Sex differences are central to late-onset Alzheimer’s disease (AD)1,2, with women displaying higher lifetime prevalence3, higher incidence rates at old age4, and greater risk related to APOE ε45–7–the strongest, common genetic risk factor for AD–while also differing from men in clinicopathological trajectories8–10, resilience10,11, and response to anti-amyloid therapies12. The gene discussed is APOE; the disease is Alzheimer disease.