TREM2, a receptor specificallyexpressed on the microglial surface,has been demonstrated to play a crucial part in learning and memoryby modulating synaptic pruning during CNS development. In our study model, the expression of TREM2in hippocampal microglia did not change after SD, though it was reportedto be downregulated after chronic SD., Intriguingly,we observed a significant downregulation of its cognate ligand APOEin the hippocampus of SD mice. Here, TREM2 is linked to Salla disease.