Overview

Are you interested in learning about neurodegenerative disorders? Do you know someone who struggles with such a condition and would like to know more? In this article, we will focus on one neurodegenerative disorder known as Huntington’s Disease (or HD in short). So, to start off we will go over what this disease is and how it progresses with time.

What is HD? It is a rare genetic disease that progressively gets worse with time.¹ Huntington’s disease is characterised by the degeneration of the neurons in the brain (mainly the basal ganglia and cerebral cortex).² This degeneration can lead to involuntary choreatic movements alongside cognitive and behavioural problems.³ HD occurs when there is a mutation in the Huntingtin gene (HTT), which is an abnormal expansion of the CAG trinucleotide repeats.³ This can lead to abnormal proteins that can lead to neurodegeneration.³

HD usually affects people who are 30-50 years old, but can appear earlier if there are more CAG repeats – the longer the CAG repeats, the earlier the symptoms will be.³

Since HD is a genetic disease, it is inherited from the parents.³ It is inherited in an autosomal dominant manner, with each child of an affected parent having a 50% chance of getting the illness.^3,4

Since HD is a progressive disease, it is important to understand the signs and symptoms and how to handle this illness to be able to provide the best possible life for the affected individual. Some of the symptoms of Huntington’s include:⁴

• Concentration difficulties
• Memory lapses
• Clumsiness
• Involuntary jerking or fidgeting of the limbs/body
• Difficulty moving
• Difficulty swallowing, speaking, and breathing
• Depression, mood swings, and personality changes

Treatment of HD is currently limited to treating the symptoms as there is no cure yet, these include:⁴

• Medication for depression and mood swings
• Medication for involuntary movements
• Speech therapy for communication issues
• Physiotherapy to improve balance and movement
• Occupational therapy to help with everyday tasks and make them easier

There are different stages for this disease, which is what this article aims to cover and provide helpful information on this topic.

Huntington's Disease progression

HD is a rare disease, however it can affect people worldwide.³ It commonly affects people in their 30s to 50s but can also start in childhood and to late adulthood.³ If HD affects people before the age of 20, then it is referred to as juvenile HD and is characterised by learning difficulties and behavioural issues in school.³ 

As mentioned previously, the symptoms start as subtle movement difficulties, mood, and personality changes that progressively get worse with cognitive impairment. It is a slow and steady decline with the disease usually lasting from 15-20 years.³ This is linked to the CAG repeats as not only does it provide information on when the symptoms start, but also can be used to predict the age of death.³ Although progression speeds vary among people, it will eventually lead to full time dependency and needing care.³ However, the most common cause of death for HD patients is pneumonia.³

Stages of Huntington's Disease

Early stage

The first stage for HD is the early stage – in this timeframe, there are mild symptoms such as lack of concentration, short term memory lapses, and mood changes (e.g. depression, mood swings, personality changes).⁵ Additionally, slight uncontrollable movements (also known as chorea) like stumbling and clumsiness start to take place, having difficulty organising and planning things, and becoming forgetful.⁵ Some of the symptoms might be present, but some may be absent.⁵ In this stage, people with HD can take care of themselves and are still capable of going to work, although it is advisable to have less hours.⁶ It can take up to 8 years before the disease progresses to the next stage, but starting early treatment can help the person to deal with some of the symptoms such as depression.^5,6

Middle stage 

This stage will have more pronounced involuntary movements and more visible psychological deterioration.⁵ There will be muscle movement changes where the muscles become stiff and rigid, as well as contract involuntarily.⁵ This causes the movements to slow down and make the arms and legs more clumsy, and it can even affect the speech where forming words will become more difficult, however it is possible to have speech therapy and specialised equipment to help with this issue.⁵ This stage further extends to affect swallowing and mouth movement, making it more difficult to eat and causing loss of weight.⁵ Contacting a dietician can help keep the weight in healthy ranges.⁵ 

There is a significant decline in the mental health of the individual where anger, depression, and frustration become more severe and may be challenging for both the person and their loved ones.⁵ It is important to have a good support group to help you around when battling this illness, and even provide a caregiver if required.

Late Stage

This stage is a more developed stage where the patient will most likely not be able to go to work and will require assistance with everyday tasks.⁶ It will include a magnitude of symptoms such as:^5,6

• Severe twitches and involuntary movements
• Falling often
• Difficulties with memory
• More severe mood swings and depression
• Issues walking
• Weight loss and nutritional issues
• Speech and swallowing problems
• Communication difficulties

The late stage can become advanced, and we can split it into early advanced and advanced stages. The early advanced stage takes about 10 to 21 years to occur after the initial onset of HD.⁶ In this stage, the patient will require more advanced care and help with personal and financial matters.⁶ Sometimes, going to a nursing home or specialised facility might be an option to provide the appropriate care for the individual.⁶ Some of the symptoms associated with this stage include:⁶

• Psychosis
• Rigidity
• Apathy
• Severe loss of cognitive function
• Unusually slow movements

Once this stage progresses further, it becomes an advanced stage, which is the final level.⁶ In this state, the patient will most likely require care 24/7 and will be bedridden.⁶ It will be difficult to perform basic motor activities like swallowing.⁶ In this stage, the affected individual will be completely reliant on others for care and help. Usually, patients in this stage will become sick due to infections and injuries, and often this can result in death.⁶

Factors influencing disease progression

Genetic factors

Genetics play a role in the progression of HD; for example, the more CAG repeats in the HTT gene, the more severe the disease (early onset, faster progression).³ This is also linked to inheritance where the illness may appear earlier and progress faster in successive generations due to the increased amounts of CAG repeat expansion.³

Environmental and lifestyle factors

Taking hold of your health through regular exercise and a proper diet can help improve the quality of life and delay the onset of the disease.^7,8 The same can be said towards chronic stress and its management; the less stress you have the better you feel and the healthier the body is, this also includes having the proper and supportive social care from your family, loved ones, and even caregivers.⁷

Medical interventions

Keeping a close eye on your health and having early diagnosis can help in approaching this illness in a more efficient manner; early detection can help you set up plans early on to battle the symptoms ahead and improve your quality of life, or even delay the disease. Additionally, having help from specialised therapists (e.g. physical therapists) can help provide a better outcome when dealing with physical or cognitive challenges.

Summary

Huntington’s disease is a rare and genetic illness that affects every aspect of the patient’s life. It is a progressive neurodegenerative disease that may start off as a minor inconvenience that leads to a full-time debilitating disease. HD has 3 distinct stages: early, middle and late. Symptoms can take years to appear and progress, but ultimately will lead to being bedridden and completely dependent on others for care until death. Each person’s experience with HD is different and will require a personalised plan tailored to their needs, stage, and health. Having a healthy lifestyle full of exercise, a good diet and a good support system will help delay HD, and provide a better quality of life for the patient.