Studies found that periodontitis induced by P. gingivalis increased the deposition of Aβ in the brain, and the levels of IL-1β and TNF-α, which affected the cognitive ability of mice.156 Another study induced experimental chronic periodontitis by orally feeding 10 C57BL/6 mice with P. gingivalis or gingipains for 22 weeks. The gene discussed is TNF; the disease is periodontitis.