Huntington Disease (HD) is a neurologic and degenerative disease due to a genetic mistake, for which there is no cure. It can affect people’s movement, cognition and mental health. Movement, or motor, symptoms are the most visible parts of HD. These include chorea- which is an involuntary jerky movement that can involve any part of the body. People with HD can also be unsteady in their gait, have a twisted posture of their limbs or trunk, and have difficulty with speech and swallowing. Unfortunately as a result, it is not uncommon for the public- or even the Police- to mistake people with HD to be drunk or intoxicated, thus adding to the stigma associated with the disease.
While chorea, or involuntary movement, is the best known symptom of HD, we now know that people can have subtle cognitive difficulties up to 15 years before a formal diagnosis of HD. Cognitive problems in a later stage include difficulty multi-tasking, poor memory, impaired judgment, personality changes and behavioral disturbances. Behavioral symptoms can be particularly difficult to manage at home. Last but not least, HD can also lead to a range of mental health issues- including depression and psychosis. Depression is particularly common and needs to be treated adequately, because there is an increased risk of suicide in HD.
The first symptoms of HD typically occur in one’s 30s or 40s- although the age of onset can range from childhood to the 90s. Typically, people would have had subtle cognitive and movement symptoms for a few years before diagnosis, and there may be limited insight. Unfortunately HD is a neurodegenerative condition, and people with HD invariably deteriorate over time. The typical period of survival from diagnosis is about 20 years- although the speed of progression can vary. People with childhood onset of HD tend to do worse, and people with a late onset (over 65 years of age) tend to progress more slowly.
The HD-NSW study builds on a study conducted by the Huntington Disease Service at Westmead in 1996, where the number of people with HD was counted all over the State of New South Wales. Since then, genetic testing for HD has become more accessible, and a recent commentary in the journal Lancet also suggested that HD can be more common in the community than we originally thought.
The HD-NSW study aims to re-count the number of people diagnosed with HD, at the time of the 2011 National Census, to establish whether the number of people with HD in the State has changed on a per capita basis. Importantly, Phase I of HD-NSW will also provide a solid basis for Phase II of the study- where people with HD are assessed and followed over time. The detailed clinical and genetic data collected will improve our understanding of HD, and ultimately contributing towards better treatment for people with HD.