OCULOMOTOR RESPONSE-INHIBITION ABNORMALITIES IN PEDIATRIC OBSESSIVE-COMPULSIVE DISORDER

Background: Disturbances in the orbital prefrontal cortex and its vent ral striatal target fields have been identified in neuroimaging studie s of obsessive-compulsive disorder (OCD). In animal models and studies of patients with lesions to this brain circuitry, a selective disturb ance in the ability to suppress responses to irrelevant stimuli has be en demonstrated. Such a deficit in response suppression might underlie the apparent inhibitory deficit suggested by the symptoms of OCD. To date, little direct evidence of such a deficit has been reported. Furt her, although OCD commonly emerges during childhood or adolescence, fe w studies have examined psychotropic-naive pediatric patients near the onset of illness to find the possible role of atypical. developmental processes in this disorder. Methods: Oculomotor tests were administer ed to 18 psychotropic medication-naive, nondepressed patients with OCD aged 8.8 to 16.9 years and 18 case-matched healthy comparison subject s to assess the following 3 well-delineated aspects of prefrontal cort ical function: the ability to suppress responses, the volitional execu tion of delayed responses, and the anticipation of predictable events. Results: A significantly higher percentage of response suppression fa ilures was observed in patients with OCD (P=.003), particularly in you nger patients compared with their, case-matched controls. No significa nt differences between patients with OCD and controls were observed on other prefrontal cortical functions. Severity of OCD symptoms was rel ated to response suppression deficits. Conclusion: A basic disturbance of behavioral inhibition in OCD was detected that may underlie the re petitive symptomatic behavior that characterizes the illness.