Huntington’s disease is a disease that causes a breakdown of the nervous system, especially in the brain. This is why it is called a neurodegenerative (neuro = nerves + degenerative = causing breakdown) disease. It is a genetic disease and so is transferred by parents who are carriers to children – similar to Cystic Fibrosis. It is incurable and may end up causing the death of the person. The disease usually starts in most people in their 30’s to 40’s. When the symptoms begin before the age of 20, the term “juvenile Huntington’s disease” is used. In these cases, the clinical prognosis is something different from the usual and the progress of the disease is usually faster.

Let’s take a little history lesson here.

In 1872, Huntington’s disease was first described by a man named George Huntington. He called it hereditary chorea. He described it to be related to psychiatric and cognitive symptoms meaning it affects the emotions and thinking of a person. Talking about the progressive nature of the disease, he stated: “Once it begins, it clings to the bitter end”.

Moving on to some statistics ..

Huntington’s disease is relatively rare, affecting about 10.6 to 13.7 people in every 100,000 people. This is even lower among Asians and Africans. Huntington’s disease can cause death within 10 to 30 years. Common reasons for death in Huntington’s disease are pneumonia and other infections, injuries due to falls, and complications from the inability to swallow.

SYMPTOMS OF HUNTINGTON’S DISEASE

Huntington’s disease is characterized by Psychiatric, Cognitive and movement disorders. The most characteristic sign of this disease is the chorea that gives it the name Huntington’s chorea. Chorea is a set of neurological disorders that cause involuntary and irregular contractions of the muscles of the feet and hands. Similar movements also occur on the face. In addition to chorea, the person also shows dystonia which is the abnormal rigidity of the muscles. Cognitive disorders include difficulty in learning, slow processing of thoughts, difficulty in focusing and organizing tasks. Psychiatric disorders include emotional disorders like anxiety and depression, insomnia, thoughts of suicide etc.

CAUSES OF THIS DISORDER

Huntington’s disease is caused by a defect in a gene called the huntingtin (HTT) gene. Huntington’s chorea is due to a genetic mutation that is inherited through an autosomal dominant mechanism. This implies that just one defective gene will lead to the disease. All carriers of this defective gene will have the disease. The children of an affected person have a 50% chance of inheriting the gene, regardless of their biological sex. The severity of the mutation also partially depends on the inheritance and influences the development of the symptoms. In the most severe cases, the affected gene (the “huntingtin”) manifests very early. This disease affects the entire brain; however, the most important lesions occur in the basal ganglia, subcortical structures related to movement. The area which is composed of the caudate nucleus and the putamen is especially affected.

DEVELOPMENT OF THE DISEASE

The symptoms of Huntington’s disease vary depending on the specific case. However, their progress is usually grouped into three distinct phases. The alterations worsen in psychophysiological stress conditions, as well as when the person is exposed to intense stimulation. Likewise, weight loss is common in all phases of the disease; It is important to control it since it can have very negative consequences for health.

Initial Phase

During the first years, it is possible that the disease goes unnoticed: the early signs of Huntington can be subtle, relatively unremarkable deteriorations in movement or in cognition. The emotional and psychiatric alterations are very common already in the initial stage. In particular, irritability, emotional instability, and depression which can reach the criteria of major depression can occur.

Intermediate Phase

In this phase, Huntington’s disease is more visible and interferes to a greater extent in patients’ lives. Movement disorders such as Chorea is particularly problematic. The difficulties to speak, walk or handle objects also increase; Together with cognitive impairment, which becomes increasingly significant, these symptoms may make the person with Huntington’s disease to become dependent on others for daily activities. On the other hand, the worsening of emotional symptoms tends to damage social relationships. In large part, this is due to the reduced ability of the person suffering from Huntington to suppress emotions, which causes in some people to be aggressive or hypersexual, among other disruptive behaviors. Later the sexual desire will decrease. Other typical symptoms of the intermediate phase are decreased pleasure (anhedonia) and insomnia, which are very distressing for patients.

Advanced Phase

The last stage of Huntington’s chorea is characterized by the inability to speak and to execute voluntary movements, although most people retain an awareness of the environment. There are also difficulties to urinate and defecate. Therefore, in this period patients depend completely on their caregivers. Although the chorea may be aggravated, in other cases they diminish when the disease is at a very advanced stage. The difficulties to swallow increase, being able to cause death. In other cases, death occurs as a result of infections. There are also many suicides in this phase. The progress of the disease is usually faster when it appears at an early age, especially in children and adolescents, so the symptoms of the advanced stage appear earlier.

TREATMENT, MANAGEMENT, AND PREVENTION

At present, there is no known cure for Huntington’s disease, so the physical and cognitive deterioration cannot be stopped. However, there are symptomatic treatments that can alleviate the discomfort and increase the independence of the affected people to a certain extent. Treatment is based on the judgment of the healthcare professional. Treatment will require the services of many medical professionals including doctors, speech and language therapists, dieticians, and so on. Neuroleptics like risperidone and sulpiride are useful for psychiatric symptoms especially when the patient is feeling overly excited. They also help in treating chorea. Antidepressants like venlafaxine can also be used for depression. Methylphenidate, atomoxetine, bromocriptine or bupropion can be used to treat apathy. Motor symptoms like chorea can be treated using approved drugs like tetrabenazine or deutetrabenazine.

As the disease progresses, physical supports are introduced that facilitate or allow movement, such as handrails. Physiotherapy can also be useful to improve the control of movements, and physical exercise benefits general health, including psychological and emotional symptoms. Difficulties in speaking and swallowing can be reduced by speech and language therapy. Likewise, special utensils are used to eat until it becomes necessary to resort to tube feeding. It is recommended that the diet should be based on foods rich in nutrients and easy to chew to minimize the patient’s problems. There are treatments that target the huntingtin genes which show great promise in the treatment of Huntington’s disease. However, these are still in the trial phase.

Huntington’s disease is a genetic disease so people suffering from Huntington’s disease can pass it to their children. A way to prevent this is to go for genetic counseling. There are currently labs which can isolate sperms and eggs without the defective huntingtin’s gene from couples and implant them into the couples using in-vitro fertilization. This prevents genetic transmission of the disease from parents to children.