Huntington’s disease: a rare cause of dementia

Symptoms of Huntington’s disease usually begin when a person is aged 30-50, but if they occur before the age of 21, it is classified as Juvenile Huntington’s disease. Huntington’s disease is diagnosed by taking a sample of a person’s blood and running a genetic test on it.

Huntington’s disease is caused by just one faulty gene called Huntingtin. Ordinarily, this gene produces a protein called huntingtin that is crucial in development and in maintaining healthy neurones (nerve cells in the brain). These functions are disrupted in the defective Huntingtin gene causing damage to the brain.

Although everyone with Huntington’s disease experiences it differently – just like any other type of dementia – there are some common patterns of symptoms. There are three main functions that are affected by Huntington’s disease: movement, behaviour, and cognition.

The movement symptoms usually appear first and include involuntary movements, difficulty making voluntary movements, clumsiness, slowness, and stiffness. As the condition progresses, the movement disorder becomes more pronounced, and people often have a trouble eating and speaking due to lack of muscle control.

Changes in behaviour and personality are more common in Juvenile Huntington’s disease and can involve becoming more irritable, depressed, and angry. Cognitive symptoms include difficulty planning, concentrating and thinking – you can read more about cognition in this blog post.

Dementia can occur at any stage in the progression of Huntington’s disease and is distinct from other causes of dementia like Alzheimer’s disease. The way the diseases affect memory can be different – people with Huntington’s disease often forget how to do things rather than forgetting events, people and places, like in Alzheimer’s disease.

People with dementia in Huntington’s disease have a distinctive pattern of atrophy (loss of cells) in their brains. Dementia in Huntington’s disease is associated with the outer layer of the brain becoming thinner and loss of nerve cells throughout the whole brain.

Unfortunately, there is currently no cure or specific treatment for Huntington’s disease, and it is usually fatal within 20 years. However, there are interventions that can help manage some of the symptoms such as speech and language therapy and physiotherapy.

Research is also ongoing to devise ways of inhibiting the underlying mechanisms involved in Huntington’s disease. You can learn more about the latest research into Huntington’s disease and much more on the Huntington’s Disease Association website.