TREM2 and Alzheimer disease: Next, we asked whether the number of TREM2 microglia at the plaque niche in the AD/cKO is driven by higher total TREM2+ microglia and/or a shift from TREM2+ non plaque associated (NPAM) to plaque associated (PAM) microglia, defined as TREM2+ microglia associated with Aβ deposition.