Poor Dental Health May Raise Alzheimer’s Risk

One of the first hygiene lessons kids learn is to floss and brush their teeth twice a day. Some of us were also taught to swish with mouthwash. Good oral health, we’re told, will help keep cavities and bad breath at bay. Over the years, more research has been conducted on oral health—and it turns out that the benefits may go beyond your mouth.

For example, did you know that regularly flossing can help reduce inflammation, not just in your gums, but throughout the body? There’s even a connection between poor oral health and heart disease and diabetes. And scientists are now making stronger connections between oral health and brain health.

Researchers from Korea performed a scoping review that included 45 previously published studies on oral health and Alzheimer’s disease. They published their findings in the journal Japanese Dental Science Review. Let’s break down what they found.

How Was This Study Conducted?

Researchers searched databases for studies on oral health and Alzheimer’s disease with specific criteria. After weeding out the studies that didn’t meet their criteria, they ended up with 45 studies that were about the associations between:

• Alzheimer’s disease and oral health
• Periodontal diseases and Alzheimer’s disease
• Inflammation and Alzheimer’s disease
• Amyloid-β plaque build-up in the brain (a hallmark of Alzheimer’s) and periodontal disease
• Genetic susceptibility to periodontitis, APOE4 genotype and Alzheimer’s disease
• Cavities and Alzheimer’s disease
• Tooth loss, denture use and Alzheimer’s disease

What Did This Study Find?

After reviewing all the evidence, researchers found that chronic oral diseases, especially periodontitis and tooth loss, appear to play a possible role in the onset and progression of Alzheimer’s disease. Periodontitis, or periodontal disease, is an infection of the tissues surrounding the tooth, including the gums, bone and ligaments.

Regarding the “why” behind the connection between Alzheimer’s disease, periodontitis and tooth loss, researchers proposed several mechanisms. Those possible explanations include systemic inflammation, the spread of oral pathogens into the bloodstream, disruption of the blood-brain barrier and interactions with genetic factors such as the APOE4 allele. Loss of teeth without prosthetic rehabilitation—like dentures—may further increase dementia risk by reducing chewing efficiency and altering nutritional status. 

Researchers note several limitations of this review, including the various study designs, differences in diagnostic criteria—how oral diseases are diagnosed—and varying follow-up periods between studies. Many of the studies also did not control for confounding variables, such as socioeconomic status, medical comorbidities, medication use and other lifestyle factors. Collectively, this presents some challenges in accurately comparing results. 

How Does This Apply to Real Life?

Over 700 microorganisms live in your mouth. Some of them are helpful, some are potentially harmful. When bacteria are allowed to sit on your teeth and gums, they begin to go to work to degrade them, which could lead to periodontitis and tooth loss. This is where regular brushing and flossing come in. Drinking plenty of plain water can help prevent tooth decay by helping to rinse away food particles and bacteria, dilute acids in the mouth and help your mouth produce more saliva.

It’s important to note that one reason tooth loss is connected with a higher risk of Alzheimer’s disease is that it makes eating and chewing nutritious foods more difficult. For this reason, it’s important to address tooth loss with a dental professional to find a solution that works best for you. 

While many believe in mouthwash for good oral health, using mouthwash can have some downsides. Yes, alcohol-based mouthwash kills many harmful bacteria, but it also kills the good ones. And when the oral microbiome is knocked out of balance, it can ultimately affect the gut microbiome. Gut health, in turn, impacts brain health, including mood and cognition.

There is some evidence that the Mediterranean diet may reduce the risk of periodontal disease, partly thanks to its connection with reduced inflammation in the body. Eating less red meat and increasing your intake of nuts, seeds, beans, olive oil and seafood could go a long way toward reducing gum inflammation. The Mediterranean diet has also been linked with a reduced risk of dementia, due to its high levels of polyphenols and omega-3s. This all adds up to a win-win for your brain.

Whether you’re looking for some recipe ideas or a full meal plan that’s great for both brain and oral health, check out our 30-Day MIND Diet Meal Plan for Cognitive Health. The MIND diet is a hybrid of the Mediterranean and DASH diets. It focuses on whole, brain-healthy foods, like plants, healthy fats and lean proteins, and limits sugar, salt and highly processed foods. 

Our Expert Take

A new study suggests that poor oral health may increase the risk of Alzheimer’s disease. Based on the evidence, this is especially true of periodontitis and tooth loss. Both conditions may be prevented by proper oral care—including brushing and flossing regularly—staying well-hydrated with plain water, and eating a diet lower in sugar, red meat and ultra-processed foods, while increasing your consumption of whole foods in line with the Mediterranean diet.