The cortical signatures were analyzed as continuous variables, but for illustration purposes, results are displayed by groups based on cortical signature tertiles (tertile 1 has the thickest cortex, tertile 3 has the thinnest cortex, interpreted as the greatest atrophy) and delirium (present [+] or absent [−]). Tertiles are generated separately for AD signature and for Aging-Only signature measures, leading to slight differences in group size. Estimated slopes are reported based on model coefficients and average cortical thickness in the respective tertile.