Shen et al. (2017) compared the gut microbiota of APP/PS1 transgenic mice with AD and C57/BL6 wild-type (WT) mice and found that the abundance of Helicobacteraceae increased significantly in APP/PS1 mice compared to WT mice. Bäuerl et al. (2018) reported the presence of Helicobacteraceae and a higher abundance of Desulfovibrionaceae in transgenic mice at the family level. Taken together, it is reasonable to assume that Helicobacteraceae are the most likely family of colonic bacteria to influence cognitive dysfunction. Here, APP is linked to Alzheimer disease.