The effects on suicidal ideation were independent of effects on depressive symptom.
Toronto: A specific kind of brain stimulation may be effective in reducing suicidal thinking in people with hard-to-treat depression, as well as other mental illnesses, according to a study.
Forty per cent of people in the study, published in The Journal of Clinical Psychiatry, reported that they no longer experienced suicidal thoughts after receiving bilateral repetitive transcranial magnetic stimulation (rTMS).
"This is one of the first large studies showing rTMS is effective in treating suicidal ideation," said Jeff Daskalakis from Centre for Addiction and Mental Health (CAMH) in Canada.
"The effects on suicidal ideation were independent of effects on depressive symptom," said Daskalakis.
The findings give hope that, with further evidence, rTMS may offer a new way to prevent suicide in people with hard-to-treat depression, as well as other mental illnesses, researchers said.
Suicidal thinking can occur in several mental illnesses, including post-traumatic stress disorder, bipolar disorder, schizophrenia and borderline personality disorder.
It is estimated that about 90 per cent of people who die by suicide have a mental illness, they said.
While medications and psychotherapy are effective treatments for many people with mental illnesses, there is an urgent need for new treatments that quickly and specifically reverse suicidal thinking.
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.
The researchers analysed data from two earlier studies on rTMS given to people with treatment-resistant depression. At the start of these studies, 156 people reported that they experienced suicidal thoughts.
A non-invasive form of brain stimulation, rTMS directs magnetic pulses at a targeted area of the brain.
In these studies, rTMS was applied to the dorsolateral prefrontal cortex, an area in the frontal lobes, five times a week for either three or six weeks.
Participants were randomised 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 showed the biggest effect, and outperformed both other types, researchers said.
Forty per cent of people who received bilateral rTMS reported that they no longer experienced suicidal thoughts by the study end, they said.
By comparison, 27 per cent of those who received unilateral rTMS, and 19 per cent of those who received sham rTMS no longer experienced suicidal thoughts.
Bilateral rTMS was also the most effective at preventing the development of suicidal thoughts in people who were not experiencing suicidal thinking at the start of the study.