What Is Huntington’s Disease? An Australian Guide

What is Huntington’s disease? An Australian guide

In 1842 a woman from Somerset, in the west of England, arrived in Launceston. She carried a gene.

Nearly two centuries later, Tasmania has what Huntington’s Australia describes as the second-highest per capita rate of Huntington’s disease in the world, behind only the communities around Lake Maracaibo in Venezuela that made the gene findable in the first place. Around 150 Tasmanians are living with the condition and several hundred more are at risk of it.

That is not a piece of trivia. It is the clearest possible illustration of what Huntington’s disease is: a condition that moves through families rather than through populations, that is passed on with a coin-flip’s probability to every child, and that can be traced along a line of descent for generations.

About 2,600 Australians are living with Huntington’s disease, and roughly 9,000 more are at risk of it — people who have an affected parent and therefore a 50 per cent chance of carrying the gene themselves, most of whom have never been tested and do not know.

This guide covers what Huntington’s actually is at the level of the brain, the three separate conditions it produces at once, the course it takes, the Australian numbers and what is known and unknown about them, and what distinguishes HD from the conditions it gets confused with. The genetics has a guide of its own, as does predictive testing, which is where the newest and most consequential Australian development sits.

Three conditions in one body

The first thing to understand about Huntington’s is why it is so much harder to support than conditions with a similar level of physical disability.

HD is the progressive loss of neurons, beginning in the basal ganglia — specifically the striatum — and spreading to the cortex. The basal ganglia sit at the centre of circuits controlling movement, but also circuits controlling motivation, impulse control, planning and emotional regulation. So damage there produces three distinct sets of problems at the same time, and the three interact.

The movement disorder. Chorea is the hallmark: involuntary, irregular, flowing movements that look almost like restlessness or fidgeting and that the person cannot suppress. It is present in most people with HD, generally worsens over the first decade, happens during waking hours, and gets worse with stress. Alongside it: difficulty with voluntary movement and fine motor control, an unsteady gait, slowed movement, and dysarthria — slurred, difficult speech — early. As the disease advances, chorea often gives way to dystonia (sustained abnormal postures), bradykinesia (slowness) and rigidity. Eye movement problems are early and present in up to 75 per cent of people, and hyperreflexia appears early in around 90 per cent.

The cognitive disorder. A progressive decline that affects everybody with HD, but which looks quite different from Alzheimer’s. The early losses are in executive function — planning, sequencing, organising, switching between tasks — along with slowed thinking, distractibility and visuospatial difficulty. Memory is affected, but retrieval rather than storage, which means cues and time genuinely help in a way they do not in Alzheimer’s. Language stays relatively intact until late. GeneReviews describes the pattern as resembling frontotemporal dementia far more than it resembles Alzheimer’s disease. And lack of awareness of one’s own deficits is common, which has consequences for almost everything.

The psychiatric disorder. Depression affects around 40 per cent of people with HD, at more than twice the rate of the general population, and anxiety follows. Apathy is common and deepens as the disease progresses. Irritability, explosiveness, aggression, personality change and disinhibition are frequent. Paranoid delusions are common; hallucinations less so; psychosis can occur later. Notably, the psychiatric symptoms do not track the motor and cognitive decline — they tend to progress less steeply, which means somebody physically mild can be psychiatrically severe, and the reverse.

Why the combination matters so much. Each of these alone is manageable within existing service models. A movement disorder goes to neurology and physiotherapy. A cognitive disorder goes to a memory service. A psychiatric disorder goes to mental health. Huntington’s produces all three, in the same person, and Australian services are organised around treating one at a time.

The practical consequence turns up constantly in family accounts: a person is too physically disabled for a mental health service, too psychiatrically unwell for an aged care facility, too cognitively impaired for a disability service designed around physical support, and too young for anything built for dementia. A Monash-authored gap analysis for Huntington’s Victoria recorded the phrase a relative used, which captures it exactly — “too young for aged care, but too impaired to live at home.”

The course, and the honest numbers

Onset. The mean age of onset is around 45. Huntington’s Australia describes symptoms as typically beginning between 30 and 50. About 25 per cent of people have onset after 50, and onset can occur in childhood.

The earliest signs are subtle and usually only recognised in hindsight: slight eye movement and coordination changes, minor involuntary movements that look like fidgeting, difficulty with mental planning, and depressed or irritable mood. Families frequently describe two or three years in which somebody became unreliable, short-tempered, or “not themselves” before any movement disorder was obvious.

Duration. Median survival after onset is 15 to 18 years, with a range from about 5 to more than 25. Average age at death is 54 to 58.

That duration figure is important and it distinguishes HD sharply from the other progressive neurological conditions covered elsewhere in this library. Motor neurone disease runs two to three years. Huntington’s runs fifteen to eighteen. Which means HD is not primarily a crisis-management problem; it is a long-haul problem. Support arrangements have to be built to last a decade and a half, through several distinct phases, while a person who was 42 at diagnosis becomes 57 and their children grow up.

Later stages. Advanced HD typically leaves people totally dependent, often unable to speak, and incontinent. Swallowing difficulty arrives later than in MND but is serious when it does: choking and aspiration pneumonia are a frequent cause of death.

The Australian numbers, and what we do not know

Here is an uncomfortable fact: Australia does not know how many people have Huntington’s disease.

The gap analysis produced by Monash University’s RAIL Research Centre for Huntington’s Victoria in December 2020 set this out plainly. There is no national registry. Australian Bureau of Statistics data folds HD into a broader “progressive neurological” category, so it cannot be counted from death data. Clinics reported that counting accurately is difficult and said a national database is needed.

The best available estimates:

Two rows in that table deserve to be read twice.

833 NDIS packages against an estimated 2,600 people with the condition. Even allowing for the years since and for people over 65 at the time the scheme began, that gap is large. Some of it is age; some of it is people who have not applied, or applied and failed, or do not know they are eligible.

149 people under 65 in permanent residential aged care. These are working-age Australians with a disability living in nursing homes, in a country that has spent a decade and three national targets trying to end that practice. HD is overrepresented in that population because of exactly the combination described above: physical need plus behaviour plus cognition, which almost nothing in the disability housing system is built for. See supported independent living with Huntington’s.

The same gap analysis measured how well served the community feels. Of those surveyed, 59 per cent reported a gap between the formal services they needed and received, 67 per cent for semi-formal services, and 65 per cent for informal supports.

Specialist services, and where they are not

Australia has a small number of dedicated Huntington’s services, almost entirely in capital cities. Huntington’s Australia lists:

New South Wales — the Huntington Disease Service at Westmead Hospital, which is the most comprehensive in the country (neurology, speech pathology, occupational therapy, dietetics, physiotherapy, clinical nursing and social work), and an HD service at John Hunter Hospital in Newcastle offering neurology and social work.

Queensland — the Huntington’s Clinic at Royal Brisbane and Women’s Hospital, with neurology, speech pathology, psychiatry and clinical nursing. A GP referral letter is required.

South Australia — the SA Huntington Disease Service at Flinders Medical Centre, with genetic counselling, neurology, psychiatry and social work.

Victoria — the Neuropsychiatry Centre at Royal Melbourne Hospital, and the Statewide Progressive Neurological Disease Service at Calvary Health Care Bethlehem.

Western Australia — the Neurosciences Unit, North Metropolitan Health Services.

Tasmania — services through the Older Persons Mental Health Service across three regions.

The Australian Capital Territory and the Northern Territory have no listed HD clinic at all.

And the services that exist are fragile. In late 2025, Huntington’s Australia announced it had been forced to cut Tasmania’s only dedicated HD Specialist position after an agreement with the Tasmanian Department of Health was not renewed. The organisation’s head of community programs described the loss of the state’s only full-time specialist as “the complete dismantling of essential, local support” — in the jurisdiction with the second-highest rate of the disease on earth. Remote support continues through a national team.

The practical reading for families: get yourself onto the list at the nearest specialist service even if it is interstate, because general neurology, general psychiatry and general disability services will each manage their third of the problem competently without anybody managing the whole of it. And ring Huntington’s Australia on 1800 244 735, which coordinates support nationally and knows what exists where you live.

What Huntington’s is confused with

Motor neurone disease, surprisingly often. The 2020 gap analysis specifically recorded that HD is frequently confused with MND, including by health professionals. They are not similar: MND is a pure motor disorder with intact cognition in most people, no inherited pattern in 90 per cent of cases, and a two-to-three-year course. HD is a movement, cognitive and psychiatric disorder, inherited in half of all offspring, running fifteen years or more.

Psychiatric illness. Where psychiatric and behavioural symptoms come first — which they often do — people spend years in mental health services with diagnoses of depression, bipolar disorder, schizophrenia or personality disorder before anybody asks about family history.

Alcohol or drug problems. Chorea, slurred speech and unsteady gait read as intoxication to people who do not know. The gap analysis recorded a workplace complaint about a man’s supposed drinking, which the family described as deeply destructive. People with HD are stopped by police, refused service, and assumed drunk. This happens constantly and it is one of the more avoidable harms in the condition.

Early-onset Alzheimer’s or frontotemporal dementia. The cognitive pattern genuinely does resemble FTD, and in a person with no known family history that can be the first working diagnosis. See frontotemporal dementia.

Tardive dyskinesia, from previous antipsychotic use, which can produce similar involuntary movements.

Other inherited movement disorders — spinocerebellar ataxias, neuroacanthocytosis, Wilson’s disease — several of which are treatable, which is why a genetic test is done rather than assumed.

Treatment: what exists and what does not

There is no treatment that slows Huntington’s disease. Everything currently available treats symptoms.

Chorea can be reduced with tetrabenazine, deutetrabenazine or valbenazine, which deplete dopamine, and with typical or atypical antipsychotics or benzodiazepines. Tetrabenazine is available in Australia on the PBS. The trade-off is real: dopamine-depleting drugs can worsen depression and apathy, which in a condition with a 40 per cent depression rate and elevated suicide risk is not a minor consideration. Treating chorea is a judgment call about whether the movements are actually causing harm.

Depression, anxiety and obsessive symptoms are treated with SSRIs and related medications, and this is frequently the highest-value intervention available in HD.

Irritability and aggression with antipsychotics, often the same ones used for chorea.

Apathy with amantadine, atomoxetine, methylphenidate, modafinil or bupropion, with modest results.

Mood instability with lamotrigine or carbamazepine; insomnia with mirtazapine or short-term agents.

Things to avoid: levodopa-containing drugs, which can worsen chorea, and MAO inhibitors. Alcohol is discouraged.

And the non-drug interventions, which carry more weight than their profile suggests. Physiotherapy for gait and falls. Speech pathology for dysarthria and later for swallowing. Occupational therapy for equipment and the home. Dietetics, because weight loss in HD is both severe and clinically significant. Psychology, including cognitive behavioural approaches. A behaviour support practitioner who actually understands HD. And a support team that stays the same, which in this condition is a clinical intervention rather than a preference.

Research is active. In January 2025 international trial results in gene-targeting therapies were reported widely in Australia as a milestone, and Australian centres including Monash are part of the global research network. Nothing has yet changed what is available in clinic.

Where this library goes next

The genetics, including CAG repeats, anticipation and why fathers transmit differently from mothers — Huntington’s genetics and the 50 per cent.

Predictive testing, and the Australian law that changed on 8 October 2026 — predictive testing for Huntington’s.

Funding — Huntington’s disease and the NDIS.

Each part of the triad — movement and chorea, cognitive change, and behaviour and mental health.

Nutrition, which matters more in HD than in almost any neurological condition — eating, weight and swallowing.

Juvenile Huntington’s — juvenile Huntington’s disease.

Housing and support — supported independent living with Huntington’s.

And the families, who in this condition are in a position no other illness creates — families and children.