Structural T1-weighted brain MRI scans were acquired and processed locally at each site. Image acquisition parameters are listed elsewhere7. Parcellations were performed using FreeSurfer software version 5.3 (http://surfer.nmr.mgh.harvard.edu), following standardized ENIGMA protocols to harmonize analyses and quality control procedures across multiple sites (see http://enigma.usc.edu/protocols/imaging-protocols/). Mean values of parcellations of 34 cortical (Desikan-Killiany atlas-based28) and 7 subcortical gray matter structures per hemisphere, lateral ventricle volumes, two whole-hemisphere measures and total intracranial volume were extracted, visually inspected and statistically evaluated for outliers (quality assurance is reported elsewhere7). Brain regions (features) used for classification included cortical thickness (CT), surface area (SA) and subcortical volumes of ROIs, two lateral ventricular and intra-cranial volumes (ICV), and two whole-hemisphere measures for SA and CT.
