The longer, the better ? Longer left-sided prolonged intermittent theta burst stimulation in patients with major depressive disorder: A randomized sham-controlled study

Background: Prolonged intermittent theta-burst stimulation (iTBS) is effective for major depressive disorder (MDD). However, whether longer piTBS treatment in a single session could have antidepressant efficacy remains elusive. Therefore, this double-blind, randomized, sham-controlled study aimed to investigate the antidepressant efficacy of 2 daily piTBS sessions for treating MDD patients with a history of poor responses to at least 1 adequate antidepressant trial in the current episode. Methods: All patients received 2 uninterrupted sessions per day for 10 weekdays (i.e., 2 weeks; a total of 20 sessions). Seventy-two patients were recruited and 1:1:1 randomly assigned to one of three groups: piTBS (piTBSx2), 10-Hz rTMS (rTMSx2), or sham treatment (shamx2, randomly assigned to piTBS or rTMS). 10-Hz rTMS group was included as an active comparison group to enhance assay sensitivity. Results: piTBSx2 group had significantly more responders at week 2 than shamx2 group, but it did not yield better antidepressant effects regarding the %depression changes. The changes of antidepressant scores were not different among the three groups at week 1 (−26.2% vs. −23.3% vs. −22.%) or at week 2 (−34.1% vs. −37.1% vs. −30.1%). Longer treatment duration did not result in stronger placebo effects [sham(piTBS)x2: − 31.7% vs. sham(rTMS)x2: − 26.7%]. Conclusion: The present sham-controlled study confirmed that piTBS is an effective antidepressant option, but found no evidence to support that longer piTBS treatment duration resulted in more rapid or better antidepressant effects. A high placebo effect was observed, but longer treatment duration of brain stimulation was not linearly associated with stronger placebo effects.