There is indirect evidence from previous research that several executive disturbances in obsessive-compulsive disorder (OCD) are mediated by comorbid depressive symptoms. For the present study, the authors investigated whether OCD patients with elevated Hamilton Rating Scale for Depression (HRSD) scores would exhibit deficits in tasks sensitive to the medial and dorsolateral frontal cortex as well as other executive tasks. The 36 OCD patients were split along the median according to their HRSD scores and compared with matched control subjects. Patients with high HRSD scores performed significantly worse than control subjects and patients with low HRSD scores on the Wisconsin Card Sorting Test, the Trail-Making Test (TMT, Part B), and the TMT difference score. Moreover, patients with high HRSD scores exhibited deficits on a (creative) verbal fluency task. It is suggested that comorbid depressive symptoms may have artificially inflated some executive deficit scores in previous studies.
