Huntington’s disease is a neurodegenerative, progressive disease that affects brain cells, causing motor, psychiatric, and cognitive deterioration.
We will be doing a detailed description of Huntington’s disease in this article, its cause, its symptoms, and the patient’s life expectancy. We are also going to discuss how to diagnose it and if there are treatments available.
You are going to obtain a thorough but clear explanation of Huntington’s disease by reading this article. Continue reading to learn about this uncommon but deadly disease with the information provided directly by a doctor.
What is Huntington’s disease?
Huntington’s disease (HD) is a progressive, genetic, hereditary, neurodegenerative disease that affects the brain’s nerve cells. It affects 1 in every 10.000 people worldwide without any specifically known inclination for race or sex.
Huntington disease happens because of a defective gene that passes along from generation to generation through the carriers. When one of the parents has Huntington disease, there is a 50% chance their child gets the faulty gene.
This disease occurs in the brain, one of the most complex structures in the human body, and still the less understood one. But what we do know of it, is that it is made of specific cells that communicate between them. This communication allows the organ to practice its functions, from moving to learning and thinking to feeling. These roles take place in different areas of the brain that are still connected to one another. This disease attacks most brain cells progressively, causing a slow loss of functions, leading to the patient’s death.
Scientists don’t quite understand yet the disease, which complicates the lives of the patients and their family members. There are a few places in the world where it’s more common but in small areas, such as Maracaibo, Venezuela. You can find at least 1 case out of 10 people in a particular town in the region. A scientist that went to the area believes that it is because of endogamy that happens between the small populations. Other places in the world with a high amount of cases are regions in the UK, Egypt, and Tasmania.
What is the cause of Huntington’s disease?
Huntington’s disease happens because of a genetic disorder that causes brain cells’ death that has the defective gene. The huntingtin gene (HTT) carries the genetic information that leads to producing a protein of the same name. When the HD gene is present, huntingtin is abnormally made by the cells, causing issues in neurons’ normal metabolism.
Research has shown there is a CAG repeat in the mutant HTT gene of people with Huntington’s. CAG is one of the many sequences of molecules that build the DNA, which makes the body’s proteins. For huntingtin, there is a particular number of sequences that need to happen in order to produce the protein correctly. So when there is a CAG repeat, more of these sequences lead to abnormally made huntingtin protein. The amount of CAG repeats is proportional to the severity of the disease. If it’s low, there is a reduced penetrance of the disease.
HD patients get the HTT gene through one of their parents, which gives them the gene plus another mutant allele. This means the person has a 50% chance of developing the disease, and if both parents have it, they have a 75% chance.
What are the symptoms of Huntington’s disease?
The main symptoms of Huntington’s disease consist of 3 spheres: motor, cognitive and psychiatric disorders.
- Motor: At the beginning of this chronic disease occurs a movement disorder, and doctors call it Huntington’s Chorea. This motor symptom starts with small involuntary muscle spasms in the fingers, toes, and facial muscles. These might seem like nervousness but clearly visible for other people, whether they know the person. These movements later progress to arms, legs, and back muscles, which looks like the extremities’ uncontainable waving. As the disease continues, the person starts to move slowly, become rigid, and lose postural stability contrary to the initial symptoms. The latter type of symptoms is more severe and disabling than the first since they can prompt swallow difficulty.
- Cognitive: People with Huntington’s disease suffer from a dementia syndrome from early on the disease marking the behavioral symptoms. HD patients become irritable, messy, lose interest in their main activities, and have short-term memory loss. All of this, along with the motor symptoms, make the progressive disease very characteristic, although for some people also similar to Parkinson’s disease.
- Psychiatric: Psychiatric symptoms are broad and non-specific, but the most common one is depression since it occurs in 30%-70% of patients. There is a significant amount of patients that commit suicide just before the symptoms become disabling to them. Some people also have bipolar disorder in which there are periods of depression and mania or hypomania. In mania, there’s a state of euphoria, hypersexuality, eccentricity and can suffer from alcoholism, causing damage to themselves or others. Besides, patients can manifest psychotic symptoms, obsessive-compulsive symptoms, and sleep disorders.
What are the stages of Huntington’s disease?
A patient with Huntington’s disease passes through different disease stages, even before they have any HD symptoms. Doctors divide the patient’s life into a preclinical stage and a clinical stage of the disease.
- Preclinical stage: This begins with an uncertainty of actually having the disease since there is a 50% chance they carry the gene. The person suffers from anxiety about the future; meanwhile, they care for an ill parent. Then the patient finds out they do have the HD mutation, which creates worries for their individual lives and family. At the same time, they care for a parent in a bad state and assume new family positions. Finally, in this stage, the Huntington patient starts to realize changes in their cognition and behavior. Small changes in their motor activity may also occur at this time, increasing the uncertainty and anxiety they face.
- Clinical stage: In the first clinical-stage, the symptoms become very noticeable to the patient and others, especially Huntington’s chorea. They still do have independence in their daily lives but feel like a burden to the family psychologically. Patients in the early stages don’t die unless it is due to suicide because of anxiety and depression. Progressively motor symptoms worsen, and rigidity becomes an issue that starts physical dependency on others, becoming a burden for the family. For the final stages of the disease, the motor symptoms are severe and are totally reliant on the family’s care. Death is inevitable for the person because of different reasons such as infections or even euthanasia in countries where it is legal.
What is the life expectancy for people with Huntington’s disease?
The life expectancy of a person that has Huntington disease will depend on when do the symptoms start. Doctors estimate that it takes approximately 15 to 20 years for the person’s death when they develop symptoms. It is important to note that the estimation does not take into account that the patient commits suicide before they suffer from a fatal condition.
Studies have also shown that patients that inherit the disease from their father have an earlier onset of symptoms. This would mean that those who got the gene from their fathers will probably have a lower life expectancy.
Professionals define another form of juvenile Huntington’s disease, which happens to people younger than 20 years old. This particular form has a shorter disease duration since the symptoms appear as early as eight years old or less. It also has a different progression of symptoms comparing it to the regular disease. Rigidity is the main symptom, instead of chorea, and seizures are another common thing for these patients. Besides, there is cognitive decline and dementia, sadly, at this very early age, showing the worse of the disease progression.
How do you know if someone has Huntington’s disease?
Huntington’s diagnosis is mainly made by evaluating the symptoms and the history of the parent with the disease. That is why the parent must confirm the disease with a genetic test. If not, the symptoms alone aren’t sufficient. The certainty must be one hundred percent.
When the motor symptoms with or without psychiatric symptoms don’t have a proven family history, a genetic test is necessary. It counts the number of CAG repeats in the HTT gene, and if it has more than normal, it’s positive. This test must have consent from the patient since it would mean further studies to relatives at risk of Huntington’s. Genetic studies can also be done to people who are at risk of the disease but are asymptomatic or without symptoms.
Other types of tests, such as blood tests, MRIs, CT scanning, are useless to diagnose the disease at any stage. Recently there have been studies with MRIs to these patients’ brains even years before the symptoms begin. They have shown changes in different brain areas, although they still don’t function as a diagnosing tool.
When the genetic tests are negative, and symptoms are similar to Huntington’s, several other diseases need studying, such as:
- Systemic Lupus Erythematosus: Autoimmune disease which causes mainly kidney problems, skin problems, and also causes dementia and depression.
- Alzheimer’s disease: A neurodegenerative disease that causes dementia and loss of memory.
- Parkinson’s disease: A progressive brain disorder that causes motor problems such as shakiness and rigidity.
- Amyotrophic lateral sclerosis: A degenerative disease that affects the nerves that control the muscles.
- Vascular dementia: It is a widespread type of dementia that happens because of low blood flow to the brain, causing damage and cell death. One of the leading causes is high blood pressure, which is a very common condition.
Can Huntington’s disease be treated?
Currently, there is no known cure for Huntington’s disease or any treatment that can slow down the disease. The available treatments are only for symptoms in order to give the patient a better lifestyle.
For decreasing chorea, the patient is given medication that reduces the brain’s molecules that cause the erratic movements. These can be risperidone, olanzapine, tetrabenazine, pimozide, and many others, depending on their needs and the drugs’ availability.
In recent studies, tetrabenazine has proven to be the most effective against these symptoms, but the FDA hasn’t approved it.
For psychiatric symptoms, there is a whole other spectrum of drugs that diminish these types of symptoms. Doctors treat irritability and depression with the same type of drugs, such as; serotonin reuptake inhibitors, tricyclic antidepressants, and carbamazepine.
For psychotic symptoms like hallucinations, other drugs function for treatment like; olanzapine, risperidone, clozapine, and quetiapine.
A new surgical study was recently born that consists of the transplant of neural cells with special fetal cells. It has shown improvement in some of the patients that applied to the research, but it is still too early to have precise results.
How do people cope with Huntington’s disease?
There are several measures that people can take to deal with the disease on a daily basis. It is important to remember that Huntington’s disease affects not only the person who has the symptoms. This disease affects the whole family in various ways, and all of them should find ways to cope.
Therapy is a big help for people who personally suffer from the disease, their caregivers, and their descendant. It is a grim outlook to feel your life decline and for your loved ones to see. Support groups and organizations also provide orientation and help to people who need it.
Another big problem, besides the psychological ones, is the mobility issues the patient faces. They may have to also go to a physiotherapist, a dietician, and even a speech therapist to deal with the progressive motor difficulties.
When the disease progresses, it may become harder for family members to take care of the patient on their own. They might have to consider additional help at home from a nurse or take them to a care facility. Specialized social agencies exist to orientate the families in those difficult processes and decisions they have to make.
What is the most common cause of death in this condition?
The most common cause of death in Huntington’s disease is pneumonia and suffocation. Motor symptoms cause both problems.
When the condition is in its later stages, the person has poor muscle control, including those in the throat. This causes the main problem that leads to the patient’s death, which is not swallowing most foods adequately.
When the HD patient is being fed the food, whether it is liquid or not, it can go to the lungs. This small portion of food in the lungs carries anaerobic bacteria that cause pneumonia, which leads to the patient’s death.
Aspiration pneumonia can be more severe than common infections, especially if doctors do not identify quicky that it’s this type of infection, the one causing trouble and treat it as ordinary pneumonia. Suffocation happens when solid foods obstruct the upper airways in its totality because of the patient’s lack of muscle control.
Other causes of death are common such as:
- Heart disease: People with this disease suffer from nerve conduction in the heart that can cause low heart rate and arrhythmia. It also generates heart failure.
- Suicide: Usually in early or mid-stages of the disease because of the depression proper of the gene mutation that affects the brain.
- Cachexia: Is a state in which the body deteriorates through the loss of muscle mass and fat. It happens mostly in chronic diseases and is not because of less food ingestion.
What’s the difference between Parkinson’s and Huntington’s?
Although Parkinson’s and Huntington’s disease are very similar, they also have some marked differences that can help in the diagnosis.
First of all, the disease’s onset is quite different since Parkinson’s patients do not suffer from chorea. Instead, they begin with small tremors in their fingers that look as if they were rubbing coins.
It continues as rigidity and very slow movements, small steps as they walk and not balancing their arms. Their facial expression also disappears, giving them a ¨permanent poker face¨.
In this disease, there is a direct link to the loss of neurons that produce dopamine, which causes these particular symptoms. It isn’t well known the precise cause of this disease, although it’s most likely genetics, some patients don’t show precise mutations.
What is certain is the presence of Lewy Bodies in the brain cells, which this disease affects. Lewy bodies are inclusions in brain cells with a-synuclein; protein cells cannot get rid of, causing their death.
Parkinson’s patients also suffer from psychiatric symptoms such as dementia and depression, making it even more similar to Huntington’s.
What differentiates both diseases without a doubt is the presence of mutant huntingtin in Huntington’s patients. A gene test confirms its existence and excludes Parkinson’s diseases from being a potential diagnosis.
Are you having symptoms of it?
This tool is a Huntington disease symptoms checker. It gathers the most important signs, symptoms, and risk factors for this condition. Therefore, it will aid anybody who uses it to determine the likelihood of having Huntington disease or developing it in the future. Besides, this tool is free and would only take you a few minutes to use it.