Can Repetitive Transcranial Magnetic Stimulation Offer a New Therapeutic Avenue for Obsessive-Compulsive Disorder? A Systematic Review of Clinical Evidence

AbstractObsessive-Compulsive Disorder (OCD) is a chronic psychiatric disorder characterized by intrusive thoughts and repetitive behaviors, leading to significant distress and functional impairment. First-line treatments include selective serotonin reuptake inhibitors (SSRIs) and cognitive-behavioral therapy (CBT), particularly exposure and response prevention (ERP). However, a substantial proportion of patients exhibit limited or no response to these interventions. Non-invasive brain stimulation (NIBS) techniques, especially repetitive transcranial magnetic stimulation (rTMS), have shown potential in modulating dysfunctional cortical circuits implicated in OCD pathophysiology. Despite promising findings, clinical studies on rTMS report heterogeneous outcomes, possibly due to variations in stimulation parameters, target regions, and study designs. These inconsistencies underscore the need for a comprehensive synthesis of current evidence. A comprehensive literature search was conducted across PubMed, ScienceDirect, Web of Science, and Scopus up to March 2, 2025. Eligible studies included adult OCD patients receiving multi-session rTMS protocols. Case reports, non-English studies, and non-primary literature were excluded. Risk of bias was assessed using the Cochrane Collaboration tool. Forty-five studies involving 1,563 participants were included. The most frequently targeted regions were the dorsolateral prefrontal cortex (dlPFC) and supplementary motor area (SMA). Low-frequency (1 Hz) stimulation was the most commonly applied protocol. While several randomized controlled trials (RCTs) and open-label studies demonstrated significant symptom reductions, others reported minimal or no benefit. Methodological heterogeneity, particularly in stimulation parameters and target selection, precludes definitive conclusions. Notably, studies combining rTMS with pharmacological or psychotherapeutic interventions and those incorporating neurobiological predictors such as neuroimaging or genetic polymorphisms suggest potential for enhanced outcomes through personalized treatment strategies. Current evidence supports rTMS as a potentially effective adjunctive treatment for OCD, particularly when targeting the SMA and dlPFC. However, variability in methodological quality and treatment parameters underscores the need for standardized protocols and high-quality RCTs. Integrating neurobiological predictors and combining rTMS with established therapies may optimize treatment efficacy in future investigations.Keywords: Repetitive Transcranial Magnetic Stimulation, Obsessive-Compulsive Disorder, Non-invasive brain stimulation, Dorsolateral prefrontal cortex, Supplementary motor area