Definition

Huntington's disease (HD) is an inherited disorder that affects the brain. HD causes slow, progressive degeneration of nerve cells in certain areas of the brain. Eventually, HD results in:

• Abnormal body movements
• Gradual deterioration or loss of intellectual abilities ( dementia )
• Behavior problems

The disease is named for George Huntington, the physician who first described the condition in the 1870s.

Causes

HD is caused by a faulty gene on chromosome #4. All people who inherit the faulty gene may eventually develop HD.

Risk Factors

A risk factor is something that increases your chance of getting a disease or condition.

• Family members with HD: Each person whose parent has HD has a 50% chance of inheriting the disorder.
• Age: Onset of symptoms on average range 35 to 50 years old.

Symptoms

Symptoms are mild at first and are often barely noticeable, but usually worsen over 15 to 20 years.

Physical symptoms may include:

• Abnormal body movements that worsen over time, including:
  • Sudden jerks or uncontrolled movements of the limbs or trunk
  • Facial grimacing
  • Continuous need to turn head and shift gaze
  • Walking that is unsteady or dance-like
• Difficulty with eating, dressing, sitting, and caring for oneself
• Difficulty swallowing
• Grunting or poor articulation of speech

Intellectual and emotional symptoms may include:

• Trouble with attention and awareness
• Confusion or disorientation
• Loss of memory
• Loss of judgment
• Loss of ability to think rationally
• Irritability and moodiness
• Depression (common)
• Anxiety
• Social withdrawal or antisocial behavior
• Irresponsible behavior
• Obsessive-compulsive behavior
• Personality changes
• Psychosis—a severe emotional and behavioral disorder that often interferes with a person's ability to relate to others and to function in daily life
• Paranoia—a mental disorder that involves feelings of being watched, followed, or harmed by others
• Hallucinations—the perception of a thing or person that is not present

Ultimately, HD can:

• Cause the loss of the physical and mental ability to care for oneself
• Cause severe disability, making full-time or nursing home care necessary
• Result in death, often due to a fall or pneumonia

Diagnosis

The doctor will ask about your symptoms and medical history (including family medical history), and perform a physical exam. Tests may include:

• CT scan —a type of x-ray that uses a computer to make pictures of the brain
• MRI scan —a test that uses magnetic waves to make pictures of the brain
• PET scan —a test that uses radioactive isotopes (substances that are absorbed by certain areas of the brain) to assess brain function

	CT Scan of the Head
	© 2008 Nucleus Medical Art, Inc.

There is a test that can determine if a person has inherited the gene for HD. This test may help to make the diagnosis of HD, and it may also help to determine, before symptoms appear, if a person has inherited the HD gene. Genetic counseling is recommended before taking this test to review risks and benefits.

Treatment

There is no cure for HD. Treatment aims to help control symptoms.

Medications

Drugs can help control abnormal movements and emotional symptoms of HD. These include:

• Sedatives or minor tranquilizers, such as benzodiazepines
• Major tranquilizers, like phenothiazine
• Antidepressants

Physical Fitness

Staying physically active helps people with HD to function better and longer. Often physical and occupational therapy may be of some benefit.

Prevention

There is no way to prevent the onset of HD if a person has inherited the gene for the disorder. Medications aimed at slowing and treating the disease progression are actively being investigated in the context of clinical trials. A prospective parent with HD or a family history of HD can seek genetic counseling when deciding whether or not to have children. Genetic counseling is extremely important since half of the children of an affected parent are at risk for inheriting HD, and symptoms of the disorder do not usually start until after the childbearing years.

RESOURCES:

Hereditary Disease Foundation
http://www.hdfoundation.org

The Huntington Disease Society of America
http://www.hdsa.org

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

National Institute of Neurological Disorders and Stroke
http://www.ninds.nih.gov

CANADIAN RESOURCES:

Canadian Health Network
http://www.canadian-health-network.ca/

Huntington Society of Canada
http://www.huntingtonsociety.ca/english/index.asp

References:

Medline Plus website. Available at: http://www.nlm.nih.gov/medlineplus/huntingtonsdisease.html .

The Merck Manual of Medical Information . 2nd ed. Pocket; 2003.

National Institute of Neurological Disorders and Stroke website. Available at: http://www.ninds.nih.gov/ .

US National Library of Medicine website. Available at: http://www.nlm.nih.gov/ .

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