While previous studies have found lower FAFWcorr and higher FW in limbic, association, and transcallosal (TC) tracts25, 26, 28, 29, 30 associated with cognitive impairment and AD, there has yet to be a large‐scale analysis leveraging FW measures to understand how sex and APOE ε4 carrier status are associated with longitudinal white matter microstructure. The gene discussed is APOE; the disease is Cognitive impairment.