Huntington's disease

Published by Bupa's Health Information Team, June 2010.

This factsheet is for people who have Huntington's disease, or who would like information about it.

Huntington's disease is an inherited disorder that causes degeneration of brain cells. This results in a progressive loss of mental ability, control of movement, and changes in personality.

About Huntington's disease

Huntington's disease causes progressive damage to cells in areas of your brain called the basal ganglia and cerebral cortex. These areas are involved in your control of movement, planning, motivation and personality.

Huntington's disease usually develops between the ages of 30 and 50, but it can start at any age. Symptoms, which differ from person to person, get gradually worse, sometimes over a period of up to 20 years.

Huntington's disease was previously called Huntington's chorea. Chorea means jerky, involuntary movements - a main symptom of the condition.

Juvenile Huntington's disease

Juvenile Huntington's disease is a type of Huntington's disease that develops before you're 20 and is usually more severe. It affects around five to 10 in 100 people with Huntington's disease.

Symptoms of Huntington's disease

The early symptoms of Huntington's disease are sometimes overlooked. This is because they are mild at first and people without the disease can have the same symptoms.

You may have symptoms of Huntington's disease for a long time before you find out you have the condition.

Early symptoms include:

• mild tremor
  
• clumsiness
  
• lack of concentration
  
• irritability
  
• short-term memory problems
  
• mood changes
  
• depression

If you have these symptoms, see your GP.

Later symptoms fall into three categories. Over time these symptoms get worse and eventually you will need full-time nursing care.

Physical symptoms

Physical symptoms include chorea (involuntary movements of your limbs, face and body). Chorea may lead to difficulty walking, speaking and swallowing. You may lose weight because you're having difficulty eating and drinking and because you're burning more calories due to the continuous movement. Your ability to co-ordinate your movement will get gradually worse as the disease progresses.

Emotional symptoms

Emotional symptoms include depression, not only because of the burden of having a progressive disorder, but as a direct result of the damage to certain brain cells. You may become frustrated at being unable to work or do previously simple tasks. You may behave stubbornly, have mood swings, become more irritable and antisocial than usual, or have fewer inhibitions.

Behavioural symptoms

Behavioural symptoms include a loss of drive and initiative. You may appear lazy or uninterested in life, spending days doing little or neglecting your personal hygiene. You may also lose the ability to organise yourself and do more than one task at once. In the later stages of the disease, you may have memory loss and be less able to understand speech.

The behavioural symptoms of Huntington's disease are often the most distressing for you, your family and your carers. Your personality can become gradually more self-centred and unmotivated, putting a strain on personal relationships.

Symptoms of Juvenile Huntington's disease

Symptoms are similar to those of Huntington's disease, but muscular rigidity (stiff muscles) is more common and involuntary movements are less likely.

If you have juvenile Huntington's disease you will usually first develop symptoms in your teens. You may be irritable and aggressive and start to act out of character, possibly displaying inappropriate social or sexual behaviour.

Causes of Huntington's disease

Huntington's disease is caused by a faulty gene that runs in families. The gene produces a protein called Huntingtin. Scientists are still researching how this faulty gene causes the disease.

Most of your genes are present in two copies: one from your mother and one from your father. The faulty gene that causes Huntington's disease is dominant. This means that if you inherit a copy of this gene from either parent, you will go on to develop the disease at some point in your life.

If you have one parent with Huntington's disease, you have a one in two chance of inheriting the faulty gene. The risk is one in two for each child.

Around three in 100 people with Huntington's disease appear to have no family history of the condition. This may be because relatives from previous generations weren't diagnosed - either because of early death from other causes, or loss of contact, for example through adoption.

Diagnosis of Huntington's disease

Genetic tests can show whether you have the faulty gene that causes Huntington's disease. They fall into three categories: diagnostic, pre-symptomatic and antenatal.

Diagnostic tests

These tests are carried out if you have symptoms of Huntington's disease. You will have two blood tests. The results of these tests will take between four and six weeks to come back. You will be offered counselling before you have the blood tests.

Pre-symptomatic tests

These tests are carried out if you have no symptoms of Huntington's disease, but you have family members who are affected by it. The tests will show whether or not you will develop the disease, but not when it will happen.

The decision to have these tests is a serious one and you're advised not to rush into making a decision. A positive result can be devastating as it means that one day you will become seriously ill. Many people prefer not to find out and instead aim to live their lives to the full. There are also issues surrounding testing if your parents haven't been tested, as if you have a positive result this means that one of your parents also has the faulty gene.

You will need to take advice from a genetic counsellor about the implications of taking the test before you go ahead. In the UK you can't have pre-symptomatic tests if you're under 18.

Antenatal tests

These tests can be carried out on your unborn baby if your family is affected by Huntington's disease. Antenatal tests are done at the end of the first trimester (first 12 weeks) of pregnancy. They can be used to calculate the risk of your child going on to develop the disease in their adult life. You will be offered counselling before you have antenatal tests.

Treatment of Huntington's disease

At the moment, there is no cure for Huntington's disease, but there are ways to manage the symptoms.

You may be prescribed medicines to reduce the involuntary movements, and alleviate depression. Mood stabilisers and antipsychotic medicines can also help with some of the emotional disturbances.

Other ways of managing your symptoms include the following.

• Speech and language therapists can help improve your communication and help you to swallow.
  
• Dieticians can advise you on adequate calorie and nutrient intake to stop weight loss.
  
• Occupational therapists can provide you with equipment to help you eat, such as non-slip mats and straws, and help make your home safe by adapting it to your needs.
  
• Physiotherapists can help with any balance or musculoskeletal problems.

Counselling and support groups can be helpful, both for you and your family.

Special considerations

Having a baby

If you know that you carry the gene for Huntington's disease, you can choose to have in-vitro fertilisation (IVF), where embryos are tested for the Huntington's disease gene, and only those that don't carry the faulty gene are placed in your womb. This is called pre-implantation genetic diagnosis.

In the UK, pre-implantation genetic diagnosis is only available to parents who already know whether or not they carry the gene for Huntington's disease, at certain clinics licensed by the Human Fertilisation and Embryology Authority.

Future promise

Scientists are investigating several medicines that could slow the progress of Huntington's disease. Some of these have shown promise and are being tested in clinical trials. Examples include an antibiotic medicine called minocycline and the nutritional supplement, coenzyme Q10.

Some clinical studies have used stem cells (the most basic form of cells from which others develop) to grow cells that can be transplanted into the brain of people with Huntington's disease to improve their outlook. However, research is still in the very early stages.

Scientists are also hopeful that research into RNA interference (RNAi), which can potentially shut off any gene in the body, may lead to an effective treatment in the future.

For answers to frequently asked questions on this topic, see Common questions.

For sources and links to further information, see Resources.