Impairment of olfactory identification in obsessive-compulsive disorder

Background. Olfactory identification ability has been associated with proce ssing in the orbitofrontal cortex (OFC), an area that has been implicated i n the pathophysiology of obsessive-compulsive disorder (OCD). Although olfa ctory sensitivity is normal in patients with OCD, no study has investigated olfactory identification in this disorder. Methods. A group of 20 subjects with OCD and 23 age- and education-matched controls performed a standardized test of olfactory identification. They al so performed computerized tests of spatial memory span, spatial working mem ory and spatial recognition memory that have been shown previously to be se nsitive to cognitive deficits in patients with OCD. Results. Performance on the olfactory identification task, spatial recognit ion task and spatial span task was significantly worse in the OCD group tha n controls. Conclusions. While impairment in spatial cognition is consistent with previ ous studies of OCD, its significance for brain-behaviour models of OCD is u nclear. However, the finding of abnormal olfactory identification in patien ts with OCD is consistent with the hypothesis that there is a disruption to processing at the level of the OFC in the disorder.