Ossenkoppele R, Smith R, Mattsson-Carlgren N, et al. - According to this prognostic study, tau positron emission tomography (PET) is a promising tool for anticipating cognitive change that is superior to amyloid PET and magnetic resonance imaging (MRI), and that it may aid the prognostic process in the preclinical and prodromal stages of Alzheimer disease (AD).

• The sample consisted of 1,431 participants, the mean (SD) age was 71.2 (8.8) years; 751 (52.5%) were male.

• The effects of [¹⁸ F]flortaucipir PET on longitudinal changes in MMSE were larger than those of AD-signature cortical thickness and amyloid PET across all participants in the Aβ-positive MCI and Aβ-positive cognitively unimpaired (CU) groups.

• Such findings were confirmed in the [¹⁸ F]RO948 PET cohort.

• The link between [¹⁸ F]flortaucipir PET and MMSE was mediated by MRI in the groups with AD dementia and Aβ-positive MCI, but not the Aβ-positive CU group.

• The association between baseline [¹⁸ F]flortaucipir PET and cognitive change was modified by age, but not by gender or APOE genotype, with older people showing faster cognitive decline at similar tau PET levels.