages of the disease.

  • Muscle problems, such as rigidity or muscle contracture (dystonia).

  • Eye movements become slow or abnormal.

  • Difficulty with talking and swallowing leads to slurred speech. At later stages in the disease it severely impedes communication and may necessitate tube feeding.

Cognitive impairments

Those with Huntington’s Disease experience cognitive changes which affect their awareness, judgement, and perception. Some of the symptoms may include:

  • Affected individuals initially have difficulty organizing, prioritizing, making decisions, and focusing on tasks. As a result their jobs may become more time-consuming. In later stages of the disease some people prefer to take on a job that’s less demanding rather than give up working entirely.

  • Ability to recall information, process thoughts, and “find” the right words diminishes so people with HD may appear forgetful.

  • Learning new information becomes increasingly difficult.

  • People with HD develop a lack of awareness of their own behaviors and abilities.

  • Coping with new situations becomes difficult and affected individuals exhibit a lack of flexibility or perseveration which is the repetition of a particular response, such as a word, phrase, or gesture.

  • A lack of impulse control can lead to outbursts, acting without thinking, and sexual promiscuity.

Psychiatric disorders

The most common behavioral and emotional changes in people with HD can result from the following psychiatric disorders:

  • Depression is the most common psychiatric disorder associated with HD. In addition to persistent feelings of sadness and worthlessness, and a lack of desire to engage in formerly pleasurable activities, signs of depression may include a loss of energy, insomnia, social withdrawal, irritability, apathy, and frequent thoughts of death, dying or suicide. Depression occurs in those with HD as a result of changes in the brain, and not simply as a reaction to receiving the diagnosis. Although the psychiatric disorders associated with HD are not correlated with disease progression, it has been noted that depression occurs more frequently at the early stages.

  • Obsessive Compulsive Disorder: a condition which causes severe anxiety and is characterized by recurrent, unwanted thoughts and repetitive behaviors.

  • Bipolar Disorder: a condition marked by extreme mood swings where affected individuals alternate between periods of mania (elation) and depression.

How is Huntington’s Disease diagnosed?

Several of the signs and symptoms of HD can be caused by a number of different conditions so it’s important to consult your doctor if you’re concerned about them.

If you or someone close to you notice any signs or symptoms associated with Huntington’s Disease, such as changes in your emotional state, mental ability, or movements, you should consult a doctor who will likely refer you to a neurologist. You will then undergo a thorough examination which will include a general physical exam, a review of your family’s medical history, neurological tests, a psychiatric evaluation, and brain imaging. If the symptoms strongly indicate that you may have Huntington’s Disease your neurologist may suggest that you take a genetic test to confirm whether or not you carry the defective gene.

Genetic testing

If one of your parents has HD but you haven’t presented any symptoms and you’d like to find out if you carry the gene, you can take the genetic test from the age of 18. The test is also an option for those parents who still are unaware of their HD status. Some take the predictive test because they find it stressful not knowing if they will develop the disease. Others, however, prefer not to know if they’ve inherited the faulty gene as there are as yet no treatments which can reverse the effects of the disease. If your doctor suspects that you have the disease you can take the test at any age.

If you know that you or your partner carries the defective gene and are expecting a baby, a genetic test can be performed at 11 weeks into the pregnancy to determine if the baby has the gene. If one of you is at risk of having HD but would prefer not to know, one option is preimplantation genetic diagnosis. This allows the embryo to be tested for the disease and only implanted in the womb if it doesn’t have the gene and is not at risk of developing HD after In Vitro Fertilization (IVF) has been performed.

If you’re considering genetic testing, a genetic counselor can provide support, information, and advice about the condition, and explain the benefits and drawbacks of taking the test and learning the results.

Juvenile Huntington’s Disease

If someone develops HD before the age of 20 it is known as Juvenile Huntington’s Disease but only 5% to 10% of people with the disease are affected by it. The onset and progression of symptoms may differ from that in adults and problems which appear in the early stages include:

Behavioral changes

  • Children and young adults experience a loss of previously learned academic or physical skills.

  • A rapid, significant drop in school performance.

  • Behavioral problems can arise.

Physical changes

  • Muscles become contracted and rigid, affecting gait (particularly in young children).

  • Changes in fine motor skills that might be noticeable in, for example, handwriting.

  • Young people can experience seizures in addition to tremors or slight involuntary movements.

Living with Huntington’s Disease

As the disease advances affected individuals will undergo a number of physical and mental changes so it’s important for them and their loved ones to be aware of the changes they will have to make in order to allow them to maintain as much independence as possible.

Eating meals can be frustrating and exhausting at later stages of the disease, so in order to help with this food should be easy to chew, swallow, and digest. To avoid choking, food should be cut into small pieces or puréed. Adapted cutlery and straws, as well as non-slip mats can make eating easier for affected individuals. At later stages of the disease a person may choose to be fed through a tube. If someone with HD doesn't want to be artificially fed when the disease advances, they should make their wishes known to their family and doctor and make a living will or statement of wishes.

As mobility and balance become affected social services and occupational therapists can help people with HD to adapt their homes in order to make day- to-day living easier and to reduce the risk of injuries. A person’s shower, bath, toilet, chairs, and bed may need to be modified, and at later stages of the disease the home may need to be adapted to allow for wheelchair access.

HD will affect a person’s ability to drive so as soon as they start to experience symptoms of the disease they are legally obligated to inform the DVLA in the UK (and relevant authorities elsewhere) of their condition. They will then write to your doctor, with your permission, to ask for their opinion about your condition and make a decision about whether you can still drive and for how long before another assessment is needed. Such obligation does not exist in the USA.

What treatment is available to individuals with Huntington’s Disease?

There is unfortunately no cure for Huntington’s Disease, but although the mental, physical and behavioral decline cannot be slowed down or reversed, there are medications available which can help manage the symptoms. The following treatments and therapies have been found to be effective in managing some of the symptoms of Huntington’s Disease.

Therapies

  • Speech and language therapy can help to improve communication skills as well as memory. Language therapy can teach affected individuals alternative ways of communicating aside from talking.

  • Occupational therapy can help people with HD to perform day-to-day activities and provide practical support which allows them to continue to do the things that matter to them thus helping them to maintain, regain, or improve their independence.

  • Physiotherapy can help a patient to maintain or regain mobility and balance. Treatments including massage, muscle manipulation, exercise, electrotherapy and hydrotherapy can be effective.

  • Regular exercise has been found to be extremely important. Individuals with HD who exercise feel much better both physically and mentally than those who don’t exercise.

  • A dietician can help to design a nutritious, high-calorie diet plan for someone with the disease to counter weight loss.

  • Support groups can make a huge difference to the lives of those with HD as well as their loved ones. HD can put a great deal of strain on relationships, and is very stressful and upsetting for those with the disease as well as their families. Talking through issues with specialists and other people in the same situation in support groups can provide a degree of comfort.

Medications

Medications can be prescribed by a doctor to help manage some of the symptoms of Huntington’s disease but most of them have side effects so many patients choose not to take them.

  • A variety of antidepressants can be taken to improve mood swings. SSRI antidepressants – such as fluoxetine, citalopram, and paroxetine. Tricyclic antidepressants – such as amitriptyline. Other types of antidepressants – including mirtazapine, duloxetine, and venlafaxine. Side effects of antidepressants may include: nausea, diarrhea, constipation, excessive sweating, drowsiness, insomnia, trembling or shaking, and low blood pressure.

  • Mood stabilisers like carbamazepine, olanzapine, sodium valproate, and lamotrigine can treat mood swings and irritability. Side effects of mood stabilisers may include: weight gain, tremors, and gastrointestinal problems.

  • When they severely impair quality of life, medications which help to suppress involuntary movements include, antipsychotic medication (like olanzapine, sulpiride, risperidone and quetiapine), tetrabenazine, and benzodiazepines (such as clonazepam and diazepam). Antipsychotic medication can also control delusions and violent outbursts but doctors usually prescribe the lowest dose possible as they can also have severe side effects. Side effects of antipsychotic medication may include: drowsiness, nausea, and restlessness. They can also worsen involuntary contractions (dystonia) and muscle rigidity, and worsen or trigger depression or other psychiatric conditions.

In order to manage symptoms, it is crucial that the patient’s treatment goals and medication plan are regularly reviewed and updated by a specialist.

Where can I learn more about treatment options for Huntington’s Disease?

The following resources provide more information about Huntington's Disease, as well as the treatment and support options available to those living with the disease:

International

The International Huntington Association http://www.huntington-assoc.com/

Huntington's Disease Youth Organization: http://de.hdyo.org/

Europe

European Huntington’s Disease Network http://www.euro-hd.net/html/network

European Huntington Association: http://eurohuntington.org/

U.K.

Scotland

Scotland Huntington’s Association http://hdscotland.org/

England and Wales

Huntington’s Disease Association http://hda.org.uk/

North America

U.S.A.

Huntington’s Disease Society of America: http://hdsa.org/what-is-hd/?gclid=CKno8ofa39ACFRHgGwodJncCuQ>

Huntington’s Disease Foundation http://www.huntingtonsdiseasefoundation.org/

Huntington's Outreach Project for Education, at Stanford (HOPES): http://web.stanford.edu/group/hopes/cgi-bin/hopes_test/home-mobile-version/

National Foundation of Swallowing Disorders http://swallowingdisorderfoundation.com/

Canada

Huntington Society of Canada http://www.huntingtonsociety.ca

South America

Agrupación Chilena de Huntington: http://www.huntington.cl/

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