Abstract
BACKGROUND: Numerous studies have investigated response inhibition (RI) in obsessive-compulsive disorder (OCD), with many reporting that OCD patients demonstrate deficits in RI as compared to controls. However, reported effect sizes tend to be modest and results have been inconsistent, with some studies finding intact RI in OCD. To date, no study has examined the effect of medications on RI in OCD patients. METHODS: We analyzed results from a stop-signal task to probe RI in 65 OCD patients (32 of whom were medicated) and 58 healthy controls (HCs). RESULTS: There was no statistically significant difference in stop-signal reaction time between the OCD group and the HC group, or between the medicated and unmedicated OCD patients. However, variability was significantly greater in the medicated OCD group compared to the unmedicated group. CONCLUSIONS: These results indicate that some samples of OCD patients do not have deficits in RI, making it unlikely that deficient RI underlies repetitive behaviors in all OCD patients. Future research is needed to fully elucidate the impact of medication use on stop-signal performance. Implications for future research on the cognitive processes underlying repetitive thoughts and behaviors are discussed.