ARIAs occurred more often in ε4 allele of apolipoprotein E gene (APOE4) carriers, the strongest genetic risk factor for the late-onset AD, than non-carriers (Cummings et al., 2018; Lin et al., 2018), which was a main safety finding and could justify further application of aducanumab for the treatment of AD (Sevigny et al., 2016). Here, APOE is linked to Alzheimer disease.