APP and Cognitive impairment: For example, oral application of live Porphyromonas gingivalis significantly enhances amyloid and tau pathology, neuroinflammation and cognitive impairment in aged wild type mice and APP/PS1 transgenic mice (Ding et al., 2018; Ilievski et al., 2018; Dominy et al., 2019) and a real live Bordetella pertussis respiratory infection results in increased neuroinflammation and Aβ40 load (McManus et al., 2014).