Are Periodontitis, Stroke, and Alzheimer's Disease Linked?

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• peridontal disease (2 posts to December 2015)

Are Periodontitis, Stroke, and Alzheimer's Disease Linked?

MADRID — Recent research has confirmed the impact of periodontitis on risk of neurologic diseases, especially the increased risks for stroke and Alzheimer's disease.

The Spanish Society of Dentistry and Osseointegration (SEPA) and the Spanish Society of Neurology (SEN) recently released a report with the latest data on this topic. The report reviews, updates, and presents the most recent scientific evidence regarding this link. It also provides practical recommendations that, on the basis of the evidence, should be applied in dental clinics and neurology centers.

As Yago Leira, DDS, PhD, periodontist and coordinator of the SEPA-SEN working group, told Medscape Spanish Edition, "The main takeaway from this scientific report is that patients with periodontitis are at nearly twice the risk of developing Alzheimer's disease and at triple the risk of ischemic stroke."

Data from the report show that individuals with periodontitis are at 2.8 times' higher risk of ischemic stroke. The available evidence regarding hemorrhagic stroke, however, is conflicting.

How does this dental condition affect the course of cardiovascular disease? Observational studies have shown that those who have had an ischemic stroke and have a confirmed diagnosis of periodontitis are at greater risk of suffering a recurrent vascular event, worse neurologic deficit, and postictal depression than patients without periodontitis.

Immune‐Mediated Inflammation

As far as its link to Alzheimer's disease, meta-analyses of epidemiologic studies show that periodontitis is associated with a 1.7 times greater risk of this type of dementia and that the risk triples among patients with more serious forms of periodontitis.

Likewise, studies suggest that individuals with dementia or neurocognitive impairment are at a greater risk of suffering periodontitis. Other studies indicate that individuals with periodontitis have worse outcomes on various neuropsychological tests of cognitive function.

The current report presents the evidence from three clearly defined perspectives: the epidemiologic association between periodontitis and these neurologic diseases, the biological mechanisms that may explain this link, and interventional studies of dental treatment as a means of preventing stroke and Alzheimer's disease.

"There is a possible biological explanation for these epidemiological findings. The report concludes that the low-grade chronic, systemic, immune-mediated inflammatory response induced by the bacteria and their endotoxins and the proinflammatory mediators circulating through the blood contributes to various biological processes that are involved in neurological impairment and cerebral ischemia," said Leira, who is one of the report's authors.

Ana Frank, MD, PhD, another author of this study, is head of the neurology department at the La Paz University Hospital in Madrid and a member of the SEPA-SEN group. She explained to Medscape Spanish Edition that the main biological mechanism in stroke and Alzheimer's disease is chronic exposure of the entire brain (vasculature, neurons, and astrocytes) to the harmful effects of periodontal infection. "Although low in intensity, this [exposure] is sufficient to set off a series of events that eventually lead to vascular endothelial injury, changes to neurons and astrocytes, and damage to the neuropil."

As far as the evidence of an epidemiologic association between periodontitis and both neurologic diseases, Frank cited the exponential increase in risk brought on by periodontitis. She said that further epidemiologic studies are necessary to gain a better understanding of the magnitude of the problem.

A Preventive Alternative?

Leira cited evidence that periodontal treatment could provide a means of preventing stroke and dementia. He pointed out that numerous population studies have observed various oral health interventions (eg, periodic dental prophylaxis or periodontal treatment) and regular dental visits to reduce the risk of developing dementia and stroke. "However, we don't currently have randomized clinical trials that were designed to investigate whether periodontal treatment may be a primary or a secondary preventive measure against these neurological conditions."

According to Leira, "There are currently several research groups in the United States and Europe, including ours, that are performing clinical trials to assess the impact of periodontal treatment on recurrent vascular events in patients with cerebrovascular disease.

"On the other hand, there are various interventional studies underway that are evaluating the potential effect of periodontal treatment on cognitive function in patients with dementia. Along these lines, there appear to be encouraging results from the 1-year follow-up in the GAIN study, which was a phase 2/3 clinical trial testing atuzaginstat. Atuzaginstat is an inhibitor of gingipain, the endotoxin produced by Porphyromonas gingivalis, which is one of the bacteria thought to be responsible for periodontitis. The drug reduces neurocognitive impairment in patients with high levels of antibodies against this periodontal pathogen."

Toward Clinical Practice

The report has a practical focus. The intention is that this evidence will make its way into recommendations for dentists to implement in clinical practice, especially with elderly patients or patients with risk factors for stroke.

In this regard, Leira said, "On one hand, dentists have to know how to approach patients who have already suffered a stroke (most of whom have vascular risk factors like diabetes and hypertension), many of whom have polypharmacy and are [taking] certain drugs like blood thinners that could negatively impact various dental procedures. In such cases, it is important to maintain direct contact with a neurologist, since these patients ought to be treated with a multidisciplinary approach.

"On the other hand, each patient who comes to the dental office and has a diagnosis of periodontitis could be screened to identify potential vascular risk factors, even though the definitive diagnosis would need to be given by a specialist physician. To this end, SEPA is carrying out the Promosalud ("Health Promotion") project, which will soon be applied in a large number of dental clinics in Spain," added Leira.

"Lastly, specialists in odontology must understand the potential positive benefits surrounding systemic vascular inflammation that periodontal treatment could provide, including, for example, metabolic control and lowering blood pressure."

For patients with cognitive impairment, the authors of the report recommended adhering to the following steps during dental visits: inform the patient and the patient's caregiver about the importance of good dental hygiene and monitor for any signs of infection or dental disease; address pain in every patient with cognitive impairment and dental problems, especially those with agitation, even if the patient isn't specifically complaining of pain (also, try not to give opioids); finally, avoid sedation as much as possible and use the smallest effective dose if it becomes necessary.

Prescribe Oral Hygiene

Regarding recommendations that neurologists should follow during consultations in light of the link between these diseases and periodontitis, Frank said, "Regardless of how old our patients are, I believe it's important to emphasize the importance of practicing good oral and dental hygiene. It's a good strategy to put this in writing in medical reports, alongside the usual recommendations about healthy lifestyle habits and monitoring for diseases like high blood pressure, diabetes, or dyslipidemia. These, among other factors like smoking, a sedentary lifestyle, alcoholism, and other drug addictions, are vascular risk factors and are therefore risk factors for stroke and dementia."

According to Frank, the public is largely unaware of the relationship between periodontitis and incident neurologic diseases. "We still have a long way to go before we can say that the public is aware of this potential link. And not just the public, either. I believe we must stress among our colleagues and among healthcare professionals in general the importance of promoting dental health to improve people's overall health."

In this regard, Leira emphasized the authors' intention to make this report available not only to oral health and neurologic healthcare professionals but also to primary care physicians and nurses so that patients with cerebrovascular disease or Alzheimer's disease and their caregivers can develop a greater awareness and thereby improve prevention.

"This study will also provide the scientific basis to support the SEPA-SEN working group as they implement their future activities and projects," Leira concluded.