22/10/2025
Alzheimer’s disease has long been thought of as just a brain disorder, but growing evidence suggests the problem could begin in the mouth. Scientists have found that Porphyromonas gingivalis, the bacteria responsible for chronic gum disease, may travel from the mouth to the brain and set off harmful changes linked to dementia. In brain samples from people who died with Alzheimer’s, researchers detected not only this bacteria but also toxic enzymes it produces, called gingipains. These enzymes were found alongside tau tangles and other protein markers of the disease, suggesting a strong connection.
What makes this even more striking is that traces of gingipains were also discovered in people who never had a dementia diagnosis but showed early signs of Alzheimer’s changes in their brains. This points to the possibility that infection could be an early trigger, rather than just a side effect of poor dental care in later life. Animal studies added weight to the idea, showing that oral infection allowed the bacteria to reach the brain, boosting levels of amyloid beta, the sticky protein that clogs brain cells.
Researchers are now testing experimental drugs designed to block the damaging effects of these bacterial toxins. In mice, one such compound reduced both infection and brain inflammation, raising hope for new treatment strategies. While it is still too early to say for sure, the link between gum disease and Alzheimer’s may open an unexpected pathway for prevention and therapy.
Research Paper 📄
PMID: 30746447
