The goal of this randomized controlled trial is to explore the efficacy and safety of two different dTMS devices in adolescent depression: deep TMS H1 coil and deep TMS H7 coil.

The main questions it aims to answer are:

Type of study: Clinical trial. Participant population: Adolescents with major depressive disorder (MDD). Objective: To explore whether the H7 coil is no less effective than the H1 coil for adolescents with MDD, further providing clinicians with additional treatment options for patients.

Transcranial magnetic stimulation (TMS) is a safe and well-tolerated intervention that has been extensively studied as a treatment for MDD. However, little is known about the effectiveness of deep transcranial magnetic stimulation (dTMS) in adolescents with major depressive disorder (MDD). Only one open-label trial tested dTMS using H1 coils in adolescents with treatment-resistant depression, the results showed that the severity of depressive symptoms was significantly reduced after treatment, with a response rate of 42%. Hence, the continued efforts are needed to improve and optimize these treatments.

One important factor that influence the efficacy of TMS was the seletion of stimulation target. In recent years, medial prefrontal cortex (MPFC) and anterior cingulate cortex (ACC) have recently been considered promising alternative targets for treatment of adolescents with MDD, due to their association with reward, emotion, mood, and habits. Additionally, the stimulation target for dTMS with the H7 coil is the MPFC. Current relevant clinical studies show that after dTMS intervention using the H7 coil, depressive symptoms and overall clinical impressions in adults with MDD are significantly improved. However, whether alternative strategies for TMS treatment (e.g., H1 coil versus H7 coil) are more effective in adolescents with MDD remains unknown.

The purpose of this randomized controlled trial is to evaluate the efficacy and safety of two different dTMS devices (H1 coil and H7 coil) in the treatment of adolescent with MDD, further providing clinicians with additional treatment options for patients.

Inclusion Criteria:

• Patients of all genders, aged between 11 and 23 years old, and right-handedness.
• In accordance with the diagnostic criteria for the major depressive disorder of the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5).
• The current major depressive episode (MDE) must be confirmed using the Mini International Neuropsychiatric Interview (M.I.N.I).
• Beck Depression Inventory, Second Edition (BDI-II): total BDI-II score> 13 at screening.
• Subjects who can understand and are willing to strictly follow the clinical trial protocol to complete this study and sign informed consent.

Exclusion Criteria:

• A diagnosis of other psychiatric disorders in the DSM-5.
• Clinically significant laboratory abnormality or medical condition, that in the opinion of the investigator would hinder the subject in completing the procedures required by the study.
• History of significant neurologic disease, including subdural hematoma, brain tumor, unexpected seizure/epilepsy disorder, or history of significant head trauma.
• Have obvious suicide risk, or have actual suicide behavior within 6 months before the screening.
• History of treatment with electroconvulsive therapy (ECT), transcranial magnetic stimulation (TMS), transcranial Direct Current Stimulation (tDCS), or transcranial Alternating Current Stimulation (tACS) treatments for any disorders.
• There are contraindications to magnetic resonance imaging (MRI) scanning or TMS treatment, such as metal or electronic instruments.
• Participation in any investigational drug trial within 6 months before the baseline visit.
• Other conditions that are not suitable for the study object in the researcher's judgment.

Given the study's design, blinding TMS operators will not be possible. Still, participants、staff responsible for participant assessments and data analysis will be blinded to treatment conditions and external to the clinic staff. Patients will be instructed not to reveal their group assignment to the raters. Patients will not be given the specifics of the treatment parameters and will be instructed not to talk to each other during the study period. Both treatments will be presented as effective to them. Lastly, the data management center will strictly control access to the randomization code.