As already shown in previous meta‐analyses across related mental disorders, some neural correlates are common across mental disorders, whereas others are more disorder‐specific (Goodkind et al., 2015; Radua et al., 2010). The ENIGMA consortium, with different working groups using the same pipelines for data processing and data analysis, is an ideal setting for studying common and distinct features of mental disorders. Our first attempt to do so focused on neurodevelopmental disorders in the impulsive‐compulsive spectrum, comparing OCD with ASD and ADHD. Using structural T1‐weighted MRI scans from 151 cohorts worldwide with data from patients with OCD (n = 2,323), ASD (n = 1,777), and ADHD (n = 2,271), and matched healthy controls (n = 5,827), we performed a mega‐analysis of cortical thickness, surface area and subcortical volume across groups, with separate analyses for children (<12 years), adolescents (12–17 years), and adults (>18 years) (Boedhoe et al., 2019). We found no shared alterations among all three disorders (even with uncorrected analyses), while shared alterations between any two disorders did not survive correction for multiple comparisons. Children with ADHD compared to those
