Some studies [34] demonstrated that T. Denticola releases Aβ1–40 and Aβ1–42 from its parent protein (amyloid precursor protein) due to the activation of β-secretase and γ secretase, resulting in the GSK-3β activation and tau phosphorylation; this protein is important for the stabilization of the cytoskeleton of neurons, but in this form, it can contribute to AD. Here, APP is linked to Alzheimer disease.