The Wisconsin Card Sorting Test and the assessment of frontal function in obsessive-compulsive patients: An event-related potential study

Abstract

The most consistent finding across the studies in obsessive-compulsive disorder (OCD) is the deficit in tasks involving shifting in cognitive set. The cognitive operations needed to perform the Wisconsin Card Sorting Test (WCST), searching for a new category and the consolidation of the correct classification category, are closely related to shifting cognitive set. This work aimed to study whether patients with OCD present difficulties in shifting cognitive set and to examine the topographical distribution of brain electrical changes and their temporal dynamics during the performance of the WCST. For this purpose, we selected 18 nondepressed OCD patients. The effects of clomipramine treatment on these variables were also assessed. Both behavioural and neuroelectric data supported the idea that OCD patients have an impaired capacity for shifting cognitive set. This deficit was interpreted as being due to problems in inhibitory control, as a consequence of a dysfunction in an inhibitory pathway in the prefrontal cortex. This would explain the poor performance of OCD patients in the WCST in terms of their inability to inhibit or suppress previous incorrect responses. Nevertheless, it is not clear whether shifting cognitive set is an enduring "trait" marker or a finding that fluctuates with changes in the clinical state.