database (http://adni.loni.ucla.edu/) for 621 participants. For each scan, mean regional SUVR values were extracted for the frontal, parietal, temporal, limbic, and occipital lobes using the MarsBaR toolbox implemented in the Statistical Parametric Mapping 8 (SPM8) software (http://www.fil.ion.ucl.ac.uk/spm/software/spm8/). The average SUVR for these 5 regions was then calculated to represent a global cortical measure of Aβ deposition to be used as a quantitative phenotype for GWAS. Overall, 19 participants (11 HC, 6 MCI, 2 AD) were excluded due to missing scan data or failed processing, leaving data for 602 individuals available for further analysis.
