No Impaired Inhibition of Stimulus-Driven Behavior in Pediatric Obsessive-Compulsive Disorder: a Partial Test of the Habit Formation Model

The mechanisms that underlie obsessive-compulsive disorder (OCD) are elusive. The habit formation model of OCD postulates that compulsions arise from an imbalance between goal-directed and habit formation systems, stemming from impaired inhibition of stimulus-driven actions. Few studies have examined the core tenets of the habit formation model in pediatric OCD. We administered the object-interference task, which assesses the ability to inhibit stimulus-driven behavior, to 67 youths with OCD, 43 youths with an anxiety disorder (and no OCD), and 48 youths without any mental disorder. Impaired inhibition of stimulus-driven behavior was calculated by comparing response times to neutral non-nameable objects, neutral nameable objects, distress-eliciting objects, and incompleteness-eliciting objects. Youths with OCD did not differ significantly from youths with anxiety disorders and the non-clinical group on any response cost measure. All groups showed small response costs in relation to all three categories of non-neutral objects, with the clearest cost emerging in relation to distress-eliciting objects. Individual differences in response cost were not significantly correlated with any interview- or self-rated measure of OCD severity. Using the object-interference task, no evidence was found for impaired inhibition of stimulus-driven behavior in youths with OCD. We explore several possible interpretations of this result, including limitations of the task itself, the broader constraints of experimental methods in detecting such mechanisms, and the possibility that an imbalance between goal-directed and habit systems may not be a fundamental feature of pediatric OCD.