Bidirectional relations between cognitive function and oral health in ageing persons: a longitudinal cohort study

Complete Loss of Natural Teeth and Loneliness: A Fixed-Effect Analysis

Psychosocial properties of oral health have been reported. The present study aimed to investigate the causal effect of complete loss of natural teeth on loneliness by using fixed-effects analysis to control for confounding factors, including unmeasured time-invariant factors. Data from older adults participating in at least 2 consecutive waves of the English Longitudinal Study of Ageing in waves 3 (2006/2007), 5 (2010/2011), and 7 (2014/2015) were analyzed (N = 18,682 observations from 7,298 individuals). The association between complete loss of natural teeth and loneliness score (ranging from 3 to 9) was examined using fixed-effect linear regression analysis adjusting for time-varying confounders, including sociodemographic and health characteristics. The prevalence of complete tooth loss was 12.7%, 12.8%, and 10.6% in waves 3, 5, and 7, respectively. Individuals who transitioned to complete tooth loss during any 2 consecutive waves had an increase in loneliness score by 0.27 (95% confidence interval [CI] 0.03, 0.52), which was greater than those who maintained natural teeth (-0.03; 95% CI -0.05, -0.01). Fixed-effects analysis adjusting for time-varying confounders revealed a significant association between complete loss of natural teeth and an increase in loneliness score by 0.31 (95% CI 0.17, 0.46). Complete loss of natural teeth among older adults in England was associated with loneliness, even after accounting for measured time-varying and (un)measured time-invariant confounders. Retaining natural teeth may reduce the risk of loneliness.

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.

Exploring the link between tooth loss, cognitive function, and brain wellness in the context of healthy aging

AIMS

The aim of this study was to evaluate the utility of using MRI-derived tooth count, an indirect and nonspecific indicator of oral/periodontal health, and brain age gap (BAG), an MRI-based measure of premature brain aging, in predicting cognition in a population of otherwise healthy adults.

METHODS

This retrospective study utilized data from 329 participants from the University of South Carolina's Aging Brain Cohort Repository. Participants underwent neuropsychological testing including the Montreal Cognitive Assessment (MoCA), completed an oral/periodontal health questionnaire, and submitted to high-resolution structural MRI imaging. The study compared variability on cognitive scores (MoCA) accounted for by MRI-derived BAG, MRI-derived total tooth count, and self-reported oral/periodontal health.

RESULTS

We report a significant positive correlation between the total number of teeth and MoCA total scores after controlling for age, sex, and race, indicating a robust relationship between tooth count and cognition, r(208) = .233, p < .001. In a subsample of participants identified as being at risk for MCI (MoCA <= 25, N = 36) inclusion of MRI-based tooth count resulted in an R2 change of .192 (H0 = 0.138 → H1 = 0.330), F(1,31) = 8.86, p = .006. Notably, inclusion of BAG, a valid and reliable measure of overall brain health, did not significantly improve prediction of MoCA scores in similar linear regression models.

CONCLUSIONS

Our data support the idea that inclusion of MRI-based total tooth count may enhance the ability to predict clinically meaningful differences in cognitive abilities in healthy adults. This study contributes to the growing body of evidence linking oral/periodontal health with cognitive function.

Do missing teeth cause early-onset cognitive impairment? Re-examining the evidence using a quasi-natural experiment

PURPOSE

Multiple studies have reported a positive association between missing teeth and cognitive impairment. While some authors have postulated causal mechanisms, existing designs preclude assessing this.

METHODS

We sought evidence of a causal effect of missing teeth on early-onset cognitive impairment in a natural experiment, using differential exposure to fluoridated water during critical childhood years (ages 5-20 years) in England as the instrument. We coded missing teeth from 0 (≤ 12 missing) to 3 (all missing) and measured the association with cognitive impairment in the English Longitudinal Study of Ageing data (2014-5), covering 4958 persons aged 50-70 years.

RESULTS

We first replicated previous evidence of the strongly positive association of missing teeth with cognitive impairment (β = 0.25 [0.11, 0.39]), after adjusting for socio-demographic covariates, such as age, gender, education, and wealth. Using an instrumental variable design, we found that childhood exposure to water fluoridation was strongly associated with fewer missing teeth, with being exposed to fluoridated water during childhood (16 years) associated with a 0.96 reduction in the missing teeth scale (β = - 0.06 [- 0.10, - 0.02]). However, when using the instrumented measure of missing teeth, predicted by probability of fluoride exposure, we found that missing teeth no longer had an association with cognitive impairment (β = 1.48 [- 1.22, 4.17]), suggesting that previous oral health-cognitive impairment associations had unobserved confounding.

CONCLUSIONS

Our findings are consistent with the possibility that unobserved confounding leads to the oft-observed association between missing teeth and early-onset cognitive impairment, suggesting that the relationship is spurious rather than causal.

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.

Improving oral hygiene for better cognitive health: Interrelationships of oral hygiene habits, oral health status, and cognitive function in older adults

OBJECTIVES

To explore the interrelationships between oral hygiene habits, oral health status and cognitive function in older adults.

DESIGN

A cross-sectional study.

SETTING AND PARTICIPANTS

A total of 371 participants (age 76.79 [7.99] years) were enrolled from June 2020 to November 2021 in an aged care facility.

METHODS

Cognitive function was screened using the mini-mental state examination (MMSE) with adjusted cut-off points for age and education. Periodontal status (Biofilm-Gingival Interface index based on periodontal probing depth and bleeding on probing), dental status (plaque, calculus, and caries), and tooth loss were assessed through full-mouth examination. Oral hygiene habits were based on self- or informant-reporting.

RESULTS

Poor periodontal status was an associated factor for MCI (OR = 2.89, 95% CI = 1.20-6.95), while multiple tooth loss (OR = 4.90, 95% CI = 1.06 ~ 22.59), brushing teeth less than once a day (OR = 2.88, 95% CI = 1.12 ~ 7.45) and delayed dental visits (OR = 2.45, 95% CI = 1.05 ~ 5.68) were associated factors for cognitive impairment. An indirect effect of brushing teeth ≥2 daily on MMSE score through periodontal status was observed only in older adults without cognitive impairment (Bootstrap-corrected B = 0.17, 95%CI = 0.03 ~ 0.36, SE = 0.08, β = 0.08).

CONCLUSIONS AND IMPLICATIONS

Adequate toothbrushing might prevent cognitive decline indirectly by improving periodontal health only in older adults without cognitive impairment. Multiple tooth loss, infrequent toothbrushing, and delayed dental visits were associated factors for cognitive impairment. Nursing professionals and health care policymakers should advocate for the improvement of basic oral hygiene in older adults, and provide regular professional oral hygiene care for older adults with cognitive impairment.

PATIENT OR PUBLIC CONTRIBUTION

The information on oral health habits of this study was based on an interview with the participants or their caregivers during the study period.

White matter abnormalities mediate the association between masticatory dysfunction and cognition among older adults

BACKGROUND

Masticatory parameters, such as reduced number of teeth and posterior contacts, have been shown to be associated with reduced cognitive status. The underlying mechanisms that affect these associations, are however, not well understood.

OBJECTIVES

The study aims to investigate the association between masticatory dysfunction and cognition and explore the mediating effect of brain structure.

METHODS

In this cross-sectional study, 45 older adults with subjective masticatory dysfunction (mean age 72.3 ± 4.0 years) were included. Mini-Mental State Examination score <25, brain trauma, neurological disease, neurodegenerative disorders, depression or poor Swedish language skills were criteria for exclusion. Cognitive functions (executive function and episodic memory) and masticatory dysfunction defined by functional occluding status (FOS; the number of occluding units and number of remaining teeth) were analysed with partial correlation models. Structural magnetic resonance imaging was performed on 28 feasible participants. Multiple regression analyses were performed to evaluate the predictive value of brain structure and white matter hypointensities (WM-hypo) on cognitive functions. A mediation analysis was applied to assess significant predictor/s of the association between FOS and cognition.

RESULTS

Both episodic memory and executive functions were positively correlated with FOS. WM-hypo predicted cognitive status (executive function, p ≤ .01). WM-hypo mediated 66.6% (p = 0.06) of the association between FOS and executive functions.

CONCLUSION

Associations between FOS and cognitive functions are reported, where FOS, a potential modifiable risk factor, was related to both episodic memory and executive functions. The mediating effect of WM-hypo on the association between FOS and executive functions highlights the impact of the vascularisation of the brain on the link between mastication and cognition. The present study provides increased knowledge that bridges the gap between masticatory dysfunction and cognition.

Bidirectional Associations Between Sleep Quality and Grip Strength and the Mediating Role of Depression: Evidence From Two Nationally Representative Cohorts

BACKGROUND

Although studies have demonstrated associations between sleep quality (SQ) and grip strength (GS) in older adults, the direction and underlying mechanisms of this relationship are yet to be better delineated. We aimed to longitudinally investigate the bidirectional association between SQ and GS and the mediating role of depression in this association.

METHODS

Based on 2 nationally representative samples with people aged ≥50 years from the China Health and Retirement Longitudinal Study (CHARLS; 4 200 participants) and English Longitudinal Study of Ageing (ELSA; 5 922 participants), cross-lagged panel models were employed to examine the potential bidirectional relationships between objectively measured GS and self-reported SQ.

RESULTS

We observed a GS-SQ bidirectional association dominated by GS. After adjusting for potential confounders, a higher GS at T1 predicted better SQ at T2 (ELSA: β = 0.075; CHARLS: β = 0.104, p < .001) and vice versa (ELSA: β = 0.034; CHARLS: β = 0.030, p < .01). Moreover, depression partially mediated the impact of GS on subsequent SQ (ELSA, indirect effect: 0.0057, 95% confidence interval [CI]: 0.0035-0.0084; CHARLS, indirect effect: 0.0086, 95% CI: 0.0051, 0.0131), but not vice versa.

CONCLUSIONS

The results regarding data from both cohorts consistently supported a bidirectional association between GS and SQ and the mediating role of depression in the dominant pathway of this bidirectional relationship. Older adults with a low GS should be made aware of a potentially vicious cycle related to depression that can affect their sleep. Regular screening for depression may help to break this cycle.

Geroscience: Aging and Oral Health Research

Research in aging has significantly advanced; scientists are now able to identify interventions that slow the biologic aging processes (i.e., the "hallmarks of aging"), thus delaying the onset and progression of multiple diseases, including oral conditions. Presentations given during the 3-part session "Geroscience: Aging and Oral Health Research," held during the 2023 American Association for Dental, Oral, and Craniofacial Research meeting, are summarized in this publication. Speakers' topics spanned the translational research spectrum. Session 1 provided an overview of the geroscience and health span (disease-free and functional health throughout life) concepts. The common molecular mechanisms between oral cancer and aging were discussed, and research was presented that showed periodontal microflora as a potential factor in Alzheimer's disease progression. Session 2 focused on behavioral and social science aspects of aging and their oral health significance. The keynote provided evidence that loneliness and isolation can have major health effects. These social conditions, along with poor oral health, tooth loss, and cognitive decline, could potentially affect healthy eating ability and systemic health in older adults. Research could help elucidate the directions and pathways connecting these seemingly disparate conditions. Session 3 focused on the delivery of oral care in different settings and the many barriers to access care faced by older adults. Research is needed to identify and implement effective technology and strategies to improve access to dental care, including new delivery and financing mechanisms, workforce models, interprofessional provider education and practice, and use of big data from medical-dental integration of electronic health records. Research to improve the "oral health span," reduce oral health disparities, and increase health equity must be tackled at all levels from biologic pathways to social determinants of health and health policies.

Role of behavioural and age-related factors in the long-term impact of tooth loss on oral health-related quality of life: A 25-year follow-up of Swedish older adults

OBJECTIVES

The primary aim of this study was to assess any long-term association between tooth loss at age 50 and subsequent impaired oral health-related quality of life, OHRQoL, at age 65, 70 and 75, adjusted for time invariant socio-demographic-and time variant behavioural and age-related factors in terms of disadvantages with functional, social, health and psychological concerns. As a second aim, this study examined whether behavioural- and age-related factors played a role in explaining any long-term association between early tooth loss and subsequent OHRQoL.

METHODS

In 1992, 6346 residents, aged 50, consented to participate in a prospective cohort study and 3060 completed postal questionnaire follow-ups every fifth year (six in total) until 2017. Information on tooth loss was assessed at baseline at age 50. Behavioural- and age-related covariates were assessed repeatedly at ages 65, 70 and 75. OHRQoL was the repeated outcome measure assessed by the Oral Impact on Daily Performance, OIDP at age 65, 70 and 75. Generalized Estimating Equations, GEE, with binomial logit function was used to test the association between tooth loss and prevalence of oral impacts (OIDP) adjusting for counfounders and potential mediators. The role of behavioural and age-related factors in explaining the association between early tooth loss and OHRQoL was tested using the change in estimate approach.

RESULTS

Tooth loss and time variant behavioural- and age-related covariates associated independently with higher odds of impaired OHRQoL across time. The long-term impact of tooth loss seemed to be partly explained by time variant covariates related to functional and psychological concerns. Participants who had excessive tooth loss at age 50 were 2.5 times more likely to experience oral impacts before adjustment of covariates. After adjustment of functional- and psychological-covariates, participants were, respectively, 1.6 times and 1.4 times more likely to experience oral impacts.

CONCLUSION

This study revealed that early tooth loss at age 50 was independently associated with subsequent impaired OHRQoL at ages 65, 70 and 75. The aspects of behavioural- and age-related factors in terms of disadvantages in functional and psychological concerns seemed to play a role in explaining the long-term impact of tooth loss on impaired OHRQoL. A mid-life approach to the prevention of tooth loss for the protection of subsequent adverse health outcomes should guide health promotion interventions and also be recognized by oral health care providers both for patient interaction and clinical decision making.

Periodontitis and risk of immune-mediated systemic conditions: A systematic review and meta-analysis

INTRODUCTION

The aim of this review is to examine and quantify the long-term risk of immune-mediated systemic conditions in people with periodontitis compared to people without periodontitis.

METHODS

Medline, EMBASE and Cochrane databases were searched up to June 2022 using keywords and MeSH headings. The 'Risk of Bias in Non-Randomised Studies of Interventions' tool was used to assess bias. Cohort studies comparing incident metabolic/autoimmune/inflammatory diseases in periodontitis to healthy controls were included. Meta-analysis and meta-regression quantified risks and showed impact of periodontitis diagnosis type and severity.

RESULTS

The search retrieved 3354 studies; 166 studies were eligible for full-text screening, and 30 studies were included for review. Twenty-seven studies were eligible for meta-analysis. The risks of diabetes, rheumatoid arthritis (RA) and osteoporosis were increased in people with periodontitis compared to without periodontitis (diabetes-relative risk [RR]: 1.22, 95% CI: 1.13-1.33; RA-RR: 1.27, 95% CI: 1.07-1.52; osteoporosis-RR: 1.40, 95% CI: 1.12-1.75). Risk of diabetes showed gradient increase by periodontitis severity (moderate-RR = 1.20, 95% CI = 1.11-1.31; severe-RR = 1.34, 95% CI = 1.10-1.63).

CONCLUSION

People with moderate-to-severe cases of periodontitis have the highest risk of developing diabetes, while the effect of periodontal severity on risk of other immune-mediated systemic conditions requires further investigation. More homologous evidence is required to form robust conclusions regarding periodontitis-multimorbidity associations.

Investigating the relationship between periodontitis and specific memory processes in the search for cognitive markers of Alzheimer's disease risk

The spontaneous retrieval deficit (SRD) hypothesis argues that individuals in the preclinical stages of Alzheimer's disease (AD) are particularly impaired in spontaneous retrieval, which manifests in reduced mind-wandering. Our main purpose was to provide novel evidence to support the SRD hypothesis by investigating, for the first time, the relationship between mind-wandering and periodontitis, the latter being the risk factor for AD. The second objective was to address the lack of deeper understanding of the relationship between oral health and specific cognitive abilities by investigating whether periodontitis would be primarily associated with memory. Sixty community-dwelling dementia-free older adults completed neuropsychological tests that focused on various cognitive abilities and a computerised task, during which mind-wandering was evaluated. Periodontal health was assessed subjectively, and through an oral examination by a qualified dentist that focused on visible periodontitis-related changes in gingival tissues and the number of periodontitis bacteria. In line with our predictions, objective and subjective symptoms of poorer periodontal health were associated with less mind-wandering, providing further support for the SRD hypothesis. Again in line with predictions, poorer periodontal health was associated with worse episodic memory, with no relationship between periodontitis and the measure targeting various cognitive abilities, from which memory was excluded.

Association between self-reported oral health and cognitive function among the community-dwelling elderly in Jinan, China: the mediating effect of life satisfaction

Background

Deterioration of self-reported oral health and decline in cognitive function are two main adverse health outcomes experienced by the older adults. Little evidence was found on the psychosocial mechanism between self-reported oral health and cognitive function. This study explores the association between self-reported oral health and cognitive function and examines the mediating effect of life satisfaction among the community-dwelling elderly in Jinan, China.

Methods

A total of 512 older individuals (60+) were included in the study. Cognitive function was assessed using the Chinese version of the Mini-Mental State Examination scale (MMSE), and self-reported oral health was measured using the Chinese version of the Geriatric Oral Health Assessment Index (GOHAI). Pearson correlation analysis was used to determine the relationship between self-reported oral health, life satisfaction, and cognitive function. Multivariate linear regression analysis was conducted to explore the possible effect of covariates. Structural equation modelling and Bootstrap analyses were conducted to verify the mediating role of life satisfaction.

Results

The mean MMSE score was 25.65 ± 4.42. Better self-reported oral health was significantly associated with a higher level of life satisfaction, and those with higher life satisfaction experienced better cognitive function. Age, educational level and source of living expenses were found to be cofounding variables. Life satisfaction partially mediated the effect of self-reported oral health on cognitive function (95% confidence interval [CI]: 0.010 to 0.075). The mediating effect of life satisfaction accounted for 24% of the total effect.

Conclusion

The level of cognitive function was relatively high. Self-reported oral health was positively associated with cognitive function, and the mediating effect of life satisfaction was proven to exist in the community-dwelling older individuals. Early screening for oral diseases and a greater focus on life satisfaction are recommended.

Tooth loss, body mass index and cognitive function among middle-aged and older adults in China: Does gender matter?

BACKGROUND

Previous studies have shown a longitudinal association between tooth loss and cognitive function. Body mass index (BMI) is an essential applicable indicator of health status screening. However, the underlying mechanism among these factors remains unclear. This study aimed to determine the mediating role of BMI in the tooth loss-cognition relationship by gender among Chinese middle-aged and older adults.

METHODS

This is a prospective and cohort study. We used three waves of follow-up data (2011, 2013, and 2015) from the China Health and Retirement Longitudinal Survey, including 10,013 participants aged 45 years or above. Cognitive function was evaluated by Telephone Interview of Cognitive Status, words recall, and figure drawing. The cross-lagged panel model was applied to test the hypothesized model.

RESULTS

Tooth loss is associated with higher BMI and lower level of cognitive function. We found significant total effects (B = -0.017, P = 0.008), direct effect (B = -0.015, P = 0.022) and indirect effects (B = -0.002, P = 0.010) of tooth loss on cognition mediated through BMI only among middle-aged and older men. For middle-aged and older women, the total effect (B = -0.010, P = 0.125) and direct effect (B = -0.007, P = 0.249) were no more significant.

CONCLUSIONS

The longitudinal association between tooth loss and cognition was primarily indirect through BMI among middle-aged Chinese males but not women. Public health authorities should remind middle-aged and older males with tooth loss and high BMI to participate in timely medical checkups for improving cognition.

Social isolation, loneliness and accelerated tooth loss among Chinese older adults: A longitudinal study

OBJECTIVE

Social isolation and loneliness have been linked to numerous determinants of health and well-being. However, the effects of social isolation and loneliness on oral health remain unclear. The purpose of this study was to examine the effects of social isolation and loneliness on the number of remaining teeth and the rate of tooth loss over time among Chinese older adults.

METHODS

We used three waves of data (2011/2012, 2014 and 2018) from the Chinese Longitudinal Healthy Longevity Survey with 4268 older adults aged 65 and older who were interviewed in at least two waves. The number of remaining teeth was first evaluated at baseline and then subsequently at follow-up visits. Mixed-effects Poisson regression was used to examine the associations between social isolation, loneliness, and both the number of remaining teeth and the rate of tooth loss.

RESULTS

Social isolation was associated with fewer remaining teeth (β = -.06, 95% CI = -0.13 to 0.00, p < .05) and accelerated tooth loss (β = -.02, 95% CI = -0.02 to -0.01, p < .01) after adjusting for sociodemographic covariates, lifestyle and oral hygiene behaviours, physical and cognitive health, and loneliness. Loneliness was neither associated with the number of remaining teeth (β = .15, 95% CI = -0.01 to 0.30, p = .06) nor with the rate of tooth loss (β = -.01, 95% CI = -0.02 to 0.00, p = .16) after adjusting for all other factors.

CONCLUSIONS

This study provides strong evidence that social isolation was associated with fewer remaining teeth and accelerated tooth loss among Chinese older adults. These findings expand our knowledge about the impact of social disconnection on tooth loss. More future studies are needed to further examine the associations between social connections and oral conditions using longitudinal cohort studies and intervention studies.

Investigating the causal effect of cognition on the self-reported loss of functional dentition using marginal structural models: The Panel on Health and Ageing of Singaporean Elderly study

AIM

To assess the effect of cognition on the loss of functional dentition.

MATERIALS AND METHODS

We used data from the three waves of the Panel on Health and Ageing of Singaporean Elderly study (n = 4990 at baseline, 774 complete cases analysed) over 6 years (2009-2015). The outcome was the loss of functional dentition (<21 teeth). The exposure was cognitive impairment, while baseline confounders included age, sex, education, and ethnicity. Time-varying confounders included income, living arrangements, smoking, diabetes, depressive symptoms, cardiovascular disease, and body mass index. We used marginal structural mean models with inverse probability treatment weighted.

RESULTS

The mean age of the participants was 70.2 years at baseline. The proportion of participants with loss of functional dentition increased from 74.6% to 89.9% over 6 years. Women, ethnic Chinese, less educated, smokers, people with diabetes, and individuals with depression had a higher proportion of loss of functional dentition than their counterparts. Loss of functional dentition was 1.8 times higher (odds ratio 1.80; 95% confidence interval 0.88-3.69) among those with cognitive impairment after taking well-known confounders into account.

CONCLUSIONS

After accounting for the time-varying exposure and confounding evidence, the association between cognition and functional dentition among the elderly in Singapore remains uncertain.

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.

Time-varying exposure analysis of the relationship between sustained natural dentition and cognitive decline

AIM

Tooth loss and cognitive decline progress over time and influence each other. This study estimated the impact of sustaining natural dentition on cognitive function in U.S. adults, accounting for the fact that dental and cognitive statuses change over time.

MATERIALS AND METHODS

Data from adults aged ≥51 years who participated in five waves of the Health and Retirement Study from 2004 to 2016 (n = 10,953) were analysed. The impact of retaining some natural teeth from 2006 to 2012 on cognitive function score (0-27) and cognitive impairment (defined as having a cognitive function score of <12) in 2016 was evaluated using the doubly robust targeted maximum likelihood estimation method by considering both time-invariant and time-varying confounders, including cognitive function at baseline and during follow-up.

RESULTS

Respondents with some natural teeth between 2006 and 2012 had a 0.40 point (95% confidence interval [CI]: 0.10-0.71) higher cognitive function score and 3.27 percentage point (95% CI: 0.11-6.66) lower cognitive impairment prevalence in 2016 than those with complete tooth loss.

CONCLUSIONS

Considering past cognitive function assessed at multiple time points, sustained natural dentition was associated with better cognitive function.

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

AIM

The aim was to assess study factors that impact the association of cognitive disorders in people with periodontal disease (PD).

METHOD

Medline, EMBASE and Cochrane databases were searched until February 2022 using keywords and MeSH: (periodon* OR tooth loss OR missing teeth) AND (dementia OR Alzheimer's Disease OR cognitive*). Observational studies reporting prevalence or risk of cognitive decline, dementia or Alzheimer's disease (AD) in people with PD compared with healthy controls were included. Meta-analysis quantified the prevalence and risk (relative risk[RR]) of cognitive decline, dementia/AD, respectively. Meta-regression/subgroup analysis explored the impact of study factors including PD severity and classification type, and gender.

RESULTS

Overall, 39 studies were eligible for meta-analysis: 13 cross-sectional and 26 longitudinal studies. PD demonstrated increased risks of cognitive disorders (cognitive decline-RR = 1.33, 95% CI = 1.13-1.55; dementia/AD-RR = 1.22, 95% CI = 1.14-1.31). Risk of cognitive decline increased with PD severity (moderate-[RR] = 1.14, 95% confidence interval [CI] = 1.07-1.22; severe-RR = 1.25, 95% CI = 1.18-1.32). For every 10% population increase in females, the risk of cognitive decline increased by 34% (RR = 1.34, 95% CI = 1.16-1.55). Self-reported PD showed a lower risk of cognitive disorders compared with clinical classification (cognitive decline-RR = 0.77, 95% CI = 0.65-0.91; dementia/AD-RR = 0.86, 95% CI = 0.77-0.96).

CONCLUSION

The prevalence and risk estimates of cognitive disorders in association with PD can be influenced by gender, the disease classification of PD and its severity. Further homologous evidence taking these study factors into consideration is needed to form robust conclusions.

Association of the number of natural teeth with dietary diversity and nutritional status in older adults: A cross-sectional study in China

AIM

To investigate the association of the number of natural teeth with overall dietary diversity and nutritional status in a nationally representative study among older adults in China.

MATERIALS AND METHODS

A cross-sectional analysis was conducted among community-dwelling adults aged 65 years or older from the Chinese Longitudinal Healthy Longevity Study. According to the self-reported number of natural teeth, participants were categorized into ≥20, 10-19, 1-9 natural teeth, and edentulous. Dietary diversity score (DDS) was constructed based on intake frequencies of 10 food groups assessed by a simplified food frequency questionnaire. The geriatric nutritional risk index was used to measure the malnutrition status (i.e., normal, mild malnutrition, and moderate-to-severe malnutrition) among a subgroup of participants. Linear and multinomial logistic regression models were used to examine the corresponding associations.

RESULTS

Among 54,796 study participants, the mean (SD) age was 87.86 (11.45) years, 82.7% had poor dentition (<20 natural teeth), and 27.3% wore dentures. After multivariable adjustment, participants with poor dentition had lower DDSs (β_edentulous  = -0.39, 95% confidence interval [CI], -0.48, -0.30; β_{1-9 teeth}  = -0.46, 95% CI, -0.55, -0.37; β_{10-19 teeth}  = -0.36, 95% CI, -0.46, -0.26) than those with 20 natural teeth or more. For individual food items, edentulous, 1-9 and 10-19 natural teeth were associated with lower odds of regular intake of fresh fruits, fresh vegetables, meat, fish and aquatic products, eggs, legumes, preserved vegetables, tea, and garlic, but higher odds of regular intake of sugar and sweets. Among participants with poor dentition, individuals without dentures had lower intake frequencies of most food groups than those wearing dentures. In addition, poor dentition was related to lower odds of normal nutritional status (odds ratio = 0.49, 95% CI, 0.27, 0.89).

CONCLUSIONS

Older adults with poor dentition had significantly lower dietary diversity and worse nutritional status. Future studies are warranted to identify effective interventions to improve the dietary quality and nutrition status among partially and fully edentulous individuals, including those with Stage IV periodontitis.

Self-efficacy and attitudes of nurses providing oral care in geriatric care facilities: A cross-sectional study in Shanghai

AIMS

To investigate nurses' self-efficacy and attitudes of providing oral care in geriatric care facilities (GCFs) and compare differences between individuals, facilities and countries.

DESIGN

A cross-sectional and multicentre study.

METHODS

Data were collected from 852 nurses in 42 GCFs using two scales, "Self-Efficacy for Providing Mouth Care" (SE-PMC) and "Attitudes for Providing Mouth Care" (A-PMC), and analysed using t-test and ANOVA.

RESULTS

Totally 852 nurses (844 females, 99%) participated in this study with an effective response rate of 85.2%. Scores of SE-PMC and A-PMC of nurses varied significantly among GCFs with different sizes, types and years of establishment and differentiated among staff about the length of employment (p < .05). Nurses (N = 434) in North Carolina scored higher than nurses in Shanghai both in SE-PMC and A-PMC (p < .05). Establishment and implementation of Oral health promotion programmes were desired based on characteristics of different institutions and nurses' clinical ladder.

Combined association of cognitive impairment and poor oral health on mortality risk in older adults: Results from the NHANES with 15 years of follow-up

Background

Cognitive impairment and poor oral health are frequently seen among older adults. Both conditions have been identified as risk factors for mortality. However, the combined associations of cognitive impairment and poor oral health with mortality have not been well studied and are therefore the aim of this cohort study.

Methods

We analyzed data from the National Health and Nutrition Examination Survey (1999–2002) linked with mortality data obtained from the 2015 public‐use linked mortality file. Cognitive impairment was defined as a digit symbol substitution test score lower than the lowest quartile. Oral health status was assessed based on presence of untreated caries, moderate to severe periodontitis, and edentulism. The combined effects of caries/periodontitis or edentulism and cognitive impairment on all‐cause and cardiometabolic mortality were examined using the Cox proportional hazard models after adjusting for potential confounders including demographic characteristics, lifestyle, biomarkers, and comorbidities.

Results

In total, 1973 participants were enrolled in the prospective study. At a median follow‐up of 13.4 years, 978 participants had died (264 deaths because of cardiometabolic disease). Cognitive impairment, periodontitis, and edentulism were each found to be significant predictors of all‐cause mortality. Caries, however, was not significantly related to mortality. When analyzing these predictors in combination, a diagnosis of cognitive impairment and periodontitis was associated with an 83.1% increase in all‐cause mortality risk and an 87.7% increase in cardiometabolic mortality risk compared with healthy controls. Similarly, the risk for all‐cause mortality was highest in cases where impaired cognition and edentulism co‐occurred (adjusted hazard ratio = 1.701, 1.338–2.161).

Conclusion

Concomitant presence of cognitive impairment and periodontitis or edentulism can be associated with a higher risk of mortality among older U.S. adults.

Alzheimer's Disease and Oral-Systemic Health: Bidirectional Care Integration Improving Outcomes

Dentistry is an effective healthcare field that can impact Alzheimer's disease through prevention and education. Every day dental providers use an arsenal of assessment protocols directly coinciding with modifiable Alzheimer's risk factors. An innovative way to help in the prevention of Alzheimer's disease is to utilize oral health professionals who reach the public in ways other health care providers may not. Bidirectional care integration is needed to stifle many systemic diseases and Alzheimer's disease is no different. Ultimately with collaborative care the patient reaps the benefits. Alzheimer's is associated with many etiologies and pathophysiological processes. These include cardiovascular health, smoking, sleep, inflammatory pathogens, and diabetes. In the United States, dental providers assess each of these factors daily and can be instrumental in educating patients on the influence of these factors for dementia prevention. Globally, by 2025, the number of people with Alzheimer's disease is expected to rise by at least 14%. Such increases will strain local and national health care systems, but for the US if Medicare were expanded to include dental services, many older adults could be spared needless suffering. The goal of this perspective article is to highlight existing practices being used in the field of dentistry that can easily be adapted to educate patients in preventive care and treat risk factors. It is the duty of healthcare professionals to explore all opportunities to stem the advance of this disease and by integrating oral and systemic health into transdisciplinary science, health care and policy may do just that.

Exploring the reciprocal relationship between cognitive function and edentulism among middle-aged and older adults in China

OBJECTIVE

Previous longitudinal studies have found that cognitive function affected oral health, and vice versa. However, research is lacking on the reciprocal relationships between cognitive function and edentulism simultaneously, especially in developing countries. The present study aimed to examine the reciprocal relationship between cognitive function and edentulism among middle-aged and older adults in China.

METHODS

Data were derived from the 2011 and 2015 waves of the China Health and Retirement Longitudinal Study. The sample included 14,038 respondents aged 45 or older. A two-wave cross-lagged analysis was adopted to test the hypothesized model.

RESULTS

Among respondents aged 45-59, baseline cognitive function was associated with subsequent edentulism [b = -0.017, standard deviation (SD) = 0.006, P < 0.01]. In contrast, baseline edentulism was not significantly associated with poorer cognitive function at the follow-up wave (b = -0.744, SD = 0.383, P > 0.05). However, among respondents aged 60 or older, baseline cognitive function was associated with subsequent edentulism (b = -0.017, SD = 0.005, P < 0.01), and baseline edentulism was also associated with follow-up lower levels of cognitive function (b = -0.419, SD = 0.143, P < 0.01).

CONCLUSIONS

These findings demonstrated the reciprocal relationships of cognitive function and edentulism. However, such relationships varied across age groups. This study demonstrates the importance of developing programs and services to promote both cognitive and oral health, especially for those in older age.

Longitudinal association between oral status and cognitive decline by fixed-effects analysis

Background

Although the feasibility of randomized trials for investigating the long-term association between oral health and cognitive decline is low, deriving causal inferences from observational data is challenging. We aimed to investigate the association between poor oral status and subjective cognitive complaints (SCC) using fixed-effects model to eliminate the confounding effect of unobserved time-invariant factors.

Methods

We used data from Japan Gerontological Evaluation Study (JAGES) which was conducted in 2010, 2013, and 2016. β regression coefficients and 95% confidence intervals [CIs] were calculated using fixed-effects models to determine the effect of deteriorating oral status on developing SCC. Onset of SCC was evaluated using the Kihon Checklist-Cognitive function score. Four oral status variables were used: awareness of swallowing difficulty, decline in masticatory function, dry mouth, and number of teeth.

Results

We included 13,594 participants (55.8% women) without SCC at baseline. The mean age was 72.4 (standard deviation [SD], 5.1) years for men and 72.4 (SD, 4.9) years for women. Within the 6-year follow-up, 26.6% of men and 24.9% of women developed SCC. The probability of developing SCC was significantly higher when participants acquired swallowing difficulty (β = 0.088; 95% CI, 0.065–0.111 for men and β = 0.077; 95% CI, 0.057–0.097 for women), decline in masticatory function (β = 0.039; 95% CI, 0.021–0.057 for men and β = 0.030; 95% CI, 0.013–0.046 for women), dry mouth (β = 0.026; 95% CI, 0.005–0.048 for men and β = 0.064; 95% CI, 0.045–0.083 for women), and tooth loss (β = 0.043; 95% CI, 0.001–0.085 for men and β = 0.058; 95% CI, 0.015–0.102 for women).

Conclusion

The findings suggest that good oral health needs to be maintained to prevent the development of SCC, which increases the risk for future dementia.

Evaluating Cognitive/Emotional and Behavioral Mediators of Oral Health Outcomes in Vulnerable Older Adults

Inconsistent outcomes of oral hygiene interventions require testable theories combining cognitive and behavioral domains to guide intervention and improve results. This article evaluates the integrated model as a cognitive-behavioral approach to improve oral health clinical outcomes in ethnically diverse low-income older adults. Baseline data from a clinical trial utilizing the integrative model (IM) model evaluated predictors of gingival index (GI) and plaque score (PS). Individual logistic regression was performed for all predictors in relation to GI and PS. Multiple logistic regression was performed with significant predictors of GI and PS only. Greater locus of control and more brushing predicted lower GI; greater locus of control predicted lower PS. Both cognitive and behavioral domains impact GI, requiring more prolonged effort for improvement while locus of control, a cognitive variable, predicts PS, immediately improved by daily brushing/flossing. A streamlined IM including locus of control and tooth brushing should improve oral hygiene of low-income older adults.

Disparities in Dental Service Utilization among Adults in Chinese Megacities: Do Health Insurance and City of Residence Matter?

The aims of the study were to present the prevalence of dental service utilization among adults (age between 18 and 65) in Chinese megacities and to examine the associations of health insurance and city of residence with dental visits. This study was a cross-sectional analysis of the 2019 New Era and Living Conditions in Megacities Survey data with a sample of 4835 participants aged 18–65 from 10 different megacities in China. The data including gross domestic product (GDP) per capita of each megacity obtained from the National Bureau of Statistics of China as a city-level characteristic. After adjusting sampling weights, approximately 24.28% of the participants had at least one dental visit per year. Findings from multilevel mixed-effects linear models showed that participants residing in megacities with higher GDP per capita (β = 0.07, p < 0.001) who had Urban Employee Basic Medical Insurance (β = 0.25, p < 0.001) or Urban Resident Basic Medical Insurance (β = 0.19, p < 0.01) had more frequent dental visits after adjusting demographic characteristics, socioeconomic status, health status, health behavior and attitude, and oral health indicators. Margins post-estimation model results demonstrated disparities in the predicted probability of having never visited a dentist by types of health insurance and city of residence. In conclusion, the prevalence of dental visits in China was found to be low. This study highlights socioeconomic inequalities in dental service utilization. There is a great need to develop more dental care programs and services and expand health insurance to cover dental care in China.

Tooth Loss and Dementia: A Critical Examination

Dementia is a major contributor to dependence and disability in older people, with aging societies characterized by growing numbers of people living with the condition. Dementia rates are highest in those with low education early in life, midlife hypertension, midlife hearing loss, depression, obesity, loneliness, a sedentary lifestyle, or sustained exposure to smoking or diabetes. Tooth loss is a putative risk factor for dementia which has received increasing research attention, but systematic review findings are mixed. Three main mechanisms have been proposed, involving 1) tooth loss leading to compromised nutrition and then leading to poorer central nervous system (CNS) function; 2) tooth loss resulting in fewer interocclusal contacts and so less somatosensory feedback to the CNS, leading to impaired cognition; and (3) chronic periodontitis resulting in tooth loss, but not before the inflammation has affected the CNS, impairing cognition. None of these is supported by compelling empirical evidence. Here, we use the life course approach to propose a plausible, empirically supported explanation for the associations between missing teeth and poorer cognitive function in older people. Evidence from longstanding cohort studies demonstrates that the putative association arises from cognitive function much earlier in life, in childhood. People with better childhood cognitive function have better oral health and access to routine dental care as they go through life, losing fewer teeth along the life course. They are also much more likely to have better cognitive function in old age. Their less cognitively able childhood counterparts will experience higher disease rates and poorer access to care, resulting in greater incremental tooth loss. Comparison of the 2 groups at any age from the mid-20s on will show greater numbers of missing teeth in the group who were less cognitively able in childhood. Those differences will be most pronounced in old age.