Bilateral theta burst stimulation for patients with acute unipolar or bipolar depressive episodes: A systematic review of randomized controlled studies

This meta-analysis of randomized controlled trials (RCTs) evaluated the overall efficacy and safety of bilateral theta-burst stimulation (TBS) as an intervention for patients with mood disorders. A systematic search (up to December 7, 2022) of RCTs was conducted to address the study aims. A random-effects meta-analysis was performed by including study-defined responses and remission as primary outcomes. Analyses included six RCTs comprising 285 participants with major depressive disorder (MDD) (n = 233) or a depressive episode in the course of bipolar disorder (BD) (n = 52) who had undergone active bilateral TBS (n = 142) versus sham stimulation (n = 143). Active bilateral TBS outperformed sham stimulation with respect to study-defined improvements (55.1 % versus 20.3 %, 4 RCTs, n = 152, 95%CI: 1.63 to 4.39, P < 0.0001; I2 = 0 %) and remission rates (37.2 % versus 14.3 %, 2 RCTs, n = 85, 95%CI: 1.13 to 5.95, P = 0.02; I2 = 0 %) in MDD patients but not those with bipolar or unipolar mixed depression. Superiority of active bilateral TBS over sham stimulation was confirmed for improvements in depressive symptoms at post-bilateral TBS assessments and 8-week follow-ups in patients with either MDD or mixed depression (all P < 0.05). Discontinuation rates due to any reason and adverse events (i.e., headache, dizziness) were similar between TBS and sham stimulation groups with MDD or mixed depression (all P > 0.05). Bilateral TBS targeting the dorsolateral prefrontal cortex (DLPFC) appears to be a well-tolerated form of repetitive transcranial magnetic stimulation (rTMS) that has substantial antidepressant effects, particularly in patients with MDD. Effects of bilateral TBS on bipolar and unipolar mixed depression should be further investigated.