First drug for Huntington's disease approved for use in the U.S.

Aug 18 2008

Approval in the U.S. for the first drug to treat Huntington's disease is welcome news.

Huntington's disease is a fatal, inherited neurodegenerative disorder for which there is no cure and usually affects people in their 30s and 40s, but some patients are affected as early as childhood, while others aren't affected until they are older.

The disease is caused by the death of brain cells known as medium spiny neurons, which are killed off by a mutant protein and this destruction of brain cells causes an array of symptoms such as chorea, cognitive problems, changes in personality, and psychiatric problems like depression.

Chorea one of the trademark symptoms of the disease is the most disabling symptom of Huntington's disease, as it causes involuntary writhing movements.

Huntington's disease affects about 30,000 people in the United States alone and it is expected that another 70,000 people who are alive today will be diagnosed with the disease.

Many patients with the disease attempt suicide, and many suffer from progressive cognitive decline but 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.

Almost 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.

The gene responsible for the disease was identified 15 years ago and now a simple blood test can tell people whether they will develop the disease or not, but as there is no way known to prevent the disease or halt its progression, many patients decline the test, and simply wait and see if they develop symptoms.

The FDA has classified the drug tetrabenazine as an "orphan drug," since it targets a disease that directly affects fewer than 200,000 people in the nation and the action comes about eight months after an advisory panel unanimously voted that the drug should be made available to treat the disease.

Tetrabenazine is already widely used in Europe, Canada and Australia to treat chorea and research has found that the medication reduces the involuntary movements by about 25 percent, with many patients experiencing a greater improvement.

Experts say 90% of patients with Huntington's disease have chorea, and many suffer terribly and undergo ongoing torment.

Patients given the drug experienced a dramatic improvement in their quality of life and were able again to enjoy social activities they had been unable to participate in for for years.

They say many have been able to reclaim parts of life that they once thought were lost forever because of the disease.

Tetrabenazine does have some side effects, including the ability to worsen depression and to make movement more difficult and does not appear to help other symptoms of Huntington's disease or slow down the progression of the disease.

However most neurologists believe that overall, the benefits of the drug outweigh the side effects, especially considering that there has been no other medication approved for the treatment of Huntington's patients.