Transcranial magnetic stimulation of the medial prefrontal cortex for psychiatric disorders: a systematic review

Abstract

Objective:The medial prefrontal cortex (mPFC) is a highly connected cortical region that acts as a hub in major large-scale brain networks. Its dysfunction is associated with a number of psychiatric disorders, such as schizophrenia, autism, depression, substance use disorder (SUD), obsessive-compulsive disorder (OCD), and anxiety disorders. Repetitive transcranial magnetic stimulation (rTMS) studies targeting the mPFC indicate that it may be a useful therapeutic resource in psychiatry due to its selective modulation of this area and connected regions.Methods:This review examines six mPFC rTMS trials selected from 697 initial search results. We discuss the main results, technical and methodological details, safety, tolerability, and localization strategies.Results:Six different protocols were identified, including inhibitory (1 Hz) and excitatory (5, 10, and 20 Hz) frequencies applied therapeutically to patient populations diagnosed with major depressive disorder, OCD, autistic spectrum disorder, SUD, specific phobia, and post-traumatic stress disorder (PTSD). In the OCD and acrophobia trials, rTMS significantly reduced symptoms compared to placebo.Conclusion:These protocols were considered safe and add interesting new evidence to the growing body of mPFC rTMS literature. However, the small number and low methodological quality of the studies indicate the need for further research.

Comment on “Transcranial magnetic stimulation of the medial prefrontal cortex for psychiatric disorders: a systematic review”

“…2020 Jan-Feb;42(1):109-110 doi:10.1590/1516-4446-2019-0707 00000000-0002- In a recent issue, the Brazilian Journal of Psychiatry published a systematic review on transcranial magnetic stimulation of the medial prefrontal cortex for psychiatric disorders conducted by two of the authors of this letter (RCM and AC). 1 It has since come to our attention that a multicenter clinical trial of great relevance to the topic was not included in the review. This unfortunate oversight was due to the trial's publication taking place after acceptance of the review.…”

Precision noninvasive brain stimulation: is it precise? Is it needed?

“…These questions resonate in the systematic review recently published in this journal. Marques et al examined the results of six randomized controlled trials involving the use of repetitive transcranial magnetic stimulation (rTMS) on the medial prefrontal cortex (mPFC) for different psychiatric disorders 2. So-called “precision noninvasive brain stimulation (NIBS)” carries an added level of complexity: the spatial coil or electrode localization should be taken into account.…”

“…In depression, on the other hand, resting-state analyses have shown overactivation of the DMN, with associated maladaptive rumination 6. The salience network, in turn, is composed of two subsystems, one of which links the mPFC with the amygdala, and the other with the striatum 2. This system normally detects “salient” changes in the environment and appraisal/expression of emotions 6.…”

“…This system normally detects “salient” changes in the environment and appraisal/expression of emotions 6. Its dysfunction has been associated with both anxious avoidance and anhedonia 2. Interestingly, Williams suggests TMS for patients with DMN dysfunction, and deep brain stimulation (DBS) for patients with salience network dysfunction,6 in line with the precision psychiatry paradigm.…”

“…Another important point in the review by Marques et al is the evaluation of the different types of coils used in randomized controlled trials. Most of the reviewed trials used deep TMS (dTMS) coils, but in one trial with positive outcomes in obsessive-compulsive disorder and acrophobia, a superficial, circular coil was used instead 2. Headache and local discomfort were frequent, and one patient receiving a frequency of 20 Hz experienced a generalized (tonic-clonic) seizure 2.…”