Thus, the presence in the brain of lipopolysaccharides from T. denticola, T. forsythia, and P. gingivalis that can be associated with increased expression of major proinflammatory cytokines (IL-1β, IL-6, TNFα, and IFNγ) and decreased anti-inflammatory cytokines (IL-10) suggests an involvement of the oral microbiota in the occurrence and progression of AD. This evidence concerns the gene IL6 and Alzheimer disease.