One of the best known hereditary diseases is Huntington’s chorea, a degenerative and incurable disorder that causes involuntary movements and other symptoms that affect multiple areas of a person’s life, progressively disabling them.
In this article we will describe the causes of Huntington’s disease, as well as the most common symptoms and the phases through which they progress . Finally, we will discuss the treatments that are usually applied to minimize the alterations as much as possible.
Huntington’s Chorea: definition and symptoms
Huntington’s chorea is a hereditary degenerative disease that affects the brain and causes various physical, cognitive and emotional symptoms.
It becomes incurable and ends up causing the person’s death, usually after 10 to 25 years. Drowning, pneumonia, and heart failure are common causes of death in Huntington’s disease.
When symptoms begin before age 20, the term “juvenile Huntington’s disease” is used. In these cases the clinical picture is somewhat different from the usual one and the disease progresses more quickly.
The most characteristic sign of this disease is the chorea that gives it its name . A group of neurological disorders that cause involuntary and irregular contractions of the muscles of the feet and hands are known as “chorea”. Similar movements also occur in the face.
In the case of juvenile Huntington’s chorea the symptoms may be somewhat different. They include difficulties in learning new information, motor clumsiness, loss of skills, stiffness of gait and the appearance of speech disorders.
Causes of this disorder
Huntington’s chorea is due to a genetic mutation that is inherited through an autosomal dominant mechanism . This means that 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 depends partly on heredity and influences the development of symptoms. In the most severe cases, the affected gene (the “huntingtin”) manifests itself very early and severely.
This disease affects the entire brain; however, the most important lesions are in the basal ganglia , subcortical structures related to movement. The area known as the “neostriatal”, which is composed of the caudate nucleus and the putamen, is especially affected.
Development of the disease
The symptoms of Huntington’s disease vary from case to case. However, its progress is usually grouped into three distinct phases.
The alterations worsen in conditions of psychophysiological stress, as well as when the person is exposed to intense stimulation. Weight loss is also common in all phases of the disease; it is important to control it as it can have very negative consequences for health.
1. Initial phase
During the first few years the disease may go unnoticed : the early signs of Huntington’s can be subtle, involving unnoticeable impairments in speed of movement, cognition, coordination or gait, as well as the appearance of choreic movements and stiffness.
Emotional disturbances are also very common already in the initial stage. In particular, irritability, emotional instability and decreased mood occur, which may meet the criteria for major depression.
2. Intermediate phase
In this phase, Huntington’s disease is more visible and interferes more in the lives of patients. Chorea is particularly problematic. Difficulties in speaking, walking or handling objects are also increased; together with cognitive impairment, which begins to be significant, these symptoms make independence and self-care difficult.
On the other hand, worsening emotional symptoms tend to damage social relationships. In large part this is due to Huntington’s-derived behavioral disinhibition, which causes some people to develop aggression or hypersexuality, among other disruptive behaviors. Later on, sexual desire will decrease.
Other typical symptoms of the intermediate phase are decreased pleasure (anhedonia) and sleep disturbances , which are very distressing for patients.
3. Advanced phase
The last stage of Huntington’s chorea is characterized by the inability to speak and to perform voluntary movements , although most people remain aware of their surroundings. There are also difficulties with urination and defecation. Therefore, in this period patients are completely dependent on their caregivers.
Although Korean movements can be aggravated, in other cases they are attenuated when the disease is at a very advanced stage. Swallowing difficulties increase and can lead to death by drowning. In other cases, death occurs as a result of infection. Also many suicides occur in this phase .
The progression 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 and handling
There is currently no known cure for Huntington’s disease, so the physical and cognitive decline cannot be stopped . However, there are symptomatic treatments that can ease the discomfort and increase the independence of affected people to some extent.
Dopamine blockers are used to treat the abnormal behaviours that are characteristic of the disease, while drugs such as tetrabenazine and amantadine are usually prescribed for additional movements.
As the disease progresses, physical supports that facilitate or allow movement are introduced , such as handrails. Physical therapy may also be helpful in improving movement control, and physical exercise benefits overall health, including psychological and emotional symptoms.
Speech and swallowing difficulties can be reduced through language therapy. Special eating utensils are also used until tube feeding becomes necessary. It is recommended that the diet be based on nutrient-rich and easy-to-chew foods to minimize the patient’s problems.