Huntington's disease is an adult-onset, genetic brain disorder characterized by loss of muscle control and advancing deterioration of the thought processes. The early stages of Huntington's disease primarily affect the muscular system. With progressive deterioration of the brain tissue, other organ systems exhibit manifestations of the disease. The National Institute of Neurological Disorders and Stroke states that more than 15,000 adults in the United States are living with Huntington's disease as of 2010.
Huntington's disease profoundly affects the musculoskeletal system due to loss of brain cells, or neurons, that control the initiation, coordination and fluidity of movement. The first symptoms of Huntington's disease typically appear between the ages of 30 to 50, reports the University of Utah Genetic Science Learning Center. Muscle twitching and lack of coordination often herald the disease. Progressive loss of the neurons that control movement leads to additional symptoms, including speaking difficulties, clumsiness, random eye movements and involuntary jerking.
Lack of coordination and involuntary jerking, or chorea, lead to an increased risk for falls and broken bones. In the advanced stages of Huntington's disease, loss of controlled muscular function leaves patients incapable of performing the tasks of daily living, such as feeding themselves, dressing, bathing and walking. People with late-stage Huntington's disease are frequently bedridden and unable to speak.
Huntington's disease adversely affects the digestive system. Loss of muscle control causes chewing and swallowing difficulties. The American Speech-Language-Hearing Association notes that people with Huntington's disease typically have difficulty holding food and liquids in the mouth, initiating swallowing and clearing food from the mouth. Uncoordinated activity of the esophagus, which transports food from the mouth to the stomach, often leads to regurgitation of swallowed food. Eating difficulties result in progressive weight loss, a hallmark symptom of advanced Huntington's disease. A declining appetite may also contribute to poor nutritional intake.
Loss of muscle control usually leads to an inability to control the passage of stool. Most people with advanced Huntington's disease have fecal incontinence. Fecal contamination of the external opening for urine passage may lead to urinary tract infection, especially among women.
Swallowing normally triggers a reflex muscular contraction of the epiglottis, a piece of tissue in the throat that covers the opening to the airway to prevent food from entering the lungs. The disordered swallowing associated with Huntington's disease commonly interferes with the coordinated closure of the airway, causing frequent episodes of choking and contamination of the airway with ingested food and liquids. Food contamination of the lungs frequently leads to pneumonia. The Huntington's Outreach Project for Education at Stanford University reports that pneumonia is the leading cause of death among people with Huntington's disease.