Aim: Clinical trials and meta-analyses have demonstrated the efficacy of high-frequency repetitive transcranial magnetic stimulation (rTMS) over the left prefrontal cortex in treatment-resistant depression. The aim of this study was to prospectively evaluate the effectiveness of the conventional 37.5-minute vs 18.75-minute rTMS protocol over the left prefrontal cortex in patients with treatment-resistant depressive episode.

Methods: Thirty patients with treatment-resistant depression or bipolar disorder depressive episode were randomized 1:1 to either 37.5-minute or 18.75-minute rTMS protocol groups. rTMS treatment was applied at 120% resting motor threshold with 10 Hz over the left prefrontal cortex. Treatment sessions were delivered for a total of 3000 pulses/d, 5 days a week, for 4-6 weeks. Patients received a 75 trains with "4 sec on and 26 sec off" for 37.5 minutes or a 75 trains with "4 sec on and 11 sec off" for 18.75 minutes. Severity of depression was rated with the Quick Inventory of Depressive Symptomatology (QIDS) and Patient Health Questionnaire (PHQ-9). Remission was defined as a total score of 5 or less on the QIDS. The primary outcome measure was to compare the remission rate between the both groups.

Results: Thirteen of 30 patients (43.3%) showed remission at week 6. There were no significant differences in the remission rate between the conventional 37.5- and 18.75-minute protocol groups (46.7% and 40.0%, respectively). No seizures or treatment-emergent mania/hypomania were occurred.

Conclusion: These findings suggest that, compared with the conventional one, rTMS with 18.75-minute protocol might be equally effective and clinically beneficial in saving the treatment session length. Further well-designed studies are needed.