The one-year results from a new surgical approach that targets tough-to-treat depression show a significant benefit, according to Canadian researchers.

Deep brain stimulation, in which electrical impulses are sent through electrodes that are implanted in the section of the brain called the subcallosal cingulate gyrus, was shown to offer relief from depression in 60 per cent of patients, say researchers at Toronto Western Hospital.

These patients, who suffered from major depressant disorder, a severe form of depression that is unresponsive to other treatments, were able to reduce their medication as symptoms improved.

"Our research confirmed that 60 per cent of patients have shown a clinically significant response to the surgery and the benefits were sustained for at least one year," said Dr. Andres Lozano, neurosurgeon at Krembil Neurosciences Centre, Toronto Western Hospital, in a release.

The therapy appears to change the metabolic activity of what's known as the depression circuit. This means that, in effect, the brain is rewired, altering the cycle of depression.

In the study, researchers found that one month after surgery, 35 per cent of patients responded well to the therapy, with 10 per cent of patients entering remission. Six months after surgery, 60 per cent of patients responded well to the surgery and 35 per cent were in remission.

Few side-effects

The researchers say the procedure is safe, with few serious side-effects reported and no patients suffering long-term harm from the procedure. The side-effects reported included wound infection and removal of hardware, one case of a seizure following surgery, two cases of worsening mood or irritability, four cases of headache after surgery and one case of pain at the operative site.

"The procedure is well tolerated and no patient suffered a permanent serious adverse effect," said Lozano. "In contrast to previously utilized ablative neurosurgical procedures for depression, DBS is adjustable and stimulation is reversible.

"These features increase safety and may offer advantages for both the efficacy of the therapy and its acceptance in the patient, medical, and psychiatric community."

Depression affects one in 50 Canadians at any moment in time, one in 20 in the course of a year and one in 10 in over a lifetime, according to Statistics Canada.

The results are published Monday in the journal Biological Psychiatry.