For the first time, researchers have shown what happens to the brain when a person receives a treatment for depression known as repetitive transcranial magnetic stimulation (rTMS). The results were published today in the American Journal of Psychiatry.
rTMS is a treatment for depression that is usually used when other methods – such as medication – have not been effective for the patient. It is estimated that approximately 40 percent of people with major depression do not respond to antidepressants.
During an rTMS session, a device containing an electromagnetic coil is placed on the patient’s scalp. The device then delivers a painless magnetic pulse that stimulates neurons in a region of the brain involved in mood control – called the dorsolateral frontal cortex.
Although its efficacy has been demonstrated, the mechanisms underlying how repetitive transcranial magnetic stimulation affects the brain are not well understood.
“When we first started this research, the question we were asking was very simple: We wanted to find out what happens to the brain when rTMS is given,” says Dr. Fidel Villa Rodriguez, associate professor in the UBC Department of Psychiatry and a researcher at the Javad Movgian Center for Brain Health. (DMCBH).
To answer this question, Dr. Villa Rodriguez and his team gave patients one round of rTMS while they were inside a magnetic resonance imaging (MRI) scanner. Because MRI can measure brain activity, the researchers were able to see changes in the brain in real time.
The team found that by stimulating the dorsolateral frontal cortex, several other brain regions were also activated. These other areas are involved in multiple functions – from managing emotional responses to memory and movement control.
The participants then underwent another four weeks of rTMS treatment and the team evaluated whether the active areas were associated with patients with fewer symptoms of depression when treatment ended.
“We wanted to find out what happens to the brain when rTMS is given.
Dr. Fidel Villa Rodriguez
“We found that brain regions activated during simultaneous rTMS-fMRI were significantly associated with good outcomes,” says Dr. Vila-Rodriguez.
With this new map of how rTMS stimulates different regions of the brain, Dr. Villa Rodriguez hopes the findings can be used to determine a patient’s response to rTMS treatments.
“By demonstrating this principle and identifying which areas of the brain are activated by rTMS, we can now try to understand whether or not this pattern can be used as a biomarker,” he says.
Dr. Vila-Rodriguez is now exploring how rTMS can be used to treat a range of neuropsychiatric disorders. It received funding through the Javad Movgian Center for Brain Health’s Alzheimer’s Research Competition to look at rTMS as a way to enhance memory in patients showing early signs of Alzheimer’s disease. He also received a grant from the Canadian Institutes of Health Research (CIHR) to study whether rTMS brain activation patterns can be detected through changes in heart rate.
Dr. Vila-Rodriguez says this is the kind of research that we hope will encourage widespread adoption and access to rTMS treatments across the country. Although approved by Health Canada 20 years ago, rTMS is still not widely available. In British Columbia, there are some private clinics that offer repetitive transcranial magnetic stimulation (rTMS), but it is not covered by the regional health plan.
This research was a collaborative effort across the Center for Brain Health, including DMCBH researchers Dr. Sophia Frango, Dr. Rebecca Todd, and Dr. Erin MacMillan, as well as members of the UBC MRI Research Center including Laura Barlow.