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Relation
Schwahn C, Frenzel S, Holtfreter B, et al. Effect of periodontal treatment on preclinical Alzheimer's disease - results of a trial emulation approach.Alzheimer's dementia. May 29, 2021 doi: 10.1002/alz.12378. Online before print.
Draft
A simulated controlled clinical trial was conducted using recently developed statistical models that allowed data from treated and untreated patients from two different population cohorts to be combined.
Participant
Data from 409 untreated participants in the Study of Health in Pomerania (SHIP), a cohort followed since 1997 to track the influence of dental disease on general health, were combined with data from 177 periodontally treated patients in the Greifswald GANI-MED study. All patients were younger than 60 years at the time of their MRI scan. For participants in the active group, periodontal treatment was carried out an average of 7.3 years before the MRI examination.
Study medication and dosage
The 177 patients in the Greifswald GANIMED study were treated for periodontitis using standard treatment. All participants were assessed for Alzheimer's disease using magnetic resonance imaging (MRI).
Target parameters
MRI has been used as an indicator of the onset of Alzheimer's disease.
Key insights
Periodontal treatment performed by a dentist specializing in gum disease was associated with a significant reduction in brain matter loss. Periodontal treatment had a beneficial effect on AD-related brain atrophy (-0.41; 95% CI: -0.70 to -0.12;P=0.0051), which corresponds to a shift from the 50th to the 37th percentile of the result distribution.
Practice implications
Alzheimer's disease (AD) is the most common form of dementia. The disease was first described in 1906 by German psychiatrist and neuroanatomist Alois Alzheimer after he examined the brain of a woman who had suffered from severe memory loss and behavioral problems before her death.1It is estimated that approximately 27 million people worldwide suffer from AD.
Other illnesses can also cause dementia. After AD, the most common are cerebrovascular dementia, Lewy body dementia and frontotemporal dementia. The total number of these diseases is enormous. An estimated 44 million people in the world suffer from dementia today. In the United States alone, treatment costs exceed $600 billion per year.2
Alzheimer's disease has two characteristic features: the deposition of extracellular amyloid β (Aβ) and abnormally phosphorylated tau in nerve cells. Although drugs targeting amyloid-β have been developed, study results have so far been unsatisfactory in altering the disease. This failure has called into question the classic amyloid cascade hypothesis. Attention has shifted to a new hypothesis suggesting that chronic inflammation and microbial infections of the brain lead to Alzheimer's disease. The suspicion was concretePorphylomonas gingivalis, the bacteria responsible for periodontal infections. These bacteria have been detected in the brain tissue of AD patients. This is suggested by experiments on miceP gingivaliscould be causal.3
Proving that this is true in humans is challenging. These two diseases AD and periodontitis have many risk factors in common, including age, obesity, smoking, diabetes, alcohol, depression, stress and education level. Cognitive decline also increases the risk of poor oral hygiene, so people with AD tend to have higher rates of periodontitis.4.5Sorting through this tangle of associations and relationships has made it difficult to distinguish between causation and association. However, the biggest challenge in sorting out the relationship is ethical. One cannot ethically refuse a medical procedure, in this case dental care, if it can cause disease, in this case periodontitis and possibly Alzheimer's.
These results strongly suggest that timely intervention and treatment of periodontitis may have significant benefits in the coming years.
This ethical imperative has led us to rely on observational studies. This recent study by Schwahn et al. is very similar to a clinical trial and may be the closest thing to a randomized clinical trial to test the hypothesis thatP gingivaliscauses AD.
The statistical models used in this study made it possible to pool data from treated and untreated individuals who were participants in two different studies, allowing individuals in the SHIP cohort to serve as a control group. The participants in both cohorts live in the same region of Germany.
What is notable is the relative youthfulness of the participants in these two cohorts at the start of the study. Because participants were under 60 years of age at the time of their MRI scan and their dental exams were more than 7 years prior, we examine the effects of an intervention administered to people in their early 50s.
These results strongly suggest that timely intervention and treatment of periodontitis may have significant benefits in the coming years. It strengthens our understanding of whole-body medicine and reminds us that in many cases we must act as teammates with other healthcare providers. In this case, it is good preventative medicine to actively encourage our patients to visit dentists and dental hygienists.
We may be able to offer our patients some suggestions to maximize the benefits of treatment. A paper by Rowinska and colleagues published in March 2021 can serve as a resource for understanding how pathogenic microorganisms cause oral diseases and may be particularly useful because it describes the influence of different dietary components on the disease process. The authors pay particular attention to how diet influences biofilm formation and offer suggestions for diets that may reduce the biofilm and subgingival plaque that cause periodontitis.6
While certain diets may reduce biofilm formation, they do not remove it. The biofilm adheres firmly to the teeth and cannot be washed away. Physical removal is required using either a toothbrush or dental tools. No matter how compliant your patient is with diet and supplements, this does not replace the need for dental treatment.
The diet that Rowinska and colleagues suggest isn't all that far from what we commonly think of as a healthy diet - one that avoids simple sugars and refined carbohydrates, while emphasizing vegetables and fresh fruit, and that is rich in antioxidants, essential fats, fiber and collagen.7.8As specific dietary supplements, Rowinska et al. Coenzyme Q10, green tea and quercetin.9.10
People with high levels of stress and poor coping skills have twice as many periodontal diseases as people with minimal stress and good coping skills. There is a connection between cortisol levels and the degree of periodontitis.11,12While reducing pathogens remains key to controlling periodontitis, reducing stress may be just as or nearly as important. Oxidative stress can play just as important a role in periodontitis as emotional stress.13We should already be aware that stress is linked to Alzheimer's disease. Americans who live under high levels of psychological stress are almost twice as likely to die from Alzheimer's disease than people with lower levels of stress.14
A Mediterranean diet and exercise can be helpful in maintaining cognitive function.fifteenThe idea that such lifestyle interventions can also improve periodontitis is quite plausible and has been studied but not conclusively proven.16,17One such analysis suggested that consuming olive oil may reduce the risk of periodontal disease.18Chewable probiotic lozenges have been reported to improve periodontitis in addition to physical plaque removal.19What we offer as naturopathic doctors may certainly be helpful, but it does not appear to be sufficient on its own.20
This study by Schwahn et al. contributes to the knowledge that periodontitis contributes greatly to the development of Alzheimer's disease and that early intervention to prevent periodontitis may also reduce the incidence of AD. A healthy diet helps, and certain supplements may be useful. But routine dental examinations and proper oral hygiene practiced by the patient can be the basis of prevention.