Even though its protective and harmful roles during the pathogenesis of AD remain incompletely defined (Jay et al., 2015; Wang et al., 2015; Zhong et al., 2019), increasing evidence suggest that TREM2 is closely related to microgliosis, astrogliosis, neuroinflammation, neuronal loss and cognition impairment in AD (Jay et al., 2017). Here, TREM2 is linked to Alzheimer disease.