MAPT and Alzheimer disease: Similarly, a study of plasma AD biomarkers found that APOE ε4 carriers receiving MHT had less reduction in plasma Aβ42/phosphorylated tau (p‐tau)231 ratios than those on placebo, and that within MHT users, carriers showed greater reductions of Aβ42 levels than non‐carriers, indicating less likely progression toward AD pathology after 6 months.34