Studies using APP/PS1 transgenic mice and BV2 microglial models have revealed that TREM2 deficiency aggravates AD pathology through TLR4-dependent MAPK pathway activation, resulting in accelerated Aβ deposition, enhanced gliosis around amyloid plaques, and substantial neuronal/synaptic protein loss alongside cognitive decline. This evidence concerns the gene TREM2 and Alzheimer disease.