PSEN1 and Alzheimer disease: The results showed that the expression level of colonic BACE1 was significantly higher in the WT mice transplanted with feces of APP/PS1 mice (FMT-AD) than that of FMT-con (Figure 4e & f, P < 0.05) and the expression level of APP showed an increasing trend although not statistically significant (Figure 4e & f, P = 0.1221).