Huntington's Disease

Huntington's disease, sometimes called Huntington's chorea, is a progressive degenerative disease of the central nervous system. Although the course of this non-contagious disease can be as long as 30 years, it always results in death. Huntington's disease is a genetic disease - that is, children can inherit it from their parents. An estimated 30,000 Americans have Huntington's disease.

• What are the main symptoms?
• Who gets Huntington's disease, and what causes it?
• How is Huntington's disease diagnosed, and what is the course of the disease?

What are the main symptoms of Huntington's disease?

The symptoms of Huntington's disease vary significantly. The main symptoms can be divided into three categories:

• Psychiatric disturbances - these symptoms don't affect everyone with Huntington's. They can include depression, apathy and irritability, personality changes, abnormally elevated mood (mania) and obsessive-compulsive disorder.
• Movement disorders - these symptoms usually begin with involuntary twitching of the fingers and toes, which then progresses to include the entire body. Clumsiness, stiffness and trouble with walking also are common.
• Dementia - a gradual loss of intellectual abilities such as memory, concentration, problem-solving and judgment.

Who gets Huntington's disease, and what causes it?

Every tissue in the body is made up of cells. Each cell has genetic material (genes) that determine how that cell functions. Everyone has two copies of each gene, one from each parent, which are found on structures called chromosomes. Genes for some traits, like dark eyes, are said to be dominant (just one copy of the gene causes the trait to appear in the offspring). Genes for other traits, like blue eyes, are recessive, which means that a child must inherit two copies of the gene for that trait to appear.

Huntington's disease is a dominant genetic disease. That means that a person will develop the disorder if they receive one copy of the gene from an affected parent - so children with a parent who has Huntington's have a 50% chance of inheriting the gene and developing the disease. If children don't inherit the gene, however; they cannot pass it on to their own children. The chain of inheritance is broken.

Huntington's disease typically doesn't appear until the patient is between 30 and 50 years of age. Men and women are equally affected by the disease, and it crosses all racial and ethnic boundaries.

How is Huntington's disease diagnosed, and what is the course of the disease?

Huntington's disease often is diagnosed through a careful family history. Brain scans and genetic testing may also be used to confirm the diagnosis. Often, relatives are familiar with the disease and can recognize the signs of early Huntington's disease in family members.

Children of people with Huntington's disease are said to be "at risk" of developing the disease themselves. They may choose to take a genetic test to see if they have inherited the faulty gene. At risk people may want to take the test for peace of mind, to plan for the future or before having children of their own. However, the decision about whether to take the test should be considered very carefully. Most genetic testing centers require a period of counseling before and after the test to help patients deal with the results. Support groups may also help families cope with this disease.

There is no effective treatment for Huntington's disease, although research is ongoing. Prescription drugs can help control some of the symptoms, especially the involuntary movements and psychiatric conditions such as depression.

In the early period of Huntington's disease, most patients can still enjoy most of their normal activities, including work and driving a car. Involuntary movements are infrequent, speech is unaffected and dementia, if present, is mild. Later, patients need more assistance with daily living. Falls, weight loss and problems with swallowing are common, and dementia is more obvious to casual observers. In the late stage of the disease, patients need almost total care. They may be unable to walk or speak, and rigidity may become more common than involuntary movements.

Usually, patients die from the same natural causes affecting other severely debilitated patients, including pneumonia or heart failure.