In the study performed by El Khroury and collaborators using an AD transgenic model, a CCL2-deficient APP/PS1 mouse, which has a deficiency in the Ccr2 chemokine receptor and its ligand (CCL2) on microglia, they observed a regression in the disease (El Khoury et al., 2007; Kiyota et al., 2013). This evidence concerns the gene CCL2 and Alzheimer disease.