Even as a child, Brian Chessell lived under a dark cloud of depression.

"I remember the first instance when I was six years old; of course, I didn't know what to call it then," Chessell said.

As he grew older, the symptoms got worse, until he was debilitated by depression. During one particularly intense bout, the now 47-year-old Chessell remembers being bed-ridden.

"Lying in bed not being able to move. Not wanting to eat. Wanting to sleep all the time. It was brutal," he said, speaking from his home Kincardine, Ont.

Though Chessell sought medical help for his condition, nothing seemed to work. But thanks to an experimental surgery, Chessell says the darkness that clouded his life for so long has been alleviated.

Chessell was one of 20 Canadian patients with seemingly incurable depression who recently received the surgical treatment known as deep brain stimulation (DBS).

"I was ready to try anything, and then when the DBS came along, it was (a) light at the end of the tunnel."

The procedure begins with doctors opening the scalp and drilling two holes into the skull. Doctors implant wires in the brain, and then thread wires under the skin of the scalp and neck to a pacemaker in the chest.

The wires are designed to deliver a steady electrical current to a part of the brain called cingulate 25, which is a small region about a centimetre wide. The area has been identified as a region that processes emotions, particularly sadness.

Studies have shown that the area becomes active when subjects are asked to think about something sad. However, in those with chronic depression, this region in the brain is constantly active.

Dr. Andres Lozano, a neurosurgeon at Toronto's Krembil Neuroscience Centre, says the cingulate 25 region of the brain is key. He says positron emission tomography (PET) scans of the area in depressed patients show it to be "in overdrive."

"We can see this on a PET image. And we placed electrodes in this overactive area of the brain to see if we could turn it down, and to see if we can improve the patient's depression," Lozano said.

Research suggests that up to six years after the surgery, around 64 per cent of patients continued to live a normal life. But the therapy didn't work for about a third of the patients. And in a troubling finding, two subjects committed suicide.

"In this particular group of patients, the suicide rate is very high; it is probably in the order of 15 to 20 per cent," said Lozano.

"This is like having malignant cancer, where despite all our treatments, despite chemotherapy, some of the patients will die."

Lozano said that more study into the procedure is needed, and already, researchers have insights.For example, Lozano said that younger patients with a very strong family history of depression might be more likely to respond positively.

The next step is to launch a larger study, involving 200 patients in 18 centres around North America. The team will operate on 40 patients in Toronto in total, with three operations completed as of Feb. 25, 2011.

With a report from CTV's medical specialist Avis Favaro and producer Elizabeth St. Philip