LAUSR

Introduction Half of all patients with obsessive compulsive disorder (OCD) have their disease onset in childhood and adolescence of which up to 40 percent shows persistence of symptoms into adulthood [1]. In addition to their clinical symptoms, patients also show an underperformance in neurocognitive functioning that may hamper the efficacy of cognitive behavioral therapy (CBT) [2]. Previous studies showed changes after CBT in prefrontal cortex function and cognitive performance in pediatric OCD [3]. It remains unknown whether these changes are short lasting or persistent during a period of brain maturation. Here, we investigated the long-term effects of CBT on planning performance and brain function in pediatric OCD using a longitudinal design. Methods Fifteen pediatric OCD patients and sixteen matched healthy controls ranging from the ages of 8-18 years performed the Tower of London planning paradigm during functional magnetic resonance imaging (fMRI) at three time points; before treatment, after 16 sessions of CBT and after two years of naturalistic follow up. The task consisted of six conditions: a baseline condition and five planning conditions with increasing difficulty. Weighted contrasts for each subject for the effect of all planning moves versus baseline and for the linear effect of the increasing task load were computed. Voxel-wise statistical tests were family wise error (FWE) rate corrected (P Results Pediatric OCD patients performed the planning task significantly slower than healthy controls at baseline (pre-treatment), but with the same accuracy. After two years of follow up, reaction times were at the level of healthy controls. Imaging results at baseline showed that increasing task difficulty was associated with stronger recruitment of the left inferior frontal gyrus, middle frontal gyrus and anterior insula in patients than controls. With increasing age, activity in the left insula and right cingulum decreases, opposed to increasing activity in the parietal lobe. Normalization of the anterior insula and inferior frontal gyrus that occurred shortly after CBT continued during the two-year follow-up. Conclusion Pediatric OCD patients showed longer reaction times and additional recruitment of frontal brain regions during planning complexity compared with healthy controls. These differences tended to normalize after CBT and the process continued during two years of follow-up. This longitudinal study shows long-lasting changes in cognitive performance and prefrontal cortex function after CBT during a period of ongoing brain maturation. In addition, the temporary effects of this longitudinal study suggest that modest planning dysfunction in pediatric OCD is a state rather than a trait characteristic of the disorder.