TREM2 and Atrophy: TREM2 deficiency in the setting of pure tauopathy limits gliosis and neuroinflammation, as well as protecting against brain atrophy, suggesting that TREM2 facilitates a microglial response to tau pathology and/or tau-mediated damage in the brain (Bemiller et al., 2017; Leyns et al., 2017).