Patients suffering from severe depression who have not responded to other treatments may be helped by deep brain stimulation, researchers said on Monday.

The treatment, which is like a pacemaker for the brain, uses electrodes implanted in the brain to switch off or interrupt electrical circuits linked to depression.

In four out of six patients who failed on all other treatments, deep brain stimulation relieved their depression.

“Patients would experience an immediate shutdown of a negative state,” Dr Helen Mayberg, a neurologist at Emory University School of Medicine in Atlanta, Georgia told a news conference.

The technique was developed for Parkinson’s disease patients but Mayberg and her colleagues have adapted it for patients with severe depression.

“It is the most exciting new development in terms of the treatment of depression in 10 years,” said David Nutt, the head of psychopharmacology at Bristol University, England.

Using brain-imaging techniques, the scientists implanted electrodes deep into an area of the brain that they had linked to depression while the patients were under a local anaesthetic.

As their brains were stimulated, the patients, who were awake, were told to explain what they were feeling. They described a sense of calmness or easiness.

There were no side effects, according to the researcher. “The important thing to realize about brain stimulation is that it isn’t just that you are exciting the brain, you are using electricity to basically tune or modulate a circuit,” Mayberg said.

“It is the turning off of a negative state.”

In patients who responded to the deep brain stimulation, a device similar to a pacemaker was implanted to keep simulation constant. Two years after the experiment, the patients are responding well.

“These are extremely encouraging first results,” said Mayberg.

The researchers, who are planning further studies, said the therapy would be suitable for patients with the most severe and debilitating depression who have failed to respond to all other treatments.

“These are serious interventions for serious disease,” she added.