Disturbances in the orbital prefrontal cortex and its ventral striatal target fields have been identified in neuroimaging studies of obsessive-compulsive disorder (OCD). In animal models and studies of patients with lesions to this brain circuitry, a selective disturbance in the ability to suppress responses to irrelevant stimuli has been 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. Further, although OCD commonly emerges during childhood or adolescence, few studies have examined psychotropic-naive pediatric patients near the onset of illness to find the possible role of atypical developmental processes in this disorder.
Oculomotor tests were administered to 18 psychotropic medication—naive, nondepressed patients with OCD aged 8.8 to 16.9 years and 18 case-matched healthy comparison subjects to assess the following 3 welldelineated aspects of prefrontal cortical function: the ability to suppress responses, the volitional execution of delayed responses, and the anticipation of predictable events.
A significantly higher percentage of response suppression failures was observed in patients with OCD (P=.003), particularly in younger patients compared with their case-matched controls. No significant differences between patients with OCD and controls were observed on other prefrontal cortical functions. Severity of OCD symptoms was related to response suppression deficits.
A basic disturbance of behavioral inhibition in OCD was detected that may underlie the repetitive symptomatic behavior that characterizes the ill