Whereas VBM measures volume or gray matter density in cortical regions at the voxel level (Ashburner & Friston, 2000), surface‐based methods such as FreeSurfer calculate morphometric measures from geometric models of the cortical surface (Fischl & Dale, 2000). Abnormalities in regional volume as measured with VBM can be the result of altered cortical thickness (CTh), surface area (SA), cortical folding, or a combination of these. Whereas cortical thickness changes dynamically across the lifespan as a consequence of development, disease and environmental factors (Eyler et al., 2011; Frye et al., 2010), surface area and cortical folding are more indicative of early neurodevelopment (Mangin, Jouvent, & Cachia, 2010). Atlas‐based approaches as used in FreeSurfer and voxel‐based approaches as used in VBM also differ in their approach to and interpretation of subcortical regions: Whereas VBM detects density differences at the voxel‐level, global or regional differences in subcortical structures can be inferred from atlas‐based FreeSurfer analyses. Using exactly the same OBIC sample as was used in the VBM mega‐analysis (De Wit et al., 2014), Fouche et al. (2017) used vertex‐wise FreeSurfer to compare cortical
