Complications of Huntington’s Disease
Huntington’s Disease (HD) is not fatal in itself. People with HD have a shorter life expectancy and die of other life-threatening complications related to this disease. Pneumonia and heart disease are the two leading causes of death for people with HD. Additionally, HD patients have higher incidence of choking and respiratory complications, gastrointestinal diseases (such as cancer of the pancreas), and suicide than the non-HD population. Why are HD patients more prone to the above complications than the rest of the population? This chapter aims to answer that question and draw connections between the symptoms of HD and the most common causes of death (see the table below). Although researchers have not explicitly proven these links in every case, the following information hopes to demonstrate a logical connection.
|Primary cause of death (in rank order)||Persons (total=182)||Percentage|
Other respiratory diseases
|Myocardial infarction/degeneration (heart attack
Congestive cardiac failure (heart failure)
Other diseases of the cardiovascular system
|Unspecified Huntington’s-related causes||23||12.6|
|Vascular lesions of central nervous system||10||5.5|
|Non-vascular lesions of central nervous system (e.g. meningitis)||4||2.2|
|Genito-urinary diseases (e.g. kidney failure)||5||2.7|
|Gastro-intestinal diseases (cancer of the pancreas)||3||1.6|
|Reed TE, Chandler JH, Hughes EM, et al. Huntington’s chorea in Michigan: I. Demography and Genetics. Am J Hum Gen 1958; 10: 201-225.|
One of the chief symptoms of HD is the inability to produce coordinated movements. In the latter stages of the disease, this problem becomes more pronounced to the point that people have difficulty swallowing. Although it is so common that we hardly think about it, swallowing is actually a complex series of movements by muscles in our throat to ensure passage of food into the esophagus (gastrointestinal tract) rather than the trachea (respiratory tract). As a result of these movements, the epiglottis, a flap that acts as a valve in our throat, prevents food from entering the airway. People with HD often lack this coordination, and food will accidentally enter the respiratory tract, leading to choking. Moreover, when food particles manage to get into the trachea (the “wind pipe” leading to the lungs), instead of the esophagus (the “food pipe” leading to the stomach), the lungs can become infected and cause what is known as aspiration pneumonia.
Although pneumonia is relatively common among people in the general population, it is only fatal in about 5% of these cases. However, pneumonia is much more dangerous in people with compromised immune systems. Researchers have demonstrated that stresses imposed on a person for prolonged periods of time can severely damage the body’s ability to ward off diseases. The physical, cognitive, and psychiatric symptoms of HD add a great deal of stress to everyday life for these patients (for more information on these symptoms, click here). As a result, their immune systems are compromised and diseases such as pneumonia are therefore more likely to result in death. For instance, in a long-term study conducted from 1952 until 1979 in Victoria, Australia, researchers found that more than 51% of patients with HD died from pneumonia.
The increased physical and emotional stress associated with HD can cause other problems as well. Chronic stress has been linked to high blood pressure, increased risks for heart attacks, and tumor growth. In addition, although studies have shown that suicide is not a leading cause of death for HD patients, suicide rates are higher than among the rest of the population. This is probably due to a combination of factors, including neuropsychiatric changes induced by HD and the added stress of daily life.
Although researchers have yet to find a cure for the disease, people with HD can take measures to prolong their lives. For example, extra care should be taken when eating to prevent choking and pneumonia caused by food going the wrong way. Regular exercise and sleeping in an elevated position can reduce the risk of respiratory infections. Patients can also maintain a healthy diet and reduce or eliminate other risk factors for heart disease, such as smoking and alcohol, from their lives.