The Effect of Periodontitis on Dementia and Cognitive Impairment: A Meta-Analysis

Alzheimer's Disease and Porphyromonas gingivalis: Exploring the Links

Recent research highlights compelling links between oral health, particularly periodontitis, and systemic diseases, including Alzheimer's disease (AD). Although the biological mechanisms underlying these associations remain unclear, the role of periodontal pathogens, particularly Porphyromonas gingivalis, has garnered significant attention. P. gingivalis, a major driver of periodontitis, is recognized for its potential systemic effects and its putative role in AD pathogenesis. This review examines evidence connecting P. gingivalis to hallmark AD features, such as amyloid β accumulation, tau hyperphosphorylation, neuroinflammation, and other neuropathological features consistent with AD. Virulence factors, such as gingipains and lipopolysaccharides, were shown to be implicated in blood-brain barrier disruption, neuroinflammation, and neuronal damage. P. gingivalis-derived outer membrane vesicles may serve to disseminate virulence factors to brain tissues. Indirect mechanisms, including systemic inflammation triggered by chronic periodontal infections, are also supposed to exacerbate neurodegenerative processes. While the exact pathways remain uncertain, studies detecting P. gingivalis virulence factors and its other components in AD-affected brains support their possible role in disease pathogenesis. This review underscores the need for further investigation into P. gingivalis-mediated mechanisms and their interplay with host responses. Understanding these interactions could provide critical insights into novel strategies for reducing AD risk through periodontal disease management.

Machine Learning and Mendelian Randomization Reveal Molecular Mechanisms and Causal Relationships of Immune-Related Biomarkers in Periodontitis

This study aimed to investigate the molecular mechanisms of periodontitis and identify key immune-related biomarkers using machine learning and Mendelian randomization (MR). Differentially expressed gene (DEG) analysis was performed on periodontitis datasets GSE16134 and GSE10334 from the Gene Expression Omnibus (GEO) database, followed by weighted gene co-expression network analysis (WGCNA) to identify relevant gene modules. Various machine learning algorithms were utilized to construct predictive models, highlighting core genes, while MR assessed the causal relationships between these genes and periodontitis. Additionally, immune infiltration analysis and single-cell sequencing were employed to explore the roles of key genes in immunity and their expression across different cell types. The integration of machine learning, MR, and single-cell sequencing represents a novel approach that significantly enhances our understanding of the immune dynamics and gene interactions in periodontitis. The study identified 682 significant DEGs, with WGCNA revealing seven gene modules associated with periodontitis and 471 core candidate genes. Among the 113 machine learning algorithms tested, XGBoost was the most effective in identifying periodontitis samples, leading to the selection of 19 core genes. MR confirmed significant causal relationships between CD93, CD69, and CXCL6 and periodontitis. Further analysis showed that these genes were correlated with various immune cells and exhibited specific expression patterns in periodontitis tissues. The findings suggest that CD93, CD69, and CXCL6 are closely related to the progression of periodontitis, with MR confirming their causal links to the disease. These genes have potential applications in the diagnosis and treatment of periodontitis, offering new insights into the disease's molecular mechanisms and providing valuable resources for precision medicine approaches in periodontitis management. Limitations of this study include the demographic and sample size constraints of the datasets, which may impact the generalizability of the findings. Future research is needed to validate these biomarkers in larger, diverse cohorts and to investigate their functional roles in the pathogenesis of periodontitis.

Association of Periodontitis with Mild Cognitive Impairment in Older Adults

Background

Early detection of cognitive decline, including mild cognitive impairment, is expected to provide a better prognosis. Several studies have suggested an association between periodontitis and mild cognitive impairment.

Objectives/Design

To test the hypothesis that there is an association between severe periodontitis and mild cognitive impairment in community residents who participated in a dental health check-up program.

Participants/Setting

Community residents who participated in our dental health checkup program were enrolled (age=67.5±9.9, 62.9% female).

Measurements

Mild cognitive impairment was tested using the MCI screening test. Periodontitis was diagnosed based on a widely used clinical periodontal parameter, the probing pocket depth. Statistical analysis was based on logistic regression models adjusted for potential confounders.

Results

Among 321 subjects, mild cognitive impairment was detected in 41. Severe periodontitis (probing pocket depth > 6mm) was detected in 123 cases, with a higher prevalence of mild cognitive impairment in the severe periodontitis group (65.9%) than in the unimpaired group (34.3%). The inclusion of four variables (age, education, functional teeth, and presence of severe periodontitis) in a multivariate logistic regression model revealed a statistically significant difference in the association between severe periodontitis and mild cognitive impairment (odds ratio = 4.024, p < 0.001).

Conclusions

A strong association was seen between severe periodontitis and mild cognitive impairment. Severe periodontitis appears to be a risk factor for mild cognitive impairment, and patients with severe periodontitis should be assessed for mild cognitive impairment.

Association between periodontal disease and systemic diseases: a cross-sectional analysis of current evidence

BACKGROUND

Numerous systematic reviews and meta-analyses have been published that evaluate the association between periodontal disease and systemic diseases, many of which address similar topics. Moreover, their quality requires assessment. Therefore, we performed a cross-sectional analysis to examine the evidence on the relationship between periodontal disease and systemic diseases.

METHODS

The PubMed, Embase, Web of Science, and the Cochrane Library databases were systematically searched to identify relevant systematic reviews and meta-analyses. Only studies that considered periodontal disease as the exposure factor and various systemic diseases as the outcome were included. The basic characteristics and pertinent data from the selected studies were extracted. The modified version of A Measurement Tool to Assess Systematic Reviews 2 (AMSTAR 2) was employed for quality assessment, while R software was used for statistical analysis.

RESULTS

Among the 212 relevant systematic reviews and meta-analyses, 57 were finally included in our analysis. These studies involved 75 diseases and 81 disease-related outcomes, with cancer (19/81) being the most frequently addressed topic. Of the 81 outcomes, 67 demonstrated a significant association. Notably, the highest risk estimate was found for head and neck cancer [odds ratio (OR) = 3.17, 95% confidence interval (CI) 1.78 - 5.64], while the lowest was observed for premature rupture of the amniotic sac [relative risk (RR) = 1.10, 95% CI 1.08 - 1.12]. The methodological quality ratings indicated that approximately 71.93% of included studies were classified as "Critically low", with another 17.54% rated as "Low", and only about 10.53% categorized as "Moderate".

CONCLUSIONS

Periodontal disease significantly elevates the risks associated with 15 cancer-related, 8 cardiovascular-related, 8 metabolic-related, and 5 neurological-related outcomes. However, the overall methodological quality of existing systematic reviews and meta-analyses is generally suboptimal and requires enhancement to generate higher-quality evidence in the future.

Association Between Severe Periodontitis and Cognitive Decline in Older Adults

(1) Background: Periodontal disease, a progressive inflammatory condition, disrupts the oral microbiome and releases inflammatory cytokines, leading to systemic issues, including cognitive decline. This study investigates the association between severe periodontitis and cognitive decline, exploring the role of alkaline phosphatase (ALP), an enzyme linked to systemic inflammation, as an effect modifier. (2) Methods: We analyzed cross-sectional data from the 2013-2014 National Health and Nutrition Examination Survey (NHANES). Severe periodontitis was defined using the Centers for Disease Control and Prevention (CDC) and the American Academy of Pediatrics (AAP) case definition. A weighted multivariable logistic regression model assessed the association between severe periodontitis and cognitive decline. An interaction term examined ALP's role as an effect modifier. (3) Results: This study included 1265 participants aged 65 and older. After adjusting for confounders, each one-point increase in cognitive function score was associated with a 2% decrease in the odds of severe periodontitis (OR = 0.98; 95% CI = 0.97-0.99; p = 0.008). ALP was a significant effect modifier in the relationship between severe periodontitis and cognitive decline. (4) Conclusions: This study, using a representative U.S. adult population aged 65 and over, suggests that lower cognitive performance correlates with higher likelihood of severe periodontitis. ALP enhances the association between severe periodontitis and cognitive decline.

Microglial DBP Signaling Mediates Behavioral Abnormality Induced by Chronic Periodontitis in Mice

Several lines of evidence implicate that chronic periodontitis (CP) increases the risk of mental illnesses, such as anxiety and depression, yet, the associated molecular mechanism for this remains poorly defined. Here, it is reported that mice subjected to CP exhibited depression-like behaviors and hippocampal memory deficits, accompanied by synapse loss and neurogenesis impairment in the hippocampus. RNA microarray analysis disclosed that albumin D-site-binding protein (DBP) is identified as the most prominently upregulated target gene following CP, and in vivo and in vitro immunofluorescence methods showed that DBP is preferentially expressed in microglia but not neurons or astrocytes in the hippocampus. Interestingly, it is found that the expression of DBP is significantly increased in microglia after CP, and knockdown of microglial DBP ameliorated the behavioral abnormality, as well as reversed the synapse loss and hippocampal neurogenesis damage induced by CP. Furthermore, DBP knockdown improved the CP-induced hippocampal inflammation and microglial polarization. Collectively, these results indicate a critical role of DBP in orchestrating chronic periodontitis-related behavioral abnormality, hippocampal synapse loss and neurogenesis deficits, in which the microglial activation may be indispensably involved.

Associations between Systemic and Dental Diseases in Elderly Korean Population

Background and Objectives: Modernization and population aging have increased the prevalence of systemic diseases, such as diabetes and hypertension, which are often accompanied by various dental diseases. Our aim was to investigate associations between common dental conditions and major systemic diseases in an elderly Korean population. Materials and Methods: Utilizing electronic medical record data from 43,525 elderly patients, we examined the prevalence of systemic diseases (diabetes, hypertension, rheumatoid arthritis, osteoporosis, dementia) and dental conditions (caries, periodontal disease, pulp necrosis, tooth loss). The analysis focused on the correlations between these diseases. Results: Significant associations were found between systemic diseases and an increased prevalence of dental conditions. Patients with systemic diseases, especially those with multiple conditions, had higher incidences of periodontal disease and tooth loss. The correlation was particularly strong in patients with diabetes and rheumatoid arthritis. Interestingly, temporomandibular joint disorder was less frequent in this cohort. Conclusions: The findings highlight the importance of integrated dental care in managing systemic diseases in elderly populations. Enhanced dental monitoring and proactive treatment are essential due to the strong association between systemic diseases and dental conditions. Collaboration between dental and medical professionals is crucial for comprehensive care that improves health outcomes and quality of life for elderly patients.

Using SWATH-MS to identify new molecular biomarkers in gingival crevicular fluid for detecting periodontitis and its response to treatment

AIM

To identify new biomarkers to detect untreated and treated periodontitis in gingival crevicular fluid (GCF) using sequential window acquisition of all theoretical mass spectra (SWATH-MS).

MATERIALS AND METHODS

GCF samples were collected from 44 periodontally healthy subjects and 40 with periodontitis (Stages III-IV). In the latter, 25 improved clinically 2 months after treatment. Samples were analysed using SWATH-MS, and proteins were identified by the UniProt human-specific database. The diagnostic capability of the proteins was determined with generalized additive models to distinguish the three clinical conditions.

RESULTS

In the untreated periodontitis vs. periodontal health modelling, five proteins showed excellent or good bias-corrected (bc)-sensitivity/bc-specificity values of >80%. These were GAPDH, ZG16B, carbonic anhydrase 1, plasma protease inhibitor C1 and haemoglobin subunit beta. GAPDH with MMP-9, MMP-8, zinc-α-2-glycoprotein and neutrophil gelatinase-associated lipocalin and ZG16B with cornulin provided increased bc-sensitivity/bc-specificity of >95%. For distinguishing treated periodontitis vs. periodontal health, most of these proteins and their combinations revealed a predictive ability similar to previous modelling. No model obtained relevant results to differentiate between periodontitis conditions.

CONCLUSIONS

New single and dual GCF protein biomarkers showed outstanding results in discriminating untreated and treated periodontitis from periodontal health. Periodontitis conditions were indistinguishable. Future research must validate these findings.

Environmental, Metabolic, and Nutritional Factors Concerning Dementia in African American and Hispanic American Populations

African Americans and Hispanic Americans experience a higher incidence and prevalence of dementia than white Americans while also experiencing more environmental, metabolic, and nutritional factors potentially promoting such disparities. Greater exposure to air, water, and soil pollutants, including toxic metals associated with neurodegeneration, accrues in both minorities, as does worse dental care than Whites exposing them to periodontitis, raising dementia risk. Hispanic Americans experience greater occupational exposure to herbicides and pesticides, and have a higher rate of developing non-alcoholic fatty liver disease (NAFLD), predisposing to dementia. African Americans have a greater likelihood of both vitamin D deficiency and magnesium deficiency, increasing neuroinflammation and dementia risk. Both have greater air pollution exposure, a known dementia risk. Nutritional changes, including greater nut consumption and reduced sugar drink consumption, improved dental care, and reduced toxicant exposure, may help reduce this higher risk of dementia among African Americans and Hispanic Americans.

Interaction Between Tobacco Smoke Exposure and Zinc Intake and Its Effect on Periodontitis: Evidence From NHANES

AIM

Tobacco smoke exposure, zinc intake, and periodontitis are closely related. This study intended to assess the relationship between tobacco smoke exposure and zinc intake and its effect on periodontitis.

MATERIALS AND METHODS

This cross-sectional study included 9364 participants from the National Health and Nutrition Examination Survey (NHANES) of USA. A weighted multivariate logistic regression model was used to investigate the independent relationship and interaction effect among tobacco smoke exposure, zinc intake, and periodontitis. Odds ratio (OR) with 95% confidence interval (CI) was calculated. The additive interaction was evaluated using relative excess risk due to interaction (RERI), attributable proportion of interaction (AP), and synergy index (SI).

RESULTS

In all, 56.57% participants had periodontitis. Compared with participants without tobacco smoke exposure, those with tobacco smoke exposure had increased odds of having periodontitis (OR, 1.96; 95% CI, 1.67-2.31). Similarly, patients with adequate zinc intake were found to have decreased odds of having periodontitis than those with inadequate zinc intake (OR, 0.86; 95% CI, 0.76-0.98). Importantly, there was antagonistic interaction effect between zinc intake and tobacco smoke exposure on periodontitis (RERI: OR,  -0.432; 95% CI, -0.829 to -0.034; AP: OR, -0.242; 95% CI, -0.470 to -0.014; SI:  OR, 0.645; 95% CI, 0.446 to 0.932).

CONCLUSIONS

Tobacco smoke exposure and zinc intake were independently correlated with periodontitis risk. Decreasing tobacco smoke exposure and optimizing dietary zinc intake appear to be important measures that could be taken to control periodontitis.

Influence of dental status on postoperative complications in major visceral surgical and organ transplantation procedures-the bellydent retrospective observational study

PURPOSE

The significance of dental status and oral hygiene on a range of medical conditions is well-recognised. However, the correlation between periodontitis, oral bacterial dysbiosis and visceral surgical outcomes is less well established. To this end, we study sought to determine the influence of dental health and oral hygiene on the rates of postoperative complications following major visceral and transplant surgery in an exploratory, single-center, retrospective, non-interventional study.

METHODS

Our retrospective non-interventional study was conducted at the Department of General, Visceral, and Transplant Surgery, University Hospital Heidelberg, Germany. Patients operated on between January 2018 and December 2019 were retrospectively enrolled in the study based on inclusion (minimum age of 18 years, surgery at our Department, intensive care / IMC treatment after major surgery, availability of patient-specific preoperative dental status assessment, documentation of postoperative complications) and exclusion criteria (minor patients or legally incapacitated patients, lack of intensive care or intermediate care (IMC) monitoring, incomplete documentation of preoperative dental status, intestinal surgery with potential intraoperative contamination of the site by intestinal microbes, pre-existing preoperative infection, absence of data regarding the primary endpoints of the study). The primary study endpoint was the incidence of postoperative complications. Secondary study endpoints were: 30-day mortality, length of hospital stay, duration of intensive care stay, Incidence of infectious complications, the microbial spectrum of infectious complication. A bacteriology examination was added whenever possible (if and only if the examination was safe for the patient)for infectious complications.

RESULTS

The final patient cohort consisted of 417 patients. While dental status did not show an influence (p = 0.73) on postoperative complications, BMI (p = 0.035), age (p = 0.049) and quick (p = 0.033) were shown to be significant prognostic factors. There was significant association between oral health and the rate of infectious complications for all surgical procedures (p = 0.034), excluding transplant surgery. However, this did not result in increased 30-day mortality rates, prolonged intensive care unit treatment or an increase in the length of hospital stay (LOS) for the cohort as a whole. In contrast there was a significant correlation between the presence of oral pathogens and postoperative complications for a group as a whole (p < 0.001) and the visceral surgery subgroup (p < 0.001). Whilst this was not the case in the cohort who underwent transplant surgery, there was a correlation between oral health and LOS in this subgroup (p = 0.040). Bacterial swabs supports the link between poor oral health and infectious morbidity.

CONCLUSIONS

Dental status was a significant predictor of postoperative infectious complications in this visceral surgery cohort. This study highlights the importance preoperative dental assessment and treatment prior to major surgery, particularly in the case of elective surgical procedures. Further research is required to determine the effect of oral health on surgical outcomes in order to inform future practice.

TRIAL REGISTRATION

Trial registered under the ethics-number S-082/2022 (Ethic Committee of the University Heidelberg).

Link between periodontitis and diabetic retinopathy: Inflammatory pathways and clinical implications

The bidirectional relationship between periodontitis and type 2 diabetes mellitus has been well-established. However, the underlying molecular mechanisms remain unclear. Diabetic retinopathy (DR) is an important complication of diabetes, but there are few studies on the relationship between DR and periodontitis, especially on the intrinsic inflammatory pathway mechanism. This article reviews the latest clinical data on how diabetes promotes susceptibility to periodontitis from the epidemiological and molecular perspectives, with a special focus on the key roles of systemic inflammation and endothelial dysfunction in the interplay between DR and periodontitis. Comprehension of the intertwined pathogenesis of DR and periodontitis can better guide the development of comprehensive management strategies for glycemic control and periodontal health, with the aim of mitigating the progression of DR and enhancing overall well-being.

Tooth Loss in Periodontitis Patients-A Risk Factor for Mild Cognitive Impairment: A Systematic Review and Meta-Analysis

BACKGROUND

Periodontal disease and tooth loss have been long suggested as risk factors of mild cognitive impairment. The underlying mechanisms could be systemic chronic inflammatory mediators, direct pathologic challenge to the nervous system, malnutrition and/or loss of neurosensory stimulation input causing brain atrophy. This review aimed to examine the existing literature studies linking the effect of periodontal disease and tooth loss on the development of mild cognitive impairment.

METHODS

A systematic review using PEO was conducted. Three electronic databases, namely Embase, Medline and DOSS (UCLan), were searched for relevant articles published up to April 2023. Google Scholar and a hand search were also conducted to ensure no relevant studies had been missed. The Newcastle-Ottawa scale was used to assess the quality of studies.

RESULTS

The findings showed that chronic periodontitis and tooth loss, both individually and in combination, led to an increased risk of mild cognitive decline in adults over 50 years. Within the limitations of this review, periodontitis and tooth loss both contribute to an increased risk of mild cognitive impairment and dementia, but the evidence so far is not strong.

CONCLUSIONS

In future, more robustly designed studies investigating periodontal disease and tooth losslink with cognitive health decline are required with a longer follow-up duration.

Effects of oral health interventions on cognition of people with dementia: a systematic review with meta-analysis

BACKGROUND

Increasing studies have shown that poor oral health contributes to the progression of dementia. It is meaningful to find out the role of oral health interventions in maintaining people's cognition levels and delaying the progression of dementia. Thus, we conducted this review to summarize the present evidence on the effect of oral health interventions on the cognition change of people with dementia.

METHODS

Literature search was conducted in the databases of PubMed, Embase, Web of Science, Cochrane library, and Dentistry and Oral Sciences by two independent reviewers from inception to 6 March 2024. Clinical studies such as randomized controlled trials reporting on the effect of oral health interventions on the cognition of people with dementia were included in this review. Mini-Mental State Examination (MMSE) scores were used to measure cognition level. The mean deviation (MD), generated by subtracting the baseline MMSE score from the MMSE score at follow-up was used to assess the change in cognition. Studies with oral hygiene practice as an oral health intervention were further conducted with a meta-analysis.

RESULTS

A total of 6646 references were identified by the literature search, and 5 studies were eligible to be included in this review. Among the included studies, 4 studies reported the cognition change after having various oral hygiene practice as oral health intervention, while the other study adopted oral exercises as the intervention. Two studies presented positive MD values after intervention provided, indicating improved cognition level at follow-up (MD = 0.6, MD = 0.9, respectively). Another two studies reported less cognition deterioration with smaller absolute MD values in the intervention group, (intervention vs. control, -0.18 vs. -0.75, p < 0.05 and - 1.50 vs. -3.00, p < 0.05, respectively). The random-effect model was selected in the meta-analysis, and the weighted mean difference (WMD) was 1.08 (95% confidence interval, 0.44 to 1.71), favoring the intervention group.

CONCLUSION

With limited evidence, oral hygiene care may play a positive role in maintaining the cognition level of people with dementia. However, further studies are needed to provide direct evidence on the effectiveness of oral health interventions on oral health conditions as well as cognition status and to disclose the rationale behind it.

Dementia exacerbates periodontal bone loss in females

BACKGROUND

Periodontitis is a chronic inflammatory disease defined by the pathologic loss of the periodontal ligament and alveolar bone in relation to aging. Although clinical cohort studies reported that periodontitis is significantly elevated in males compared to females, emerging evidence indicates that females with dementia are at a greater risk for periodontitis and decreased alveolar bone.

OBJECTIVE

This study aimed to evaluate whether dementia is a potential sex-dependent risk factor for periodontal bone loss using an experimental model of periodontitis induced in the triple transgenic (3x-Tg) dementia-like mice and clinical samples collected from senior 65 plus age patients with diagnosed dementia.

MATERIALS AND METHODS

We induced periodontitis in dementia-like triple-transgenic (3x-Tg) male and female mice and age-matched wild-type (WT) control mice by ligature placement. Then, alveolar bone loss and osteoclast activity were evaluated using micro-CT and in situ imaging assays. In addition, we performed dental examinations on patients with diagnosed dementia. Finally, dementia-associated Aβ42 and p-Tau (T181) and osteoclastogenic receptor activator of nuclear factor kappa-Β ligand (RANKL) in gingival crevicular fluid (GCF) collected from mice and clinical samples were measured by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Alveolar bone loss and in situ osteoclast activity were significantly elevated in periodontal lesions of 3x-Tg females but not males, compared to wild-type control mice. In addition, we also observed that the probing pocket depth (PPD) was also significantly elevated in female patients with dementia. Using ELISA assay, we observed that females had elevated levels of osteoclastogenic RANKL and dementia-associated Aβ42 and p-Tau (T181) in the GCF collected from experimental periodontitis lesions and clinical samples.

CONCLUSION

Altogether, we demonstrate that females with dementia have an increased risk for periodontal bone loss compared to males.

Association Between Oral Malodor and Dementia: An 11-Year Follow-Up Study in Japan

Background

As infrequent social interaction is a potential risk of dementia, oral malodor may increase the risk of dementia, including Alzheimer's disease.

Objective

This study investigated the association between malodor and dementia.

Methods

We used the Japan Public Health Center-based Prospective Study data obtained at Yokote City. A total of 1,493 individuals aged 56 to 75 years underwent a dental examination and self-reported survey from May 2005 to January 2006. Follow-up for the onset of dementia was conducted using long-term care insurance data from 2006 to 2016. Hazard ratios of oral malodor on dementia were estimated by the Cox proportional hazards model. The inverse probability-weighted Cox model was used as a sensitivity analysis.

Results

The study comprised 1493 participants (53.6% women) with a mean age of 65.6 (SD = 5.8) years old; at the end of the follow-up, 6.4% (n = 96) developed dementia, and the percentage was 20.7 in severe malodor group. Throughout 15274.133 person-years of follow-up, the average incidence rate for the onset of dementia per 1000 person-years was 6.29. The highest incidence rate was seen in participants with severe malodor (22.4 per 1000 person-years). After adjusting for confounders, compared to those with no malodor, there was a 3.8 (95% confidence interval: 1.5 to 9.4) times greater hazard of developing dementia in participants with severe malodor. The inverse probability weighted Cox model confirmed the same trend with an adjusted marginal hazard ratio of 4.4 (1.2 to 16.4).

CONCLUSIONS

A significant association between oral malodor and the onset of dementia exists.

Association of Poor Oral Health With Neuroimaging Markers of White Matter Injury in Middle-Aged Participants in the UK Biobank

BACKGROUND AND OBJECTIVES

Poor oral health is a modifiable risk factor that is associated with clinically observed cardiovascular disease. However, the relationship between oral and brain health is not well understood. We tested the hypothesis that poor oral health is associated with worse neuroimaging brain health profiles in middle-aged persons without stroke or dementia.

METHODS

We performed a 2-stage cross-sectional neuroimaging study using UK Biobank data. First, we tested for association between self-reported poor oral health and MRI neuroimaging markers of brain health. Second, we used Mendelian randomization (MR) analyses to test for association between genetically determined poor oral health and the same neuroimaging markers. Poor oral health was defined as the presence of dentures or loose teeth. As instruments for the MR analysis, we used 116 independent DNA sequence variants linked to increased composite risk of dentures or teeth that are decayed, missing, or filled. Neuroimaging markers of brain health included white matter hyperintensity (WMH) volume and aggregate measures of fractional anisotropy (FA) and mean diffusivity (MD), 2 metrics indicative of white matter tract disintegrity obtained through diffusion tensor imaging across 48 brain regions.

RESULTS

We included 40,175 persons (mean age 55 years, female sex 53%) enrolled from 2006 to 2010, who underwent a dedicated research brain MRI between 2014 and 2016. Among participants, 5,470 (14%) had poor oral health. Poor oral health was associated with a 9% increase in WMH volume (β = 0.09, SD = 0.014, p < 0.001), 10% change in aggregate FA score (β = 0.10, SD = 0.013, p < 0.001), and 5% change in aggregate MD score (β = 0.05, SD = 0.013, p < 0.001). Genetically determined poor oral health was associated with a 30% increase in WMH volume (β = 0.30, SD = 0.06, p < 0.001), 43% change in aggregate FA score (β = 0.43, SD = 0.06, p < 0.001), and 10% change in aggregate MD score (β = 0.10, SD = 0.03, p < 0.01).

DISCUSSION

Among middle age Britons without stroke or dementia, poor oral health was associated with worse neuroimaging brain health profiles. Genetic analyses confirmed these associations, supporting a potentially causal association. Because the neuroimaging markers evaluated in this study precede and are established risk factors of stroke and dementia, our results suggest that oral health, an easily modifiable process, may be a promising target for very early interventions focused on improving brain health.

Mitochondrial Dysfunction in Periodontitis and Associated Systemic Diseases: Implications for Pathomechanisms and Therapeutic Strategies

Periodontitis is a chronic infectious disorder damaging periodontal tissues, including the gingiva, periodontal ligament, cementum, and alveolar bone. It arises from the complex interplay between pathogenic oral bacteria and host immune response. Contrary to the previous view of "energy factories", mitochondria have recently been recognized as semi-autonomous organelles that fine-tune cell survival, death, metabolism, and other functions. Under physiological conditions, periodontal tissue cells participate in dynamic processes, including differentiation, mineralization, and regeneration. These fundamental activities depend on properly functioning mitochondria, which play a crucial role through bioenergetics, dynamics, mitophagy, and quality control. However, during the initiation and progression of periodontitis, mitochondrial quality control is compromised due to a range of challenges, such as bacterial-host interactions, inflammation, and oxidative stress. Currently, mounting evidence suggests that mitochondria dysfunction serves as a common pathological mechanism linking periodontitis with systemic conditions like type II diabetes, obesity, and cardiovascular diseases. Therefore, targeting mitochondria to intervene in periodontitis and multiple associated systemic diseases holds great therapeutic potential. This review provides advanced insights into the interplay between mitochondria, periodontitis, and associated systemic diseases. Moreover, we emphasize the significance of diverse therapeutic modulators and signaling pathways that regulate mitochondrial function in periodontal and systemic cells.

Digital oral health biomarkers for early detection of cognitive decline

BACKGROUND

Oral health could influence cognitive function by stimulating brain activity and blood flow. The quantified oral status from oral inflammation, frailty and masticatory performance were rarely applied to the cognitive function screening. We aimed to adopt non-invasive digital biomarkers to quantify oral health and employ machine learning algorithms to detect cognitive decline in the community.

METHODS

We conducted a prospective case-control study to recruit 196 participants between 50 and 80 years old from Puzi Hospital (Chiayi County, Taiwan) between December 01, 2021, and December 31, 2022, including 163 with normal cognitive function and 33 with cognitive decline. Demographics, daily interactions, electronically stored medical records, masticatory ability, plaque index, oral diadochokinesis (ODK), periodontal status, and digital oral health indicators were collected. Cognitive function was classified, and confirmed mild cognitive impairment diagnoses were used for sensitivity analysis.

RESULTS

The cognitive decline group significantly differed in ODK rate (P = 0.003) and acidity from SILL-Ha (P = 0.04). Younger age, increased social interactions, fewer cariogenic bacteria, high leukocytes, and high buffering capacity led to lower risk of cognitive decline. Patients with slow ODK, high plaque index, variance of hue (VOH) from bicolor chewing gum, and acidity had increased risk of cognitive decline. The prediction model area under the curve was 0.86 and was 0.99 for the sensitivity analysis.

CONCLUSIONS

A digital oral health biomarker approach is feasible for tracing cognitive function. When maintaining oral hygiene and oral health, cognitive status can be assessed simultaneously and early monitoring of cognitive status can prevent disease burden in the future.

Genetic Control of GCF Exudation: Innate Immunity Genes and Periodontitis Susceptibility

Chronic periodontitis is a bacterial infection associated with dentally adherent biofilm (plaque) accumulation and age-related comorbidities. The disease begins as an inflammatory exudate from gingival margins, gingival crevicular fluid (GCF) in response to biofilm lysine. After a week of experimental gingivitis (no oral hygiene), biofilm lysine concentration was linearly related to biofilm accumulation (plaque index) but to GCF as an arch-shaped double curve which separated 9 strong from 6 weak GCF responders (hosts). Host DNA was examined for single nucleotide polymorphisms (SNPs) of alleles reported in 7 periodontitis-associated genes. Across all 15 hosts, an adenine SNP (A) at IL1B-511 (rs16944), was significant for strong GCF (Fisher's exact test, p < 0.05), and a thymidine SNP (T) at IL1B+3954 (rs1143634) for weak GCF provided 2 hosts possessing IL6-1363(T), rs2069827, were included. The phenotype of IL1B+3954(T) was converted from weak to strong in one host, and of the non-T allele from strong to weak in the other (specific epistasis, Fisher's exact test, p < 0.01). Together with homozygous alternate or reference SNPs at IL10-1082 or CD14-260 in 4 hosts, all hosts were identified as strong or weak GCF responders. The GCF response is therefore a strong or weak genetic trait that indicates strong or weak innate immunity in EG and controllable or uncontrollable periodontal disease, dental implant survival and late-life comorbidities.

Coffee consumption and periodontitis: a Mendelian Randomization study

BACKGROUND

Coffee is one of the most consumed beverages in the world, coffee consumption has been growing in the United States over the past 20 years. Periodontitis is defined by the pathologic loss of the periodontal ligament and destruction of the connective tissue attachment and alveolar bone loss and is related to different systemic diseases and conditions. However, the causality has remained unclarified, thus we regarded discovering the causal relationship between coffee consumption and the liability to periodontitis as the objective of the study.

METHODS

Coffee consumption was subdivided into binary coffee consumption and continuous coffee consumption to refine the study design. Genetic instruments were stretched from the MRC-IEU's (MRC Integrative Epidemiology Unit) output from the GWAS pipeline using phesant-derived variables based on the UK Biobank, the Gene-Lifestyle Interactions in Dental Endpoints (GLIDE) project, and the joint meta-analysis of a recent GWAS. The IVW (Inverse Variance Weighted) was regarded as the primary method to estimate the causality, a scatter plot revealed the intuitive result, and tests for stability were also carried out.

RESULTS

An effect of continuous coffee consumption on the risk of periodontitis was found, with per SD of coffee consumed increases, the risk of periodontitis rises by 1.04% (Odds Ratio of IVW is 1.0104), while the effect of binary coffee consumption on periodontitis did not meet the requirement of indicating a strong causal association, neither were the reverse causality analyses.

CONCLUSIONS

The study indicated the causality of continuous coffee consumption to the risk of periodontitis with a relatively small scale of effect estimate and no strong evidence for an effect of binary coffee-consuming behavior on periodontitis. There was also no intensive evidence suggesting reverse causality.

Beyond the mouth: the impact of periodontal disease on dementia

DATA SOURCES

The authors searched Medline via PubMed, Scopus, CINAHL, Web of Science, and PsycINFO for relevant studies published until April 2022.

STUDY SELECTION

Longitudinal studies that assessed periodontal health as the exposure and cognitive decline and/or dementia as the outcome were included. Case reports, reviews, cross-sectional studies, and animal studies were excluded. DATA EXTRACTION AND SYNTHESIS: Two authors independently reviewed studies for inclusion, extracted data, and assessed study quality. Meta-analysis was conducted to generate pooled odds ratios (ORs) for cognitive decline and hazard ratios (HRs) for dementia. Sources of heterogeneity were explored through subgroup analyses.

RESULTS

A total of 24 studies were included for cognitive decline and 23 for dementia. Poor periodontal health was associated with increased odds of cognitive decline (OR = 1.23; 95% CI: 1.05-1.44) and dementia (HR = 1.21; 95% CI: 1.07-1.38). Tooth loss also appeared to increase the risk independently. However, significant heterogeneity existed between studies.

CONCLUSIONS

Poor periodontal health may increase the risk of cognitive decline and dementia, but the quality of evidence was low. Further high-quality, longitudinal studies with standardized assessments are needed to establish causality.

Mouse maternal odontogenic infection with Porphyromonas gingivalis induces cognitive decline in offspring

Introduction

Porphyromonas gingivalis (P. gingivalis), a major periodontal pathogen, causes intrauterine infection/inflammation. Offspring exposed to intrauterine infection/inflammation have an increased risk of neurological disorders, regardless of gestational age. However, the relationship between maternal periodontitis and offspring functional/histological changes in the brain has not yet been elucidated.

Methods

In this study, we used a gestational mouse model to investigate the effects of maternal odontogenic infection of P. gingivalis on offspring behavior and brain tissue.

Results

The step-through passive avoidance test showed that the latency of the acquisition trial was significantly shorter in the P. gingivalis group (p < 0.05), but no difference in spontaneous motor/exploratory parameters by open-field test. P. gingivalis was diffusely distributed throughout the brain, especially in the hippocampus. In the hippocampus and amygdala, the numbers of neuron cells and cyclic adenosine monophosphate response element binding protein-positive cells were significantly reduced (p < 0.05), whereas the number of ionized calcium binding adapter protein 1-positive microglia was significantly increased (p < 0.05). In the hippocampus, the number of glial fibrillary acidic protein-positive astrocytes was also significantly increased (p < 0.05).

Discussion

The offspring of P. gingivalis-infected mothers have reduced cognitive function. Neurodegeneration/neuroinflammation in the hippocampus and amygdala may be caused by P. gingivalis infection, which is maternally transmitted. The importance of eliminating maternal P. gingivalis-odontogenic infection before or during gestation in maintenance healthy brain function in offspring should be addressed in near future.

Tooth Loss, Periodontal Disease, and Mild Cognitive Impairment Among Hispanic/Latino Immigrants: The Moderating Effects of Age at Immigration

BACKGROUND

The objectives were to assess (a) the association between poor oral health and mild cognitive impairment (MCI) in Hispanic/Latino immigrants and (b) potential modification effects on this association by age at immigration.

METHODS

Data were from the Hispanic Community Health Study/Study of Latinos and its ancillary study-the Study of Latinos-Investigation of Neurocognitive Aging. MCI, a binary outcome variable, defined by the National Institute on Aging-Alzheimer's Association criteria. The main exposure was significant tooth loss (STL), defined as a loss of 8 or more teeth, and periodontitis, classified using the Centers for Disease Control and Prevention and American Academy of Periodontology case classification. Multiple logistic regression was used to assess the association between STL/periodontitis and MCI and test moderation effects of age at immigration. The analytical sample comprised 5 709 Hispanic/Latino adult immigrants.

RESULTS

Hispanic/Latino immigrants with STL (adjusted odds ratio [AOR] = 1.36, 95% confidence interval [CI]: 1.01-1.85) were more likely to have MCI than those with greater tooth retention. Overall, migration to the United States after age 18 was associated with greater odds of MCI than migration at a younger age. A significant interaction effect between STL and age at immigration revealed that the effect of STL on MCI is even higher in those who immigrated to the United States at ages 35-49 years.

CONCLUSIONS

STL is a significant risk factor for MCI and age at immigration had a modification effect on the association between STL and MCI. Better access to dental care, health education on risk factors of MCI, and promotion of good oral health may mitigate the burden of cognitive impairment in Hispanics/Latinos.

Poor Oral Health Is Associated with Worse Brain Imaging Profiles

Importance

Poor oral health is a modifiable risk factor that is associated with a variety of health outcomes. However, the relationship between oral and brain health is not well understood.

Objective

To test the hypothesis that poor oral health is associated with worse neuroimaging brain health profiles in persons without stroke or dementia.

Design

We conducted a 2-stage cross-sectional neuroimaging study using data from the UK Biobank (UKB). First, we tested for association between self-reported poor oral health and MRI neuroimaging markers of brain health. Second, we used Mendelian Randomization (MR) analyses to test for association between genetically-determined poor oral health and the same neuroimaging markers.

Setting

Ongoing population study in the United Kingdom. The UKB enrolled participants between 2006 and 2010. Data analysis was performed from September 1, 2022, to January 10, 2023.

Participants

40,175 persons aged 40 to 70 enrolled between 2006 to 2010 who underwent a dedicated research brain MRI between 2012 and 2013.

Exposures

During MRI assessment, poor oral health was defined as the presence of dentures or loose teeth. As instruments for the MR analysis, we used 116 independent DNA sequence variants known to significantly increase the composite risk of decayed, missing, or filled teeth and dentures.

Main Outcomes and Measures

As neuroimaging markers of brain health, we assessed the volume of white matter hyperintensities (WMH), as well as aggregate measures of fractional anisotropy (FA) and mean diffusivity (MD), two metrics indicative of white matter tract disintegrity obtained through diffusion tensor imaging. These measurements were evaluated across 48 distinct brain regions, with FA and MD values for each region also considered as individual outcomes for the MR method.

Results

Among study participants, 5,470 (14%) had poor oral health. We found that poor oral health was associated with a 9% increase in WMH volume (beta = 0.09, standard deviation (SD) = 0.014, p P< 0.001), a 10% change in the aggregate FA score (beta = 0.10, SD = 0.013, P < 0.001), and a 5% change in the aggregate MD score (beta = 0.05, SD = 0.013, P < 0.001). Genetically-determined poor oral health was associated with a 30% increase in WMH volume (beta = 0.30, SD = 0.06, P < 0.001), a 43% change in aggregate FA score (beta = 0.42, SD = 0.06, P < 0.001), and an 10% change in aggregate MD score (beta = 0.10, SD = 0.03, P = 0.01).

Conclusions and Relevance

Among middle age Britons without stroke or dementia enrolled in a large population study, poor oral health was associated with worse neuroimaging brain health profiles. Genetic analyses confirmed these associations, supporting a potential causal association. Because the neuroimaging markers evaluated in the current study are established risk factors for stroke and dementia, our results suggest that oral health may be a promising target for interventions focused on improving brain health.

Subgingival microbiome at different levels of cognition

Oral health and declining cognition may have a bi-directional association. We characterized the subgingival microbiota composition of subjects from normal cognition to severe cognitive decline in two cohorts. Memory and Periodontitis (MINOPAR) include 202 home-living participants (50-80 years) in Sweden. Finnish Oral Health Studies in Older Adults (FINORAL) include 174 participants (≥65 years) living in long-term care in Finland. We performed oral examination and assessed the cognitive level with Mini Mental State Examination (MMSE). We sequenced the 16S-rRNA gene (V3-V4 regions) to analyse the subgingival bacterial compositions. The microbial diversities only tended to differ between the MMSE categories, and the strongest determinants were increased probing pocket depth (PPD) and presence of caries. However, abundances of 101 taxa were associated with the MMSE score. After adjusting for age, sex, medications, PPD, and caries, only eight taxa retained the significance in the meta-analyses of the two cohorts. Especially Lachnospiraceae [XIV] at the family, genus, and species level increased with decreasing MMSE. Cognitive decline is associated with obvious changes in the composition of the oral microbiota. Impaired cognition is accompanied with poor oral health status and the appearance of major taxa of the gut microbiota in the oral cavity. Good oral health-care practices require special deliberations among older adults.

Current Perspectives on Periodontitis in Systemic Sclerosis: Associative Relationships, Pathogenic Links, and Best Practices

Systemic sclerosis is a chronic, autoimmune, multisystemic disease characterized by aberrant extracellular matrix protein deposition and extreme progressive microvasculopathy. These processes lead to damage within the skin, lungs, or gastrointestinal tract, but also to facial changes with physiognomic and functional alterations, and dental and periodontal lesions. Orofacial manifestations are common in SSc but are frequently overshadowed by systemic complications. In clinical practice, oral manifestations of SSc are suboptimally addressed, while their management is not included in the general treatment recommendations. Periodontitis is associated with autoimmune-mediated systemic diseases, including systemic sclerosis. In periodontitis, the microbial subgingival biofilm induces host-mediated inflammation with subsequent tissue damage, periodontal attachment, and bone loss. When these diseases coexist, patients experience additive damage, increasing malnutrition, and morbidity. The present review discusses the links between SSc and periodontitis, and provides a clinical guide for preventive and therapeutical approaches in the management of these patients.

Alleviation of Porphyromonas gingivalis or Its Extracellular Vesicles Provoked Periodontitis and Cognitive Impairment by Lactobacillus pentosus NK357 and Bifidobacterium bifidum NK391

Porphyromonas gingivalis (PG) is closely involved in the outbreak of periodontitis and cognitive impairment (CI). Herein, we examined the effects of anti-inflammatory Lactobacillus pentosus NK357 and Bifidobacterium bifidum NK391 on PG- or its extracellular vesicles (pEVs)-induced periodontitis and CI in mice. Oral administration of NK357 or NK391 significantly decreased PG-induced tumor necrosis factor (TNF)-α, receptor activator of nuclear factors κB (RANK), and RANK ligand (RANKL) expression, gingipain (GP)⁺lipopolysaccharide (LPS)⁺ and NF-κB⁺CD11c⁺ populations, and PG 16S rDNA level in the periodontal tissue. Their treatments also suppressed PG-induced CI -like behaviors, TNF-α expression and NF-κB-positive immune cells in the hippocampus and colon, while PG-suppressed hippocampal BDNF and N-methyl-D-aspartate receptor (NMDAR) expression increased. The combination of NK357 and NK391 additively alleviated PG- or pEVs-induced periodontitis, neuroinflammation, CI-like behaviors, colitis, and gut microbiota dysbiosis and increased PG- or pEVs-suppressed BDNF and NMDAR expression in the hippocampus. In conclusion, NK357 and NK391 may alleviate periodontitis and dementia by regulating NF-κB, RANKL/RANK, and BDNF-NMDAR signaling and gut microbiota.

Porphyromonas gingivalis bacteremia increases the permeability of the blood-brain barrier via the Mfsd2a/Caveolin-1 mediated transcytosis pathway

Bacteremia induced by periodontal infection is an important factor for periodontitis to threaten general health. P. gingivalis DNA/virulence factors have been found in the brain tissues from patients with Alzheimer's disease (AD). The blood-brain barrier (BBB) is essential for keeping toxic substances from entering brain tissues. However, the effect of P. gingivalis bacteremia on BBB permeability and its underlying mechanism remains unclear. In the present study, rats were injected by tail vein with P. gingivalis three times a week for eight weeks to induce bacteremia. An in vitro BBB model infected with P. gingivalis was also established. We found that the infiltration of Evans blue dye and Albumin protein deposition in the rat brain tissues were increased in the rat brain tissues with P. gingivalis bacteremia and P. gingivalis could pass through the in vitro BBB model. Caveolae were detected after P. gingivalis infection in BMECs both in vivo and in vitro. Caveolin-1 (Cav-1) expression was enhanced after P. gingivalis infection. Downregulation of Cav-1 rescued P. gingivalis-enhanced BMECs permeability. We further found P. gingivalis-gingipain could be colocalized with Cav-1 and the strong hydrogen bonding between Cav-1 and arg-specific-gingipain (RgpA) were detected. Moreover, P. gingivalis significantly inhibited the major facilitator superfamily domain containing 2a (Mfsd2a) expression. Mfsd2a overexpression reversed P. gingivalis-increased BMECs permeability and Cav-1 expression. These results revealed that Mfsd2a/Cav-1 mediated transcytosis is a key pathway governing BBB BMECs permeability induced by P. gingivalis, which may contribute to P. gingivalis/virulence factors entrance and the subsequent neurological impairments.

Poor Oral Health as a Risk Factor for Dementia in a Swedish Population: A Cohort Study with 40 Years of Follow-Up

BACKGROUND

Whether poor oral health is associated with dementia risk remains unclear.

OBJECTIVE

We conducted a cohort study of 14,439 participants who were followed up for up to 40 years in Uppsala County, central Sweden, aiming to explore the association between poor oral health, namely the number of tooth loss, dental plaque status, and oral mucosal lesions, and the risk of dementia.

METHODS

We used Cox proportional hazards regression model to derive cause-specific hazard ratios (HR) and corresponding 95% confidence intervals (CI), while adjusting for baseline potential confounders as well as a time-varying covariate, Charlson's Comorbidity Index score.

RESULTS

Dementia risk was substantially higher among those with a higher number of tooth loss; compared to the group with tooth loss 0-10, the HRs were 1.21 (95% CI: 1.02, 1.42), 1.17 (95% CI: 0.97, 1.40), and 1.30 (95% CI: 1.09, 1.54) respectively for groups with increasing number of tooth loss. There was some evidence of dose-risk association in this study, with a HR of 1.10 (1.04, 1.18) comparing adjacent groups (ptrend = 0.001). In a stratified analysis by attained age, tooth loss was more pronouncedly associated with the risk of dementia onset before age 80 (those with 21-32 versus 0-10 lost teeth, HR = 1.82, (95% CI: 1.32, 2.51); HR = 1.22 (95% CI: 1.10, 1.35) comparing adjacent groups, ptrend < 0.001).

CONCLUSION

In summary, there are some indications that poor oral health, as indicated by more tooth loss, is positively associated with an increased risk of dementia, especially for dementia onset before age 80.

Unhealthy oral status contributes to the older patients with cognitive frailty: an analysis based on a 5-year database

BACKGROUND

Oral health is associated with the onset and deterioration of cognitive function and physical frailty, which can be improved with appropriate interventions. However, far too little attention has been paid to oral health status of elderly with cognitive frailty. The objective of this study was to investigate the oral health status and potential risk factors of elderly hospitalized patients aged 60 years or older with cognitive frailty.

METHODS

The participants' assessment data derived from the Comprehensive Geriatric Assessment Database of hospitalized patients from The First Affiliated Hospital of Chongqing Medical University. Data were collected from April 2016 to December 2021. All participants underwent a face-to-face assessment conducted by professional evaluators. Physical frailty was defined by Fried's criteria. Cognitive function was assessed by Mini Mental State Examination (MMSE). The cognitive frailty is characterized by the simultaneous presence of at least 1 Fried's criteria and mild cognitive impairment according to Diagnostic and Statistical Manual of Mental Disorders 5th edition. The oral health was assessed according to 10-item Brief Oral Health Status Examination (BOHSE). The general demographic characteristics, BOHSE scores were compared between the cognitive frailty and non-cognitive frailty (control group). The score of BOHSE and ten items were included in the binary logistic regression analysis. The covariate characteristics were adjusted for a final model with a multivariate analysis.

RESULTS

A total of 425 patients (245 females) with cognitive frailty and 491 patients (283 females) with non-cognitive frailty were enrolled in this retrospective study. Univariate analysis showed statistically significant differences in age, education level, living arrangement, diabetes, Body Mass Index (BMI), Pittsburgh Sleep Quality Index (PSQI), depression between the two groups. The total BOHSE score of cognitive frailty was higher than that of the control group (4.35 ± 2.68 vs. 3.64 ± 2.60, Z = 4.07, P < 0.001). The average scores and the proportions of health changes and unhealthy states of tongue, mucosa tissue, gums, natural teeth, dentures, masticatory teeth and oral hygiene in cognitive frailty were greater than those of the control group (all P < 0.05). The binary logistical regression analysis showed that four or more natural teeth decayed or broken was independently associated with cognitive frailty after adjusting the age, gender, education level, living arrangement and BMI, PSQI, diabetes and depression (OR = 1.91, 95%CI: 1.20-3.07, P = 0.007). Additionally, while in the chewing position, those cases with a normal-occlusal-relationship number of less than 11 pairs had a higher risk of cognitive frailty than those with 12 pairs or more.

CONCLUSIONS

The oral health status of older hospitalized patients over 60 years with cognitive frailty was worse than that of patients with non-cognitive frailty. But only four or more natural teeth decayed or broken and a reduction in chewing pairs were independent risk factors for cognitive frailty.

Is Periodontitis Associated with Age-Related Cognitive Impairment? The Systematic Review, Confounders Assessment and Meta-Analysis of Clinical Studies

It has been suggested that molecular pathological mechanisms responsible for periodontitis can be linked with biochemical alterations in neurodegenerative disorders. Hypothetically, chronic systemic inflammation as a response to periodontitis plays a role in the etiology of cognitive impairment. This study aimed to determine whether periodontitis (PDS) is a risk factor for age-related cognitive impairment (ACI) based on evidence of clinical studies. A comprehensive, structured systematic review of existing data adhering to the Preferred Reporting Items for Systematic Review and Meta Analyses (PRISMA) guidelines was carried out. Five electronic databases, PubMed, Embase, Scopus, Web of Science, and Cochrane, were searched for key terms published in peer-reviewed journals until January 2021. The Newcastle-Ottawa scale was used to assess the quality of studies and risk of bias. The primary and residual confounders were explored and evaluated. A meta-analysis synthesizing quantitative data was carried out using a random-effects model. Seventeen clinical studies were identified, including 14 cohort, one cross-sectional, and two case-control studies. Study samples ranged from 85 to 262,349 subjects, with follow-up between 2 and 32 years, and age above 45 years, except for two studies. The findings of studies suggesting the PDS-ACI relationship revealed substantial differences in design and methods. A noticeable variation related to the treatment of confounders was observed. Quality assessment unveiled a moderate quality of evidence and risk of bias. The subgroups meta-analysis and pooled sensitivity analysis of results from seven eligible studies demonstrated overall that the presence of PDS is associated with an increased risk of incidence of cognitive impairment (OR = 1.36, 95% CI 1.03-1.79), particularly dementia (OR = 1.39, 95% CI 1.02-1.88) and Alzheimer's disease (OR = 1.03 95% CI 0.98-1.07)). However, a considerable heterogeneity of synthesized data (I2 = 96%) and potential publication bias might affect obtained results. While there is a moderate statistical association between periodontitis and dementia, as well as Alzheimer's disease, the risk of bias in the evidence prevents conclusions being drawn about the role of periodontitis as a risk factor for age-related cognitive impairment.

Periodontal health, cognitive decline, and dementia: A systematic review and meta-analysis of longitudinal studies

BACKGROUND

Emerging evidence indicates that poor periodontal health adversely impacts cognition. This review examined the available longitudinal evidence concerning the effect of poor periodontal health on cognitive decline and dementia.

METHODS

Comprehensive literature search was conducted on five electronic databases for relevant studies published until April 2022. Longitudinal studies having periodontal health as exposure and cognitive decline and/or dementia as outcomes were considered. Random effects pooled estimates and 95% confidence intervals were generated (pooled odds ratio for cognitive decline and hazards ratio for dementia) to assess whether poor periodontal health increases the risk of cognitive decline and dementia. Heterogeneity between studies was estimated by I2 and the quality of available evidence was assessed through quality assessment criteria.

RESULTS

Adopted search strategy produced 2132 studies for cognitive decline and 2023 for dementia, from which 47 studies (24 for cognitive decline and 23 for dementia) were included in this review. Poor periodontal health (reflected by having periodontitis, tooth loss, deep periodontal pockets, or alveolar bone loss) was associated with both cognitive decline (OR = 1.23; 1.05-1.44) and dementia (HR = 1.21; 1.07-1.38). Further analysis, based on measures of periodontal assessment, found tooth loss to independently increase the risk of both cognitive decline (OR = 1.23; 1.09-1.39) and dementia (HR = 1.13; 1.04-1.23). Stratified analysis based on the extent of tooth loss indicated partial tooth loss to be important for cognitive decline (OR = 1.50; 1.02-2.23) and complete tooth loss for dementia (HR = 1.23; 1.05-1.45). However, the overall quality of evidence was low, and associations were at least partly due to reverse causality.

CONCLUSIONS

Poor periodontal health and tooth loss appear to increase the risk of both cognitive decline and dementia. However, the available evidence is limited (e.g., highly heterogenous, lacking robust methodology) to draw firm conclusions. Further well-designed studies involving standardized periodontal and cognitive health assessment and addressing reverse causality are highly warranted.

The Red and Orange Complex Subgingival Microbiome of Cognitive Impairment and Cognitively Normal Elderly with Periodontitis

Increasing evidence has shown an association between periodontitis and cognitive impairment. Subgingival microbiota play a great role in periodontitis pathogenesis. However, the correlation between the subgingival microbiome and cognitive impairment remains unclear. This study aimed to evaluate the red and orange complex subgingival microbiome of cognitively impaired and cognitively normal elderly Indonesian subjects with periodontitis. Twenty-eight elderly subjects diagnosed with periodontitis underwent two cognitive examinations using the Hopkins Verbal Learning Test and the Mini-Mental State Examination. Gingival crevicular fluid taken from the periodontal pocket, at a depth between 5 and 7 mm, using a paper point was used as the subgingival samples. The subgingival microbiome in the cognitive impairment group (n = 14) and cognitively normal group (n = 14) was compared using the 16S rRNA Metagenomic iSeq™ 100 Sequencing System. There was β-diversity in the subgingival microbiota between the cognitively impaired and cognitively normal subjects. The metagenomic analysis showed a higher abundance of Porphyromonas and Treponema bacteria in the cognitive impairment group than in the normal cognitive group (p < 0.05). The abundance of Porphyromonas gingivalis and Treponema denticola was higher in the cognitively impaired elderly subjects. The role of P. gingivalis and T. denticola in the pathogenesis of cognitive impairment needs further investigation.

Association between microbiological risk factors and neurodegenerative disorders: An umbrella review of systematic reviews and meta-analyses

The role of microbiological factors in the development of neurodegenerative diseases is attracting increasing attention, while the relationship remains debated. This study aimed to comprehensively summarize and evaluate the associations between microbiological factors and the risk of neurodegenerative disorders with an umbrella review. PubMed, Embase, and the Cochrane library were used to search for papers from the earliest to March 2021 for identifying meta-analyses and systematic reviews that examined associations between microbiological factors and neurodegenerative diseases. AMSTAR2 tool was employed to evaluate the methodical quality of systematic reviews and meta-analyses. The effect size and 95% confidence interval (95% CI) were recalculated with a random effect model after the overlap was recognized by the corrected covered area (CCA) method. The heterogeneity of each meta-analysis was measured by the I ² statistic and 95% prediction interval (95% PI). Additionally, publication bias and the quality of evidence were evaluated for all 37 unique associations. Only 4 associations had above the medium level of evidence, and the rest associations presented a low level of evidence. Among them, helicobacter pylori (HP), infection, and bacteria are associated with Parkinson's disease (PD), and the other one verifies that periodontal disease is a risk factor for all types of dementia. Following the evidence of our study, eradication of HP and aggressive treatment of periodontitis are beneficial for the prevention of PD and dementia, respectively. This umbrella review provides comprehensive quality-grade evidence on the relationship between microbial factors and neurodegenerative disease. Regardless of much evidence linking microbial factors to neurodegenerative diseases, these associations are not necessarily causal, and the evidence level is generally low. Thus, more effective studies are required.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/PROSPERO/#searchadvanced, PROSPERO, identifier: CRD42021239512.