Preliminary assessment of the therapeutic efficacy of continuous theta-burst magnetic stimulation (cTBS) in major depression: A double-blind sham-controlled study

Background Theta-burst transcranial magnetic stimulation (TBS) has been shown to induce potent and long lasting effects on cortical excitability. In a previous open study, we demonstrated safety, tolerability and antidepressant properties of continuous TBS (cTBS) in major depression (MD). The present study was aimed to evaluate the therapeutic efficacy of cTBS in depressed patients using a double-blind, sham-controlled design.

Methods Twenty nine patients with MD were randomized to receive either active cTBS to the right dorsolateral prefrontal cortex (n=15) or sham cTBS (n=14) for 10 consecutive work days. After the 10th session, patients who received sham TBS were crossed over to active cTBS which consisted of 10 daily sessions. Patients who received active cTBS continued with the same treatment protocol for additional 10 treatments. Each treatment session consisted of 3600 stimuli at an intensity of 100% of the active motor threshold. Severity of depression was assessed weekly.

Results Overall, there was no significant difference in the degree of clinical improvement between active and sham cTBS groups. However, in patients whose medication status remained unchanged before the trial (n=8) and in those who were medication-free (n=3), active cTBS resulted in a significantly greater reduction of Hamilton depression scores as compared to sham cTBS.

Limitations A small sample size, confounding effect of medication and short treatment period.

Conclusions Our results suggest that the antidepressant effect of cTBS is modest, yet it might be beneficial to patients nonresponsive to ongoing pharmacological treatment. A direct comparison between cTBS and conventional rTMS protocols is warranted.