The symptom that tetrabenazine treats ?involuntary, writhing movements of the limbs, face, and sometimes the entire body ?is the hallmark symptom of Huntington's disease, an inherited neurodegenerative disorder that worsens as brain cells known as medium spiny neurons are killed off by a mutant protein.
The disease brings with it an array of other difficulties as well, including cognitive problems, changes in personality, and psychiatric problems like depression. As many as one-quarter of patients with the disease attempt suicide, and many suffer from progressive cognitive decline.
Unlike Alzheimer's disease, where patients usually lose their memory and insight into their disease at some point, most Huntington's patients understand exactly what is happening to them throughout most of their illness.
The disease usually strikes people in their 30s and 40s, though some patients are affected as early as childhood, while others aren't affected until their older years. Virtually everyone with the disease had a parent with the disease, and children of a person with Huntington's have a 50-percent chance of inheriting the disease.
Thirteen years ago the gene that causes the disease was identified by scientists, and now a simple blood test can tell people whether they will develop the disease or not. But since there is no way known to prevent the disease or slow its progression, and for other reasons as well, many patients decline the test, instead waiting to see if they develop symptoms like the ones they witnessed in a parent.
Patients usually live for 15 to 20 years after the onset of symptoms.
"Tetrabenazine does not help all the features of Huntington's disease, and other medications are commonly needed to improve mood and behavior. For those Huntington's disease patients whose function is impaired by chorea, however,
Source:Rush University Medical Center