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What is Huntington’s Disease?
Huntington’s Disease (HD) is a genetic disease, which means it can be passed down through families.
The gene that causes HD is normally responsible for the production of a protein called huntingtin. This is found in cells throughout the human body, but particularly in the brain and spinal cord. The mutated, disease-causing gene makes the protein to form clumps within the cell, which disrupts the cells’ function.
This damage occurs most frequently within the area of the brain called the basal ganglia. The basal ganglia control movement, understanding, problem solving and emotions. That is why Huntington’s disease symptoms often include problems with movement, thinking and emotions. Moreover, these problems tend to change a persons behaviour.
Huntington’s disease is a progressive disease which means the condition deteriorates, or worsen, over time. Based on physical symptoms, it can be divided into 4 stages: pre manifest, early stage, mid stage and late stage. The Total Functional Capacity Score (TFC) is therefore indicating degree of independence at each stage: the more physical symptoms, the more a person will depend on help. The higher the TFC score, the more independent the person is.
- Pre manifest: before onset of physical symptoms
- Early stage: has physical symptoms with TFC score 11-13
- Mid stage: has physical symptoms and a TFC score 7-10 or 3-6
- Late stage: has physical symptoms and a TFC score 1-2 or 0 (2)
In 1872, George Huntington wrote a paper on the disease: “On Chorea”, which is why the disease later became known as ‘Huntington’s chorea’. Huntington because of the doctor’s name, chorea because of the movements. The term is derived from the Greek word ‘choreia’ which means “to dance”.
Today, we call it ‘Huntington’s disease’, because Huntington’s presents with various symptoms (including cognitive changes). We tend to say that symptoms usually appear between the ages of 35 to 40 years, but there are big individual differences.
Early in Huntington’s disease, the damage may result in mild problems with movement, thoughts and behaviour. You may observe unwanted movements of the arms, legs or face. This is termed chorea or dystonia and can result in difficulties with walking. Difficulties with concentrating, planning and organising tasks or sadness, depression; or irritability are also common.
Later in Huntington’s disease the damage tends to result in different problems involving movement, thoughts and behaviour. You may observe muscle stiffness (rigidity) and slowness of movement (called bradykinesia), balance problems which may result in falls and problems with speech (dysphagia). Thought problems include slowness with thinking and the ability to process information, lack of self-awareness particularly regarding the effects of the HD (this is termed lack of insight) and difficulty doing two things at once (dual tasking), for example walking and talking. Apathy, depression, impulsivity, perseveration, paranoia, and anti-social behaviours are common behavioural problems.
In the Autumn of 2020, the European Huntington Association hosted multiple webinars on how it is to live with Huntington’s disease – both for those of us having the disease and those of us close to them. You can learn more about symptoms and how to cope with them here.
Is there a cure?
There is still no known cure for the disease, but brilliant scientists work around the clock to develop treatments. You can read a brief summary of ongoing drug development and what to expect in the future here and get a short video presentation by Rob Haselberg, Huntington’s disease family member and scientist, below: