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Huntington's disease (Huntington's chorea) is a hereditary disease that begins with occasional involuntary jerking or spasms, then progresses to more pronounced involuntary movements (chorea and athetosis), mental deterioration, and death.
Huntington's disease affects fewer than 1 of 10,000 people. It affects both sexes equally. The gene for Huntington's disease is dominant. Therefore, children of a person who has this disease have a 50% chance of developing it (see Genetics: Dominant Disorders). Symptoms usually develop subtly, beginning between the ages of 35 and 50 but can develop before adulthood. Huntington's disease is caused by gradual degeneration of small parts of the basal ganglia called the caudate nucleus and corpus striatum. The basal ganglia help smooth out and coordinate movements.
Symptoms
During the early stages of Huntington's disease, people can blend the involuntary abnormal movements into purposeful ones so that the abnormal movements are barely noticeable. However, with time, the movements become more obvious. People may walk in a lilting or exaggeratedly jaunty way, like a puppet. They may grimace, flick the limbs, and blink more often. Movements become uncoordinated and slow. Eventually, the entire body is affected, making walking, sitting still, eating, speaking, and dressing extremely difficult.
Mental changes frequently occur before or as the abnormal movements develop. These changes are subtle at first. People may gradually become irritable and excitable. They may lose interest in their usual activities. They may be unable to control their impulses, losing their temper, having fits of despondency, or becoming promiscuous. As the disease progresses, people may behave irresponsibly and often wander aimlessly. Over years, they lose their memory and their ability to think rationally. They may become severely depressed and attempt suicide.
In advanced disease, dementia is severe, and people are confined to bed. Full-time assistance or nursing home care is needed. Death usually occurs 13 to 15 years after symptoms begin. The cause is usually pneumonia or coronary artery disease.
Diagnosis
Huntington's disease may be difficult to recognize in the early stages because symptoms are subtle. The disease may be suspected based on symptoms and a family history. Doctors should be told about relatives who have had mental problems or have been diagnosed as having a neurologic or psychiatric disorder (such as Parkinson's disease or schizophrenia) because they may have had Huntington's disease that was not diagnosed. Computed tomography (CT) or magnetic resonance imaging (MRI) is done to check for the degeneration of the basal ganglia characteristic of the disease and to rule out other disorders.
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Genetic testing is done to confirm the diagnosis. Genetic testing and counseling are important for people who have a family history of the disease but no symptoms because people are likely to have children before symptoms appear. For such people, genetic counseling should precede genetic testing. They are referred to centers that have expertise in dealing with the complex ethical and psychologic issues involved.
Treatment
As soon as possible after the diagnosis is made, people with Huntington's disease should establish advance directives, indicating what kind of medical care they want at the end of life (see Legal and Ethical Issues: Advance Directives).
No cure exists for Huntington's disease. However, drugs, such as the sedative chlorpromazine, the antipsychotic haloperidol, and the antihypertensive reserpine, can help relieve symptoms and control behavior.
Last full review/revision August 2007 by David Eidelberg, MD; Michael Pourfar, MD
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