Huntington’s A Prion Disease
Huntington’s disease is a genetic, progressive, neurodegenerative disorder. It causes involuntary muscle movements in the hands, feet, face and core. Like the diseases mentioned earlier, it also causes progressive loss of cognitive processes and memory.
Huntington’s is in part a family disease. Though everyone is born with the huntingtin gene, the disease is caused by an abnormal mutation, which parents pass to their children. Only a person born with the abnormal gene can get the illness. Every person with the abnormal gene will develop symptoms if they live long enough. In addition, it appears that HD is caused by an abnormal huntingtin protein. The protein is a form of prion (infectious and deadly proteins). This is bad news for caregivers and it likely explains the intensity of the disease within families because they are infecting each other and others who cross their paths.
Prions (PREE-ons) are formed from proteins normally present in the brain. As these proteins turn into prions, they adopt an aberrant shape, which becomes self-propagating (transmissible).
The HD gene was identified in 1993. Now a test allows a person to find out if they carry the abnormal HD gene. While the test is very accurate, it cannot determine when the symptoms will begin. People who test positive for the gene may remain unaffected for many years.
Movement abnormalities may include uncontrolled, irregular, jerking movements and slow, writhing, involuntary movements. The dementia includes progressive disorientation and confusion, muted personality, impairment of memory, restlessness and agitation. The disease can impact people for their last 10 to 25 years or more.
In the early stages of HD, people see subtle changes in mood, movement, and brain function. The person may still be able to drive and hold down a job, but might require more help than in the past.
During this stage, people lose the ability to work and drive. They need help performing daily activities. This is the stage where people often apply for disability. The movement disorder leads to difficulties with balance, swallowing, and voluntary motor tasks. Individuals have more difficulty organizing and prioritizing information. The behavioral symptoms affect everyone differently, but irritability, aggression, depression, and apathy during this stage can lead to personal and family issues, not to mention involvement by law enforcement.
In the late stage of Huntington’s disease, people require help in all aspects of daily life. At this point, the person may lose the ability to speak and respond, but is still able to comprehend what is happening around them. Chorea (writhing and shaking) can be severe. During this stage, many people enter long-term care facilities to access 24/7 care. Life-threatening complications may result from pneumonia, infections, and falls.