Electrophysiological Biomarkers in Accelerated TMS for Depression

Electrophysiological Biomarkers of Treatment Response in Major Depressive Disorder Patients Receiving Accelerated Transcranial Magnetic Stimulation

This study investigates whether physiological signals recorded during transcranial magnetic stimulation (TMS) can predict which patients with major depression respond to treatment. Thirty-two adults with major depressive disorder receive an accelerated TMS protocol targeting the dorsomedial prefrontal cortex using a double-cone coil, delivered as four sessions per day over five to eight days. Heart rate is continuously monitored throughout every stimulation session using a chest-strap sensor, and electroencephalography (EEG) is recorded before and after treatment. Heart-brain coupling was assessed in a separate dedicated session after the target stimulation dose was reached.The primary clinical outcome is the change in depression severity measured by the Hamilton Depression Rating Scale (HAMD-17) from baseline to post-treatment. Prespecified physiological outcomes include stimulation-evoked heart rate deceleration, resting-state EEG parameters, and heart-brain coupling metrics. The aim is to evaluate whether these electrophysiological measures index target engagement and predict antidepressant response, potentially supporting their use as functional biomarkers for personalizing accelerated TMS in depression.

Study Overview

• Status: Completed
• Conditions: Major Depressive Disorder (MDD)
• Intervention / Treatment: Device: Accelerated bilateral dmPFC-iTBS

• Study Type: Interventional
• Enrollment (Actual): 32
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Turkey (Türkiye)
  • Bakırköy
    • Istanbul, Bakırköy, Turkey (Türkiye)
      • Istanbul University-Cerrahpaşa Cerrahpaşa Medical Faculty Psychiatry Department

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Adults aged 18 to 65 years
• Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) diagnosis of major depressive disorder, of at least moderate severity, confirmed by structured psychiatric interview
• Insufficient response to at least one adequate trials of antidepressant pharmacotherapy during the current episode
• Stable psychotropic medication regimen for at least 4 weeks prior to enrollment
• Ability to provide written informed consent

Exclusion Criteria:

• Cardiac arrhythmia or use of antiarrhythmic medication
• Benzodiazepine use exceeding the equivalent of 1 mg/day lorazepam
• Active suicidal ideation
• Comorbid psychiatric disorders other than anxiety disorders (including bipolar disorder, psychotic disorders, substance use disorders, and primary obsessive-compulsive disorder)
• Standard contraindications to transcranial magnetic stimulation, including history of seizure, intracranial metal implants, cochlear implants, or implanted neurostimulators
• Pregnancy
• Severe or unstable medical illness

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm

Intervention / Treatment

Experimental: Accelerated bilateral dmPFC-iTBS with double-cone coil; Participants received accelerated bilateral intermittent theta-burst stimulation (iTBS) targeting the dorsomedial prefrontal cortex (dmPFC) using a Cool DB-80 double-cone coil. Treatment consisted of four sessions per day, delivering 1,200 pulses per session (600 pulses per hemisphere, applied sequentially to left and right dmPFC), at 120% of resting motor threshold. The total course comprised 20 to 30 sessions over 5 to 8 days.

Device: Accelerated bilateral dmPFC-iTBS; Stimulation was delivered using a MagPro R30 stimulator equipped with a Cool DB-80 double-cone coil (MagVenture A/S, Farum, Denmark). The stimulation site was localized using the 25% nasion-inion scalp heuristic for dorsomedial prefrontal cortex (dmPFC) targeting. The intermittent theta-burst stimulation (iTBS) protocol consisted of triplet 50 Hz bursts repeated at 5 Hz, applied as 2-second trains with 8-second inter-train intervals. Each session delivered 600 pulses sequentially to the left and right dmPFC (1,200 pulses per session), at a target intensity of 120% of the hemisphere-specific resting motor threshold. Four sessions were delivered per day with approximately 50-minute inter-session intervals. The total treatment course was 20 sessions over 5 days, extended to 30 sessions over 8 days for partial responders.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Hamilton Depression Rating Scale (HAMD-17) Score	Depression severity was assessed using the 17-item Hamilton Depression Rating Scale (HAMD-17) at baseline and within 1 week after completion of the accelerated iTBS course. The HAMD-17 is a clinician-administered scale; scores range from 0 to 52, with higher scores indicating more severe depression. Treatment response was defined as a 50% or greater reduction from baseline HAMD-17 score, and remission as a post-treatment HAMD-17 score of 7 or lower.	Baseline, Day 5, and Day 8 for extended courses

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Heart rate deceleration during stimulation	Heart rate was continuously sampled at 1-second intervals using a Polar H10 chest strap during every stimulation session. Heart rate deceleration (HRD) was calculated as the percentage reduction from the 1-minute pre-stimulation baseline heart rate to the mean stimulation heart rate, using the formula: HRD (%) = [(HR_baseline - HR_stimulation) / HR_baseline] x 100. HRD was computed across four parameters (all left-sided sessions, all right-sided sessions, highest-intensity left-sided sessions, highest-intensity right-sided sessions) and averaged per participant. Higher values indicate greater stimulation-induced heart rate deceleration.	Through completion of the treatment course, up to 8 days
Change in Beck Depression Inventory (BDI)	Beck Depression Inventory (BDI), a self-report scale; total scores range from 0 to 63, with higher scores indicating more severe depression.	Baseline, Day 5, and Day 8 for extended courses
Change in Beck Anxiety Inventory (BAI)	Beck Anxiety Inventory (BAI), a self-report scale; total scores range from 0 to 63, with higher scores indicating more severe anxiety.	Baseline, Day 5, and Day 8 for extended courses
Change in Beck Scale for Suicide Ideation (BSS)	Beck Scale for Suicide Ideation (BSS), a self-report scale; total scores range from 0 to 38, with higher scores indicating greater suicidal ideation.	Baseline, Day 5, and Day 8 for extended courses
Change in Quick Inventory of Depressive Symptomatology - Self-Report (QIDS-SR16) Total Score	Quick Inventory of Depressive Symptomatology, Self-Report (QIDS-SR16); total scores range from 0 to 27, with higher scores indicating more severe depression.	Baseline, Day 5, and Day 8 for extended courses
Change in Clinical Global Impression - Severity (CGI-S)	Clinical Global Impression - Severity (CGI-S); scores range from 1 (normal, not at all ill) to 7 (among the most extremely ill patients), with higher scores indicating greater illness severity.	Baseline, Day 5, and Day 8 for extended courses
Hamilton Depression Rating Scale (HAMD-17) Total Score at 30-Day Follow-up	17-item Hamilton Depression Rating Scale (HAMD-17) assessed 30 days after completion of treatment; total scores range from 0 to 52, with higher scores indicating more severe depression.	30 days post-treatment
Resting State Quantitative EEG (qEEG) Spectral Power and Theta Cordance	Absolute spectral power in the delta, theta, alpha, and beta frequency bands, derived from quantitative resting-state EEG (qEEG) analysis. Power was computed across standard electrode regions. Prefrontal theta cordance, a quantitative EEG measure combining absolute and relative theta-band power at prefrontal electrodes, derived from resting-state qEEG analysis.	Baseline and completion of treatment (Day5 or Day8 for extended courses)
Heart-Brain Coupling (HBC): Heart Rate Oscillation Power at the Stimulation Frequency	Heart-brain coupling (HBC), a parameter quantifying the strength of stimulation-induced heart rate deceleration, computed as the mean oscillation power of cardiac rate at the frequency determined by the stimulation train interval (Dijkstra et al., 2023). HBC ranges from 0 to 1. Measurements were obtained in a dedicated session using a 10 Hz protocol (50 pulses per train, 5-second train duration, 15 trains, 11-second inter-train interval), recorded with a Polar H10 chest strap and the HeartBrainConnect application. HBC was assessed sequentially at four sites per participant: left dmPFC, left dorsolateral prefrontal cortex (DLPFC), right dmPFC and right DLPFC. For each site, stimulation began at 28% below target intensity and increased by 2% per train, yielding 15 HBC values that were averaged to produce a per-site HBC value.	Single dedicated measurement session after the target dose was reached, up to Day 8
EEG Microstate Temporal Parameters	Temporal parameters of the canonical resting-state EEG microstate classes (A, B, C, and D), including mean duration (milliseconds), occurrence (mean appearances per second), time coverage (percentage of recording time), and transition probabilities between classes. Parameters were derived from microstate segmentation of resting-state EEG recordings.	Baseline and completion of treatment (Day5 or Day8 for extended courses)

Collaborators and Investigators

• Sponsor: Istanbul University - Cerrahpasa

Study record dates

Study Major Dates

• Study Start (Actual): June 13, 2024
• Primary Completion (Actual): March 14, 2025
• Study Completion (Actual): April 14, 2025

Study Registration Dates

• First Submitted: May 18, 2026
• First Submitted That Met QC Criteria: May 22, 2026
• First Posted (Actual): May 29, 2026

Study Record Updates

• Last Update Posted (Actual): May 29, 2026
• Last Update Submitted That Met QC Criteria: May 22, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Mental Disorders; Mood Disorders; Depressive Disorder; Depressive Disorder, Major
• Other Study ID Numbers: 37949

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: De-identified individual-level data are not publicly available due to privacy and ethical restrictions on sensitive clinical data, but may be available from the corresponding author upon reasonable request and with appropriate ethics committee approval.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No