The 55-year-old patient had dinner after the procedure and was doing well, according to Dr Michael Kaplitt of Weill Cornell Medical College in New York.

The man, who was not identified, is the first of 12 patients taking part in a study focusing on the procedure’s safety, rather than whether or not it relieves symptoms.

“Our whole goal here is to prove this is safe before we move on,” said Kaplitt, who is doing the new study in collaboration with Matthew During of the University of Auckland in Australia.

Chemical release

Certain brain areas in people with Parkinson’s becomes overactive because they lose their normal supply of a calming chemical called gaba. The new gene therapy is aimed at making one of those areas, the subthalamic nucleus, produce more gaba.

The patient was awake and making jokes during the procedure.

The chemical should not only quiet that area but also be released to the other overactive brain areas, said Kaplitt.

Key symptoms of Parkinson’s include shaking hands, arms and elsewhere, slowness of movement and impaired balance and co-ordination. Patients can have trouble walking or talking.

While drugs can relieve symptoms, they cannot stop the progression of the disease. Surgery can ease symptoms by quieting areas.

During the experimental procedure a tiny tube about the width of a hair was threaded through a hole about the size of a coin on top of the patient’s skull. The tube delivered a dose of a virus engineered to ferry copies of the gene into cells of the subthalamic nucleus, an area of the brain.

The gene will let the cells pump out gaba.

The patient was awake during the procedure and “making jokes most of the time,” said Kaplitt.

Scientists have also delivered gene doses to children’s brains in a study of treating a condition called Canavan’s disease.