Oral Infections and Cognitive Decline
Your mouth holds more than just teeth and gums. It is home to billions of bacteria, and when those bacteria cause infections, they might affect your brain health over time. Recent studies show a clear link between poor oral health and problems with thinking and memory, especially in older adults.
One common oral issue is periodontitis, a gum disease caused by plaque buildup. Bacteria from infected gums can enter the bloodstream and spread to other parts of the body, including the brain. This leads to ongoing inflammation that harms brain cells. Researchers have found a specific bacterium called Porphyromonas gingivalis in the brains of people with Alzheimer’s disease. This germ produces harmful enzymes known as gingipains, which may build up sticky proteins like amyloid beta and damage brain structures linked to memory loss.
Tooth loss is another sign of trouble. People missing many teeth often show faster declines in all areas of thinking, from memory to problem-solving and language skills. Dental plaque, the sticky film on teeth, hits executive function and memory hardest. Even self-reported gum symptoms, like bleeding or soreness, connect to weaker executive skills, which help with planning and focus.
Scientists studied over 750 older adults without dementia at the start. Over about eight years, those with more tooth loss or plaque saw their cognitive scores drop steadily across tests. The findings held even after accounting for age, education, and other health factors.
How does this happen? The mouth and brain connect through what experts call the oral-brain axis. Bad bacteria disrupt the balance in your mouth, called dysbiosis, sparking widespread inflammation. Immune signals like TLRs and NLRs ramp up this response, worsening brain swelling and neuron damage. Mouse experiments confirm it: Infecting their mouths with P. gingivalis led to bacteria reaching the brain, more amyloid production, and disease markers.
Treating gum disease might help. Early cleaning and good hygiene could lower inflammation and slow cognitive changes. While not every case of gum disease causes dementia, keeping your mouth healthy is a simple step for brain protection.
Sources
https://academic.oup.com/biomedgerontology/advance-article-abstract/doi/10.1093/gerona/glaf294/8407296
https://pubmed.ncbi.nlm.nih.gov/41420750/
https://www.emjreviews.com/neurology/news/oral-bacteria-and-alzheimers-disease-may-intersect/
https://www.sciencealert.com/the-cause-of-alzheimers-may-be-coming-from-within-your-mouth
https://alz-journals.onlinelibrary.wiley.com/doi/full/10.1002/alz.71011
https://www.emergencydentistoxford.co.uk/blog/oral-health-and-alzheimers-the-connection-explained-for-oxford-families/
