Repetitive Transcranial Magnetic Stimulation Improved Symptoms of Obsessive-Compulsive Disorders but Not Executive Functions: Results from a Randomized Clinical Trial with Crossover Design and Sham Condition.

Objective: Whereas there is growing evidence that repetitive transcranial magnetic stimulation (rTMS) favorably impacts on symptoms of obsessive-compulsive disorders (OCD), less is known regarding the influence of rTMS on cognitive performance of patients with OCD. Here, we tested the hypothesis that rTMS has a positive impact both on symptom severity and executive functions in such patients.

Methods: We assessed 10 patients diagnosed with OCD (mean age: 33.5 years) and treated with a standard medication; they were randomly assigned either to a treatment-first or to a sham-first condition. Symptom severity (experts' ratings) and executive functions (Wisconsin Card Sorting Test) were assessed by independent raters unaware of the patients' group assignments at baseline, after 2 and 4 weeks. After 2 weeks, treatment switched to sham condition, and sham condition switched to treatment condition.

Results: Under treatment but not under sham conditions, symptom severity decreased. Performance on the executive function test increased continuously with every new assessment and was unrelated to rTMS treatment.

Conclusion: Whereas the present study confirmed previous research suggesting that rTMS improved symptoms of OCD, rTMS did not improve executive functions to a greater degree than sham treatment. More research is needed to investigate the effect of rTMS on executive functions in patients with OCD.