Although we sought to control for confounding effects of age using covariates, genetic influence on cognitive ability is somewhat reduced in early childhood and adolescence relative to adulthood.67 In addition, late-life effects of cognitive decline may be mediated through somewhat disparate molecular pathways; this may explain the relatively weak effect of variation at APOE compared with prior GWAS meta-analysis.7 Nevertheless, cognitive abilities are remarkably stable across the entire lifespan,68 so we chose to include all available samples in order to maximize sample size and power. This evidence concerns the gene APOE and Mental deterioration.