Fronto-central resting-state 15-29Hz transient beta events change with therapeutic transcranial magnetic stimulation for posttraumatic stress disorder and major depressive disorder

Abstract

Repetitive transcranial magnetic stimulation (rTMS) is an established treatment for major depressive disorder (MDD) and shows promise for posttraumatic stress disorder (PTSD), yet effectiveness varies. Electroencephalography (EEG) can identify rTMS-associated brain changes. EEG oscillations are often examined using averaging approaches that mask finer time-scale dynamics. Recent advances show some brain oscillations emerge as transient increases in power, a phenomenon termed "Spectral Events," and that event characteristics correspond with cognitive functions. We applied Spectral Event analyses to identify potential EEG biomarkers of effective rTMS treatment. Resting 8-electrode EEG was collected from 23 patients with MDD and PTSD before and after 5Hz rTMS targeting the left dorsolateral prefrontal cortex. Using an open-source toolbox (https://github.com/jonescompneurolab/SpectralEvents), we quantified event features and tested for treatment associated changes. Spectral Events in delta/theta (1-6 Hz), alpha (7-14 Hz), and beta (15-29 Hz) bands occurred in all patients. rTMS-induced improvement in comorbid MDD PTSD were associated with pre- to post-treatment changes in fronto-central electrode beta event features, including frontal beta event frequency spans and durations, and central beta event maxima power. Furthermore, frontal pre-treatment beta event duration correlated negatively with MDD symptom improvement. Beta events may provide new biomarkers of clinical response and advance the understanding of rTMS.

Examining the neural mechanisms of rTMS: a naturalistic pilot study of acute and serial effects in pharmacoresistant depression

“…Despite its clinical successes, the mechanism of action of rTMS and its effects during treatment have yet to be fully elucidated. Prior studies utilizing quantitative electroencephalography (qEEG) yielded promising findings of underlying mechanisms of rTMS (Spronk et al, 2008 ; Valiulis et al, 2012 ; Noda et al, 2013 ; Wozniak-Kwasniewska et al, 2015 ; Kallioniemi and Daskalakis, 2022 ; Morris et al, 2023 ). The effects of high-frequency and low-frequency rTMS protocols on EEG power spectral analysis were assessed in a sample of 45 patients with TRD.…”

“…In contrast, the high-frequency group demonstrated more widespread changes, including increased delta power in the left hemisphere, and increased alpha power in the right (Valiulis et al, 2012 ). Similar to other rTMS studies, this trial has primarily applied a pre- vs. post-treatment comparison (Spronk et al, 2008 ; Valiulis et al, 2012 ; Noda et al, 2013 ; Morris et al, 2023 ). Since clinical improvement does not always progress linearly over time, multiple EEG acquisitions over the course of rTMS may yield novel observations that may enhance our understanding of mechanisms underlying TMS and inform the development of novel treatment protocols.…”