Huntington’s disease (HD) is an inherited brain disorder that causes cells in specific parts of the brain to die. Huntington disease is a genetic disorder. It was named after the doctor who first described it in 1872 – George Huntington – and it used to be called Huntington’s chorea. HD causes cells in specific parts of the brain to die: The caudate, the putamen and, as the disease progresses, the cerebral cortex. As the brain cells die, people with Huntington’s become less able to control movements, recall events, make decisions and control emotions. The disease leads to incapacitation and, eventually, death. About one in every 10,000 people has HD, but one in every 1,000 are touched by HD whether at risk, as a caregiver, family member or friend. The HD gene is dominant, which means that each child born to a parent with Huntington disease has a 50% chance of sharing the same fate. The symptoms of HD include:
- emotional turmoil (depression, apathy, obsessive behaviour)
- mental loss (inability to focus, think and recall, make decisions)
- physical deterioration (weight loss, involuntary movements, diminished coordination, inability to walk, talk, swallow)
The disease leads to complete incapacitation and, eventually, death. At the moment, there are no treatments that will slow down or stop the disease in humans. But hope for a meaningful treatment has never been more real. In recent years, basic research has dramatically increased our knowledge of HD. Various promising treatment strategies are now in the drug discovery pipeline. More than ever now is the time to step up the fight against HD.
Who gets it?
Huntington disease is a genetic disorder. About one in every 10,000 people has HD and approximately 5 in every 10,000 are at risk of developing the disease. 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. Primarily, HD affects adults. Symptoms usually appear between the ages of 30 and 45, but the disease can first appear in children as young as 5, or in adults in their 70s.
What are the symptoms?
There are three main types of symptoms in Huntington disease:
- Physical symptoms, including involuntary movements and diminished coordination
- Emotional symptoms, including depression, irritability and obsessiveness
- Cognitive symptoms, including loss of ability to recall information, loss of attention and difficulty with decision making
2015 HDSA Whiteboard Video
Posted by Huntington’s Disease Society of America on Wednesday, 8 April 2015
2015 HDSA Whiteboard Video posted by Huntington’s Disease Society of America on Wednesday, 8 April 2015
There is a lot of variation 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. People with early Huntington’s may find they have difficulty organizing routine matters or coping effectively with new situations. Difficulty recalling information may make them appear forgetful. Work activities may become more time-consuming and decision making and attention to details may be impaired. Early emotional symptoms may be equally subtle and can include irritability or impulsiveness, or depression. 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 look as if they’re drunk: they stagger when they walk and their speech is slurred. They 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.
Close to 10 percent of Huntington’s cases are considered “juvenile” – that is, the symptoms occur in childhood or adolescence. The symptoms of juvenile HD are somewhat different from the adult disease. Children with HD move slowly and stiffly, they have increased difficulty learning and they can have convulsions or epileptic seizures. Some children have severe behavioural problems. Because these symptoms can be very different from those in adults, it can be difficult to diagnose.
Are there any treatments?
In 2006, Canadian researchers provided bold new hope when they were able to successfully cure the disease in mice. 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 and a cure. 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. In addition, neurologists, psychologists, genetic counselors and social workers can play an important role in helping individuals or families deal with the disease. Physical therapists, occupational therapists and speech therapists can also help people with Huntington’s cope better with some of the symptoms. And because people with HD often lose a lot of weight, a nutritionist can be very helpful. It is important that all of these professionals work together to help manage the most effective treatment for each individual, since the disease often develops differently in different people.