Huntington's disease is a progressive brain condition that causes uncontrolled movements, emotional problems, and cognitive difficulties.
Huntington's disease is also called:
How Common Is It?
Huntington's disease affects an estimated 3 to 7 per 100,000 people of European ancestry. The condition appears to be less common in other populations, such as African Americans.
In the United States alone, about 30,000 people have Huntington's disease; about 1 in every 10,000 people is thought to have the condition. At least 150,000 other people have a 50 percent risk of developing it, and thousands more of their relatives live with the possibility that they, too, might develop HD.
Huntington's disease typically begins in middle age. This form is called adult-onset Huntington's disease. There is also an early-onset form (juvenile Huntington disease) that begins in childhood or adolescence.
What Is the Cause of Huntington's Disease?
Huntington's disease (also known as Huntington disease or HD) is caused by a defect in a gene on chromosome number 4. This gene is known as the Huntington disease gene or HD gene.
Understanding the HD Gene and Huntington's Disease
The HD gene makes a protein called huntingtin. The function of this protein is unknown, but it most likely plays an important role in nerve cells. When a defect occurs in the HD gene, it leads to the body creating an abnormal huntingtin protein. This abnormal protein disrupts the normal function of certain nerve cells and ultimately leads to their premature death. The signs and symptoms of Huntington disease are caused by this dysfunction and loss of nerve cells.
The area of the brain most affected by an abnormal Huntington disease gene is the basal ganglia, which coordinates movement. This degeneration from the Huntington's disease gene causes uncontrolled movements, loss of intellectual faculties, and emotional disturbance. Also affected is the brain's outer surface, or cortex, which controls thought, perception, and memory.
Chances of Inheriting Huntington's Disease
Each parent has two copies of every chromosome but gives only one copy to each child. Therefore, each child of a person with Huntington's disease has a 50-50 chance of inheriting the Huntington disease gene. A person who inherits the Huntington disease gene, and survives long enough, will sooner or later develop Huntington's disease.
If a child does not inherit the Huntington disease gene, he or she will not develop Huntington's disease and cannot pass it to his or her children.
In some families, all the children may inherit the Huntington disease gene; in others, none do. Whether one child inherits the gene has no bearing on whether others will or will not share the same fate.
Is Huntington's Disease Always Inherited?
A small number of cases of Huntington disease are sporadic; that is, they occur even though there is no family history of Huntington's disease. These cases are thought to be caused by a new genetic mutation -- an alteration in the Huntington disease gene that occurs during sperm development.
Adult-Onset Huntington Disease Symptoms
Symptoms of adult-onset Huntington disease can include:
Trouble learning new information or making decisions.
As the disease progresses, involuntary jerking movements (chorea) become more pronounced. Affected individuals may have trouble walking, speaking, and swallowing. People with symptoms of Huntington disease also typically experience changes in personality and a decline in thinking and reasoning abilities.
Individuals with this form of Huntington disease generally survive about 15 to 25 years after the symptoms appear.
Symptoms of Early-Onset Huntington's Disease
Early-onset Huntington disease symptoms can include:
Seizures occur in 30 to 50 percent of individuals with early-onset Huntington disease.
The course of early-onset Huntington disease may be shorter than the adult-onset form; affected individuals generally survive 10 to 15 years after the disease begins.
Symptoms of Huntington Disease: Final Thoughts
The rate of Huntington disease progression, as well as the age at onset for symptoms, vary from person to person. Adult-onset Huntington disease most often begins in middle age. Individuals with the juvenile form develop symptoms of Huntington disease when they are young -- before age 20.
There are other variations of Huntington disease distinguished not just by the age at onset, but also by the associated symptoms. For example, some people develop the disease as adults, but without chorea. They may appear rigid and move very little, or not at all, a condition called akinesia.
In general, the duration of Huntington disease ranges from 10 to 30 years. The most common causes of death are infection (most often pneumonia), injuries related to a fall, or other complications.
Diagnosing Huntington's Disease
Diagnosing Huntington's disease is generally done by an experienced neurologist. A neurologist making a Huntington's disease diagnosis usually begins by interviewing the patient extensively about his or her symptoms and personal and family medical history. The neurologist then typically performs a series of assessments, testing such things as hearing, eye movements, strength, coordination, reflexes, and mental status. Tests used in diagnosing Huntington's disease may include genetic testing and imaging tests (such as CT scans or MRIs).
Treatment for Huntington's Disease
At this point, there is no cure for Huntington's disease or way of slowing its progression. Therefore, Huntington's disease treatment focuses on controlling the emotional and movement problems associated with the disorder (which is also known as Huntington disease or HD). Treatment for Huntington's disease also focuses on providing care to make living with the disorder easier.
Medications Used in Treatment for Huntington's Disease
There are several medicines that can be prescribed for symptoms of Huntington disease. Most drugs used to treat the symptoms of HD have side effects such as fatigue, restlessness, or hyperexcitability. Sometimes it may be difficult to tell if a particular symptom, such as apathy or incontinence, is a sign of the disease or a reaction to medication.
Antipsychotic drugs, such as haloperidol, or other drugs, such asclonazepam, may help to alleviate choreic movements and may also be used to help control hallucinations, delusions, and violent outbursts.
Antipsychotic drugs, however, are not prescribed for another form of muscle contraction associated with Huntington's disease, called dystonia, and may in fact worsen the condition, causing stiffness and rigidity. These medications may also have severe side effects, including sedation, and for that reason should be used in the lowest possible doses.
For depression, physicians may prescribe fluoxetine, sertraline,nortriptyline, or other compounds. Tranquilizers can help controlanxiety, and lithium may be prescribed to combat pathological excitement and severe mood swings. Medications may also be needed to treat the severe obsessive-compulsive rituals of some individuals with Huntington's disease.
It is important to remember that while medicines may help keep symptoms of Huntington disease under control, there is no treatment to stop or reverse the course of the disease.
Lifestyle and Care Issues Involved in Treatment for Huntington's Disease
An important aspect of treatment for Huntington's disease involves addressing lifestyle and care issues to help people with the disorder cope with the condition. Such treatment may include:
Regular physical activity
Assistance with feeding-related issues (which may include swallowing therapy)
Problems may arise when individuals try to express complex thoughts in words they can no longer pronounce intelligibly. It can be helpful to repeat words back to the person with Huntington's disease, so that he or she knows that some thoughts are understood. Sometimes people mistakenly assume that if individuals do not talk, they also do not understand. Never isolate individuals by not talking, and try to keep their environment as normal as possible. Speech therapy may improve the individual's ability to communicate.
As part of Huntington's disease treatment, it is extremely important for the person with Huntington's disease to maintain physical fitness as much as his or her condition and the course of the disease allows. Individuals who exercise and keep active tend to do better than those who do not. A daily regimen of exercise can help the person feel better physically and mentally.
Although their coordination may be poor, individuals should continue walking, with assistance if necessary. Those who want to walk independently should be allowed to do so as long as possible, and careful attention should be given in keeping their environment free of hard, sharp objects. This will help ensure the most independence possible while minimizing the risk of injury from a fall.
Individuals can also wear special padding during walks to help protect against injury from falls. Some people have found that small weights around the ankles can help stability. Wearing sturdy shoes that fit well can help too, especially shoes without laces that can be slipped on or off easily.
Impaired coordination may make it difficult for people with Huntington's disease to feed themselves and to swallow. As the disease progresses, people with Huntington's disease may even choke.
In helping individuals to eat, caregivers should allow plenty of time for meals. Food can be cut into small pieces, softened, or pureed to ease swallowing and prevent choking. While some foods may require the addition of thickeners, other foods may need to be thinned. Dairy products in particular tend to increase the secretion of mucus, which in turn increases the risk of choking.
Some individuals may benefit from swallowing therapy, which is especially helpful if started before serious problems arise. Suction cups for plates, special tableware designed for people with disabilities, and plastic cups with tops can help prevent spilling. The individual's physician can offer additional advice about diet and about how to handle swallowing difficulties or gastrointestinal problems that might arise, such as incontinence or constipation.
Proper nutrition is very important as part of Huntington's disease treatment. Caregivers should pay attention to proper nutrition so that the individual with Huntington's disease takes in enough calories to maintain his or her body weight. Sometimes people with Huntington's disease, who may burn as many as 5,000 calories a day without gaining weight, require five meals a day to take in the necessary number of calories. Physicians may recommend vitamins or other nutritional supplements. In a long-term care institution, staff will need to assist with meals in order to ensure that the individual's special caloric and nutritional requirements are met. Some individuals and their families choose to use a feeding tube; others choose not to.
Individuals with Huntington's disease are at special risk for dehydration, and therefore, require large quantities of fluids, especially during hot weather. Bendable straws can make drinking easier for the person. In some cases, water may have to be thickened with commercial additives to give it the consistency of syrup or honey.
Huntington's Disease Support:
Individuals and families affected by Huntington's disease can take steps to ensure that they receive the best advice and care possible. Physicians and state and local health service agencies can provide information on community resources and family support groups that may exist.
Support for people with Huntington's disease may involve:
Legal and social aid
Home care services
Recreation and work centers
Legal and Social Aid
Huntington's disease affects a person's capacity to reason, make judgments, and handle responsibilities. Individuals with Huntington's disease may need help with legal affairs. Wills and other important documents should be drawn up early to avoid legal problems when the person with Huntington's disease may no longer be able to represent his or her own interests. Family members should also seek out assistance if they face discrimination regarding insurance, employment, or other matters.
Home Care Services
Caring for a person with Huntington's disease at home can be exhausting, but part-time assistance with household chores or physical care of the individual can ease this burden. Domestic help, meal programs, nursing assistance, occupational therapy, or other home services may be available from federal, state, or local health service agencies.
Recreation and Work Centers
Many people with Huntington's disease are eager and able to participate in activities outside the home. Therapeutic work and recreation centers give individuals an opportunity to pursue hobbies and interests and to meet new people. Participation in these programs, including occupational, music, and recreational therapy, can reduce the person's dependence on family members and provide home caregivers with a temporary, much needed break.
A few communities have group housing facilities that are supervised by a resident attendant. These facilities provide meals, housekeeping services, social activities, and local transportation services for residents. These living arrangements are particularly suited to the needs of individuals who are alone and who, although still independent and capable, risk injury when they undertake routine chores like cooking and cleaning.
The physical and emotional demands of caring for a person with Huntington's disease may eventually become overwhelming. While many families may prefer to keep relatives with Huntington's disease at home whenever possible, a long-term care facility may prove to be the best option. To hospitalize or place a family member in a care facility is a difficult decision; professional counseling can help families with this.
Finding the proper facility can be a difficult task. Organizations such as the Huntington's Disease Society of America may be able to refer the family to facilities that have met standards set for the care of individuals with Huntington's disease. Very few of these exist, however, and even fewer have experience with individuals with juvenile (early-onset) Huntington's disease who require special care because of their age and symptoms.
Huntington's Disease Research
In the case of Huntington's disease, research is being conducted across the U.S. to answer important questions about the disease and to find more effective methods of diagnosing and treating it. Some of the research currently under way includes studies of the HD gene, fetal tissue research, and work being done with PET scans and other imaging technology to better understand the effects of Huntington's disease on the brain. Research for Huntington's disease has already led to many advances; however, controlling the disorder remains a challenge.