Gene therapy might have the potential to reverse symptoms of Parkinson’s disease, according to a new study published in the Lancet Neurology today.

The phase 2 trial involving 45 patients found that after six months, patients treated with gene therapy experienced on average a 23% improvement in motor score as compared to 13% for those who received a fake surgery.

This is the first time that gene therapy has been proven effective for Parkinson’s disease in a double-blind phase 2 trial.

“We have now reached a milestone that has not been achieved before,” says study author Michael Kaplitt of Weill Cornell Medical Center in New York. “We are now one step closer to using these procedures in general practice.”

The treatment involves using a harmless adeno-associated virus as a vector to deliver the gene for glutamic acid decarboxylase into cells. This, in turn, boosts cells’ production of the key nerve signaling compound gamma-aminobutyric acid (GABA), thought to help inhibit overactive brain activity that could cause the movement problems seen in Parkinson’s.

The promising results announced today come after a phase 1 open-label trial involving 12 patients who after six months demonstrated improvements in movement comparable to those seen in the more recent trial.

Follow-up studies are ongoing to determine if the procedure is safe and effective long-term. The team hopes to launch a phase 3 trial for Parkinson’s disease soon.

“This could be the beginning of a new era for Parkison’s patients,” says Kaplitt, who also serves as scientific co-founder of Neurologix, a New Jersey-based biotech company developing this gene therapy strategy.