Progress in psychiatry | A “pacemaker” for severe depression

“It’s because I visited the Jurassic Park…” Camille Heyen-Dubé sometimes responds like this when her little patients ask her about the red mark on her neck.

No child would guess that his intriguing scar is not the result of dinosaur scratches, but rather of an operation as fascinating as it is extremely rare. That barely forty Quebecers suffered so as not to fall back into the abyss of depression.

For a year and a half, the Montreal nurse’s body has housed two electrodes connected to a thin electricity generator similar to the one implanted in cardiac patients. Except that instead of being connected to the heart, its device stimulates the vagus nerve. A very long bundle of fibers which innervate the organs and go up through the neck, to relay incalculable information to the brain.

When people learn that I have an implant, some can’t believe it! I was once told, “Oh my God, take some vitamin D and it will take care of itself…”

Camille Heyen-Dubé


An example of a battery-powered generator used to stimulate the vagus nerve of patients suffering from hyper-refractory depression.

Every five minutes, its generator emits current. For 30 seconds, it slightly paralyzes the vocal cord located near the electrodes. “My voice then becomes lower and muffled, and I get a little out of breath if I go up the stairs. At first, I felt like an unpleasant tightness. But now I don’t feel it anymore, unless I’m very tired. » If necessary, the young woman can deactivate her stimulator using a magnet.

Treat night and day

Before being operated on, Camille Heyen-Dubé had received another cutting-edge treatment: transcranial magnetic stimulation, as we told in the first part of this report1. But after two years of remission, she had to start doing one session after another to avoid falling back into it. “It became difficult to spend so many half days in the hospital, since I had gone back to school to do my master’s degree and was about to return to work,” she says.

The 32-year-old nurse therefore began to do countless research, which allowed her to discover that her psychiatrist, Paul Lspérance, was also in charge of a neurostimulator implantation program. About three or four hand-picked people undergo this operation each year at the University of Montreal Hospital Center (CHUM), which is the only one to offer it in Quebec, and the main one in Canada.


The Dr Paul Lspérance, director of the psychiatric neuromodulation program at the CHUM

Depression is often a recurring illness. When relapses are very numerous, treating patients continuously – 24 hours a day – helps prevent them. Once operated on, many were never hospitalized again, although they were frequently before.

The Dr Paul Lspérance, director of the psychiatric neuromodulation program at the CHUM

The intervention – reversible – succeeds in getting one in two patients out of hyper-refractory depression, and often improves their cognitive functions even before their mood, says the specialist. “But some refuse. They cannot imagine being operated on for nothing and we cannot guarantee that it will improve their condition. »

A mystery

Predicting who the treatment will help or not remains difficult, since its psychiatric benefits were discovered by pure chance 25 years ago.

Researchers had just started to stimulate the vagus nerve of people with epilepsy. In some cases, they did not get better afterwards, but still refused to have their implant removed. Because it failed to control their seizures, but strangely improved their mood, explains the Dr Hope.

Despite the passage of time, the reasons for explaining this phenomenon remain partly mysterious.

Carrying current to the brain probably gives a beneficial boost to neurons, by modulating their production of neurotransmitters. Without these chemical messengers – which antidepressants also target – cells cannot exchange all the information required to carry out their missions.

But the vagus nerve has so many ramifications and plays so many roles that several mechanisms could be at work, specifies the Dr Hope. “We have lots and lots of hypotheses, but there are no certainties; nothing has been demonstrated. »

Some researchers suggest that revitalizing the vagus nerve acts on the insula – an ancient brain region involved in what are sometimes referred to as “gut feelings”, such as stomach aches and nausea. Others believe the treatment activates the growth of hippocampal cells, which could affect emotional memory.

Or finally, that the essential role of the vagus nerve in the control of neuro-inflammatory processes is in question.

For Camille, it doesn’t matter. She feels transformed. “When my father died recently,” she says, “I experienced normal grief, not depression. And I’m no longer afraid of it coming back every fall, when the leaves change color. »

Breathe to stimulate your vagus nerve

Since stress and anxiety inhibit the activity of the vagus nerve, it sometimes struggles to play its many roles well, even in the absence of depression. Fortunately, anyone can stimulate their nerve by practicing deep breathing exercises, such as “heart coherence”, which many mobile applications allow you to practice without having to count the seconds. The effect is not as powerful as that of a neurostimulator. “But it would probably be useful in preventing depression or relapses,” says Dr.r Paul Lspérance, psychiatrist at the CHUM. The problem is doing it regularly. »


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