Homozygous APOE4 carriers show as high as a 15-fold increased risk for Alzheimer’s disease compared with non-carriers, with heterozygous and homozygous female carriers at even greater risk than male carriers.120 In addition, female carriers show more Alzheimer’s disease neuropathology (i.e. greater cerebrospinal fluid amyloid-β, greater total tau and elevated tau-to-amyloid-β ratio) compared with male carriers.121 Thus, APOE4 status is a non-modifiable risk factor for Alzheimer’s disease that confers a greater risk in women. This evidence concerns the gene MAPT and Alzheimer disease.