In addition, significant associations were identified between cognitive performance and microbial communities, as well as various systemic and gut biomarkers (Colon Tlr9 correlated positively with STM, P = 0.041; and negatively with amyloid plaque, P = 0.028; spleen Il-10 correlated negatively with amyloid plaque, P = 0.046; spleen Il-1β correlated positively with them, P = 0.033; Fig. 11A, B). Here, TLR9 is linked to amyloidosis.