Periodontitis is Associated with an Increase in Cognitive Decline in Alzheimer’s Disease

Poor oral health can adversely affect systemic circulation and result in systemic disease. Untreated gum disease may turn into periodontitis. Periodontitis is a condition in which the inflammation and infection in the gums spread to the bone supporting the teeth. This condition results from the buildup of a sticky substance called plaque which adheres to the teeth. Bacteria form in the plaque and the result is gum inflammation. The plaque takes on the form of biofilm and consists of numerous microorganisms. Common symptoms include red, bloody and swollen gums, halitosis, tooth sensitivity and the formation of gum pockets.

Periodontitis is considered to be a low grade systemic disease which can harm one’s general systemic health. The microorganisms from this condition are responsible for the release of proinflammatory cytokines into the blood stream. “Cytokines” are defined as “any number of substances which are secreted by certain cells of the immune system and have an effect on other cells.” They are small proteins that are important in cell signaling, and they modulate immune responses. The release of these proinflammatory cytokines leads to system inflammation which in turn, penetrates the blood brain barrier and activates microglial cells.

Microglial cells are the primary immune cells of the central nervous system (brain and spinal cord) and act as a major inflammatory cell type in the brain. Their function is to find plaques and other infectious agents. Interestingly, small amounts of these microglial cells can be protective, whereas an abundance of the cells can be damaging. When the cells are providing a protective function, they clear away the plaques as well as protect the brain from toxic assaults. As we age, and as a result of certain genetic variants, microglial cells lose their ability to protect the brain. As the function of the microglial cells diminish, chronic inflammation increases. Instead of protecting the brain, the inflammatory signals cause the microglial cells to become neurotoxic and further contribute to Alzheimer’s disease.

The particular bacteria, Porphyromonas gingivalis has been identified as the keystone pathogen in chronic periodontitis which has been identified in the brains of patients with Alzheimer’s disease.

It is thought that periodontitis increases the severity of dementia as well as accelerates cognitive decline. Studies have shown that the presence of periodontitis contributed to a six fold increase in the rate of cognitive decline.

https://www.ncbi.nlm.nih.gov/pubmed/25491073

https://www.nature.com/articles/nrmicro.2016178

https://www.researchgate.net/publication/293010038

https://journals.plos.org/plosone/article?id=10.13711journal.pone.0151081