Scientists have found a way to delay the onset of Huntington's disease and slow its progress in mice by targeting an enzyme that is believed to trigger cell death, according to a study in Thursday's issue of the journal Nature.
The symptoms of the disorder generally appear between 30 and 50 years of age and include an unsteady walk, involuntary movements, slurred speech, seizures and personality changes. The disorder affects 30,000 Americans.
Victims cannot control their limbs and suffer from dementia. There is no cure and each child of a parent with the disorder has a 50-50 chance of getting it.
The latest finding is a promising lead for drug researchers working to extend the lives of Huntington's sufferers.
"I think this is important and exciting. This is the first demonstration of a drug that can slow the progress of HD in an animal model," said Dr. Christopher Ross, a Johns Hopkins Medical School professor and a scientific adviser to the Huntington's Disease Society of America. "It says this goal of slowing progress probably can be accomplished."
Huntington's has been linked to enzymes called caspases, which cause brain cells to die slowly.
Caspase-1 apparently plays a role in the cell death that marks Huntington's, which usually kills sufferers within 15 to 20 years. How the enzyme works is unclear, but scientists think that it slices up the so-called Huntington gene, and that the fragments then kill the cell.
In the study, scientists from Harvard University's Brigham and Women's Hospital blocked a particular caspase in mice that had been genetically engineered to contract the disease. These mice developed Huntington's symptoms about 10 percent later in life and lived about 20 percent longer.
The Harvard researchers slowed that process by breeding mice with a mutant protein that counteracts caspase-1.
The mice showed Huntington's symptoms after 84 days, on average, compared with 77 days in the other mice. The mice with the caspase blocker lived an average of 121 days, compared with 101 days for the other mice.
"If one drug can do this, hopefully, in the future, you can find others," said one of the researchers, Dr. Robert Friedlander.
What is exciting, Friedlander said, is that the same mechanism at work in this study may be applied to research on brain injuries and illnesses such as Lou Gehrig's disease and Parkinson's.
"Caspase inhibition may turn out to be the magic bullet against neurodegenerative disease," University of Munich biochemist Christian Haass said in an accompanying editorial.
One Huntington's disease specialist told CBS News the results of the study are exciting, but more research on mice will probably be needed before movinon to human trials. The study's researchers say they hope to have a drug for human trials in the next few years.