Yes, dental health can affect your risk of dementia — and the evidence has grown considerably stronger in recent years. People who have lost all their teeth are nearly twice as likely to develop dementia as those who maintain healthy gums and a full set of teeth: 23% versus 14%, according to research cited by the National Institute on Aging. That gap is not trivial, and it mirrors a broader pattern seen across multiple large studies linking poor oral health to cognitive decline. This article covers what the research currently shows, what biological mechanisms are thought to connect your mouth to your brain, what daily habits may lower your risk, and where the science still has important limits.
The connection is not simply that sick people tend to have both bad teeth and memory problems. Researchers are uncovering specific pathways through which bacteria in the mouth may directly trigger processes in the brain associated with Alzheimer’s disease and other dementias. A 2025 CDC analysis of more than 83,000 adults found that those aged 45 and older with poor oral health had a 13.6% prevalence of subjective cognitive decline, compared to 7.7% among those with good oral health. That near-doubling of risk appears consistently across studies conducted on different continents, with different populations, and using different methodologies.
Table of Contents
- Does Gum Disease Raise Your Risk of Dementia?
- How Bacteria May Travel from Mouth to Brain
- What Toothbrushing Frequency Has to Do With Cognitive Decline
- Practical Steps to Protect Both Your Teeth and Your Brain
- Who Is at Greatest Risk From the Oral Health–Dementia Link
- The Social Isolation Pathway — A Less Obvious Connection
- Where the Research Is Heading
- Conclusion
- Frequently Asked Questions
Does Gum Disease Raise Your Risk of Dementia?
Gum disease — periodontitis — is not just a dental nuisance. It is a chronic bacterial infection, and roughly 70% of adults aged 65 and older have some degree of it, according to University Hospitals. That figure puts the majority of the very population most vulnerable to dementia in a state of chronic oral inflammation. The overlap is not coincidental. The key bacterium implicated in this connection is Porphyromonas gingivalis, the primary driver of periodontal disease. This organism produces toxic enzymes called gingipains, which researchers believe can travel beyond the mouth and contribute to neuroinflammation and the formation of amyloid-beta plaques — the same abnormal protein deposits that accumulate in the brains of Alzheimer’s patients.
When researchers examined brain tissue from 53 deceased Alzheimer’s patients, they found elevated gingipain levels in nearly all of them, and those levels appeared to increase as disease progressed. That finding, reported by Harvard Health and supported by work from the Forsyth Institute, is striking because it suggests the bacteria are not merely bystanders. To put this in concrete terms: imagine a 68-year-old with untreated gum disease who notices some bleeding when they brush. That bleeding is not isolated to the mouth — it represents open tissue that allows bacteria to enter the bloodstream. From there, the inflammatory cascade those bacteria trigger can reach the brain. NIA-led research has found oral bacteria associated with both Alzheimer’s and vascular dementia, two of the most common forms of the condition.
How Bacteria May Travel from Mouth to Brain
The biological mechanism connecting oral health and dementia is still being actively studied, and it is worth being clear about what is established versus what remains a working hypothesis. What researchers are confident about is that P. gingivalis and its gingipains have been found in Alzheimer’s brain tissue. What is still under investigation is whether the bacteria themselves cross the blood-brain barrier, or whether they trigger a systemic inflammatory response that the brain then reacts to over years or decades. One leading theory is that chronic low-grade inflammation from gum disease raises levels of inflammatory markers throughout the body. The brain is sensitive to sustained inflammation, and over time, this may accelerate the damage associated with neurodegeneration.
A January 2026 analysis published in Sage Journals examined this through causal inference models and identified two main pathways: a biological one involving direct bacterial and inflammatory effects, and a social one in which oral health problems make eating and speaking difficult, leading to social withdrawal and isolation — which is itself an established risk factor for cognitive decline. Losing teeth, for instance, can alter diet, restrict social meals, and reduce the kinds of stimulating interaction that support brain health. However, it is important to note a significant limitation here. The 2024 Lancet Commission on dementia prevention, intervention, and care — a highly respected benchmark in the field — did not find sufficiently consistent, high-quality evidence to formally list oral health as an established modifiable risk factor for dementia. The association is real and the biological plausibility is compelling, but the scientific community has not yet reached full consensus on causality. This does not mean the evidence should be dismissed; it means it should be interpreted carefully.
What Toothbrushing Frequency Has to Do With Cognitive Decline
If gum disease raises dementia risk, then preventing gum disease should, in theory, lower it. The most basic tool for doing that is a toothbrush. A 2025 systematic review published in the Journal of Advanced Nursing — drawing on data from 261,772 participants across eight studies — found that brushing teeth at least twice daily is linked to a significantly reduced risk of cognitive decline and dementia. That is a large evidence base for what is ultimately a very simple daily habit.
A separate 2025 Korean cohort study published in Yonsei Medical Journal found that the combination of frequent toothbrushing and interdental cleaning — using floss or interdental brushes — reduced dementia risk further than brushing alone. Notably, the study found that brushing before sleep was especially significant, which aligns with what dentists have long recommended for plaque control: nighttime oral bacteria have hours to work without the natural cleansing effects of eating and drinking. Consider the practical example of someone who brushes once in the morning but skips the evening routine. Overnight, bacteria in the mouth have an extended window to multiply, and if gum disease is present or developing, that window matters. The Korean study suggests the timing of brushing — not just the frequency — may be a meaningful variable when it comes to long-term brain health.
Practical Steps to Protect Both Your Teeth and Your Brain
The CDC’s 2025 analysis found that visiting a dentist at least annually was associated with lower prevalence of subjective cognitive decline in middle-aged adults. Regular dental visits allow for professional plaque removal, early identification of gum disease, and treatment before the condition becomes entrenched. For older adults or those with limited mobility, access to dental care can be a barrier — but when access is available, consistent checkups appear to offer measurable benefit. At home, the evidence supports a layered approach. Twice-daily brushing is the baseline, with interdental cleaning added for additional protection. Electric toothbrushes generally outperform manual ones in clinical trials for reducing plaque and gingivitis, which may make them worth the investment for older adults with dexterity limitations.
The tradeoff is cost — a quality electric toothbrush can run $50 to $150 — but compared to the compounding costs of dental disease, that is a favorable ratio. Diet plays a role as well, though it is harder to isolate. Diets high in sugar and refined carbohydrates feed the bacteria that cause gum disease. Diets rich in vegetables, fish, and whole grains are associated with both better periodontal health and lower dementia risk — though here, as elsewhere in this research, the direction of causality is difficult to untangle cleanly. It is possible that healthier people simply do everything better. The studies cited above attempt to control for this, but observational research always carries residual confounding.
Who Is at Greatest Risk From the Oral Health–Dementia Link
The people who carry the most risk from the combination of poor oral health and cognitive vulnerability are, broadly, older adults — particularly those over 65 who already have some degree of gum disease, which, as noted, is most of them. But there are specific subgroups where the concern is particularly acute. Adults with diabetes are significantly more likely to develop severe gum disease, and diabetes is itself a recognized risk factor for dementia. The interplay between these conditions is bidirectional: gum disease can worsen blood sugar control, and poor blood sugar control worsens periodontal disease. For someone managing diabetes in their 60s, oral health is not a cosmetic concern — it is part of systemic disease management.
Similarly, individuals on medications that cause dry mouth, a common side effect of dozens of drugs used by older adults, lose the natural antibacterial protection of saliva and are at elevated risk of both decay and gum disease. A word of caution: the research discussed in this article is primarily observational. It does not prove that treating gum disease will prevent dementia in any individual case. Some trials of periodontal treatment as a dementia intervention are underway, but results are not yet available. The prudent approach is to treat oral health as one modifiable factor among many — alongside physical exercise, social engagement, blood pressure control, and hearing health — rather than as a singular solution.
The Social Isolation Pathway — A Less Obvious Connection
Beyond the direct biological route, there is a less-discussed mechanism worth understanding: tooth loss and chronic dental pain can limit a person’s ability to eat comfortably, speak clearly, and engage socially. A 2026 Sage Journals analysis specifically modeled this social pathway, finding that oral health problems can lead to withdrawal from social interaction, and that isolation accelerates cognitive decline. This is not abstract.
An older adult who has lost most of their teeth and cannot afford dentures may stop accepting dinner invitations or avoid situations where their speech or eating might draw attention. Over months and years, that social withdrawal — not the bacteria itself, in this pathway — becomes the driver of cognitive risk. It is a reminder that dementia prevention is rarely about a single variable and that oral health connects to brain health through more than one door.
Where the Research Is Heading
The science here is moving quickly. Several clinical trials are currently examining whether treating periodontitis in older adults reduces markers of Alzheimer’s progression — including amyloid-beta levels and inflammatory biomarkers in blood and cerebrospinal fluid. If those trials show positive results, oral health will likely earn a formal place in dementia prevention guidelines, potentially joining the list of modifiable risk factors in the next Lancet Commission update. Pharmaceutical researchers are also exploring whether gingipain inhibitors — drugs that block the toxic enzymes produced by P.
gingivalis — might slow Alzheimer’s progression. Early-phase human trials have been conducted, though no treatment has reached approval. The direction of that research, however, underscores how seriously the scientific community now takes the mouth-brain connection. What was once dismissed as a folk observation is increasingly a focus of funded, peer-reviewed investigation.
Conclusion
The relationship between dental health and dementia risk is not proven in the strict causal sense, but the evidence is substantial and consistent. People with gum disease and tooth loss develop dementia at higher rates. The bacterium at the center of gum disease has been found in Alzheimer’s brain tissue. Large-scale studies show that brushing twice daily, flossing, and seeing a dentist regularly are associated with lower rates of cognitive decline.
These are not weak signals. For caregivers and family members supporting someone at risk of dementia, oral hygiene deserves a place in the care plan alongside medication management and cognitive stimulation. For individuals concerned about their own brain health, the message is straightforward: the same bacteria causing your gum disease may be doing more than damaging your teeth. Treating oral health as a serious component of overall health — not a secondary concern to be addressed only when something hurts — is both well-supported by the current evidence and, unlike many dementia risk factors, largely within reach.
Frequently Asked Questions
Does losing teeth cause dementia?
Tooth loss is associated with higher dementia risk, but the relationship is not simply cause and effect. People who have lost all their teeth developed dementia at a rate of 23% compared to 14% among those with healthy gums and teeth, according to NIA-cited research. However, tooth loss may reflect years of untreated gum disease and chronic inflammation, rather than being a direct cause itself.
Can brushing your teeth really lower dementia risk?
The evidence suggests it can contribute to lower risk. A 2025 meta-analysis of nearly 262,000 people found that brushing at least twice daily is linked to meaningfully reduced rates of cognitive decline and dementia. It is not a guarantee, but it is a low-cost, evidence-supported habit with no downside.
What is Porphyromonas gingivalis and why does it matter?
P. gingivalis is the primary bacterium responsible for gum disease. Its toxic enzymes, called gingipains, have been found in the brain tissue of Alzheimer’s patients at elevated levels. Researchers believe this bacterium may contribute to neuroinflammation and amyloid-beta plaque formation associated with Alzheimer’s disease.
Has treating gum disease been proven to prevent dementia?
Not yet. Clinical trials are underway, but results are not available. The 2024 Lancet Commission did not formally list oral health as an established modifiable dementia risk factor due to insufficient high-quality causal evidence. The association is strong, but treatment trials will be needed to confirm that intervening on gum disease lowers dementia incidence.
At what age should I start taking the dental-dementia connection seriously?
The CDC’s 2025 study focused on adults aged 45 and older, and that is a reasonable age to treat oral health with heightened attention. Gum disease develops over years, and the inflammatory damage it causes accumulates over time. Earlier prevention is better than later treatment.
Can dentures offset the dementia risk from tooth loss?
This is an area where more research is needed. Some studies suggest that restoring chewing function with dentures may help, potentially through reducing the social isolation and dietary limitations that come with tooth loss. However, dentures do not eliminate the underlying gum tissue or bacteria risk. Maintaining gum health even after tooth loss remains important.
