TMS for depression works better when the magnetic pulses hit the right spot. A 2024 mapping study looked at 16 healthy adults. Targets toward the back and middle of the dorsolateral prefrontal cortex (a front part of the brain tied to mood) gave brain responses 102% larger than other targets. Picking a target for each person added another 36%.
Depression is the most common mental health problem. It can also be very severe. It is one of the leading causes of suicide among young adults. Cases have been rising around the world. What was a rare disease about 50 years ago is now common.
There are hundreds of US FDA-approved drugs to manage it. Yet no drug works for everyone. Worse, many people with depression do not respond to any drug at all. Some seem to resist medical treatment completely.
Talk-based approaches like cognitive behavioral therapy have a special place in treating depression. But many new treatments are also coming up, like transcranial magnetic stimulation (TMS).
Transcranial Magnetic Stimulation (TMS) uses magnetic fields to stimulate nerve cells in the brain, with no surgery. It may also work in some hard-to-treat cases. A coil is placed against the scalp. It sends short magnetic pulses through the skull. These pulses create small electric currents in the target part of the brain.
These currents can turn brain activity up or down. TMS can also change how specific brain centers work. Because it can tune brain activity so precisely, TMS is a powerful tool. It helps us understand how the brain works. It also helps build better treatments for mental health conditions.
TMS Might Help in Certain Cases of Depression
The study looked at how much early local TMS-evoked potentials (EL-TEPs, the brain’s first electrical response to a pulse) changed across targets in the dorsolateral prefrontal cortex (dlPFC). It paired transcranial magnetic stimulation (TMS) with electroencephalography (EEG, a recording of brain waves). The dlPFC is often involved in mental illness, including depression.
Researchers stimulated six TMS targets in the dlPFC in 16 healthy people. They studied the EEG responses to learn what TMS did in the brain. They also measured the muscle signals TMS set off.
The researchers found that EL-TEPs changed significantly based on where TMS was aimed. Targets toward the back and middle of the dlPFC gave significantly larger EL-TEPs than targets toward the front. The difference came down to muscle noise. Areas with less muscle noise showed larger EL-TEPs. Areas with more muscle noise showed smaller ones. The best target for the group sat toward the back and middle. It gave EL-TEPs 102% larger than other dlPFC targets.
The study also found that the best dlPFC target differed from person to person. Aiming at each person’s own best spot could boost the EL-TEP response by another 36%. So a personal approach to aiming TMS could work better and improve results.
These results matter because they let doctors measure how active the brain surface is without much muscle noise getting in the way. That is most true in the back-middle part of the dlPFC. Finding one best target for the group, and the gains from a personal target, could make TMS treatment for depression work better.
This study shows why careful mapping and a personal approach matter in TMS. They get the most benefit out of the treatment. It shows that TMS can be very good for depression. But doctors must know how to use TMS and where to aim it. More studies are also needed on how well TMS works with different methods.
Source:
Gogulski, J., Cline, C. C., Ross, J. M., Truong, J., Sarkar, M., Parmigiani, S., & Keller, C. J. (2024). Mapping cortical excitability in the human dorsolateral prefrontal cortex. Clinical Neurophysiology, 164, 138–148. https://doi.org/10.1016/j.clinph.2024.05.008
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