GFAP and Atrophy: Regarding the hippocampal atrophy and AD-signature cortical thinning, higher plasma GFAP concentrations were associated with more hippocampal atrophy (βstd = -0.146[95% ci, -0.246, -0.047], p = 0.004) before controlling for plasma Aβ42/Aβ40 and plasma p-Tau181, whereas the relation disappeared (βstd = -0.066[95% ci, -0.171, 0.039], p = 0.218) after including them as the covariates in the model (Supplemental Fig. 8A-B).