TNF and Alzheimer disease: Accordingly, a study using a ligature model of periodontitis, supporting oral local dysbiosis and inflammation, found increased levels of the pro-inflammatory mediators, IL-6, TNF-α, and Aβ 1–42 in the cerebral cortex, and IL-1 in the hippocampus, compatible with neurodegenerative signs of AD, in comparison with control rats [42].