Is there a link between Alzheimer's disease and oral bacteria, specifically periodontal (gum) disease-causing microorganisms?

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Last updated: March 8, 2025View editorial policy

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From the Guidelines

There is a potential link between Alzheimer's disease and oral bacteria, specifically periodontal disease-causing microorganisms, as suggested by recent research 1.

Key Findings

  • Periodontal disease has been associated with systemic diseases, including diabetes, cardiovascular disease, cancer, and Alzheimer's disease 1.
  • Certain oral bacteria, such as Porphyromonas gingivalis, which causes gum disease, may contribute to Alzheimer's development when they enter the bloodstream and reach the brain 1.
  • Poor oral hygiene can lead to chronic gum disease, potentially increasing this risk.

Recommendations

  • To reduce this potential risk factor, maintain good oral health through regular brushing twice daily with fluoride toothpaste, daily flossing, regular dental check-ups every six months, and prompt treatment of any gum disease.
  • Using antimicrobial mouthwash containing chlorhexidine or essential oils may provide additional protection.
  • While this connection is still being researched and isn't definitively proven as a direct cause of Alzheimer's, the evidence suggests that maintaining oral health may be one modifiable factor in reducing Alzheimer's risk, alongside other established preventive measures like physical activity, healthy diet, and cognitive stimulation 1.

Clinical Implications

  • Dental practitioners should be aware of the potential link between periodontal disease and Alzheimer's disease, and take necessary precautions to maintain good oral health in their patients.
  • Patients with cognitive impairment or Alzheimer's disease should receive regular dental check-ups and prompt treatment of any gum disease to reduce the risk of exacerbating their condition.

From the Research

Association Between Oral Bacteria and Alzheimer's Disease

  • There is evidence to suggest a link between Alzheimer's disease and oral bacteria, specifically periodontal (gum) disease-causing microorganisms 2, 3, 4, 5, 6.
  • Studies have found that poor oral hygiene is associated with an increased risk of dementia, and the number of oral bacteria significantly increases in the brain tissues of patients with Alzheimer's disease 3, 5.
  • The oral microbiome has been found to be altered in patients with Alzheimer's disease, with a decrease in microbial diversity and a different composition compared to cognitively healthy subjects 2, 3.
  • Certain oral bacteria, such as Porphyromonas gingivalis, have been detected in post-mortem brain samples and have been found to induce Alzheimer's disease-related alterations in animal models 2, 6.
  • The association between oral bacteria and Alzheimer's disease has been found to be moderate, with oral bacteria being a risk factor for the disease 6.

Key Findings

  • A systematic review and meta-analysis found a ten-fold increased risk of Alzheimer's disease when oral bacteria were present in the brain 6.
  • Another study found that Alzheimer's disease patients exhibited lower alpha diversity of oral microbiota than healthy controls 3.
  • Periodontitis-associated bacteria have been found to play a role in the pathogenesis of Alzheimer's disease, with toxic bacterial products reaching the central nervous system and evoking inflammatory responses 4.
  • The composition of salivary microbiome has been found to be altered in Alzheimer's disease patients, with an increase in certain bacteria such as Moraxella, Leptotrichia, and Sphaerochaeta 3.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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