Compared to controls (N=324), medicated children with OCD (N=183) showed lower cortical thickness of the bilateral inferior parietal and superior parietal cortices and left lateral occipital cortex (Cohen’s d ~−0.31; Supplementary Table S10a and Figure S5). We did not detect significant differences in cortical thickness in unmedicated pediatric OCD patients (N=222) compared to controls and when comparing medicated with unmedicated patients (Supplementary Tables S10b–c). More widespread surface area differences were detected when comparing medicated pediatric OCD patients to controls mainly in several frontal regions (Cohen’s d between −0.27 and −0.33; Supplementary Table S11a and Figure 4). No differences in surface area were observed when comparing unmedicated patients to controls (Supplementary Table S11b). We did observe lower surface area of the right lingual (Cohen’s d −0.34) and pericalcarine (Cohen’s d −0.40) cortices in medicated compared to unmedicated pediatric OCD patients (Supplementary Table S11c and Figure S6).
