One-Day cTBS Over the Precuneus

Summary

The goal of this clinical trial is to learn whether two forms of one-day accelerated transcranial magnetic stimulation (TMS) can reduce depressive symptoms in adults with treatment-resistant depression. Treatment-resistant depression is depression that has not improved enough after at least two adequate antidepressant medication treatments. TMS is a non-invasive treatment that uses magnetic pulses to stimulate specific areas of the brain. The main questions this study aims to answer are: * Does continuous theta-burst stimulation (cTBS) targeting the precuneus reduce depressive symptoms 4 weeks after treatment compared with sham stimulation? * Does intermittent theta-burst stimulation (iTBS) targeting the left dorsolateral prefrontal cortex reduce depressive symptoms 4 weeks after treatment compared with sham stimulation? Researchers will compare precuneus cTBS, left dorsolateral prefrontal cortex iTBS, and sham stimulation to determine whether either active treatment reduces depressive symptoms more than sham stimulation. Participants will be randomly assigned to one of the three groups and will not be told which treatment they initially receive. Participants will: * Complete screening procedures and baseline assessments of depression, rumination, and cognitive function * Receive 20 sessions of active or sham TMS during one in-person study day * Complete follow-up assessments 1, 2, 3, and 4 weeks after the intervention * Report any side effects or medical problems experienced during the study Participants initially assigned to sham stimulation may choose to receive active TMS after completing the 4-week follow-up period. Those who choose this option will receive either precuneus cTBS or left dorsolateral prefrontal cortex iTBS and will complete additional follow-up assessments.

Detailed Description

Treatment-resistant depression may involve dysfunction across distributed brain networks rather than a disturbance confined to a single brain region. The precuneus is a posterior hub of the default mode network and is involved in internally directed and self-referential processing. Altered interactions among the default mode, affective, and cognitive control networks have been implicated in depressive symptoms and rumination. In this study, precuneus continuous theta-burst stimulation (cTBS) is conceptualized as a hypothesis-driven network intervention that may modulate precuneus-centered network interactions implicated in depression. A double-cone coil will be used to increase electric-field penetration toward the medial posteromedial cortex beneath the Pz scalp location of the international 10-20 electroencephalography system. Intermittent theta-burst stimulation (iTBS) of the left dorsolateral prefrontal cortex is included as an additional active treatment arm because this region is an established stimulation target for depression treatment. The three-arm design allows the novel precuneus target and the established left dorsolateral prefrontal cortex target to be evaluated within the same accelerated treatment framework and compared with sham stimulation. Participants will be assigned to the three initial study groups using the minimal sufficient balance (MSB) randomization method, with sex and baseline depression severity, as measured by the Montgomery-Åsberg Depression Rating Scale, used as balancing factors. The target allocation ratio for the randomized, sham-controlled phase will be 1:1:1. Group allocation will be concealed from participants. Each active or sham intervention will consist of 20 stimulation sessions administered during a single day, with session onsets separated by approximately 30 minutes. The primary efficacy analyses will use a longitudinal mixed-model framework to estimate treatment effects and evaluate the two prespecified active-versus-sham comparisons. The familywise type I error rate will be controlled across these two comparisons. The direct comparison between precuneus cTBS and left dorsolateral prefrontal cortex iTBS will be considered exploratory. After completing the 4-week follow-up period, participants initially assigned to sham stimulation may elect to enter an open-label active TMS extension. Extension participants will be assigned to precuneus cTBS or left dorsolateral prefrontal cortex iTBS using the MSB method, with a target allocation ratio of 1:1. Sex and depression severity at the end of the sham-controlled phase, as measured by the Week 4 Montgomery-Åsberg Depression Rating Scale score, will be used as balancing factors. Because only a subset of participants assigned to sham stimulation is expected to enter the extension, extension analyses will be considered exploratory and hypothesis-generating.

Eligibility Criteria

Interventions