Compared with non-AD patients, AD continuum and AD participants showed increased levels of plasma P-tau181 (p < 0.001, p < 0.001), GFAP (p < 0.001, p < 0.001) and P-tau181/Aβ42 (p < 0.001, p < 0.001) and decreased levels of Aβ42/Aβ40 ratios (p = 0.020, p = 0.010). This evidence concerns the gene GFAP and Alzheimer disease.