Alzheimer’s disease is the most common cause of dementia in the UK, and its exact cause is still not fully understood. Age, genetics, depression, and cardiovascular health are all known risk factors.

In recent years, some research has explored whether infections may play a role in its development. One area of interest involves gum disease and oral bacteria.

A 2019 study led by researchers including Jan Potempa found that the bacterium Porphyromonas gingivalis—a major cause of chronic gum disease—was detected in the brains of some deceased individuals with Alzheimer’s.

This bacterium produces enzymes called gingipains, which have been linked in laboratory studies to brain changes associated with Alzheimer’s, including the presence of amyloid-beta and tau proteins.

Animal studies, including mouse experiments, have suggested that oral infection with this bacterium may increase amyloid-beta production and inflammation in the brain. However, these findings are not yet confirmed in humans.

Researchers also found gingipain-related markers in some individuals without a formal Alzheimer’s diagnosis, which raised questions about whether infection could occur earlier than symptoms appear, or whether poor oral health develops alongside cognitive decline.

While these findings are scientifically interesting, experts emphasize that they do not prove Alzheimer’s is an infectious disease. The condition is widely understood to be complex and likely caused by multiple interacting factors.

Current research is exploring many possible pathways, but no infection-based treatment has been proven effective in humans so far. Most potential therapies are still in early experimental stages.

Overall, the gum disease link is a promising area of study, but it remains one piece of a much larger and still evolving scientific puzzle around Alzheimer’s disease.