Based on the above knowledge, in the third part of the present study, we focused our attention on investigating the presence of AD-related proteins (i.e., α-syn, tau and Aβ) and their heteroaggregates, including α-syn-tau and α-syn-Aβ, as well as inflammation in colonic tissues from SAMP8 mice. This evidence concerns the gene MAPT and Alzheimer disease.