IL34 and Alzheimer disease: Zuroff et al. (2020) found that IL34, another ligand of CSF1R, impairs monocyte differentiation into macrophages and reduces their ability to uptake pathological forms of Aβ. Furthermore, one study has shown that cognitive decline is delayed in CSF1R-deleted APPSwe/PS1mice, in which TREM2/ β-catenin and IL34 expression are significantly increased (Pons et al., 2021), indicating that conditional deletion of CSF1R in microglia ameliorates the physiopathology of AD.