Accelerated intermittent theta burst stimulation for pharmacological treatment-resistant bipolar depression: Protocol for double-blind, randomized, sham-controlled trial

Background: With 30%–50% of people with bipolar depression (BDep) not responding to multiple pharmacological treatments, alternative therapies are needed. Accelerated intermittent theta burst stimulation (aiTBS) over the left dorsolateral prefrontal cortex (L-DLPFC) has been employed for individuals with pharmacological treatment-resistant major depressive disorder (TR-MDD). Imaging studies have revealed reduced regional activity of the L-DLPFC for both TR-MDD and pharmacological treatment-resistant BDep (TR-BDep), suggesting that aiTBS over the L-DLPFC may be beneficial for people with TR-BDep. Methods: A 6-week, double-blind, sham-controlled, randomized trial will be conducted to compare the efficacy and safety of aiTBS to the L-DLPFC in people with TR-BDep (jRCTs042240019). Fifty iTBS sessions (1800 pulses/session) will be delivered in 10 daily sessions over 5 consecutive days at 90% resting motor threshold. This aiTBS protocol is termed as Fujita Neuromodulation Therapy for Bipolar Depression (FNT-BD). Twenty-two participants (both sexes, aged 18–64 years) with TR-BDep (DSM-5-TR, Type I) will be recruited. The response rate at any given week of follow-up will be the primary efficacy outcome, defined as a reduction of ≥50% in the Montgomery Åsberg Depression Rating Scale (MADRS) score. Other outcomes will include MADRS score changes, remission rate (10 ≥ MADRS score), Clinical Global Impression-Improvement score, Clinical Global Impression-Severity score, discontinuation rate, and incidence of individual adverse events. Results: We anticipate that individuals who receive the aiTBS treatment show significant improvement in depressing symptoms compared to those receiving sham treatment. Conclusions: This study will provide valuable evidence for both patients with TR-BDep and clinicians.