Objective: This case-control study was designed to compare the composition of the predominant oral bacterial microbiome in Alzheimer's disease (AD) and control group.
Subject: A total of 30 adult participants (15 AD and 15 healthy individuals) were entered in this study. The composition of oral bacterial microbiome was examined by quantitative real-time polymerase chain reaction (qPCR) using bacterial 16S rDNA gene. The levels of systemic inflammatory cytokines in both groups were assessed using enzyme-linked immunosorbent assays (ELISA).
Results: The loads of Porphyromonas gingivalis, Fusobacterium nucleatum, and Prevotella intermedia were significantly more abundant in the AD compared to the control group (p < 0.05). Although Aggregatibacter actinomycetemcomitans and Streptococcus mutans were relatively frequent in the AD group, no significance difference was observed in their copy number between two groups. Although the concentrations of IL-1, IL-6, and TNF-α were higher in the AD group, there was a significant difference in their levels between the two groups (p < 0.05). Finally, there was a significant relationship between increased number of pathogenic bacteria in oral microbiome and higher concentration of cytokines in patient's blood.
Conclusion: Our knowledge of oral microbiome and its exact association with AD is rather limited; our study showed a significant association between changes in oral microbiome bacteria, increased inflammatory cytokines, and AD.
Keywords: Alzheimer's disease; inflammatory cytokines; neurological disease; oral microbiome; periodontitis; qPCR.
© 2022 The Authors. Journal of Clinical Laboratory Analysis published by Wiley Periodicals LLC.