The impact of study factors in the association of periodontal disease and cognitive disorders: systematic review and meta-analysis

The Association Between Cognitive Function and Oral Health in Home Dwellers and Nursing Home Residents: The HUNT Study

OBJECTIVES

To evaluate the relationships of cognitive function and care dependency with oral health in a Norwegian older adult population.

METHODS

This cross-sectional study included 2623 participants aged 70 and older from the fourth wave of the Trøndelag health study (HUNT4 70+) and the city of Trondheim (Trondheim 70+). Neurocognitive disorders (NCDs) were diagnosed by clinical experts according to the DSM-5 framework. Care dependency referred to nursing home residency. Oral health was assessed by using the Revised Oral Assessment Guide-Jönköping (ROAG-J). Individuals were considered as 'having oral problem' if the score was two or three in at least one of the nine ROAG-J items. Poisson regression was used to estimate prevalence ratios (PRs) and 95% confidence intervals (CIs).

RESULTS

The prevalence of having oral problems was 19% higher in participants with NCDs than those with normal cognitive function after adjusting for potential confounders (PR 1.19, 95% CI: 1.09-1.29). Further analysis showed a higher prevalence of having oral problems for home dwellers with NCDs (PR 1.23, 95% CI: 1.13-1.33) and nursing home residents (PR 1.32, 95% CI: 1.20-1.45) compared to home dwellers with normal cognitive function.

CONCLUSIONS

NCDs were associated with an increased prevalence of oral problems in this Norwegian older adult population. The study suggests the need for increasing oral care for home dwellers with NCDs and nursing home residents.

Mediating and moderating effects of plasma proteomic biomarkers on the association between poor oral health problems and brain white matter microstructural integrity: the UK Biobank study

The plasma proteome can mediate associations between periodontal disease (Pd) and brain white matter integrity (WMI). We screened 5089 UK Biobank participants aged 40-70 years for poor oral health problems (POHP). We examined the association between POHP and WMI (fractional anisotropy (FA), mean diffusivity (MD), Intracellular Volume Fraction (ICVF), Isotropic Volume Fraction (ISOVF) and Orientation Diffusion (OD)), decomposing the total effect through the plasma proteome of 1463 proteins into pure mediation, pure interaction, neither, while adjusting for socio-demographic and cardiovascular health factors. Similarly, structural equations modeling (SEM) was conducted. POHP was more prevalent among men (12.3% vs. 9.6%), and was associated with lower WMI on most metrics, in a sex-specific manner. Of 15 proteins strongly associated with POHP, growth differentiation factor 15 (GDF15) and WAP four-disulfide core domain 2 (WFDC2; also known as human epididymis protein 4; HE4) were consistent mediators. Both proteins mediated 7-8% of total POHP effect on FAmean. SEM yielded significant total effects for FAmean, MDmean and ISOVFmean in full models, with %mediated by common latent factor (GDF15 and WFDC2) ranging between 13% (FAmean) and 19% (ISOVFmean). For FA, mediation by this common factor was found for 16 of 49 tract-specific and global mean metrics. Protein metabolism, immune system, and signal transduction were the most common pathways for mediational effects. POHP was associated with poorer WMI, which was partially mediated by GDF15 and WFDC2.

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.

Impact of periodontal disease on cognitive disorders, dementia, and depression: a systematic review and meta-analysis

A growing body of research suggested that there was a link between poor periodontal health and systemic diseases, particularly with the early development of cognitive disorders, dementia, and depression. This is especially true in cases of changes in diet, malnutrition, loss of muscular endurance, and abnormal systemic inflammatory response. Our study aimed to determine the extent of these associations to better target the multi-level healthy aging challenge investigating the impact of periodontal disease on cognitive disorders (cognitive impairment and cognitive decline), dementia, and depression. We conducted a comprehensive literature search up to November 2023 using six different electronic databases. Two independent researchers assessed the eligibility of 7363 records against the inclusion criteria and found only 46 records that met the requirements. The study is registered on PROSPERO (CRD42023485688). We generated random effects pooled estimates and 95% confidence intervals (CI) to evaluate whether periodontal disease increased the risk of the investigated outcomes. The quality assessment revealed moderate quality of evidence and risk of bias. Periodontal disease was found to be associated with both cognitive disorders (relative risk (RR) 1.25, 95% CI 1.11-1.40, in the analysis of cross-sectional studies); cognitive impairment (RR 3.01, 95% CI 1.52-5.95 for longitudinal studies, cognitive decline); and dementia (RR 1.22, 95% CI 1.10-1.36). However, no significant increased risk of depression among subjects with periodontal disease was found (RR 1.07, 95% CI 0.95-1.21). Despite the association with two of the three explored outcomes, the available evidence on periodontal diseases and dementia, cognitive disorders, and depression is controversial due to several limitations. Therefore, further investigations involving validated and standardized tools are required.

Mediating and moderating effects of plasma proteomic biomarkers on the association between poor oral health problems and incident dementia: The UK Biobank study

The plasma proteome can mediate poor oral health problems (POHP)'s link to incident dementia. We screened 37,269 UK Biobank participants 50-74 years old (2006-2010) for prevalent POHP, further tested against 1463 plasma proteins and incident dementia over up to 15 years of follow-up. Total effect (TE) of POHP-dementia through plasma proteomic markers was decomposed into pure indirect effect (PIE), interaction referent (INTREF), controlled direct effect (CDE), or mediated interaction (INTMED). POHP increased the risk of all-cause dementia by 17% (P < 0.05). Growth differentiation factor 15 (GDF15) exhibited the strongest mediating effects (PIE > 0, P < 0.001), explaining 28% the total effect of POHP on dementia, as a pure indirect effect. A first principal component encompassing top 4 mediators (GDF15, IL19, MMP12, and ACVRL1), explained 11% of the POHP-dementia effect as a pure indirect effect. Pathway analysis including all mediators (k = 173 plasma proteins) revealed the involvement of the immune system, signal transduction, metabolism, disease, and gene expression, while STRING analysis indicated that top mediators within the first principal component were also represented in the two largest proteomic clusters. The dominant biological GO pathway for the GDF15 cluster was GO:0007169 labeled as "transmembrane receptor protein tyrosine kinase signaling pathway." Dementia is linked to POHP mediated by GDF15 among several proteomic markers.

Genome-wide association studies on periodontitis: A systematic review

OBJECTIVES

This study aims to systematically review the existing literature and critically appraise the evidence of genome-wide association studies (GWAS) on periodontitis. This study also aims to synthesise the findings of genetic risk variants of periodontitis from included GWAS.

METHODS

A systematic search was conducted on PubMed, GWAS Catalog, MEDLINE, GLOBAL HEALTH and EMBASE via Ovid for GWAS on periodontitis. Only studies exploring single-nucleotide polymorphisms(SNPs) associated with periodontitis were eligible for inclusion. The quality of the GWAS was assessed using the Q-genie tool. Information such as study population, ethnicity, genomic data source, phenotypic characteristics(definition of periodontitis), and GWAS methods(quality control, analysis stages) were extracted. SNPs that reached conventional or suggestive GWAS significance level(5e-8 or 5e-06) were extracted and synthesized.

RESULTS

A total of 15 good-quality GWAS on periodontitis were included (Q-genie scores ranged from 38-50). There were huge heterogeneities among studies. There were 11 identified risk SNPs (rs242016, rs242014, rs10491972, rs242002, rs2978951, rs2738058, rs4284742, rs729876, rs149133391, rs1537415, rs12461706) at conventional GWAS significant level (p<5x10-8), and 41 at suggestive level (p<5x10-6), but no common SNPs were found between studies. Three SNPs (rs4284742 [G], rs11084095 [A], rs12461706 [T]) from three large studies were from the same gene region-SIGLEC5.

CONCLUSION

GWAS of periodontitis showed high heterogeneity of methodology used and provided limited SNPs statistics, making identifying reliable risk SNPs challenging. A clear guidance in dental research with requirement of expectation to make GWAS statistics available to other investigators are needed.

Infection burden, periodontal pathogens, and their interactive association with incident all-cause and Alzheimer's disease dementia in a large national survey

INTRODUCTION

Relationships and interplay of an infection burden (IB) and periodontal pathogens or periodontal disease (Pd) markers with Alzheimer's disease (AD) and all-cause dementia among US adults were examined.

METHODS

Less than or equal to 2997 participants from the National Health and Nutrition Survey III were linked to CMS-Medicare [≥45 years (1988-1994); ≤30 years follow-up].

RESULTS

Hepatitis C (hazard ratio = 3.33, p = 0.004) and herpes simplex virus 2 were strongly associated with greater all-cause dementia risk. Porphyromonas gingivalis and Streptococcus oralis were associated with greater AD risk at higher IB. The red-green periodontal pathogen cluster coupled with higher IB count increased the risk of all-cause dementia among minority racial groups. Pocket probing depth associated with dementia risk at lower IB in the overall sample.

DISCUSSION

Select viruses and bacteria were associated with all-cause and AD dementia, while the IB interacted with Pd markers in relation to these outcomes.

HIGHLIGHTS

Interplay of infection burden (IB) and periodontal disease with dementia was tested. ≤2997 participants from NHANES III were linked to Medicare. Hepatitis C and herpes simplex virus 2 strongly associated with dementia risk. Tetanus sero-positivity increased Alzheimer's disease (AD) risk. Porphyromonas gingivalis and Streptococcus oralis associated with AD at higher IB. Red-green periodontal cluster at high IB, increased dementia in racial minorities. Pocket probing depth associated with dementia risk at lower IB.

Unraveling the cognitive implications among individuals with co-occurring chronic periodontitis and type 2 diabetes mellitus: A cross-sectional study

OBJECTIVES

Chronic periodontitis and type 2 diabetes mellitus (T2DM) are associated with cognitive decline when examined individually. To gain deeper insight into the combined effects of these conditions on cognitive decline, the present study aimed to examine the cognitive status of individuals with co-occurring T2DM and chronic periodontitis.

METHODS

We recruited 220 participants categorized into four groups: Group I, healthy subjects; Group II, individuals with chronic periodontitis; Group III, individuals with T2DM; and Group IV, individuals with both T2DM and chronic periodontitis. Medical histories were recorded for all participants, followed by periodontal examination and evaluation of cognitive status using the Montreal Cognitive Assessment (MoCA) scale. Finger dexterity was assessed using the nine-hole peg test.

RESULTS

A statistically significant increase in the proportion of mild cognitive impairment (MCI) was observed between groups I and IV (p < 0.001). Logistic regression analysis revealed that, among the parameters assessed in this study, the adjusted odds ratio (OR) was significant for age, finger dexterity scores, and co-occurrence of T2DM and periodontitis.

CONCLUSIONS

The findings of this study suggest that the co-occurrence of chronic periodontitis and T2DM can have a detrimental effect on the cognitive abilities of an individual. Subsequent research should include longitudinal monitoring of the cognitive status in patients with concurrent conditions during treatment to gain deeper prognostic insights into the relationship between these co-occurring conditions and cognitive decline.

Research Trends in the Comorbidity Between Periodontitis and Neurodegenerative Diseases

INTRODUCTION AND AIMS

Evidence suggests an association between periodontitis and neurodegenerative diseases, but a comprehensive analysis of research trends remains absent. Therefore, we aim to identify research trends and hotspots on the comorbidity between periodontitis and neurodegenerative diseases, understand mechanisms, provide guidance for subsequent studies and show its clinical translational possibility.

METHODS

A bibliometric analysis covering 1982 to 2023 was conducted using the Web of Science Core Collection. English-language articles range from January 1, 1982 to November 30, 2023 were analyzed. Data were downloaded on November 30, 2023 and analyzed on December, 2023. Data visualization and statistical analysis were performed to identify trends of annual publications, countries, sources, institutions, authors, most cited articles, and keywords by using Microsoft Excel, VOSviewer, Citespace, R-bibliometrix and Origin Pro.

RESULTS

A total of 1,238 articles from 1982 to 2023 on the comorbidity between periodontitis and neurodegenerative diseases were identified. Annual publications showed an upward trend. The United States, University College of London, BRAIN and Shy, Michael E. were the leading nation, affiliation, source and author, respectively. The United States, NEUROLOGY, and Curtis Maurice A. were the most cited nation, source, and author. Keywords network analysis highlighted 'Charcot-Marie-Tooth Disease', 'Alzheimer's Disease' and 'Periodontitis' as focal points. Detection of keywords citation bursts demonstrated 'Porphyromonas gingivalis' and 'Cognitive Dysfunction' as hot topics in recent research.

CONCLUSIONS

In recent years, emerging interests of the comorbidity between periodontitis and neurodegenerative diseases (NDs) are growing. Our study enhances the understanding of recent research trends of periodontitis and NDs and provides valuable perspectives within this expanding field, offering new insights into research trends regarding the interplay between 'Porphyromonas gingivalis' and 'Cognitive Dysfunction'. Further research of the molecular mechanisms between P. gingivalis-induced periodontitis, neuroinflammation, that leads neurodegeneration are clearly warranted.

Oral diseases are associated with cognitive function in adults over 60 years old

OBJECTIVE

To investigate the bidirectional association between oral diseases and cognitive function comprehensively.

SUBJECTS AND METHODS

This cross sectional study utilized data from the National Health and Nutrition Examination Survey. Oral diseases include periodontitis, dental caries, and tooth loss (end point of oral disease resulting in tooth extraction). Cognitive function included three domains: memory, processing speed, and executive function. A global cognitive score was then derived from sum of the three cognitive domains. Oral cognition associations were examined using various statistical models: (1) Regress oral disease on cognitive function; (2) Regress cognitive function on oral disease; and (3) Structural equation modelling treating cognition and oral disease as latent variables.

RESULTS

There were 2508 participants aged 60+ who had both oral and cognitive information. Associations between various oral disease and global cognitive score were observed (Odds ratio ORcog->periodontitis 0.95, 95% Confidence Interval [0.92, 0.99]; βcog->caries -0.13, [-0.23, -0.04]; βcog->tooth loss -0.03 [-0.04, -0.01]; βtooth loss->cog -0.04 [-0.06, -0.02]; βcaries->cog -0.03 [-0.06, -0.01]; βperiodontitis->cog -0.39 [-0.69, -0.10]). Significant correlation was also found between these oral disease and cognitive function using structural equation model (r -0.22, [-0.34, -0.10]).

CONCLUSIONS

This study found robust bidirectional associations between oral disease and cognitive function using various modelling approaches among the aging population.

Poor oral health and dementia risk under time-varying confounding: A cohort study based on marginal structural models

BACKGROUND

Bidirectional association between oral health, including tooth loss and oral hypofunction, and cognitive impairment can induce time-varying confounding in association with dementia. This study aimed to investigate the association between oral health and the development of dementia among older adults, considering cognitive impairment as a time-varying confounder.

METHODS

This nine-year follow-up cohort study targeted independent older adults aged ≥65 years who participated in the Japan Gerontological Evaluation Study. The exposure variables were self-reported poor oral health (≤19 remaining teeth, edentulousness, chewing difficulty, swallowing problems, and xerostomia), which were assessed in 2010 and 2013. The outcome variable was the incidence of dementia between 2013 and 2019, which was obtained from the municipalities' administrative database. Furthermore, in 2010 and 2013, we considered cognitive impairment as a time-varying confounder and treated it based on a marginal structural model (MSM), including possible baseline confounders. Oral health and cognitive impairment were assessed using the items of Kihon checklist. We employed a Cox proportional hazards model with a stabilized inverse probability weight and estimated hazard ratios (HRs) and 95% confidence intervals (CIs).

RESULTS

Among 37,556 participants (mean age: 72.8 years [1 SD = 5.5], males: 46.8%), the dementia incidence rate was 2.2/100 person-year. The proportions of those with ≤19 remaining teeth, edentulousness, chewing difficulty, swallowing problems, and xerostomia were 61.3%, 11.0%, 24.4%, 14.7%, and 19.2%, respectively. From the regression analysis based on MSM, ≤19 remaining teeth (HR = 1.12, 95% CI = 1.03-1.23), edentulousness (HR = 1.20, 95% CI = 1.09-1.32), chewing difficulty (HR = 1.11, 95% CI = 1.02-1.21), and xerostomia (HR = 1.10, 95% CI = 1.01-1.20) were significantly associated with an increased risk of dementia; however, swallowing problems were not significantly associated with dementia onset (p > 0.05).

CONCLUSIONS

Even after considering time-varying confounding by cognitive function at baseline and follow-up, we observed significant associations between poor oral health and increased risk of dementia among older adults.

An umbrella review on the association between factors of oral health and cognitive dysfunction

An increasing number of systematic reviews and meta-analyses have been published on the association between oral health and cognitive dysfunction, also known as oral-cognitive links. However, there is great diversity in the oral and cognitive factors included in these studies, with different opinions for clinical practice drawn from the evidence. To understand which oral and cognitive factors are involved in those associations, we conducted an umbrella review of 28 systematic reviews, including 12 meta-analyses, on oral-cognitive links. We found that (a) periodontal diseases, oral microbiome, and dementia were frequently studied, while other factors, such as mastication and mild cognitive impairment, were less commonly investigated, and (b) severe deterioration of oral health, such as severe periodontitis or extensive tooth loss, rather than the presence of oral diseases alone, was strongly associated with cognitive dysfunction. In conclusion, the diversity of oral and cognitive factors included in the review studies reflects the complexity of oral-cognitive links. Clarifying the factors helps to form evidence-based clinical advice for healthcare.

Neuroinflammation and Neurodegenerative Diseases: How Much Do We Still Not Know?

The term "neuroinflammation" defines the typical inflammatory response of the brain closely related to the onset of many neurodegenerative diseases (NDs). Neuroinflammation is well known, but its mechanisms and pathways are not entirely comprehended. Some progresses have been achieved through many efforts and research. Consequently, new cellular and molecular mechanisms, diverse and conventional, are emerging. In listing some of those that will be the subject of our description and discussion, essential are the important roles of peripheral and infiltrated monocytes and clonotypic cells, alterations in the gut-brain axis, dysregulation of the apelinergic system, alterations in the endothelial glycocalyx of the endothelial component of neuronal vascular units, variations in expression of some genes and levels of the encoding molecules by the action of microRNAs (miRNAs), or other epigenetic factors and distinctive transcriptional factors, as well as the role of autophagy, ferroptosis, sex differences, and modifications in the circadian cycle. Such mechanisms can add significantly to understanding the complex etiological puzzle of neuroinflammation and ND. In addition, they could represent biomarkers and targets of ND, which is increasing in the elderly.

Risk factors of cognitive impairment: Impact of decline in oral function

Cognitive impairment and subsequent dementia are the major causes of disability and need for nursing care among older people in worldwide. The purpose is to review well-known risk factors for cognitive impairment and dementia, focusing on the relationship between decline in oral function and current prevention strategies. Various non-modifiable and modifiable risk factors are related to cognitive impairment. Effects of oral function to cognitive impairment is not yet well recognized in the medical community, although masticatory function, occlusal force, and number of teeth have been reported to be related to cognitive function. Furthermore, occlusal force rather than number of teeth was significantly related to the early stages of cognitive impairment, and that a decline in occlusal force seemed to lead to cognitive impairment directly and indirectly through dietary intake. This relationship was significant only for occlusal force, which may be associated with the early stages of cognitive decline. Nutritional change caused by reduced masticatory function is suggested as a possible explanation. Therefore, rehabilitation or maintenance of oral function should be sought to prevent cognitive impairment.

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.

Association between periodontitis and cognitive impairment in adults

DESIGN

To summarize the data on association between periodontal diseases and cognitive impairment in adults this systematic review scrutinized various observational studies till September 2021. This review was carried out in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA 2020) guidelines. The authors used PECO framework question,: population-Adults (18 years or older), exposure-adults suffering from periodontitis, comparator-adult group without periodontitis, outcome-adults at high risk for cognitive impairment.

CASE/CONTROL SELECTION

Search for the literature was conducted on PubMed, Web of Science, and Cumulative Index to Nursing and Allied Health Literature (CINAHL). Search was limited to human studies with no limitation to year of publication prior to September 2021. Search terms used were related to gingiva, oral bacteria like Porphyromonas gingivalis, gum inflammation, periodontitis, dementia, neuroinflammation, cognitive impairment, Alzheimer's disease, Parkinson disease. Following research, all the studies providing association between periodontal diseases and neurodegenerative diseases with quantitative measures were included in the study. Non-human studies, studies on patients below 18 year old, studies related to influence of treatment and in subjects already suffering from neurological disease were excluded. After removing duplicates, eligible studies were identified and data extracted by two reviewers to make ensure inter examiner reliability and to prevent data entry errors. Data from the studies were tabulated as study design, sample characteristics, diagnosis, exposure biomarkers/measures, outcomes and results.

DATA ANALYSIS

Methodological quality of studies was assessed by adapted Newcastle-Ottawa scale. Selection of study groups, comparability and exposure/outcome were used as parameters. Case-control and cohort studies were considered as high-quality studies if six or more stars were awarded out of nine maximum stars and four or more stars for cross-sectional studies out of six stars. Comparability among the groups was studied by taking into account primary factors for Alzheimer's disease such as age and sex and secondary factors like hypertension, osteoarthritis, depression, diabetes mellitus, and cerebrovascular disease. For cohort studies, 10 year follow up and dropout of <10% was considered to be successful.

RESULTS

A total of 3693 studies were identified by two independent reviewers and finally 11 studies were included in the final analysis. Six cohort studies, three cross-sectional and two case-control studies were included after excluding remaining studies. Bias in studies was assessed by adapted Newcastle-Ottawa Scale. All included studies were of high methodological quality. Association between periodontitis and cognitive impairment was determined by using different criteria like International classification of disease, clinical measurement of periodontitis subjects, inflammatory biomarkers, microbes and antibodies. It was suggested that subjects with chronic periodontitis since 8 years or more, are at a higher risk of having dementia. Clinical measures of periodontal disease like probing depth, clinical attachment loss, alveolar bone loss were found to be positively associated with cognitive impairment. Inflammatory biomarkers and pre-existing elevated levels of serum IgG specific to periodontopathogens was reported to be associated with cognitive impairment. Within the limitations of the study, the authors concluded that though the patients with long-standing periodontitis are at greater risk for developing cognitive impairment by neurodegenerative diseases, the mechanism by which periodontitis can lead to cognitive impairment is still vague.

CONCLUSIONS

Evidence suggests a strong association between periodontitis and cognitive impairment. Still further studies should be done to explore the mechanism involved.

Treatment of Periodontal Infections, the Possible Role of Hydrogels as Antibiotic Drug-Delivery Systems

With the advancement of biomedical research into antimicrobial treatments for various diseases, the source and delivery of antibiotics have attracted attention. In periodontal diseases, antibiotics are integral in positive treatment outcomes; however, the use of antibiotics is with caution as the potential for the emergence of resistant strains is of concern. Over the years, conventional routes of drug administration have been proven to be effective for the treatment of PD, yet the problem of antibiotic resistance to conventional therapies continues to remain a setback in future treatments. Hydrogels fabricated from natural and synthetic polymers have been extensively applied in biomedical sciences for the delivery of potent biological compounds. These polymeric materials either have intrinsic antibacterial properties or serve as good carriers for the delivery of antibacterial agents. The biocompatibility, low toxicity and biodegradability of some hydrogels have favoured their consideration as prospective carriers for antibacterial drug delivery in PD. This article reviews PD and its antibiotic treatment options, the role of bacteria in PD and the potential of hydrogels as antibacterial agents and for antibiotic drug delivery in PD. Finally, potential challenges and future directions of hydrogels for use in PD treatment and diagnosis are also highlighted.

Cross-Sectional Analysis of Periodontal Disease and Cognitive Impairment Conducted in a Memory Clinic: The Pearl Study

BACKGROUND

Periodontal disease (PeD) is a risk factor of Alzheimer's disease and is associated with cognitive decline in older adults. However, the relationships between subitems of neuropsychological tests and PeD have not been fully clarified.

OBJECTIVE

To evaluate associations between PeD and subitems of neuropsychological tests.

METHODS

We performed a cross-sectional analysis of data of 183 participants (women: 50%, mean age: 79 years) from a clinical study. We enrolled patients who visited our memory clinic and assessed demographics, dementia-related risk factors, neuropsychological tests, brain magnetic resonance images, and a dental screening check. We evaluated the relationships between cognitive function and PeD using multivariable logistic regression analyses.

RESULTS

Participants with dementia were less likely to make periodical visits to the dentist, had fewer teeth, had less frequent tooth brushing habits, and were more likely to have PeD. Impaired cognitive function was significantly associated with an increasing degree of PeD. In multivariable logistic regression analyses, impaired visuospatial function and attention were associated with twice the risk of moderate or severe PeD compared with individuals with preserved visuospatial function and attention (odds ratio: 2.11, 95% confidence interval: 1.04-4.29, p = 0.037). Impaired word recall and recognition and following commands were associated with increased risk of PeD (odds ratio: 2.80, 95% confidence interval: 1.41-5.32, p = 0.003).

CONCLUSIONS

Cognitive decline, such as impaired visuospatial function, attention, word recall and recognition, and inability to follow commands were independently and strongly associated with PeD. These items can be assessed easily on a daily basis.