Bilateral vs. unilateral repetitive transcranial magnetic stimulation in treating major depression: A meta-analysis of randomized controlled trials

• A meta-analysis compared the efficacy of bilateral vs. unilateral repetitive transcranial magnetic stimulation (rTMS) in treating major depression.
• Seven randomized controlled trials consisting of 509 subjects met entry criteria for meta-analysis.
• The pooled examination demonstrated that bilateral rTMS has comparable antidepressant efficacy and acceptability to unilateral rTMS in treating major depression.

Previous studies have demonstrated inconsistent findings regarding the efficacy of bilateral vs. unilateral repetitive transcranial magnetic stimulation (rTMS) in treating major depressive disorder (MDD). Therefore, this meta-analysis was conducted to compare the efficacy of these two rTMS modalities. Data were obtained from seven randomized controlled trials (RCTs) consisting of 509 subjects. Bilateral and unilateral rTMS displayed comparable efficacy in treating MDD with a pooled odds ratios of 1.06 (95% confidence interval (CI)=0.58–1.91) for response rates and 1.05 (95% CI=0.52–2.11) for remission rates. Subgroup analysis found that bilateral rTMS was equally effective in comparison with both left and right unilateral rTMS. No significant differences in drop-out rates were found. No publication bias was detected. In conclusion, the pooled examination demonstrated that bilateral rTMS displays comparable anti-depressant efficacy and acceptability to unilateral rTMS in treating MDD. These findings suggest that simultaneous rTMS of the right and left dorsolateral prefrontal cortices in MDD patients does not provide marginal benefits in terms of efficacy or acceptability. As the number of RCTs included here was limited, further large-scale multi-center RCTs are required to validate our conclusions.