Advances in the prevention and treatment of Alzheimer's disease based on oral bacteria

Abstract

With the global population undergoing demographic shift towards aging, the prevalence of Alzheimer's disease (AD), a prominent neurodegenerative disorder that primarily afflicts individuals aged 65 and above, has increased across various geographical regions. This phenomenon is accompanied by a concomitant decline in immune functionality and oral hygiene capacity among the elderly, precipitating compromised oral functionality and an augmented burden of dental plaque. Accordingly, oral afflictions, including dental caries and periodontal disease, manifest with frequency among the geriatric population worldwide. Recent scientific investigations have unveiled the potential role of oral bacteria in instigating both local and systemic chronic inflammation, thereby delineating a putative nexus between oral health and the genesis and progression of AD. They further proposed the oral microbiome as a potentially modifiable risk factor in AD development, although the precise pathological mechanisms and degree of association have yet to be fully elucidated. This review summarizes current research on the relationship between oral bacteria and AD, describing the epidemiological and pathological mechanisms that may potentially link them. The purpose is to enrich early diagnostic approaches by incorporating emerging biomarkers, offering novel insights for clinicians in the early detection of AD. Additionally, it explores the potential of vaccination strategies and guidance for clinical pharmacotherapy. It proposes the development of maintenance measures specifically targeting oral health in older adults and advocates for guiding elderly patients in adopting healthy lifestyle habits, ultimately aiming to indirectly mitigate the progression of AD while promoting oral health in the elderly.

Keywords: Alzheimer’s disease; anti-bacterial agents; dental prophylaxis; early diagnosis; healthy lifestyle; oral-gut-brain axis; probiotics; vaccine.

Figure 1

The diagram illustrates the mechanism through which periodontitis contributes to AD. Specifically, periodontal pathogens lead to chronic inflammation in oral tissues, triggering the influx of inflammatory and bacterial virulence factors into the bloodstream. These substances circulate through the blood, nervous system, and the oral-gut-brain axis, eventually causing chronic inflammation in the brain. This ultimately promotes the progression of AD. Surrounding the diagram, in a circular manner, are depicted the approaches for early diagnosis (pink area), treatment (green area), and prevention of AD (blue area) based on the aforementioned pathological mechanism. Created with BioRender.com.