Many women take hormone therapy after menopause to manage symptoms, and some have wondered if it might also help protect their brains from Alzheimer's disease. A long-term study that followed women for an average of 15 years looked at this question by measuring specific proteins in the blood that are linked to Alzheimer's pathology. The study compared women who were randomly assigned to take either estrogen alone, estrogen plus progestin, or placebo pills.
The researchers tracked changes in several biomarkers, including proteins called p-tau217, p-tau181, and GFAP, which can indicate Alzheimer's-related brain changes. They found that the rates at which these biomarkers changed over time did not significantly differ between the women taking hormones and those taking placebo. This was true for both types of hormone therapy tested.
Because women were randomly assigned to receive hormones or placebo, this study provides strong evidence about cause and effect. The 'null' finding—meaning no clear difference—suggests that these specific hormone treatments neither increase nor decrease the biological markers of Alzheimer's pathology in postmenopausal women over the long term. However, the study only measured blood biomarkers, not whether women actually developed dementia symptoms, so we can't say for certain how hormone therapy affects clinical Alzheimer's disease risk.
