Evidence for a selective developmental neurocognitive deficit in pediatric OCD

Disturbances in 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 symptomatology 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 study the role of atypical developmental processes. Oculomotor tests were administered to 18 medication-naive, non-depressed OCD patients 8.8-16.9 years of age, and 18 case-matched healthy comparison subjects, to assess three well delineated aspects of prefrontal cortical function: the ability to suppress responses, to volitionally execute delayed responses, and to anticipate predictable events. A significantly higher percentage of response suppression failures was observed in OCD patients, particularly in younger patients, compared to their case-matched controls. No significant differences between OCD patients and controls were observed on other prefrontal cortical functions. Severity of OCD symptoms was related to response suppression deficits. An apparent delay in acquisition ability of approximately four years was observed in OCD subjects. A basic disturbance of neurobehavioral inhibition in OCD was detected which may underlie the repetitive symptomatic behavior that characterizes the illness. Behavioral response inhibition abnormalities in OCD may be related to failures in developmental maturation of fronto-striatal circuitry, particularly orbital prefrontal-ventral striatal circuits.