Early TMS-EEG potentials as biomarkers for personalized neuromodulation in treatment-resistant depression

A major advance for treating depression, the leading cause of disability worldwide, has been the non- pharmacological development of repetitive transcranial magnetic stimulation (rTMS). While rTMS is effective for some, only about half of patients demonstrate a sustained clinical response. This is partly due to stimulation parameters not being fully optimized. While recent research has focused on personalizing where to stimulate, a critical gap remains in optimizing how to stimulate for each patient. This study aims to improve rTMS treatment for depression by using prefrontal electrophysiological biomarkers to personalize stimulation. We seek to enhance target engagement and better understand how brain changes relate to clinical response. Our method centers on early local TMS-evoked potentials (EL-TEPs), which provide reliable measurements of prefrontal excitability at the individual level. Prefrontal EL-TEPs are altered in depression, correlate with treatment outcomes, and respond to neuroplastic interventions like intermittent theta-burst stimulation (iTBS). Our team has pioneered a novel method to optimize EL-TEP acquisition, significantly improving signal quality and reliability. We hypothesize that personalizing iTBS pulse count and intensity to maximize EL-TEP suppression will optimize neural effects and improve clinical outcomes. We propose a R61/R33 study to develop and validate a personalized iTBS protocol. The R61 phase will demonstrate target engagement based on prefrontal excitability changes in 80 patients with treatment-resistant depression (TRD). We will characterize how iTBS parameters affect EL-TEPs in an abbreviated protocol, focusing on acute neurophysiological effects. The R33 phase will confirm target engagement and relate brain changes to clinical response in 106 new patients with TRD, comparing EL-TEP-guided personalized iTBS treatment to non-personalized iTBS treatment. This phase will involve a randomized, triple-blind design with comprehensive neurophysiological, clinical, cognitive, and functional assessments at multiple timepoints. This research is innovative as it uses prefrontal electrophysiology to deliver personalized iTBS treatment. The significance lies in its potential to select treatment parameters based on brain changes. Impact: This project aims to improve iTBS treatment through neurophysiology-guided personalization. By demonstrating target engagement and relating brain changes to clinical outcomes of personalized iTBS treatment, we seek to advance our understanding of the neural mechanisms of depression. If successful, this research could lead to more effective and efficient personalized treatments for depression. Project Number: 1R61MH140799-01 | Fiscal Year: 2026 | NIH Institute/Center: National Institute of Mental Health (NIMH) | Principal Investigator: Corey Keller | Institution: STANFORD UNIVERSITY, STANFORD, CA | Award Amount: $1,066,793 | Activity Code: R61 | Study Section: Special Emphasis Panel[ZMH1 ERB-H (03)] View on NIH RePORTER: https://reporter.nih.gov/project-details/11204805