Huntington's disease

Huntington’s disease (HD) is an inherited brain disorder that causes cells in specific parts of the brain to die, affecting both mental capability and physical control. It is a genetic disorder caused by an expanded gene. Everybody has the gene, but those who develop the disease have a longer version of the gene. The expansion causes the gene to malfunction, and it eventually leads to neurodegeneration. 

• Among western populations, one in every 10,000 people has HD.
• The prevalence of Huntington’s disease is higher among Māori.
• On average, HD patients live for 10 to 30 years after the initial appearance of symptoms.

About one in every 1,000 people is touched by HD, being either at risk themselves, a caregiver, or a family member or friend. The HD gene is dominant, which means that each child born to a parent with HD has a 50 per cent chance of having the disease.

Signs and symptoms

Most people with HD develop signs and symptoms in their 30s or 40s, but the disease can also emerge earlier or later in life.  When HD develops before the age of 20, it is referred to as juvenile HD. Generally, the earlier that the disease develops, the faster it progresses.

HD symptoms can be divided into three main types.

• Movement: these can include involuntary movements, difficulty with balance, walking and speech.
• Cognitive: these can include difficulty performing everyday tasks, problems with controlling impulses and a lack of self-awareness.
• Psychiatric: these can include depression, withdrawal and acting out of character.

Causes and treatment

Medication can help to improve the movement and psychiatric symptoms of HD, but there is currently no cure. The different types of therapy that may improve quality of life for those with HD include speech, physical, occupational and psychotherapy.

It is currently believed that the neurodegeneration in HD is caused by the huntingtin protein that is produced by the defective gene. Several pharmaceutical companies are trialling drugs that reduce the production of the huntingtin protein.

Support organisations

Huntington's Disease Association — hdauckland.org