In Toronto, 150,000 people per year are diagnosed with a form of depression. That is the equivalent of the population of Moncton, New Brunswick. The majority of them show limited or no improvement with existing medication and therapy. This intrigued Dr. Z. Jeff Daskalakis at the Centre for Addiction and Mental Health.

He notes that while electroconvulsive therapy (ECT) works very well to help address severe forms of depression, a patient must be put under general anesthesia during a 40-minute daily treatment session. With the support of a 2014 Brain Canada Multi-Investigator Research Initiative (MIRI) Team Grant, Dr. Daskalakis and his team of Canadian researchers pioneered a new method to administer less invasive brain stimulation treatment: rTMS. Repetitive transcranial magnetic stimulation (rTMS) is a treatment for patients with depression who have not responded to antidepressant medications. Not only has the treatment shown to be effective, but unlike ECT, it does not need anesthesia.

(A) EEG cap; (B) Transcranial magnetic stimulation (TMS) applied to the cortex; (C) electrophysiological tracings from the cortex in response to TMS.
(A) EEG cap; (B) Transcranial magnetic stimulation (TMS) applied to the cortex; (C) electrophysiological tracings from the cortex in response to TMS.

Specifically, Dr. Daskalakis and his team are exploring a new type of rTMS called intermittent theta-burst stimulation (iTBS). rTMS treatment duration takes about forty minutes, whereas iTBS takes only three minutes to administer. The Canadian rTMS Treatment and Biomarker Network in Depression (CARTBIND) Trial, as the project is known, started with clinical trials comparing standard rTMS to iTBS in 294 patients with medication resistant depression. Half receive conventional rTMS treatment and the other half receive iTBS.

“The goal of CARTBIND is to derive a more fulsome understanding of the brain mechanisms responsible for the therapeutic effects of rTMS in the treatment of depression,” says Dr. Daskalakis. The team’s preliminary work is encouraging. It demonstrates that iTBS, while being faster to administer, works as well as standard rTMS in depression. If successful, the project will prove a method for increasing rTMS treatment capacities which will improve access to rTMS for all Canadians. Overall, improving the efficiency of rTMS – one of the few established treatments in medication resistant depression – will produce more personalized treatment approaches.

For Dr. Daskalakis, Brain Canada is unique. It was the first granting agency to take a risk in funding his work. Once he had secured a funding base, he was able to get additional monies, including internationally; he secured a grant from the United States National Institutes of Health. Indeed, certain sites in the United States are already using transcranial magnetic stimulation, including to test as atherapy for Post-Traumatic Stress Disorder.