Intense magnetic pulses used on the scalp to activate the mind can swiftly alleviate numerous deeply despondent individuals unresponsive to typical therapies. However, the mechanism through which transcranial magnetic stimulation, the name given to this procedure, counteracts depression has long remained an enigma. Presently, a study overseen by Stanford Medicine researchers has revealed that the treatment operates by reversing the flow of atypical brain signals.
Moreover, the discoveries imply that retrograde patterns of neural functioning amid crucial brain regions might serve as a biomarker for aiding in the diagnosis of depression.
“The primary conjecture has been that TMS has the potential to modify the trajectory of neural activity within the brain,” remarked Anish Mitra, MD, PhD, a postdoctoral fellow in psychiatry and behavioral sciences. “However, to be candid, I held a fair amount of skepticism. I was eager to put it to the test.”
Mitra possessed the perfect instrument for the task. During his time as a graduate student at Washington University in Saint Louis, working under the guidance of Mark Raichle, MD, he devised a mathematical tool capable of scrutinizing functional magnetic resonance imaging (fMRI) data, which is frequently employed to identify active regions within the brain. The novel analysis technique hinged on detecting subtle temporal disparities in the activation of various brain areas, thereby unveiling the direction of said activity.
In the recently published study on May 15 in the Proceedings of the National Academy of Sciences, Mitra and Raichle joined forces with Nolan Williams, MD, an associate professor of psychiatry and behavioral sciences. Dr. Williams and his team have been at the forefront of utilizing personalized magnetic stimulation tailored to the unique brain anatomy of each patient in order to address severe depression. This innovative treatment, known as Stanford Neuromodulation Therapy (SNT), incorporates cutting-edge imaging technologies to guide the application of high-dose magnetic pulses that can modulate brain activity associated with major depression. In comparison to traditional TMS, which typically involves daily sessions spanning several weeks or months, SNT follows an accelerated schedule with 10 daily sessions over a period of just five days. This accelerated approach aims to expedite the therapeutic process.
“This was the ideal examination to ascertain whether TMS possesses the capacity to alter the dynamics of signal propagation within the brain,” expressed Mitra, who serves as the lead author of the study. “If this experiment fails to demonstrate it, then it is unlikely that anything else will.”
Raichle and Williams are senior authors of the study.
Timing is everything
The research team enlisted the participation of 33 individuals diagnosed with treatment-resistant major depressive disorder. Out of these, 23 patients underwent SNT treatment, while the remaining 10 underwent a sham treatment that replicated SNT but without the actual magnetic stimulation. The data from these patients were then compared to the data of 85 healthy individuals without depression, serving as the control group.
