These impairments in microglial responses to Aβ are not restricted to animal models; similar observations have been made in human AD patients carrying TREM2 mutations, where reduced microglial clustering around Aβ plaques and increased neuronal dystrophy are evident, reinforcing the vital role of TREM2 in protecting against Aβ toxicity [82, 85]. Here, TREM2 is linked to Alzheimer disease.