Repetitive transcranial magnetic stimulation in major depression A three-arm parallel-group dose-response randomized pilot trial

Background: The optimal dose (number of pulses per session) of repetitive transcranial magnetic stimulation (rTMS), using the H-coil, in major depressive disorder (MDD) has not previously been reported. Objective: To explore the relationship between rTMS dose and antidepressant effect, and collect data for the design of a definitive trial. Methods: This was a double-blind, three-arm parallel-group, randomized [1:1:1], pilot trial conducted in Stockholm, Sweden (September 2014 to September 2016). The primary outcome was change in depression severity measured with the Montgomery angstrom sberg Depression Rating Scale (MADRS) after 4 weeks. Participants (n = 29) with MDD were randomized to 1000, 2000, or 4000 pulses of rTMS for 20 sessions during 4 weeks. Results: At 4 weeks, the 3 treatment groups reduced the mean MADRS (95% CI) by 11.6 (4.0-19.2), 9.1 (5.0-13.3), and 11.3 (4.1-18.5) points respectively. Eleven participants met criteria for response and 10 for remission. No serious adverse events occurred. Ratings of subjective memory improved in all groups. Exploring the effect of dose and time, 4000 pulses had the largest reduction in MADRS during the first 2 weeks. A comparison of change in MADRS between 2000 and 4000 pulses after 2 weeks will require a sample size of 66 patients at power .80 and alpha .05. Conclusions: It is feasible to conduct a definitive trial investigating whether a higher number of magnetic pulses per treatment session gives a more rapid antidepressive response.

Automated summary

This study investigated the effects of different doses of magnetic pulses on MDD patients treated with rTMS, finding that 4000 pulses had the most significant effect in the initial phase of treatment. After 4 weeks, all three treatment groups showed significant improvements in depressive symptoms, with no serious adverse events reported.