PSEN2 and Alzheimer disease: As for a possible connection between H. pylori infection and AD pathology, Wang et al. [38] demonstrated that H. pylori was not only associated with cognitive impairment in rats but was also associated with the promotion of Aβ42 production and with higher levels of presenilin-2, although such an association has not been shown in humans and it is still unclear whether H. pylori is directly associated with neuronal integrity [39].