CALGARY -- Researchers at Calgary’s Cumming School of Medicine are seeing life changing improvements for some people living with treatment-resistant depression after using deep brain stimulation (DBS).

DBS has been used to treats Parkinson’s disease and other movement disorders for years but prior to the University of Calgary study, which began in 2014, little was known about its effectiveness in treating depression.

The treatment involves placing a battery in the patient's upper chest and running a wire under the skin, with its leads inserted into the brain.

Functioning like a “pacemaker for the brain”, the device stimulates the subcallosal cingulate, which is the junction of the limbic and frontal regions. Stimulating this area helps to keep a balance between the limbic and frontal regions of the brain.

"The basic understanding is the limbic system is hyperactive and frontal system is hypoactive, so that's why (these) people feel depressed," said Dr. Rajamannar Ramasubbu, a professor in the U of C departments of psychiatry and clinical neurosciences.

“So then by stimulating this region, it reverses and regulates properly.”

The surgery isn’t a cure all for everyone with depression. It is only being tested on those treatment-resistant forms of the illness, meaning those for whom therapeutic and chemical intervention has been unsuccessful. That accounts for approximately 10 per cent of people living with depression, according to Dr. Ramasubbu.

"They tried everything. So, so we have to provide some treatment options. So this is the last option, more or less."

Beth MacKay battled depression most of her life before enrolling in the research study.

"I had a lot of physical symptoms of depression. I had headaches. I had stomach aches, I was always sick," said MacKay.

"But I didn't think I was depressed. I had an idea of what depression looked like that I don't think was accurate."

Realization of how severe a problem she faced didn't come until she was 17 and tried to kill herself.

"I don't know that I realized I was depressed until I attempted suicide," she said.

Even armed with the knowledge of her illness, MacKay says it was impossible to find a successful treatment.

"It felt like I had to climb a mountain every morning to just get out of bed, shower and put on clothes, and if I made it to that point, it was a successful day," she said. "I just dragged along in a process of therapist after therapist and medication after medication. And nothing ever really worked."

So when she saw an online posting looking for research subjects for the DBS study, she signed up and stuck with her decision, even after learning it would require brain surgery.

"I was I was so low at that point that it honestly seemed totally fine," she said.

Now she’s glad she saw the research through, saying the small, battery-powered device implanted in her brain has had a huge positive impact.

"It has completely changed my life. It is turned me into a human being," she said. "I'm a much more positive person, I have an optimistic outlook about life, and I literally couldn't work before and now, to be a functional member of society, which is all I ever really wanted."

While DBS has been effective for MacKay, the U of C research has found it only seems to work on about 50 per cent of those undergoing the treatment.

Ramasubbu says further research is needed to see determine which patients with treatment-resistant depression will benefit from DBS, and notes the implants may help augment other treatments for depression.

“We have to focus on in the future. And mental health is going to be a main challenge in the future. So we have to really improve various treatment options," said Ramasubbu.

Findings from the U of Cumming School of Medicine study have been published in The Lancet Psychiatry.