Oral Health as a Risk Factor for Alzheimer Disease

Detection of Amyloid-β Peptides in Gingival Crevicular Fluid and Its Effect on Oral Pathogens

Periodontitis is the most common oral inflammatory disease, contributing to the onset and progression of Alzheimer's disease. However, a full investigation has not been performed on the expression level of amyloid-β (Aβ) peptides in gingival crevicular fluid (GCF) and its effects on oral pathogens. This study aimed to analyze the expression level of Aβ peptides in GCF of patients with periodontitis and the effects of Aβ peptides against common oral pathogens. GCF samples were collected from patients with periodontitis (n = 15) and periodontally healthy people (n = 10). The antimicrobial effects of Aβ peptides were evaluated on four common oral pathogenic strains using an MTT assay, crystal violet staining, fluorescence microscope, and transmission electron microscope. The protein levels of Aβ40 and Aβ42 were upregulated in the GCF of periodontitis group compared with the healthy group. Both Aβ40 and Aβ42 exhibited antimicrobial effects on Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, and Lactobacillus acidophilus in both planktonic and biofilm conditions. Further, only Aβ40 showed an antimicrobial effect on the Fusobacterium nucleatum. The results of this study demonstrate that Aβ peptides in GCF may be a relevant indicator of periodontitis status. Besides, the antimicrobial peptides derived from Aβ peptides have great potential in periodontal therapy.

Oral Health and Its Associated Factors Among the Elderly in the Emergency Department: A Latent Class Analysis

Purpose

The objective of this study was to investigate latent classes of oral health and the factors associated with them in acutely admitted elderly inpatients.

Patients and Methods

A cross-sectional study was conducted using purposive sampling to survey Chinese older-adult acutely inpatients. Data was collected utilizing several instruments, including a general information questionnaire, Brief Oral Health Status Examination (BOHSE), Oral Frailty Index-8 (OFI-8), Mini-Nutritional Assessment Short Form (MNA-SF), and Frailty Screening Questionnaire (FSQ). Latent class analysis was applied to identify distinct categories of oral health among elderly inpatients, and multinomial logistic regression was employed to analyze the factors associated with different oral health categories.

Results

In this study, a total of 504 elderly patients were ultimately included, leading to the identification of three latent classes of oral health: "oral health-low level group (41.27%)", "oral health-moderate level group (25.4%)", and "oral health-high level group (33.33%)". The findings revealed that patients with advanced age, elevated neutrophil percentage, and higher C-reactive protein (CRP) values were more likely to be classified in the low oral health group. Additionally, individuals experiencing malnutrition and frailty had a higher risk of falling into the low oral health category. Those with comorbidities and oral frailty were more prevalent in the moderate oral health group. At the same time, elderly patients with higher BMI (22.95±3.043) ratios were more likely to be categorized in the high oral health group.

Conclusion

This study sheds light on three distinct latent classes of oral health among acutely admitted elderly inpatients. These findings underscore the importance of healthcare professionals focusing on the assessment and health education of elderly patients' oral health. Furthermore, personalized interventions should be developed to promote healthy aging, with particularly attention to enhancing oral health outcomes in this population.

Update on modifiable risk factors for Alzheimer's disease and related dementias

PURPOSE OF REVIEW

All human beings undergo a lifelong cumulative exposure to potentially preventable adverse factors such as toxins, infections, traumatisms, and cardiovascular risk factors, collectively termed exposome. The interplay between the individual's genetics and exposome is thought to have a large impact in health outcomes such as cancer and cardiovascular disease. Likewise, a growing body of evidence is supporting the idea that preventable factors explain a sizable proportion of Alzheimer's disease and related dementia (ADRD) cases.

RECENT FINDINGS

Here, we will review the most recent epidemiological, experimental preclinical, and interventional clinical studies examining some of these potentially modifiable risk factors for ADRD. We will focus on new evidence regarding cardiovascular risk factors, air pollution, viral and other infectious agents, traumatic brain injury, and hearing loss.

SUMMARY

While greater and higher quality epidemiological and experimental evidence is needed to unequivocally confirm their causal link with ADRD and/or unravel the underlying mechanisms, these modifiable risk factors may represent a window of opportunity to reduce ADRD incidence and prevalence at the population level via health screenings, and education and health policies.

The "Hit and Run" Hypothesis for Alzheimer's Disease Pathogenesis

Alzheimer's disease (AD) is a devastating neurodegenerative disorder affecting millions worldwide. Emerging research has challenged the conventional notion of a direct correlation between amyloid deposition and neurodegeneration in AD. Recent studies have suggested that amyloid and Tau deposition act as a central nervous system (CNS) innate immune driver event, inducing chronic microglial activation that increases the susceptibility of the AD brain to the neurotoxicity of infectious insults. Although modifiable risk factors account for up to 50% of AD risk, the mechanisms by which they interact with the core process of misfolded protein deposition and neuroinflammation in AD are unclear and require further investigation. This update introduces a novel perspective, suggesting that modifiable risk factors act as external insults that, akin to infectious agents, cause neurodegeneration by inducing recurrent acute neurotoxic microglial activation. This pathological damage occurs in AD pathology-primed regions, creating a "hit and run" mechanism that leaves no discernible pathological trace of the external insult. This model, highlighting microglia as a pivotal player in risk factor-mediated neurodegeneration, offers a new point of view on the complex associations of modifiable risk factors and proteinopathy in AD pathogenesis, which may act in parallel to the thoroughly studied amyloid-driven Tau pathology, and strengthens the therapeutic rationale of combining immune modulation with tight control of risk factor-driven insults.