GFAP and early-onset autosomal dominant Alzheimer disease: In distinguishing patients with Alzheimer’s disease from patients with SIVD (Fig. 3D), plasma P-tau181 showed an AUC of 0.922 with a sensitivity of 0.72 and a specificity of 0.96 at a cutoff value of 3.86 pg/mL, followed by GFAP (AUC 0.714, sensitivity 0.65, specificity 0.71).