What's Next in Clinical TMS Study for PTSD, MDD

In a recently-published commentary, researchers discussed the growing interest in transcranial magnetic stimulation (TMS) therapy for post-traumatic stress disorder (PTSD) and major depressive disorder (MDD), and what it brings in patient symptoms.

TMS, which was approved by the US Food and Drugs Administration (FDA) for drug-resistant depression in 2009, has recently experienced a growth in clinical use, Mira Hammoud, MD, and Mohammed Milad, PhD, from the Department of Psychiatry, University of Illinois at Chicago, noted in their commentary.

Although previous studies have supported the use of TMS for treatment of PTSD, they haven’t clarified the mechanisms it uses to affect and improve symptoms. Use of TMS to treat MDD has a larger collection of literature that, according to the commentary, supports the idea that “TMS modulates functional connectivity in several brain regions implicated in the pathophysiology of MDD, including the subgenual anterior cingulate cortex (sgACC) and its connections with the default mode network (DMN).”

The current research has been related to treating MDD or PTSD individually with TMS, rather than treating the issues concurrently, which is common.

Their commentary was in response to a recent article in which a research team looked at “neural mechanisms of clinical response to TMS for comorbid PTSD and MDD” in an attempt to ascertain imaging predictors of symptom improvement following treatment with TMS, and to determine the network mechanisms of TMS.

The study much-needed insight into how TMS might “induce a clinical response in a cohort with comorbid MDD and PTSD,” Hammoud and Milad said. As a result, several brain regions commonly examined in the pathophysiology of MDD and PTSD, such as the insular cortex and amygdala, are implicated for their functional connectivity.

“These results are exciting because they are consistent with much of the existing literature regarding MDD and PTSD, and they set the stage for future research,” researchers wrote.

However, they mentioned that future research should induce specificity by including controls with sham devices in a patient population, as well as incorporating pharmacotherapy and cognitive therapies.

Hammoud and Milad wrote that the study results are promising, while aligning with neuroimaging data that implicates key DMN brain areas and the salience network in the pathophysiology of MDD and PTSD.

“The data reported are likely to inspire many more studies in this field to move forward with TMS as a viable therapeutic tool for PTSD, for patients with comorbid MDD and PTSD, and perhaps many other psychiatric disorders,” they wrote.

Hammoud and Milad concluded that refined parameters and target identification studies are needed to improve TMS’ clinical application.

The commentary, "Symptom Changes in Posttraumatic Stress Disorder and Major Depressive Disorder After Transcranial Magnetic Stimulation: Mechanisms of Where and How in the Brain," was published online in Biological Psychiatry.

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