Buckley RF, et al. - Researchers explored sex differences in the cross-sectional relationship between β-amyloid (Aβ) and regional tau deposition as quantified with positron emission tomography (PET) in this study of two cross-sectional cohorts of 296 clinically normal adults. According to findings, women with higher amyloid burden exhibited greater entorhinal cortical tau signal vs men with higher amyloid burden. There were no sex differences in amyloid load or apolipoprotein E ε4 frequency. In those on an Alzheimer's disease trajectory, early tau deposition was elevated in women vs men. These findings support an increasing body of literature that emphasizes a biological basis for sex differences in the risk of Alzheimer's disease.