It is estimated that approximately 40% of patients with major depression do not respond to antidepressants and suffer from treatment-resistant depression. Repetitive transcranial magnetic stimulation (rTMS) is a first-line treatment option for treatment-resistant depression, and it is becoming widely implemented and used around the world.
A new study maps how the brain changes during rTMS. Although proven effective, the mechanisms behind how rTMS affects the brain have not been well understood.
To determine what happens to the brain when rTMS treatment is being delivered, scientists from UBC’s department of psychiatry delivered one round of rTMS to patients while they were inside a magnetic resonance imaging (MRI) scanner. As MRI can measure brain activity, scientists can see the changes in the brain in real time.
Stimulation of the dorsolateral prefrontal cortex activated several other regions of the brain. These different regions are involved in multiple functions — from managing emotional responses to memory and motor control.
The participants were then given another four weeks of rTMS treatment. The scientists looked to see if the active regions were linked to patients having reduced depressive symptoms after the treatment.
Dr. Vila-Rodriguez, an assistant professor in UBC’s department of psychiatry, said, “We found that regions of the brain that were activated during the concurrent rTMS-fMRI were significantly related to good outcomes.”
“With this new map of how rTMS stimulates different brain areas, we could determine how well a patient is responding to rTMS treatments.”
“By demonstrating this principle and identifying regions of the brain activated by rTMS, we can now try to understand whether this pattern can be used as a biomarker.”
Scientists are now exploring how rTMS can treat a range of neuropsychiatric disorders. They are also planning to look at rTMS to enhance memory in patients who are showing early signs of Alzheimer’s disease.
Dr. Vila-Rodriguez says, “This research will hopefully encourage more widespread adoption and accessibility of rTMS treatments across the country. Despite being approved by Health Canada 20 years ago, rTMS is still not widely available. In British Columbia, there are some private clinics that offer rTMS, but it is not covered by the provincial health plan.”
- Ruiyang Ge, Predictive Value of Acute Neuroplastic Response to rTMS in Treatment Outcome in Depression: A Concurrent TMS-fMRI Trial. DOI: 10.1176/appi.ajp.21050541