Oral Health May Minimize Alzheimer’s Risk

Improving oral health may help minimize risk factors associated with the onset of neurodegenerative conditions such as Alzheimer’s disease (AD). It has long been speculated that oral health, inflammation, and neurodegenerative conditions are connected, and research suggests that chronic bacterial infections from periodontitis may contribute to neurodegenerative processes and may be risk factors for AD development.

Bacterial communities form biofilm (dental plaque) on teeth and gums, and high pathogenic load can disrupt the oral microbiome, causing inflammation and dysregulation of the immune system response. While bacterial overgrowth and chronic inflammation can lead to a variety of local diseases (e.g., periodontitis and tooth decay), pathogenic bacteria that moves into the bloodstream can reach other organs in the body, including the heart, liver, and brain. In brain tissue, oral bacteria can cause neuroinflammation and damage to neuronal cells, which, over time, contributes to cognitive decline and neurodegenerative diseases.

Periodontal disease impacts an estimated 42.7% of adults over 30, and is manifested as the accumulation of Porphyromonas gingivalis (P. gingivalis) bacteria in the mouth and the formation of biofilm on oral tissue surfaces. In adults over the age of 65, periodontal disease is estimated to occur in 70.1% of the population, and increased presence of P. gingivalis due to oral tissue depletion, gingival inflammation, and edentulism in older populations can lead to greater inflammation and immune system dysregulation. Significant oral pathogenic load is considered to be a risk factor for AD for any age group, and studies have shown that chronic periodontal disease lasting 10 years or longer increases this risk twofold.

Altered microbiota in the oral cavity can spread via the lymphatic and vascular systems, infect tissue in the brain, and indirectly contribute to inflammation through immune system activation. This immunoreactivity is consistent with increased neuroinflammation in brains afflicted with AD, and the presence of colonized P. gingivalis has been found post-mortem in both human and animal brains.

Several nutrient deficiencies may lead to an unhealthy oral microbiome. Key micronutrients that support healthy oral microbiota and decrease overall inflammatory burden include vitamin C, vitamin D, calcium, phosphorus, fluorine, and nitrite. Certain foods also have polyphenols that have anti-inflammatory, antioxidative, and antibacterial properties against P. gingivalis, including green tea, curcumin, cranberries, pomegranate, mango, grapes and wine, and rice extracts.

Therapeutic oral probiotic use has also been shown to be effective in maintaining a healthy oral microbiome. Oral probiotics have been shown to promote microbiota diversity and reduce plaque accumulation, similar to brushing and flossing. Certain bacterial strains (including Lactobacillus, Bifidobacterium, Lactococcus, and Streptococcus) have have shown to be effective microbial agents and may also support the integrity of oral tissue. Common over-the-counter products containing probiotics such as toothpastes, mints, or lozenges may be cost-effective strategies for improving a patient’s oral health at home.