Effects of Repetitive Transcranial Magnetic Stimulation on Obsessive-Compulsive Disorder: A Systematic Review, Meta-Analysis, and Meta-Regression

Abstract

Objectives: The objective of this study was to provide updated evidence on the efficacy of rTMS in OCD, to assess its sustained effects, and to identify moderators of treatment response.

Methodology: A systematic review and meta-analysis of randomised controlled trials was conducted, with publications up to September 2024 (PROSPERO: CRD42022346493). The searches encompassed the following bibliographic databases: Cochrane Library, MEDLINE, Web of Science, SCOPUS, PsycINFO, and EMBASE. The risk of bias was assessed with RoB 2, and effect sizes were calculated using mean differences (MD) on the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS). Subgroup analyses were used to evaluate variations in protocol, while meta-regression was employed to explore the role of moderators.

Results: The study incorporated a total of 31 trials. The analysis revealed substantial reductions in the left dorsolateral prefrontal cortex (MD: -4.63; 95% CI: -7.73, -1.52) and medial prefrontal/anterior cingulate cortex (MD: -3.92; 95% CI: -6.93, -0.90). The study revealed that frequencies ranging from less than 1 Hz to more than 5 Hz were found to be effective, whereas continuous theta burst stimulation (cTBS) did not demonstrate such efficacy. Repeated rTMS reduced Y-BOCS scores (MD: -3.30; 95% CI: -4.55, -2.04), although this was below the minimal clinically important difference (4.9 points). The number needed to treat (NNT) for response was 6, and the dropout rates were comparable to those in the sham group, indicating good tolerability. The analysis comparing scores from the end of treatment to follow-up showed no significant change, indicating the maintenance of the achieved effect (MD: 0.07; 95% CI: -0.60 to 0.75; I² = 0%; p = 0.83). In contrast, the analysis of the overall effect from baseline to follow-up confirmed a significant and sustained benefit of the treatment (MD: -3.17; 95% CI: -4.68 to -1.65; I² = 64%; p < 0.0001).Baseline severity moderated outcomes, while coil type and neuronavigation did not.

Conclusion: The conclusion drawn from this analysis is that rTMS constitutes an effective treatment for OCD, particularly when administered to specific targets and at specific frequencies. Nevertheless, the mean clinical impact is negligible. The findings indicate the necessity of optimised protocols and pragmatic maintenance strategies.

Keywords: Obsessive-compulsive disorder; systematic review; transcranial magnetic stimulation.