When your gums attack your brain

By Meghan McCallum | Fact-checked by Barbara Bekiesz

Published June 10, 2025

Key Takeaways

Industry Buzz

“While the evidence is far from conclusive, it seems we’ve discovered one previously unknown cause of Alzheimer’s.” – Mark Burhenne, DDS

Find more of your peers' perspectives and insights below.

There is little dispute that oral hygiene is an important piece of the overall wellness puzzle. And, in fact, it actually carries an even greater importance than we may already think. A 2025 study published in PNAS Nexus links Prevotella intermedia, a type of bacteria found in gum disease, with health issues beyond the mouth itself—including Alzheimer’s disease.^[]

Understanding this link between the mouth and brain—and adequately prioritizing oral hygiene—can result in major health benefits for patients. By reducing oral bacteria, individuals can take better care of not only the teeth and gums, but the brain as well.

Research links oral bacteria to the brain

In an April 2023 interview on The Empowering Neurologist podcast, private practice dentist Dr. Mark Burhenne detailed the importance of oral hygiene for reasons far beyond healthy teeth and gums.^[] Gum disease can, in fact, play a role in many other health issues. And although it’s incredibly common, periodontitis “is a disease that can lead to another more serious disease: Alzheimer’s,” he said.

The 2025 study found that individuals with mild cognitive impairment (MCI) and higher P. intermedia bacteria levels were at higher risk for developing dementia in the future, with authors noting that “a greater prevalence of oral P. intermedia is linked to elevated genetic risk for dementia (APOE4 genotype) in individuals with MCI prior to dementia diagnosis.”^[]

An earlier study, published by Polish researchers in the International Journal of Molecular Sciences in 2024,^[] looked at the blood-brain barrier to explain the connection between another oral bacteria, Porphyromonas gingivalis, and the brain.

The study authors wrote, “Brains of individuals with Alzheimer’s disease have substantiated the existence of microorganisms related to periodontitis, especially Porphyromonas gingivalis, which produces neurotoxic gingipains and may present the capability to breach the blood–brain barrier.”

A new future for Alzheimer’s disease?

The link between oral bacteria and brain health holds great potential for further research. On his blog Ask the Dentist, Dr. Burhenne elaborates on what the current research tells us for the future of Alzheimer’s disease.^[]

“While the evidence is far from conclusive, it seems we’ve discovered one previously unknown cause of Alzheimer’s,” he writes. “It’s unlikely that periodontal disease is the only causative factor, but this is one of the most promising findings in recent times. It also has enormous potential to assist in curing, and not just managing, this disease.”

With this knowledge, there is hope for possibly delaying cognitive decline and Alzheimer’s. The 2025 study researchers commented that “interventions that promote the oral Neisseria–Haemophilus and suppress Prevotella-dominated modules have potential for delaying cognitive decline.”^[]

So, what's next?

It’s important to educate patients on this research and instill the importance of oral hygiene habits. Maintaining oral health will support them in many ways, which “range from possibly preventing Alzheimer’s disease and tooth loss to guarding against breast cancer and cardiovascular issues,” writes Dr. Burhenne.^[]

For those with active periodontal disease or gingivitis, he adds, “taking steps to treat this issue can have major benefits for your future and your mind.”

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