A specific type of non-invasive brain stimulation, known as rTMS (repetitive transcranial magnetic stimulation), can reduce suicidal thinking in a significant portion of people with hard-to-treat depression, according to a new study published in The Journal of Clinical Psychiatry.

In fact, 40 percent of the study participants who underwent bilateral rTMS reported that they were no longer experiencing suicidal thoughts. The brain stimulation works by directing magnetic pulses at targeted areas of the brain.

Suicidal thinking is a common symptom among people with a variety of mental disorders, such as post-traumatic stress disorder (PTSD), bipolar disorder, schizophrenia and borderline personality disorder. It is estimated that about 90 percent of people who die by suicide have a mental illness.

The new findings give hope that, upon further evidence, rTMS may offer a new way to prevent suicide in people with hard-to-treat depression, as well as other mental illnesses.

“This is one of the first large studies showing rTMS is effective in treating suicidal ideation. The effects on suicidal ideation were independent of effects on depressive symptoms.” said Dr. Jeff Daskalakis, senior author of the study.

While medications and psychotherapy work for many people with mental illness, there is still an urgent need for new treatments that quickly and specifically reverse suicidal thinking.

“One of the only effective treatments for suicidal ideation is electroconvulsive therapy or ECT,” said Daskalakis, co-director of the Temerty Centre for Therapeutic Brain Intervention at the Centre for Addiction and Mental Health (CAMH) in Toronto, Canada.

“While ECT is the most effective treatment in psychiatric care, it’s rarely used, because of high stigma and adverse cognitive side effects associated with the treatment. Less than one percent of patients with hard-to-treat, or treatment-resistant, depression get ECT.”

Treatment-resistant depression is defined as the condition when people do not experience a noticeable improvement in their symptoms after trying at least two different antidepressant medications.

Up to 40 percent of people with depression are treatment resistant. Earlier CAMH studies have shown rTMS is an effective therapy for treatment-resistant depression.

For the new study, the researchers looked at data from two previous CAMH studies on rTMS given to people with treatment-resistant depression. At the beginning of these studies, 156 people said they experienced suicidal thinking.

For the new research, rTMS was applied to the brain’s dorsolateral prefrontal cortex, a region in the frontal lobes, five times a week for either three or six weeks. Participants were randomized to receive rTMS in one of three ways: to both the right and left frontal lobes (bilateral rTMS), the left frontal lobe only (unilateral rTMS) or, as a comparison group, sham rTMS, which is similar to a placebo.

Bilateral rTMS was the most effective of the three types. A total of 40 percent of people who received bilateral rTMS reported that they no longer experienced suicidal thoughts by the end of the study period.

By comparison, 27 percent of those who underwent unilateral rTMS, and 19 percent of those who received sham rTMS no longer experienced suicidal thoughts. In addition, bilateral rTMS was the most effective at preventing the development of suicidal thoughts in people who were not experiencing suicidal thinking at the start of the study.

So although left unilateral rTMS is the most common type, the findings suggest that targeting the right frontal lobe may be key to treating suicidal thinking, said first author and psychiatry resident Dr. Cory Weissman in the Temerty Centre for Therapeutic Brain Intervention.

Previous studies in people with depression and suicidal ideation has shown that this brain region may be linked with impulsivity and difficulties with regulating emotions. In the future, the researchers plan to zero in on the right frontal lobe.

Surprisingly, the reduction in suicidal thinking was not strongly connected to a decrease in the severity of depression symptoms.

“This suggests that suicidality is not necessarily just a symptom of depression — it may be a related, but separate entity,” Weissman said.

Since suicidal thinking is known to occur across multiple mental disorders, identifying an effective treatment may prevent suicide for a broad spectrum of people with mental illnesses.

Source: Centre for Addiction and Mental Health

For Hard-to-Treat Depression, Brain Stimulation Can Ease Suicidal Thinking