Mental illness presents one of the great challenges to modern society, a leading cause of disability, absenteeism and deaths due to suicide. Not only does it strike one in five Canadians, usually in their prime, but too often it defies the ability of modern medicine to treat it.
Depression, which affects one in 12 people in this country, is one of the trickiest disorders to cure. While 80 per cent of patients find effective relief with standard drug or psychotherapies, the latest numbers suggest that only 40 per cent truly feel well. Worse, experts estimate that, for 10 to 20 per cent of sufferers, nothing works.
The most promising treatment for intractable depression on the horizon is not a designer drug, a new form of talk or even genetic therapy. It's electricity that can lift the human spirit with deep brain stimulation (DBS),where surgeons implant metal rods that aim steady pulses of electrical current at the faulty neural circuits believed to underlie mental illness.
Society has long separated neurological diseases from psychiatric ones, as though physical conditions can stem from concrete malfunctions of the brain but maladies of the mind cannot. Dr. Lozano says more than 40,000 Parkinson's patients have already had DBS ease their tremors by targeting parts of the brain where motor neurons misbehave.
In 2003, University of Toronto researchers tested DBS on depression, it proved safe, it also made some subjects better. Since then, 50 patients in Toronto, Vancouver and Montreal, as well as at least 30 in the United States, Europe and South America, have undergone the procedure in a bid to see whether electrical implants can indeed mend a broken mind.
The Toronto researchers point out that it's not the use of electricity that makes their treatment a major advance – it's where they direct it. “With brain surgery, it's like real estate – it's location, location, location,” says Andres Lozano, the neurosurgeon and senior scientist who has led the trials at Toronto Western Hospital.
The only difference in using DBS for depression is that the electrodes target the brain area where sadness lives, behind the eyeballs, four centimetres back in from the forehead. That's where Dr. Mayberg found it after 20 years of brain-imaging studies, in Boston, Texas and then Toronto in the late 1990s.
Seated in the ancient limbic lobe, 'Area 25' connects to the brain structures involved in human function – emotion, memory, stress, sleep, libido, appetite, energy levels and learning. “It's linked into all the core areas involved in depression,” Dr. Mayberg says. The images led to a hypothesis: If they had found one of the sites where a feeling runs amok, could they find a way to fix it? Would the type of DBS used for Parkinson's charge the cells in Area 25 out of their “on” position?
In 2001, Dr. Mayberg and Dr. Lozano met at a conference of neurosurgeons. Dr. Lozano was world renowned for his brain-stimulation operations. He had performed DBS for Parkinson's and other neurological disorders since 1992 – about six times a month. When Dr. Mayberg suggested that they try it for depression, he thought it was “a long shot” – but right up his alley.
Deciding who makes the cut is in part the job of Sidney Kennedy, the health network's head of psychiatry. Deeply involved in planning the DBS trial, he describes the procedure as a “major paradigm shift” in the treatment of a mood disorder. “It has been an interesting role for the psychiatrist: He's evolved from psychotherapies, to pharmacotherapy … to adjustments with stimulators. … It's one of the best examples where psychiatry meets neuroscience.”
Dr. Lozano stresses that, unlike other psychosurgeries, DBS can be reversed, the electrodes removed, and five years since their first patient, none has suffered serious side effects.
The risk experience with DBS for Parkinson's suggests that one in every 500 patients will suffer a hemorrhage during the surgery. Four in a thousand will suffer a serious complication, such as a permanent neural deficit or even death. If the numbers of patients being treated rise appreciably, “it will happen” for depression as well, he says flatly.
The positive affects rarely appear right away. Dr. Giaccobe says, it can be difficult for people who have been profoundly depressed for so long suddenly to reclaim their lives. “They still have ups and downs,” and even their relationships change. Patients can have their moods improve, but still have a lazy libido or erratic appetite and need reminders that it can be tricky to distinguish depression from a mere mood swing.
Mr. Miller says. “You have to remember that every bump in the road is not a return of the depression.”
