For those with major depression, the electrodes are placed in the part of the brain that regulates mood.
That part of the brain is shown to be overactive in depressed people, and while researchers are not certain how deep brain stimulation works, it's believed that stimulating the area can help treat depression.
Researchers implanted electrodes in the brains of 20 people who were in a major depressive episode.
Nine of them were men, 11 women; all of them were in their 40s.
The study was in two parts. Six patients were treated with deep brain stimulation in 2005; the new results followed up another 14 people for a year.
Researchers found that after getting deep brain stimulation, patients were calmer, had improved moods, and were more interested and motivated in life.
The effects lasted up to a year in the 14 people who were followed up for that long.
"Our research confirmed that 60% of patients have shown a clinically significant response to the surgery and the benefits were sustained for at least one year," says researcher Andres Lozano, MD, in a news release. Lozano is a neurosurgeon at Krembil Neurosciences Centre-Toronto Western Hospital.
"The underpinnings of depression are poorly understood and this therapy, although not perfect, offers numerous advantages."
Some of those advantages, he adds, beyond lifting depression, are that the procedure carries little risk and has few side effects.
One patient who received the procedure said it "gave him his life back." In a news release, study participant Sean Miller says, "The pain, fear, anxiety and depression are pretty much completely gone and I am now a very happy, healthy, working, active, fulfilled and grateful individual."
Researchers are calling for wider study before recommending that people with major depression get deep brain stimulation.
In background information published with the study results, the researchers write that 10% to 20% of depressed people do not respond to typical treatment like psychotherapy, antidepressants, or electroconvulsive therapy.
This type of treatment-resistant depression is one of the major causes of suicide, according to the researchers.
The results are published online in Biological Psychiatry.