The present mini-review discusses possible mechanisms for the induction of neuroinflammation by P. gingivalis in AD, involving factors such as pro-inflammatory mediators, amyloid-beta, tau, microglia, cathepsin B, and protein kinase R. Inflammagens of P. gingivalis such as lipopolysaccharide and gingipains are also discussed. Here, CTSB is linked to Alzheimer disease.