Oral Microbiome and Alzheimer’s Disease: The Hidden Connection

Source: Narengaowa et al., 2021; Front. Cell. Neurosci.

 

Emerging evidence indicates a strong link between periodontal disease and Alzheimer’s disease (AD), suggesting that oral health may influence cognitive decline. Individuals with AD often exhibit poor oral hygiene, increased plaque, clinical attachment loss, and reduced salivary flow, which can exacerbate systemic inflammation (Ship & Puckett, 1994; Sari et al., 2022). Chronic periodontitis, particularly when dominated by pathogens such as Porphyromonas gingivalis, may trigger or amplify neuroinflammatory pathways, accelerating cognitive deterioration (Harding et al., 2017; Ide et al., 2016; Zhang et al., 2023). Conversely, cognitive decline can impair oral care, creating a bidirectional cycle that reinforces disease progression (Fatimah, 2017; Sochocka et al., 2017). These findings highlight the potential of integrated oral care, microbiome-targeted interventions, and early periodontal treatment as strategies to mitigate systemic inflammation and preserve cognitive function in aging populations at risk for AD. Periodontal pathogens, particularly Gram-negative bacteria such as P. gingivalis, Aggregatibacter actinomycetemcomitans, Treponema denticola, Prevotella intermedia, Campylobacter rectus, and Tannerella forsythia, are linked to Alzheimer’s disease (AD) (Liccardo et al., 2020; Narengaowa et al., 2021). Evidence suggests a bidirectional relationship between oral health and systemic disorders, with the oral microbiota potentially influencing AD development through direct or indirect mechanisms (Jin et al., 2016).

References (For extensive list of references click here)

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Liccardo, D., Marzano, F., Carraturo, F., Guida, M., Femminella, G. D., Bencivenga, L., et al. (2020). Potential bidirectional relationship between periodontitis and Alzheimer’s disease. Front. Physiol. 11:683. doi: 10.3389/fphys.2020.00683

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Narengaowa, Wei, Lan, Awan, Farooq, Hong, Qing & Ni, Junjun (2021) The Oral-Gut-Brain AXIS: The Influence of Microbes in Alzheimer’s Disease. Front. Cell. Neurosci. 15, 633735. https://doi.org/10.3389/fncel.2021.63373

Liccardo, D., Marzano, F., Carraturo, F., Guida, M., Femminella, G. D., Bencivenga, L., et al. (2020). Potential bidirectional relationship between periodontitis and Alzheimer’s disease. Front. Physiol. 11:683. doi: 10.3389/fphys.2020.00683