Cognitive frontal lobe dysfunction in obsessive-compulsive disorder

Background: There is evidence that dysfunction within associative frontostriatal circuits represents a feature of obsessive-compulsive disorder (OCD). Previous neuropsychologic studies have yielded diverging results, which may in part be explained by differences in the selection of subjects and methods. The present study focused on the question of cognitive frontal lobe performance in OCD. Methods: Twenty-nine unmedicated OCD patients were compared to a double-size control group of normal subjects matched individually for age, sex, and intelligence. A series of 12 neuropsychologic tests was applied, most of which are thought to be sensitive to different aspects of cognitive frontal lobe function. Results: OCD patients were unimpaired at tests of abstraction, problem solving, set-shifting, response inhibition, active memory search, and choice reaction speed. Deficits of approximately one standard deviation were observed at timed tests of verbal and nonverbal fluency, attentional processing, and weight sorting. Conclusions: OCD patients exhibited selective deficits in tasks involving controlled attentional processing and self-guided, spontaneous behavior. We discuss a link between this neuropsychologic profile and dyfunctioning within the anterior cingulate, but not the dorsolateral prefrontal circuit.