Pilot Study of Accelerated Low-Frequency Right-Sided Transcranial Magnetic Stimulation for Treatment-Resistant Depression

Background Repetitive transcranial magnetic stimulation (rTMS) is an effective option for treatment-resistant depression but requires prolonged repeated daily treatments for 4 to 6 weeks. Pilot studies have showed the possibility of accelerating rTMS safely and efficaciously but thus far only investigated high-frequency left-sided rTMS. We sought to investigate the safety and efficacy of accelerated low-frequency right-sided rTMS. Methods Our study was an open label accelerated rTMS pilot in 7 treatment-resistant patients (4 unipolar, 3 BP). Accelerated rTMS was given over the right dorsolateral prefrontal cortex at 120% of resting motor threshold at 1 Hz, and 900 pulses were delivered per session. A single rTMS treatment was administered on the first day to test for tolerability, followed by 5 rTMS sessions a day for 2 days, then 7 days of daily rTMS sessions. The total course consisted of 16,200 pulses across 18 sessions given over 10 consecutive weekdays. The primary outcomes of interest were self- and clinician-rated depression scores (BDI-II and MADRS). Results All patients successfully and safely completed the accelerated rTMS treatment. MADRS scores decreased significantly by the third day of treatment and BDI II scores by the end of the 10-day treatment. No patients achieved response or remission. Conclusions Accelerated low-frequency right-sided rTMS was a safe and possibly efficacious treatment for treatment-resistant depression. More research is recommended, including a controlled trial with longer duration of exposure, to establish the efficacy of left- and right-sided accelerated rTMS.