Four weeks standard vs. one week accelerated intermittent Theta Burst Stimulation for the treatment of depression - A retrospective analysis.

Introduction: Intermittent Theta Burst Stimulation (iTBS), a specific form of repetitive transcranial magnetic stimulation (rTMS) is increasingly used for treating affective disorders. Accelerated iTBS protocols (aiTBS) with shorter treatment duration may lead to equal but faster response rates compared to standard protocols.

Methods: Here, we retrospectively analyzed the records of 66 rTMS in- and out-patients with major depressive disorder in a tertiary care hospital between April 2023 and September 2023. All patients received left prefrontal iTBS with 1200 pulses, either one session/workday over 4 weeks (n = 34) or left prefrontal aiTBS on five sessions/workday for one week (n = 32). Depressive symptoms were assessed with the 21-item Hamilton Depression Rating Scale (HAMD-21) and the Major Depression Inventory (MDI) before and at the end of the respective treatment.

Results: With both treatments, iTBS and aiTBS, the severity of depression improved significantly according to HAMD-21 and MDI. Response rates for iTBS were 38 % (HAMD-21) and 35 % (MDI), for aiTBS 19 % (HAMD-21) and 16 % (MDI), respectively. Remission rates showed a similar pattern. Effect sizes for group differences were small to medium. No serious adverse events occurred in any group. Tolerability was lower in aiTBS. Overall satisfaction was low for aiTBS on a qualitative and subjective level.

Conclusion: aiTBS with 1200 pulses and five daily sessions lead to amelioration of symptoms within one week. But benefit, satisfaction, tolerability was slightly lower in contrast to four weeks of iTBS. For everyday clinical practice, aiTBS protocols can be considered after weighing up the logistical disadvantages, such as possible longer waiting time for new patients that want to start a therapy with TMS. Future studies should explore the optimal dosage regime (number of sessions per day, number of pulses per session) for fast and effective symptom reduction.