APOE and Alzheimer disease: Likewise, in the case of ALP levels, the association with AD diagnosis was not mediated by age but was significantly mediated by amyloid PET global SUVR (total effect: β = 0.0012, p = 0.002; mediating effect: β = 0.0004, p = 0.039), exclusively in the APOE ε4 carrier group (Table 11).