APOE and Alzheimer disease: Furthermore, within the AD group, as compared to non‐carriers, APOE ε4 carriers showed worse orientation function, lower plasma Aβ42 and plasma Aβ42/40 ratio, higher plasma GFAP, and plasma p‐tau181 (Bonferroni and Kruskal‐Wallis ANOVA corrected, p < 0.05).