Cortical Inhibition as a Biomarker of Response in a Comparison of Bilateral Versus Unilateral Accelerated Theta Burst Stimulation for Suicidal Ideation in Treatment-Resistant Depression -COMBAT-SI (COMBAT-SI)

Cortical Inhibition as a Biomarker of Response in a Comparison of Bilateral Versus Unilateral Accelerated Theta Burst Stimulation for Suicidal Ideation in Treatment-Resistant Depression (COMBAT-SI)

This is a prospective clinical trial to confirm the effectiveness of bilateral accelerated theta burst stimulation (aTBS) on suicidal ideation (SI), while exploring cortical inhibition measures in this treatment paradigm. In this proposed study, the investigators will evaluate the anti-suicidal effects of bilateral aTBS over the DLPFC compared to accelerated intermittent theta burst stimulation (aiTBS) over the left DLPFC in participants with TRD and SI. Additionally, the investigators aim to identify neurophysiological targets through which bilateral aTBS induces remission of SI in TRD differentially from aiTBS.

Study Overview

• Status: Recruiting
• Conditions: Suicidal Ideation; Treatment-resistant Depression
• Intervention / Treatment: Device: Accelerated Theta Burst Stimulation

Detailed Description

Suicidality is a growing epidemic, as over 700,000 people die by suicide around the world annually. Current treatments for suicidality are limited and novel treatments for suicidality are desperately needed. There is early evidence to suggest that the non-invasive brain stimulation treatment called repetitive transcranial magnetic stimulation, or rTMS, is better than placebo at eliminating suicidal ideation (SI) in patients with hard to treat depressive illness (treatment-resistant depression; TRD). The UCSD Interventional Psychiatry lab was the first group to demonstrate that bilateral rTMS, targeted to specific areas of the frontal lobes of the brain, is more effective than placebo for SI. Recent evidence from the lab also showed that improvement in SI with brain stimulation treatment is correlated with changes in specific measures of neuronal communication, that is cortical inhibition, in these same brain regions. A prospective clinical trial to confirm the effectiveness of bilateral rTMS on SI, while exploring cortical inhibition measures in this treatment paradigm, is prudent and urgently needed. In this proposed study, the investigators plan to evaluate the anti-suicidal effects of bilateral aTBS over the DLPFC (an accelerated form of rTMS delivered with multiple theta burst treatments per day) compared to aiTBS over the left DLPFC in participants with TRD and SI. Additionally, the investigators aim to identify neurophysiological targets through which bilateral aTBS induces remission of SI in TRD differentially from aiTBS.

• Study Type: Interventional
• Enrollment (Estimated): 76
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Interventional Psychiatry; Phone Number: (858) 657-6152; Email: iptrials@health.ucsd.edu

Study Locations

• United States
  • California
    • San Diego, California, United States, 92127
      • Recruiting
      • UCSD Interventional Psychiatry
      • Contact: Interventional Psychiatry; Phone Number: (858) 207-0938; Email: iptrials@health.ucsd.edu

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 70 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

1. 18-70 years old.
2. Diagnosis of major depressive episode, confirmed on Mini-International Neuropsychiatric Interview (MINI), with HRSD score ≥18.
3. Ongoing SI present beyond screening phase of study (confirmed with Beck SSI score ≥4).
4. Pass the TMS adult safety screening (TASS) questionnaire and the MRI safety screening questionnaire.
5. Have failed to achieve a clinical response to an adequate dose of two antidepressants based on an Antidepressant Treatment History Form (ATHF) score for each antidepressant trial of > 3 in the current episode OR have been unable to tolerate at least 2 separate trials of antidepressants of inadequate dose and duration (ATHF score of 1 or 2 on those 2 separate antidepressants) OR have a combination of one failed trial and one not tolerated trial, per the definitions above.
6. Psychiatric illness due to a general medical condition (GMC) has been ruled out during initial assessment.
7. Voluntary outpatients capable to consent to treatment and seen at the UC San Diego Health Interventional Psychiatry program.
8. Able to adhere to the treatment schedule.

Exclusion Criteria:

1. Have a confirmed diagnosis of substance use disorder within the last 3 months.
2. Have a lifetime diagnosis of bipolar I or II disorder, schizophrenia, schizoaffective disorder, schizophreniform disorder, delusional disorder, or current psychotic symptoms.
3. Have a diagnosis of obsessive compulsive disorder, post-traumatic stress disorder (current or within the last year), anxiety disorder (generalized anxiety disorder, social anxiety disorder, panic disorder), or dysthymia, that is assessed by a study investigator to be primary and causing greater impairment than MDD.
4. Have a diagnosis of any personality disorder, and assessed by a study investigator to be primary and causing greater impairment than MDD.
5. Have SI prompting emergent involuntary hospital stay (SI in which the participant can maintain voluntary and capable outpatient status as well as recent suicide attempt will not be exclusionary).
6. Currently pregnant or lactating, or woman or childbearing age without adequate birth control.
7. Non-correctable clinically significant sensory impairment (i.e., cannot hear well enough to cooperate with interview).
8. Not capable to consent to treatment and/or not suitable for outpatient treatment.
9. Have a concomitant major unstable medical illness, cardiac pacemaker or implanted medication pump; Have any significant neurological disorder or insult including, but not limited to: any condition likely to be associated with increased intracranial pressure, space occupying brain lesion, any history of seizure except those therapeutically induced by ECT or a febrile seizure of infancy, cerebral aneurysm, Parkinson's disease, Huntington's chorea, multiple sclerosis, significant head trauma with loss of consciousness for greater than 5 minutes; Have an intracranial implant (e.g., aneurysm clips, shunts, stimulators, cochlear implants, or electrodes) or any other metal object within or near the head, excluding the mouth, that cannot be safely removed.
10. Currently take more than lorazepam 2 mg daily (or equivalent) or any dose of an anticonvulsant due to the potential to limit rTMS efficacy.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Bilateral aTBS; Patients will receive Bilateral accelerated theta-burst stimulation bilaterally for 5 consecutive days, with a total of 10 hours a day. treatment will be 10min with 50min of breaks in between the 10 sessions.	Device: Accelerated Theta Burst Stimulation; B65 magnetic coil stimulation applied to the dorsal lateral prefrontal cortex.
Active Comparator: Unilateral aiTBS; Patients will receive unilateral accelerated theta-burst stimulation to the left side for 5 consecutive days, with a total of 10 hours a day. treatment will be 10min with 50min of breaks in between the 10 sessions. There will be a right DLPFC sham component to this treatment arm for all treatment sessions.	Device: Accelerated Theta Burst Stimulation; B65 magnetic coil stimulation applied to the dorsal lateral prefrontal cortex.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Changes in scores on the suicide scale index (SSI) from baseline	The primary outcome will be a comparison of change in score on the suicidality scale index (SSI) from baseline to endpoint of treatment between accelerated bilateral and unilateral treatment. The SSI contains 19 items scored from 0 to 2, higher scores indicating more severity, with overall scores ranging from 0 to 38The primary endpoint will be at treatment completion for both arms. The investigators will follow patients at 1, 2, 3, and 4 weeks post-treatment, as well as 3 and 6 months after treatment completion.	6-months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Neurophysiological measures of cortical inhibition, N100, short interval cortical inhibition, and cortical evoked activity	Analysis of transcranial magnetic stimulation concurrent with electroencephalogram (TMS-EEG) to extract effective connectivity metrics between the subgenual cingulate (SGC) and the dorsolateral prefrontal cortex (DLPFC) as suicidality biomarkers, as measured by changes in scores on the SSI, for left aiTBS compared to bilateral aTBS.	6-months
Categorical suicidal clinical outcomes	Suicide attempts and completions will be recorded as adverse events throughout the duration of the study. The investigators will complete categorical sensitivity analyses for these outcomes between treatment groups.	6-months

Collaborators and Investigators

• Sponsor: University of California, San Diego
• Collaborators: National Institutes of Health (NIH)

Study record dates

Study Major Dates

• Study Start (Actual): September 2, 2022
• Primary Completion (Estimated): August 1, 2029
• Study Completion (Estimated): July 30, 2030

Study Registration Dates

• First Submitted: March 24, 2022
• First Submitted That Met QC Criteria: May 10, 2022
• First Posted (Actual): May 17, 2022

Study Record Updates

• Last Update Posted (Estimated): November 5, 2025
• Last Update Submitted That Met QC Criteria: November 3, 2025
• Last Verified: November 1, 2025

More Information

Terms related to this study

• Keywords: theta burst stimulation; accelerated TBS; bilateral TBS
• Additional Relevant MeSH Terms: Mental Disorders; Behavioral Symptoms; Self-Injurious Behavior; Mood Disorders; Suicide; Depressive Disorder; Behavior; Suicidal Ideation; Depressive Disorder, Treatment-Resistant
• Other Study ID Numbers: 801566

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: Yes
• product manufactured in and exported from the U.S.: No