GFAP and Alzheimer disease: When combined with serum SV2A, the AUC of GFAP for identifying AD from VaD significantly increased from 66.3 to 83.6% (p = 0.0007) (Fig. 4b-e), and that of p-tau217 from 63.1 to 81.9% (p = 0.0008) (Fig. 4c-f).