In contrast, ASVs and genera that are less abundant in patients with AD and MCI (e.g. Alistipes, Parasutterella, Barnesiella uncl., and Erysipelotrichaceae), displayed a negative relationship (t-value <0) to AD and MCI pathology (decreasing amyloid burden, CSF p-tau/Aβ42; Fig. 4A). This evidence concerns the gene MAPT and Alzheimer disease.