Huntington’s Disease: Symptoms, Causes, and Treatment

Overview

Huntington’s disease is a neurodegenerative disease. It is a rare genetic disorder that causes uncontrolled movement, cognitive impairment, and emotional issues in an individual. Symptoms of the disease start to appear between the age of 30 to 50 years. It is incurable but manageable in various ways, including therapy and medications. 

The blog explains Huntington’s disease, its symptoms, causes, and treatment options, in detail. 

What is Huntington’s disease?

As mentioned above, Huntington’s disease is a rare genetic disorder that causes the deterioration of cells in the brain, causing uncontrolled movements, cognitive loss, and emotional disorders. Therefore, as the disease progresses, communicating, walking, and swallowing becomes a challenge. Medicines are available to manage Huntington’s disease symptoms. But treatments cannot prevent the physical, mental and behavioral decline linked to the condition. 

An inherited difference in a single gene causes Huntington’s disease. Huntington’s disease is autosomal dominant disease, meaning an individual requires only one copy of the non-typical gene to develop the disorder. The symptoms can appear at any given point in life, but they typically arise when a person is between 30 and 40 years old. 

As there is no cure for the disease now, medications help in managing the symptoms of the disease. However, treatments do not entirely prevent the physical, mental, and behavioural decrease that results from the condition.

What are the types of Huntington’s disease?

Based on the timeline of the appearance of the symptoms, there are two types of Huntington’s disease. They are as follows:

• Adult-onset of Huntington’s disease: In this, the symptoms appear in the thirties or forties. Patients develop involuntary jerking or twitching of hands and legs, known as chorea. The patient with adult onset of Huntington’s disease may live for nearly 20 years after the onset of signs and symptoms.
• Juvenile Huntington’s disease: This rare and lesser-known form of the disease begins in childhood or adolescence.Juvenile Huntington’s disease progresses faster than the adult-onset of Huntington’s disease. A patient with juvenile Huntington’s disease typically lives  15 years after the onset of signs and symptoms. About 30 to 50% of children suffer from seizures .

What are the symptoms of Huntington’s disease?

The symptoms of Huntington’s disease differ between adult-onset and juvenile Huntington’s disease. The initial signs of adult-onset of Huntington’s disease are as follows:

1. Movement disorder: this can include voluntary and involuntary movements. The symptoms are as follows:

• Involuntary jerking or writhing movements – known as cholera
• Muscle issues, such as rigidity and contracture
• Delayed and unusual eye movements
• Changes in gait, posture, and balance
• Troubled speech and swallowing

These symptoms may make an individual dependent on others, impacting the patient’s ability to work, think, talk, communicate, and perform daily activities.

2. Cognitive disorder: It is often associated with Huntington’s disease. The cognitive disorder symptoms include the following:

• Loss of organizing, prioritizing, and focusing ability
• No control over the impulse, resulting in sudden outbursts, acting out without thinking, and sexual promiscuity 
• Loss of awareness about one’s behaviour and ability
• Trouble comprehending new information
• Slow thought process or loss of finding words
• Constantly pondering over a thought, behaviour, or action

3. Psychiatric disorder: Depression is a common psychiatric disorder in patients with Huntington’s disease. It occurs not only due to the diagnosis of the disease but as a result of injury to the brain and changes in brain function. The following are the symptoms:

• Irritability, sadness, and apathy
• Insomnia
• Social withdrawal
• Tired and low on energy
• Suicidal thoughts and tendencies

4. Other common symptoms include the following

• Obsessive-compulsive disorder: A patient gets recurrent, intrusive thoughts and repetitive behaviours. 
• Mania: The patient causes improved mood, overactivity, impulsive behaviours, and inflated self-esteem.
• Bipolar disorder: In this condition, the patient alters between episodes of depression and mania. 

As the disease progresses, the symptoms also progress. They are as follows: 

• Unrestricted twitching of hand and leg movements. It is called chorea.
• Troubled walking, swallowing, and speaking
• Confusion and changes in memory
• Speech impairment
• A decline in cognitive abilities
• Changes in personality
• Weight loss

Juvenile Huntington’s disease causes  mental, emotional, and physical changes, such as the following:

1. Behavioural changes:

• Trouble paying attention
• The fast, significant drop in overall school performance
• Behavioural issues

2. Physical changes:

• Affect gait, contracted and rigid muscles
• Small involuntary movements
• Constant falls and clumsiness
• Seizures 

The other symptoms are as follows:

• Uncontrollable salivating
• Slurred speech
• Sluggish movements

What are the causes of Huntington’s disease?

The mutation of the chromosome number 4 gene. Generally, a copy of the gene generates the huntingtin (HTT) protein. When the gene is mutated, it leads to excessive production of cytosine, adenine, and guanine (CAG). CAGs are the building blocks of human DNA. 

Usually, CAG repeats 36 times or less, but in Huntington’s disease, it repeats more than 36 times, resulting in a significant form of toxic HTT protein. When the toxin accumulates in the brain, it degenerates specific brain cells.

A single defective gene can cause Huntington’s disease and is considered an autosomal dominant disorder. One copy of the mutated gene is enough to cause the disease. It is important to note that a person with a defective gene can pass it on to their children – there is a 50% chance of passing it on. 

When to seek medical help?

When a person notices symptoms, has a family history of Huntington’s disease, or planning pregnancy, prompt medical intervention is needed. 

Who is at risk of developing Huntington’s disease?

A person is at risk of developing Huntington’s disease if one of the parents has Huntington’s disease. Both men and women can develop it. If a parent has the gene, there is a one in two chance of each of the children developing the condition and a 50% chance that the children do not develop the condition. However, unaffected offspring cannot pass the gene to their children, and affected children can pass it on to the next generation. 

How is Huntington’s disease diagnosed?

The initial diagnosis of Huntington’s disease is usually based on a primary physical examination, an evaluation of family history, with neurological and psychiatric tests. The following are some of the tests prescribed by the doctor:

1. Neurological examination: 

During the examination, the neurologist asks questions and conducts simple tests to check the following:

• Motor symptoms, such as reflexes, muscle strength, and balance
• Sensory symptoms, including the sense of touch, vision, and hearing
• Psychiatric symptoms, such as mood and mental status.

2. Neuropsychological tests: These tests help determine and check a patient’s:

• Memory
• Reasoning
• Mental agility
• Language skills
• Spatial reasoning

3. Psychiatric evaluation: Neurologists may refer the patient to a psychiatrist to evaluate numerous factors that may contribute to the diagnosis, such as the following:

• Emotional state
• Behavioural pattern
• Coping skills
• Signs of disorientation
• Proof of substance abuse

4. Brain imaging and function test: Brain imaging assesses the brain’s structure or functioning in detail. These imaging tests include MRI or CT scans. These images may show the areas the brain is affected by Huntington’s disease. Such changes do not show during the early stages of the disease. The imaging tests also help rule out other conditions that may cause symptoms.
5. Genetic counselling and testing: The doctor may also recommend genetic testing to get tested for the nontypical gene, and these tests confirm the diagnosis. 
6. Predictive genetic tests: If a patient has a family history of the disease but isn’t showing any symptoms, the test help to detect the disease. Some people go for this test to put their doubts to rest or before planning to have children.

What are the treatment options for Huntington’s disease?

Huntington’s disease is incurable. However, medications and treatments can help a patient manage their symptoms. The following are the treatment options:

1. Medications: The Food and Drug Association (FDA) has approved two medications to treat the disease. However, these drugs may have adverse effects such as sedation, stiffness, and rigidity. There are numerous medications under clinical trial.
2. Speech therapy: The disease can diminish a person’s ability to control their throat and mouth muscles, thus resulting in difficulty in speech, swallowing, and eating. However, speech therapy helps improve these skills and reduces the challenges. It also aids in teaching patients to communicate by using images and activities.
3. Physical and operational therapy: The therapy helps improve muscle strength, flexibility, and balance and eliminates the risk of falling. The healthcare provider customizes exercises to suit the needs of each patient. These exercises are adjusted at regular intervals. The doctors also recommend specialized items to continue independently managing daily activities, such as handrails, special utensils to eat, and devices to help a person shower. 

Conclusion

Huntington’s disease may cause emotional, physical, and mental distress to a patient and their loved ones. Eventually, a person with Huntington’s disease requires help with all activities of daily living and care. 

Frequently Asked Questions (FAQs)

Can Huntington’s disease be prevented?

As Huntington’s disease is due to genetic mutation, and therefore, a person cannot prevent Huntington’s disease. People with a known family history of Huntington’s disease are understandably concerned about whether they may pass the Huntington gene on to their children. These people may consider genetic testing and family planning options.

What steps ensure a person can lead a quality life with Huntington’s disease?

• Stay active, exercise regularly
• Eat healthy food
• Drink plenty of water
• Join a support group 

Can a person die from Huntington’s disease?

Huntington’s disease is not fatal. However, a patient may lose their life due to complications related to the disease. Common causes of death include:

• Pneumonia or other infections
• Injuries related to falls
• Complications related to the inability to swallow