Two types of impairments in OCD: Obsessions, as problems of thought suppression; compulsions, as behavioral-executive impairment

Impairments in executive functioning have been identified as an underlying cause of Obsessive-Compulsive Disorder (OCD). Obsessive patients attempt to suppress certain unwanted thoughts through a mechanism that Wegner referred to as 'chronic thought suppression', whereas compulsive patients are unable to inhibit their rituals. We tested 51 OCD patients using the Yale-Brown Obsessive Compulsive Scale (Y-BOCS), the White Bear Suppression Inventory (WBSI) and the Dysexecutive Questionnaire (DEX). Executive functions were tested using a cognitive test battery. We found that the total WBSI score was correlated with the Y-BOCS obsessive score but not with the Y-BOCS compulsive score. A stronger correlation was observed between the Y-BOCS obsessive score and the 'unwanted intrusive thoughts' factor based on Blumberg's 3-factor model of the WBSI. The total WBSI score was not correlated with the cognitive test results. The DEX score was significantly correlated with the Y-BOCS compulsive score; however, no correlation was found between the DEX score and the Y-BOCS obsessive score. A stronger correlation was observed between the Y-BOCS compulsive score and the 'inhibition' component of the DEX score, as defined by Burgess's 5-factor model. The DEX scores were correlated with cognitive test results measuring attention, cognitive flexibility and inhibitory processes. We conclude that obsessions indicate a failure of cognitive inhibition but do not involve significant impairment of executive functions, whereas compulsions indicate ineffective behavior inhibition and impaired executive functions.