It is necessary to demonstrate the effect of microflora metabolites like amyloids on β-amyloid peptide generation and accumulation, tau protein dysfunction, neuroinflammation, neuronal death and vascular degeneration in various animal models so that the crosstalk between gut microbiome and its metabolites and neurodegeneration in Alzheimer’s disease can be fully understood. Here, PPIB is linked to early-onset autosomal dominant Alzheimer disease.