TREM2 and Alzheimer disease: To determine how amyloid plaques increase p-tau levels in the early stages of AD, Biel and colleagues (Biel et al., 2023) evaluated if tau phosphorylation was affected by the soluble fragment of triggering receptor expressed on myeloid cell 2 (sTREM2), a microglial activation marker increased in the CSF of mild AD patients that also correlates with CSF tau (Heslegrave et al., 2016; Piccio et al., 2016).