OCD is usually associated with fear-based obsessions leading to compulsions, however, many individuals with OCD report uncomfortable urge sensations that drive their compulsions (e.g. overwhelming and uncomfortable feeling of contamination drives hand-washing), even when there is no concrete fear. These urges intensify when compulsions are suppressed or delayed, and are part of “sensory phenomena” that may be harder to treat using standard treatment. These urge sensations are also similar to everyday urges, such as the urge to blink or scratch. Using eyeblink suppression to elicit urges, Dr. Eng and her team previously found that patients with OCD were less successful than controls in suppressing their eyeblinks when asked to do so, and that more failure in suppressing blinking was linked to more severe sensory phenomena. Greater activity in the postcentral gyrus (a brain region involved in processing sensory information) was also associated with more failures in eyeblink suppression and more severe sensory phenomena, suggesting that this region may underlie pathological urges related to sensory phenomena in OCD.

Transcranial magnetic stimulation (TMS) is a form of non-invasive neuromodulation technique that can be used to either reduce or increase activity in a brain region. In a small pilot investigation of four patients with OCD, inhibitory TMS delivered in a single session to an individualized target in the postcentral gyrus (compared to sham TMS) was generally associated with reduced brain activity in this region, improved eyeblink suppression during the eyeblink suppression task, and lower self-report urge to perform compulsions. The current study by Dr. Eng and her team will include a larger sample of patients to continue to test whether TMS delivered using individualized targeting can reduce activity in the postcentral gyrus and improve urge suppression in OCD. This will be the first study to test such a novel approach targeting the brain network of pathological urges in OCD. Findings will provide a critical first step toward treatment trials aimed at reducing pathological urges in OCD to enhance therapeutic outcomes for these difficult-to-treat symptoms.