Gene therapy being pioneered in the US could significantly reduce symptoms of Parkinson's disease, scientists said today.
Doctors have used injections into the brain to deliver a virus designed to calm abnormal brain cells that cause uncontrolled movement associated with the condition.
Eleven men and a woman underwent a trial at the Weill medical college, part of Cornell University in New York. The research was only conducted to assess the safety of the procedure rather than its efficiency, but results were encouraging.
Scientists established that none of the patients suffered side effects and within three months all showed "substantial" improvements that subsisted for at least a year.
Writing in The Lancet medical journal, the researchers led by Professor Matthew During concluded: "Our results show that ... gene transfer can be done safely in the human brain, with no evidence of substantial toxic effects or adverse events in the perioperative period and for at least one year after treatment."
Parkinson's disease is caused by the loss of brain neurons that release the motor nerve messaging chemical dopamine.
Symptoms include muscle rigidity, tremors and difficulty walking. The disease is linked to over-activity in a brain region called the subthalamic nucleus (STN).
By using the new gene therapy treatment, however, doctors were able to inject the glutamic acid decarboxylase (GAD) gene directly into the brain.
The gene creates a protein that calms the over-excited brain cells, which misfire in Parkinson's suffers to cause muscle rigidity and shaking.
Brain scans of the patients showed biochemical effects in the brain similar to those who have had successful surgery for Parkinson's.
Scientists said the new treatment had advantages over a current treatment that involves implanted electrodes. Infection risk was lower and some patients preferred not to have a brain implant. A larger trial is planned for later this year.
Dr Kieran Breen, director of research and development for the UK Parkinson's Disease Society, said: "The cause of Parkinson's is not known but it is likely to be a combination of genetic susceptibility and environmental factors.
"Because of this, there are many potential ways to treat or cure Parkinson's, and gene therapy is one potential route holding a lot of promise.
"This phase one study is very interesting because there has been no evidence of side effects and some evidence that this type of therapy produces positive benefits.
"As such, it is an important platform for further studies to build on.
"The results of the study are encouraging in terms of safety and efficacy and we look forward to seeing the results of the larger trial."
An estimated 120,000 people in the UK suffer from Parkinson's.
