Huntington disease (HD) is an inherited brain disorder. HD causes cells in parts of the brain to die: specifically the caudate, the putamen and, as the disease progresses, the cerebral cortex. As the brain cells die, a person with Huntington’s becomes less able to control movements, recall events, make decisions and control emotions.
WHO gets it?
Huntington disease is a genetic disorder. The HD gene is dominant, which means that each child of a parent with HD has a 50% chance of inheriting the disease and is said to be “at-risk”. Males and females have the same risk of inheriting the disease. Huntington’s occurs in all races. Symptoms usually appear between the ages of 30 and 50, but the disease can appear in children or seniors.
WHAT are the symptoms?
- Emotional turmoil (depression, apathy, irritability, anxiety, obsessive behaviour)
- Cognitive loss (inability to focus, plan, recall or make decisions; impaired insight)
- Physical deterioration (weight loss, involuntary movements, diminished coordination, difficulty walking, talking, swallowing)
There are significant variations in symptoms, and not every person will have all the symptoms to the same degree. Symptoms also vary with each stage of the disease.
- Early symptoms of the disease often include subtle cognitive changes.
- May have difficulty organizing routine matters or coping effectively with new situations
- May have difficulty recalling information, may make them appear forgetful
- Work activities may become more time-consuming
- Decision making and attention to details may be impaired
- May include irritability
Slight physical changes may also develop at this stage. There can be involuntary movements which may initially consist of “nervous” activity, fidgeting, a twitching of the hands or feet, or excessive restlessness. Individuals may also notice a little awkwardness, changes in handwriting, or difficulty with daily tasks such as driving. At this stage, people with Huntington’s can function quite well at work and at home.
As the disease progresses, the symptoms become worse. The initial physical symptoms will gradually develop into more obvious involuntary movements such as jerking and twitching of the head, neck and arms and legs. These movements may interfere with walking, speaking and swallowing. People at this stage of Huntington’s often stagger when they walk and their speech may become slurred. They may have increasing difficulty working or managing a household, but can still deal with most activities of daily living.
The advanced stages of Huntington’s typically involve fewer involuntary movements and more rigidity. People in these stages of HD can no longer manage the activities of daily living and usually require professional nursing. Difficulties with swallowing, communication, and weight loss are common.
Death usually occurs 15 to 25 years after the onset of the disease. People don’t die from Huntington’s itself, but from complications such as choking, heart failure, infection or aspiration pneumonia.
How is HD DIAGNOSED?
Huntington’s is usually diagnosed using neurological and psychological tests, and with a review of family history. Sometimes doctors use brain scans to see whether the specific parts of the brain, primarily the caudate and putamen are working properly, or genetic testing is completed to confirm the diagnosis.
Since 1986, genetic testing for HD has been available; however, a direct test for the disease was developed in 1993. This means people who are at-risk for Huntington’s or who believe they have the symptoms can take a blood test to determine whether they have the gene that causes HD. Many people at risk choose not to take the test. It is a personal decision and varies from person to person as there is still no treatment to prevent HD from developing if the gene is present. Others make the decision to be tested so they can make arrangements as far as careers, family planning, and other issues are concerned. Anyone considering taking the test should have genetic counselling. This will ensure that the person understands what the possible outcomes could be, and whether the decision to be tested is the right one for them, at that time.
Are there TREATMENTS?
In 2011, Canadian researchers provided bold new hope when they were able to successfully reverse the physical symptoms of the disease in a mouse model. This groundbreaking research is the first of its kind in the world and represents a major milestone on the path to the discovery of an effective treatment. Testing and further study of this new model of prevention are ongoing.
At the moment, however, there are no treatments that will slow down or stop the disease in humans. There are some drug treatments available that can reduce some of the symptoms of HD, such as depression, anxiety, and involuntary movements. These drugs can have side effects, so not everyone with Huntington’s uses them.
On a more promising note, there are several advanced drug trials underway under the auspices of the Huntington Study Group, an international consortium focused on clinical research in Huntington disease.
Scientists are extremely excited about the hope that these drugs may hold. Researchers are also looking at surgical treatments, such as implanting fetal brain cells into the brains of Huntington’s patients in the hope the cells will grow and take over the functions of the dead cells.
Researchers feel we are close to reliable treatments; the urgency lies in educating as many people as possible, including new outreach efforts in rural and culturally diverse communities