Clinical evidence supports a potential link between inflammation and Alzheimer’s disease. Additional studies have postulated a possible link between periodontal pathogens and Alzheimer’s disease. Additionally, a systematic review published in 2017 found a significant association between periodontal disease and Alzheimer’s disease. The current study that is the focus of this summary was published in 2018 in the Journal of Alzheimer’s Disease the authors aimed to “cast more light on a possible association of an intraoral infection with P. gingivalis, A. actinomycetemomitans, and Treponema sp with development of Alzheimer’s disease.”1
Laugisch et al hypothesized that Alzheimer’s patients produce intrathecal antibodies for periodontal pathogens, especially P. gingivalis. To verify their hypothesis, they used serum and cerebral spinal fluid to identify antibodies for pathogens found in the patient’s subgingival biofilm. A total of 40 patients were included in the study, 20 with Alzheimer’s disease and 20 with dementia due to other disease entities. Periodontal destruction did not significantly differ between groups.
Because this study was a pilot study, a sample size calculator was not used. The primary endpoint was the ratio of antibody levels for P. gingivalis in serum and cerebral spinal fluid related to the diagnosis of dementia.
The results indicate that a local production of antibodies in cerebral spinal fluid for P. gingivalis may occur in patients with dementia, but there was no association with Alzheimer’s disease. The authors note that only patients under the age of 70 were included in this study, these patients may fall within the “early-onset” criteria which is closely related to genetic factors rather than inflammation and infections. Therefore, patients with “late-onset” may be a better sample to determine if there is an association.
Nonetheless, multiple studies have shown oral bacteria can and does enter the brain. This may occur via the bloodstream, direct access through perivascular spaces or olfactory and trigeminal nerves. Laugisch et al suggest future studies focus on analyzing the total oral microbiota as it related to Alzheimer’s disease rather than focusing on certain pathogens.
In summary the authors state, “we showed that antibodies against periodontal pathogens may be produced intrathecally, but our dataset does not support a specific association of periodontal infection with an onset of Alzheimer’s disease in an age up to 70-year-old patients and early stages of the disease. Periodontal infection was found to similar degrees in patients with dementia due to Alzheimer’s disease and other forms of dementia. Further research should include patients with late-onset Alzheimer’s disease as well as healthy subjects. In the future it would be fascinating to investigate the influence of the oral; microbiome, including a detailed analysis of bacterial components capable of entering the brain, on Alzheimer’s disease development.”
Were you surprised by these findings? Would you like to see follow up studies to confirm these findings? Do you think a design flaw could have been the reason for these findings, such as a small sample size or lack of a healthy control group?
- Laugisch O, Johnen A, Maldonado A, Ehmke B, Bürgin W, Olsen I, Potempa J, Sculean A, Duning T, Eick S. Periodontal Pathogens and Associated Intrathecal Antibodies in Early Stages of Alzheimer’s Disease. J Alzheimers Dis. 2018;66(1):105-114. doi: 10.3233/JAD-180620. PMID: 30223397.