Depression is the most common mental health issue. It can also be quite severe and is among the leading causes of suicide among young adults. Depression cases have been rising globally. So, what was a rare disease about 50 years back is now a common mental health issue.
There are hundreds of US FDA drugs approved to manage the condition. Yet, there is no drug that works for all. Even worse, many of those living with the conditions do not respond to any pharmacological treatment. Some individuals appear to be quite resistant to medical treatment.
Non-pharmacological approaches like cognitive behavioral therapy and telehealth addiction treatment have a special place in managing depression. However, many other new treatment approaches, like transcranial magnetic stimulation (TMS), are emerging.
Transcranial Magnetic Stimulation (TMS) is a non-invasive technique that uses magnetic fields to stimulate nerve cells in the brain. It may also work in some resistant cases. The procedure involves placing a coil against the scalp, which generates brief magnetic pulses that penetrate the skull and induce electrical currents in the targeted brain region.
These currents can modulate neural activity, enhancing or inhibiting specific brain functions. TMS also allows for the modulation of the activity of specific brain centers. This ability to precisely modulate brain activity makes TMS a powerful tool for both understanding brain function and developing effective treatments for mental health conditions.
TMS Might Help in Certain Cases of Depression
The study examined the variability of early local TMS-evoked potentials (EL-TEPs) across different targets within the dorsolateral prefrontal cortex (dlPFC) using transcranial magnetic stimulation (TMS) paired with electroencephalography (EEG). dlPFC is often implicated in psychiatric illnesses, including depression.
Six TMS targets within the dlPFC were stimulated in 16 healthy participants, and the resulting EEG responses were analyzed to understand the neural effects and muscle artifacts induced by TMS.
The researchers found that EL-TEPs varied significantly depending on the TMS target location. Posterior and medial targets within the dlPFC produced significantly larger EL-TEPs compared to anterior targets. This variation was attributed to the amount of muscle artifacts present; regions with fewer muscle artifacts exhibited larger EL-TEPs, whereas regions with more muscle artifacts had smaller observed EL-TEPs. The optimal group-level TMS target, located postero-medially, produced EL-TEPs that were 102% larger than those from other dlPFC targets.
Furthermore, the study revealed that the best dlPFC target varied among individuals, suggesting that personalized targeting could enhance the EL-TEP response by an additional 36%. This finding implies that a personalized approach to TMS targeting could be more effective in optimizing treatment outcomes.
The significance of these results lies in the ability to measure cortical excitability without significant interference from muscle artifacts, particularly in posterior-medial regions of the dlPFC. The identification of an optimal group-level target and the potential benefits of personalized targeting holds important implications for improving the efficacy of TMS treatment protocols for depression.
This study shows the importance of detailed mapping and individualized approaches in TMS therapy to maximize therapeutic benefits. It shows that TMS can be really good for depression. However, clinicians must know how to apply TMS and where. There is also a need for studies to understand how TMS effectiveness may vary depending on various application 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
