GFAP and early-onset autosomal dominant Alzheimer disease: However, consistent with most previous findings of a more significant increase in blood GFAP in Alzheimer’s disease patients than in FTLD patients,12,13,38-40 the plasma GFAP level was 2-fold higher in the Alzheimer’s disease group than in the FTLD group and effectively distinguished these two patient groups (AUC 0.894) in this study.