Evidence for specific cognitive deficits in visual information processing in patients with OCD compared to patients with unipolar depression.

OBJECTIVE

Neuropsychological studies comparing cognitive performance in patients suffering from Obsessive-Compulsive Disorder (OCD) or Major Depressive Disorder (MDD) revealed deficits in the domains of verbal fluency and viso-motor speed/set shifting in both groups. Spatial working memory deficits, however, have been identified as specific markers of OCD. As yet, it has not been substantiated whether deficits in visual organization and complex visual memory are also specific to OCD and are not shared by MDD.

METHOD

Test performance in seven cognitive domains was assessed in 40 OCD patients, 20 MDD patients, and 40 healthy controls. Patient groups were matched according to severity of depressive symptoms.

RESULTS

Deficits shared by both patient groups, as compared to controls, were found in delayed spatial recall and verbal fluency while verbal memory was normal in both patient groups. Only patients with OCD, but not MDD patients were impaired in the domains visual memory, viso-motor speed/set shifting, visual organization, and problem solving. In addition, OCD patients differed significantly from MDD subjects in visual organization and problem solving. Visual organization scores correlated significantly with severity of current compulsions in the OCD group (r=-.324).

CONCLUSIONS

OCD patients demonstrate difficulties in visual organization and mental manipulation of complex visual material, which are not accounted for by depressive symptoms and which constitute a specific cognitive deficit of the disorder.