Deep Versus Standard Prolonged Intermittent Theta Burst Stimulation for Depression

Background:

Major depressive disorder (MDD) is associated with dysfunction in large-scale brain networks, including the central executive network (CEN), default mode network (DMN), and the salience network (SN). The anterior cingulate cortex (ACC) is a key hub in the SN, and its dysfunction is believed to be a core pathological feature of depression. While high-frequency repetitive transcranial magnetic stimulation (rTMS) over the left dorsolateral prefrontal cortex (DLPFC) is an evidence-based treatment for treatment-resistant depression (TRD), it only indirectly modulates deeper structures like the ACC. Deep TMS techniques using a double-cone coil can directly stimulate deeper regions such as the medial prefrontal cortex (mPFC) and ACC, which may offer a more direct and potentially more effective therapeutic approach. Intermittent theta burst stimulation (iTBS) is a newer form of rTMS that significantly shortens treatment time, but its application to deep brain targets like the ACC has not been well-studied.

Objective:

This study aims to compare the therapeutic efficacy of prolonged intermittent theta burst stimulation (piTBS) targeting the ACC (deep piTBS) versus the standard protocol targeting the left DLPFC (standard piTBS) for patients with TRD. The study will also evaluate the effects of these interventions on comorbid anxiety, obsessive-compulsive, and somatic symptoms, as well as on physiological indicators.

Study Design:

This is a single-center, block-randomized study. A maximum of 90 participants meeting DSM-5 criteria for major depressive disorder, who have failed to respond to at least one adequate trial of an antidepressant, will be recruited. Participants will be randomly assigned in a 2:1 ratio (deep piTBS: standard piTBS, within blocks of six) to one of two treatment arms:

Deep piTBS Group: Participants will receive stimulation targeting the ACC using a double-cone coil. Stimulation intensity will be set at 90% of the resting motor threshold (rMT) determined from the tibialis anterior muscle.

Standard piTBS Group: Participants will receive stimulation targeting the left DLPFC using a standard figure-8 coil. Intensity will be set at 90% of the rMT determined from the abductor pollicis brevis muscle.

For both groups, the piTBS protocol consists of 1800 pulses per session, delivered daily (5 days/week) for 4 weeks, for a total of 20 sessions.

Outcome Measures:

The primary outcome is the change in the 17-item Hamilton Depression Rating Scale (HAM-D17) score from baseline to the end of treatment (after 20 sessions). Secondary outcomes include changes in scores on the Hamilton Anxiety Rating Scale (HAM-A), Yale-Brown Obsessive Compulsive Scale (Y-BOCS), Patient Health Questionnaire-15 (PHQ-15), Beck Depression Inventory-II (BDI-II), Beck Anxiety Inventory (BAI), and various physiological measures including heart rate variability (HRV). Assessments will be conducted at baseline, after every 5 treatment sessions, and one week after the completion of the 20th session.

• Change From Baseline in the Hamilton Anxiety Rating Scale (HAM-A) Score [Срок оценки: Baseline (prior to first treatment), after 5 treatments (Week 1), after 10 treatments (Week 2), after 15 treatments (Week 3), after 20 treatments (End of Week 4), and at a 1-week follow-up after the final treatment session.]
• Change From Baseline in the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) Score [Срок оценки: Baseline (prior to first treatment), after 5 treatments (Week 1), after 10 treatments (Week 2), after 15 treatments (Week 3), after 20 treatments (End of Week 4), and at a 1-week follow-up after the final treatment session.]
• Change From Baseline in the Beck Depression Inventory-II (BDI-II) Score [Срок оценки: Baseline (prior to first treatment), after 5 treatments (Week 1), after 10 treatments (Week 2), after 15 treatments (Week 3), after 20 treatments (End of Week 4), and at a 1-week follow-up after the final treatment session.]
• Change From Baseline in the Beck Anxiety Inventory (BAI) Score [Срок оценки: Baseline (prior to first treatment), after 5 treatments (Week 1), after 10 treatments (Week 2), after 15 treatments (Week 3), after 20 treatments (End of Week 4), and at a 1-week follow-up after the final treatment session.]
• Change From Baseline in the Young Mania Rating Scale (YMRS) Score [Срок оценки: Baseline (prior to first treatment), after 5 treatments (Week 1), after 10 treatments (Week 2), after 15 treatments (Week 3), after 20 treatments (End of Week 4), and at a 1-week follow-up after the final treatment session.]
• Change From Baseline in the Patient Health Questionnaire-15 (PHQ-15) Score [Срок оценки: Baseline (prior to first treatment), after 5 treatments (Week 1), after 10 treatments (Week 2), after 15 treatments (Week 3), after 20 treatments (End of Week 4), and at a 1-week follow-up after the final treatment session.]
• Change From Baseline in the Health Anxiety Questionnaire (HAQ) Score [Срок оценки: Baseline (prior to first treatment), after 5 treatments (Week 1), after 10 treatments (Week 2), after 15 treatments (Week 3), after 20 treatments (End of Week 4), and at a 1-week follow-up after the final treatment session.]
• Change From Baseline in Heart Rate Variability (HRV) Indices [Срок оценки: Baseline (prior to first treatment), after 5 treatments (Week 1), after 10 treatments (Week 2), after 15 treatments (Week 3), after 20 treatments (End of Week 4), and at a 1-week follow-up after the final treatment session.]
• Change From Baseline in Skin Conductance [Срок оценки: Baseline (prior to first treatment), after 5 treatments (Week 1), after 10 treatments (Week 2), after 15 treatments (Week 3), after 20 treatments (End of Week 4), and at a 1-week follow-up after the final treatment session.]
• Change From Baseline in Respiratory Sinus Arrhythmia (RSA) [Срок оценки: Baseline (prior to first treatment), after 5 treatments (Week 1), after 10 treatments (Week 2), after 15 treatments (Week 3), after 20 treatments (End of Week 4), and at a 1-week follow-up after the final treatment session.]
• Change From Baseline in Finger Temperature [Срок оценки: Baseline (prior to first treatment), after 5 treatments (Week 1), after 10 treatments (Week 2), after 15 treatments (Week 3), after 20 treatments (End of Week 4), and at a 1-week follow-up after the final treatment session.]