A study recently published in the journal PLOS ONE has shown that periodontitis, an inflammatory disease that destroys the supporting structures of the teeth, can accelerate the onset of Alzheimer's disease.
Understanding the causes and risk factors of Alzheimer's is essential for developing treatments, since it is a sporadic or late-onset disease whose causes and mechanisms are still poorly understood.
The link between cognitive disorders and oral hygiene has been known for some time. To study the effects of oral bacteria on the brain more closely, Dr Watanabe, a lecturer in periodontics at the University of Illinois at Chicago, and her colleagues induced chronic periodontitis in a group of laboratory mice. After 22 weeks of repeated oral application of the bacteria, the researchers examined the mice's brain tissue and compared it with that of untreated mice.
The mice exposed to the bacteria had considerably higher levels of accumulated beta-amyloid, a senile plaque found in the brain tissue of patients with Alzheimer's. This group also had greater brain inflammation and fewer intact neurons as a result of degeneration.
In addition, DNA from periodontal bacteria was found in the mice's brain tissue, and a bacterial protein was observed inside their neurons, demonstrating that the bacteria had travelled from the mouth to the brain.
The results of this study therefore showed that long-term exposure to the bacteria responsible for periodontitis, a preventable and treatable gum infection, causes inflammation and degeneration of neurons in mice in a way similar to the effects of Alzheimer's in humans.
Other studies had already investigated the association between cognitive disorders and periodontitis, but this is the very first to show that exposure to periodontal bacteria causes the formation of senile plaques that trigger the accelerated cognitive decline typical of Alzheimer's.
This important finding confirms once again that looking after your oral hygiene is essential not only for the health of your mouth but for your whole body.
Source: Vladimir Ilievski, Paulina K. Zuchowska, Stefan J. Green, Peter T. Toth, Michael E. Ragozzino, Khuong Le, Haider W. Aljewari, Neil M. O’Brien-Simpson, Eric C. Reynolds, Keiko Watanabe, Chronic oral application of a periodontal pathogen results in brain inflammation, neurodegeneration and amyloid beta production in wild type mice
