The brain measures examined in this study were obtained from structural MRI data collected at participating sites around the world. Brain scans were processed and examined at each site locally, following a standardized protocol procedure to harmonize the analysis across sites. The standardized protocols for image analysis and quality assurance are openly available online (http://enigma.ini.usc.edu/protocols/imaging-protocols/). The subcortical brain measures (nucleus accumbens, amyg-dala, caudate nucleus, hippocampus, pallidum, putamen and thalamus) were delineated in the brain using well-validated, freely available brain segmentation software packages: FIRST31, part of the FMRIB Software Library (FSL), or FreeSurfer32. The agreement between the two software packages has been well documented in the literature5,33 and was further detailed here (Supplementary Table 4). Participating sites used the software package most suitable for their data set (the software used at each site is given in Supplementary Table 2) without selection based on genotype or the associations present in this study. In addition to the subcortical structures of the brain, we examined the genetic effects of a measure of global head size, the ICV. The ICV was calculated as: 1/(determinant of
