Most importantly, a higher level of Aβ42 in microglia was detected both in the cortex (Figure 7i, j, P < 0.01) and the hippocampus (Figure 7i, j, P < 0.05) of FMT-AD, suggesting that microglial activation induced by FMT of APP/PS1 mice increases the uptake of Aβ42 in the brain, especially in the microglia. Here, PSEN1 is linked to Alzheimer disease.