The ENIGMA-OCD working group includes 38 data sets from 27 international research institutes, with neuroimaging and clinical data from OCD patients and typically developing healthy control subjects (i.e., free of psychopathology), including both children and adults (participating sites are mapped in Supplementary Figure S1). Six (i.e. the entire OBIC sample) out of these 38 data sets were identical to those included in the OBIC mega-analyses using VBM (11) and vertex-based FreeSurfer (12). We defined adults as individuals aged ≥18 years and children as individuals aged <18 years. The split at the age of 18 followed from a natural selection of the age ranges used in these samples, as most samples used the age of 18 years as a cut-off for inclusion. Each sample’s demographic and clinical characteristics are detailed in Supplementary Tables S1 and S2. In total, we analyzed data from 3665 subjects including 1905 OCD patients (407 children and 1498 adults) and 1760 control subjects (324 children and 1436 adults). All local institutional review boards permitted the use of measures extracted from the anonymized data for mega-analyses.
