TREM2 and Alzheimer disease: Furthermore, in TREM2 deficient mice, loss of microglia clustering around Aβ plaques increases AD risk, supporting the idea that microglia can have a protective effect, decreasing AD pathogenesis [185], as also shown in PS2APP (PS2N141I x APPswe) mice in which continuing microglial response seemed to impart preserved cognitive performance [186].