A functional MRI comparison of patients with obsessive-compulsive disorder and normal controls during a Chinese character Stroop task.

Recent functional neuroimaging and neuropsychological studies have suggested that abnormal activity in the anterior cingulate cortex (ACC) might cause an action-monitoring dysfunction in obsessive-compulsive disorder (OCD). To identify the relationship between brain dysfunction and cognitive dysfunction, we examined regional brain changes in OCD with functional magnetic resonance imaging (fMRI) during the performance of a cognitive task. Participants comprised 24 patients with OCD and 14 normal controls. First, we compared the cognitive function in the two groups as assessed by several neuropsychological tests. Then we used fMRI to explore brain correlates of their performance during the Chinese character version of the Stroop test, a task that is strongly related to action-monitoring function. The two groups did not differ on the neuropsychological tests. Both groups also showed similar activation pattern on fMRI. The patients, however, showed weaker activation than the normal controls in the ACC and the right caudate nucleus.