Link with Alzheimer's disease

I was on the phone this afternoon with my English husband, David, and I told him I was procrastinating on my column. He suggested I find out when dental floss was first introduced to England because he's tired of "looking at bad English teeth."

Apr 1st, 2013

by LYNNE SLIM, RDH, BSDH, MSDH

I was on the phone this afternoon with my English husband, David, and I told him I was procrastinating on my column. He suggested I find out when dental floss was first introduced to England because he's tired of "looking at bad English teeth." Last week, he went online to read his old hometown newspaper in Middleton, England, and he remembered seeing a profile of a locally elected official who was very long in the tooth. The gent had a big smile on his face and his teeth were, shall we say, something straight out of a horror flick — fanglike teeth surrounded by calculus/biofilm that looked like muddy sludge.

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Bill Landers, a fellow columnist, sent me an article from the Journal of Neuroinflammation that piqued my interest in a way that was a bit shocking, just as the long-in-the-tooth photo surprised David. The title of the article was "Alzheimer's disease -- a neurospirochetosis. Analysis of the evidence following Koch's and Hill's criteria." Bill and I will collaborate in more detail on this topic in another article, but I have a few initial thoughts on this new link I would like to share. The author, Judith Miklossy, in a compelling review suggests that several types of spirochetes, including periodontal pathogen spirochetes, may be involved in the pathogenesis of Alzheimer's disease.1

Miklossy's analysis of the evidence is thorough and she is passionate about Alzheimer's research. Dr. Miklossy is an MD and she is board certified in neurology, psychiatry, and neuropathology. In addition, she is the director of the International Alzheimer's Research Center.

Here are my initial impressions of the analysis by Miklossy (and trust me, it is a read that would put even the insomniacs among us to sleep!). In periodontal medicine, researchers have been primarily focused on the association between periodontal disease and cardiovascular disease, diabetes, respiratory infections, and pregnancy complications. The association between periodontal disease and Alzheimer's disease or neurosyphilis is a less researched topic but an important one. Researchers have discovered various types of spirochetes, including six periodontal pathogen spirochetes in brains of Alzheimer's disease (AD) patients.

Statistical analysis shows a significant association between spirochetes and AD. Spirochetes were detected in the brains of patients with early stages of plaque, tangle, and curly fiber formation (tangles are localized inside neurons and curly fibers between nerve cells). Infection takes place long before the diagnosis of dementia is made. The spirochetes are able to form plaque, tangle, and curly fiberlike lesions, and their number progressively increases in patients with mild, moderate, and severe AD. Spirochetes are able to escape destruction of the host immune response and establish chronic infection and sustained inflammation. (I recently wrote about how one periodontal pathogen, P. gingivalis, sabotages the immune system in chronic periodontal lesions.)

Lingering spirochetal infection with its toxic components can initiate and sustain chronic inflammation through the activation of the innate and adaptive immune system involving various signaling pathways. The response is similar to the characteristic of chronic inflammatory response associated with sites of tissue damage in periodontal disease. The outcome of AD infection, just as with periodontal disease, is determined by the genetic predisposition of the patient, by the virulence and biology of the infecting agent, and by various environmental factors, such as exercise, stress, and nutrition.1

The strength of the association between spirochetes and Alzheimer's disease is stronger than that of the periodontal disease/cardiovascular link. The strongest indications presented in this analysis were the strong statistical association between periodontal diseases and Alzheimer's disease (OR=20, >1; p value almost zero), coupled with the biological plausibility of this association. The risk ratio was very high (20) compared to the perio/cardio link which was low to moderate (less than 2). Therefore, the association is worthy of further investigation whereas the perio/cardio link is probably not. It's important for all dental hygienists to understand risk/odds ratios, p-values, and confidence intervals when interpreting research studies.

OK, I've bored you enough with statistics and I'm not a biostatistician or an epidemiologist. But here's the important takeaway: Based on the Miklossy analysis, the statistical association between spirochetes (including six types of periodontal pathogen spirochetes) appears to be causal, and it is probably reasonable to talk about a causal association between periodontal diseases and AD. That being said, the clinical significance may appear obvious but premature because work by large international and multidisciplinary research groups needs to continue and is contingent on strong financial support. Patients with periodontal diseases may be at greater risk of Alzheimer's disease, and periodontal treatment may reduce this risk. But individuals with specialized knowledge and skills are needed to interpret this data and confirm the author's hypotheses.

Miklossy indicates that in vivo studies with long exposure times will be important to efficiently study the sequence of events and the cellular mechanisms involved in the spirochete induced host reactions and destructive plaques. Characteristics of all spirochete types and coinfecting bacteria are needed, in order to develop serological tests for the early detection of infection.1

You can read this review online at www.jneuroinflammation.com. RDH

LYNNE SLIM, RDH, BSDH, MSDH, is an award-winning writer who has published extensively in dental/dental hygiene journals. Lynne is the CEO of Perio C Dent, a dental practice management company that specializes in the incorporation of conservative periodontal therapy into the hygiene department of dental practices. Lynne is also the owner and moderator of the periotherapist yahoo group: www.yahoogroups.com/group/periotherapist. Lynne speaks on the topic of conservative periodontal therapy and other dental
hygiene-related topics. She can be reached at periocdent@mindspring.com or www.periocdent.com.

References

1. Miklossy J. Alzheimer's disease -- a neurospirochetosis. Analysis of the evidence following Koch's and Hill's criteria. J of Neuroinflamm 2011; 8:90.

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