Randomised controlled trial comparing different intersession intervals of intermittent theta burst delivered to the dorsal medial prefrontal cortex

Abstract

Background Intermittent theta burst stimulation (iTBS) is a form of repetitive transcranial magnetic stimulation (rTMS) that can be administered in a fraction of the time of standard rTMS. Applying multiple daily iTBS sessions (ie, accelerated iTBS) may enable patients to achieve remission more rapidly. However, questions remain regarding the optimal time interval between treatment sessions.Objective The overall aim of this study was to compare the efficacy and tolerability of two accelerated bilateral iTBS protocols (ie, 30-min or 60-min intervals) and a once-daily bilateral iTBS protocol (ie, 0-min interval) while the number of pulses was held constant, in patients with treatment-resistant depression (TRD).Methods 182 patients with TRD were randomised to receive two sessions per day of bilateral iTBS of the dorsomedial prefrontal cortex (DMPFC) at 60-min, 30-min or 0-min intervals. Sham treatments were delivered using a shielded ‘sham coil’ which produced the auditory and tactile sensations of stimulation. The primary outcome measure was a change in depression scores on the 17-item Hamilton Rating Scale for Depression (HRSD-17) after 20 days of treatment.Results HRSD-17 scores improved across all groups; however, these improvements did not significantly differ between the three groups after 20 days of treatment. Similarly, response and remission rates did not differ between the treatment groups.Conclusions These results suggest that contrary to our original hypothesis, implementing a 30-min or 60-min interval between two treatment sessions of DMPFC-iTBS does not lead to a more rapid improvement in symptoms, than once-daily iTBS administration.Trial registration number NCT02778035.