Pilot randomized trial of intermittent theta-burst stimulation versus H-Coil transcranial magnetic stimulation for treatment-resistant depression.
BACKGROUND: Intermittent theta burst stimulation (figure-8-coil iTBS) and H7-coil repetitive transcranial magnetic stimulation (rTMS) are FDA-cleared treatments for major depression; yet their comparative effectiveness in treatment-resistant depression (TRD) has not been evaluated in randomized trials. This pilot randomized trial was designed to obtain preliminary comparative estimates and to explore whether baseline cognitive functioning relates to early remission. METHODS: Twenty-eight adults with TRD were randomized to six weeks of figure-8-coil iTBS delivered to the dorsolateral prefrontal cortex (DLPFC) (n = 15) or H7-coil rTMS delivered to the dorsomedial prefrontal cortex (DMPFC) (n = 13). The primary outcome was change in 17-item Hamilton Depression Rating Scale (HRSD-17) score from baseline to week 6, analyzed with ANCOVA. Additional outcomes included response, remission, and symptom trajectories through week 18. Exploratory analyses examined the association between baseline cognitive functioning, such as executive functions and memory, and remission. RESULTS: Twenty-five participants completed all 30 sessions. Adjusted week-6 HRSD-17 scores did not differ between groups (mean difference -0.40, 95% CI -5.23 to 4.43; p=.865). Response rates were 40.0% for figure-8-coil iTBS and 50.0% for H7-coil rTMS (p>.60), and remission rates were identical across groups (20.0%). Remitters showed higher baseline executive functioning than non-remitters in exploratory analyses, although these associations were not confirmed in adjusted models. CONCLUSION: In this pilot trial, figure-8-coil iTBS and H7-coil rTMS showed symptom improvement, with no clear between-group differences. Exploratory findings suggest a potential signal involving executive functioning that warrants further investigation. These results inform the feasibility and design of larger comparative trials. TRIAL REGISTRATION: ClinicalTrials.gov (NCT05902312).