A recent meta-analysis published in Biological Psychiatry: Cognitive Neuroscience and Neuroimaging suggests that repetitive transcranial magnetic stimulation (rTMS) may offer a moderate therapeutic benefit for individuals suffering from obsessive-compulsive disorder (OCD), especially those with comorbid depression. The study, which included 25 randomized controlled trials (RCTs) with a total of 860 participants, assessed the efficacy of rTMS compared to sham conditions in reducing OCD severity.
The meta-analysis revealed that rTMS had a moderate therapeutic effect on OCD severity (g = 0.65, P < 0.001). Furthermore, the treatment response rate was significantly higher in the rTMS group (39.5%) compared to the sham group (8.8%), demonstrating a large treatment effect (RR = 3.15, P < 0.001).
Key Moderators of rTMS Treatment Effect
The study identified three significant moderators of the treatment effect. First, patients who experienced a greater improvement in depression severity also showed a larger treatment effect of rTMS on OCD (P = 0.02). Second, longer TMS sessions were associated with greater improvement in OCD (P = 0.05). Lastly, a lower number of TMS sessions were associated with greater improvement in OCD severity (P = 0.02).
Interestingly, factors such as patient age, sex, duration of OCD illness, concurrent use of serotonin reuptake inhibitors or antipsychotics, baseline OCD symptom severity, and medication-free status did not significantly impact the treatment effect of rTMS on OCD severity. Similarly, intervention characteristics like rTMS motor thresholds, frequencies, coils, total number of pulses, and the location of rTMS treatment (dorsolateral prefrontal cortex, orbitofrontal cortex, and supplementary motor area) were not statistically significant.
Strengths and Limitations
The meta-analysis boasts several strengths, including the inclusion of 25 studies and 860 participants, the exclusive use of RCTs, and the variety of rTMS parameters used across trials. The authors declared no conflicts of interest.
However, the study also has limitations. The included studies focused only on acute treatment outcomes, and the statistical analysis did not correct for multiple comparisons. Limited patient characteristics were available for extraction, and publication bias was present.
Clinical Implications
Given the heterogeneity and potentially debilitating nature of OCD, the findings suggest that rTMS could be a valuable intervention for alleviating OCD symptoms, particularly in patients who have failed other treatments or those with comorbid depression. Clinicians should consider rTMS as a viable option to improve outcomes in this challenging patient population.
