Oral dysfunctions and cognitive impairment/dementia

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.

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.

Prevalence of mild cognitive impairment and modifiable risk factors: A cross-sectional study in rural older adults with diabetes

To determine the prevalence and modifiable risk factors for MCI in older adults with T2DM in rural China. This cross-sectional study encompassed 96 villages, employing a cluster sampling approach to recruit eligible older adults with T2DM as study participants. Logistic regression analysis was utilized to identify modifiable risk factors associated with MCI. Average marginal effects were calculated. The discriminatory performance of these risk factors in identifying MCI was evaluated by plotting the receiver operating curve and calculating the value of the area under the curve. A total of 898 older adults with T2DM in our study. The overall prevalence of MCI was 50.22 %. Independent associations with MCI were found in poor self-management ability of diabetes (OR = 0.808, 95 % CI: 0.808, 0.766), depressive symptoms (OR = 3.500, 95 % CI: 1.933, 6.337), moderate (OR = 0.936, 95 % CI: 0.017, 0.075) and high (OR = 0.939, 95 % CI: 0.016, 0.100) levels of physical activity, poorer oral health (OR = 2.660, 95 % CI: 2.226, 3.179), and lower grip strength (OR = 0.913, 95 % CI: 0.870, 0.958). The AUC was 0.967 (95 % CI 0.508-0.470). The prevalence of MCI was high among older adults with T2DM in rural areas of China. The self-management ability of diabetes, depressive symptoms, physical activity, oral health and grip strength were modifiable risk factors of MCI. Targeted interventions should be developed and implemented to address these modifiable risk factors, aiming to enhance cognitive function and mitigate the incidence of MCI in older adults with T2DM.

Correlation between GLCM-based texture features of the lateral pterygoid muscle and cognitive function in patients with idiopathic normal pressure hydrocephalus: a preliminary report

PURPOSE

The potential relationship between mastication ability and cognitive function in idiopathic normal pressure hydrocephalus (iNPH) patients is unclear. This report investigated the association between mastication and cognitive function in iNPH patients using the gray level of the co-occurrence matrix on the lateral pterygoid muscle.

METHODS

We analyzed data from 96 unoperated iNPH patients who underwent magnetic resonance imaging (MRI) between December 2016 and February 2023. Radiomic features were extracted from T2 MRI scans of the lateral pterygoid muscle, and muscle texture parameters were correlated with the iNPH grading scale. Subgroup analysis compared the texture parameters of patients with normal cognitive function with those of patients with cognitive impairment.

RESULTS

The mini-mental state examination score correlated positively with the angular second moment (P < 0.05) and negatively with entropy (P < 0.05). The dementia scale (Eide's classification) correlated negatively with gray values (P < 0.05). Gray values were higher in the cognitive impairment group (64.7 ± 16.6) when compared with the non-cognitive impairment group (57.4 ± 13.3) (P = 0.005). Entropy was higher in the cognitive impairment group (8.2 ± 0.3) than in the non-cognitive impairment group (8.0 ± 0.3) (P < 0.001). The area under the receiver operating characteristic curve was 0.681 (P = 0.003) and 0.701 (P < 0.001) for gray value and entropy, respectively.

CONCLUSION

Our findings suggest an association between heterogeneity of mastication and impaired cognitive function in iNPH patients and highlight muscle texture analysis as a potential tool for predicting cognitive impairment in these patients.

[Analysis of the Occurrence and Influencing Factors of Oral Frailty in Elderly Residents of Elderly Care Facilities]

Objective

To investigate the occurrence and influencing factors of oral frailty in elderly residents of elderly care facilities and to provide a basis for the development of effective intervention programs for oral frailty in this population.

Methods

A combination of subjective and objective measurements of oral frailty, a general information questionnaire, a leisure activity questionnaire, the Dietary Variety Score (DVS), the Short Nutritional Assessment Questionnaire (SNAQ), the Short-Form Mini Nutritional Assessment (MNA-SF), Barthel Index (BI), the Mini-Mental State Examination (MMSE), 15-Item Geriatric Depression Scale (GDS-15), and the Generalized Anxiety Disorder Scale-2 (GAD-2) were used to survey 348 elderly residents in three elderly care facilities in Chengdu and to analyze the factors related to oral frailty.

Results

The prevalence of oral frailty in elderly residents of elderly care facilities was 31.0% (108/348). Multivariate logistic regression analysis revealed that advanced age (odds ratio [OR]=1.347, 95% confidence interval [CI]: 1.237-1.496, P<0.001), cognitive impairment (OR=6.769, 95% CI: 2.628-18.916, P<0.001), and depression (OR=8.632, 95% CI: 1.931-44.387, P=0.007) were risk factors for oral frailty in elderly residents of elderly care facilities. High scores in leisure activities (OR=0.883, 95% CI: 0.786-0.986, P=0.030), and dietary diversity (OR=0.199, 95% CI: 0.069-0.530, P=0.002) were protective factors against oral frailty.

Conclusion

The prevalence of oral frailty is relatively high among elderly residents of elderly care facilities. Risk factors for oral frailty include advanced age, cognitive impairment, and depression, while increased levels of leisure activities and dietary diversity can help prevent the occurrence of oral frailty in elderly individuals.

The long-term effect on oral health and quality of life using a powered toothbrush in individuals with mild cognitive impairment. An intervention trial

BACKGROUND

The number of older individuals with mild cognitive impairment and neurocognitive diseases is increasing, which may rapidly deteriorate oral health and Quality of life. Therefore, removing dental biofilm is essential for maintaining good oral health. The present study aimed to investigate whether introducing a powered toothbrush reduces the presence of dental plaque, bleeding on probing, and periodontal pockets ≥4 mm, leading to maintained or improved oral health and improved Quality of life in a group of older individuals with mild cognitive impairment.

METHODS

Two hundred and thirteen individuals aged 55 or older living without official home care with a Mini-Mental State Examination (MMSE) score between 20 and 28 and a history of memory problems in the previous 6 months were recruited and screened for the study. The individuals received a powered toothbrush and thorough instructions on how to use it. Clinical oral examinations, Quality of life examinations, and MMSE tests were conducted at baseline, 6, 12, and 24 months. The intervention group was compared to control groups at baseline and 24-month examination. It was divided into an MMSE high group with a score of more than 26 and an MMSE low group with a score of 26 and lower or decreasing two steps or more for 12 months.

RESULTS

PI, BOP, and PPD≥4 mm improved continuously in both MMSE groups during the 24 months of the study. The values for QoL-AD deteriorated over time, while the oral health-related Quality of life did not show any statistically significant changes.

CONCLUSIONS

Introducing a powered toothbrush improved PI, BOP, and PPD≥4 mm over 24 months, even among individuals with low or declining MMSE scores. Improved oral health is associated with a preserved OHR-QoL.

Occlusion dysfunction and Alzheimer's disease: Mendelian randomization study

Aim

Occlusion dysfunction (OD) is increasingly linked to Alzheimer's disease (AD). This study aimed to elucidate the causal relationship between OD and AD using Mendelian randomization (MR) analysis.

Materials and methods

Genome-wide association study (GWAS) meta-analysis data obtained from FinnGen, IEU Open GWAS, and UK Biobank (UKBB) was represented as instrumental variables. We validated the causal relationship between periodontal disease (PD), loose teeth (PD & occlusion dysfunction), dentures restoration (occlusion recovery), and AD.

Results

According to the MR analysis, PD and AD have no direct causal relationship (P = 0.395, IVW). However, loose teeth significantly increased the risk of AD progression (P = 0.017, IVW, OR = 187.3567, 95%CI = 2.54E+00-1.38E+04). These findings were further supported by the negative causal relationship between dentures restoration and AD (P = 0.015, IVW, OR = 0.0234, 95%CI = 1.13E-03-0.485).

Conclusion

The occlusion dysfunction can ultimately induce Alzheimer's disease. Occlusion function was a potentially protective factor for maintaining neurological health.

Long-lasting adverse effects of short-term stress during the suckling-mastication transition period on masticatory function and intraoral sensation in rats

Early-life stress affects brain development, eventually resulting in adverse behavioral and physical health consequences in adulthood. The present study assessed the hypothesis that short-term early-life stress during infancy before weaning, a period for the maturation of mastication and sleep, poses long-lasting adverse effects on masticatory function and intraoral sensations later in life.Rat pups were exposed to either maternal separation (MS) or intermittent hypoxia (IH-Infancy) for 6 h/day in the light/sleep phase from postnatal day (P)17 to P20 to generate "neglect" and "pediatric obstructive sleep apnea" models, respectively. The remaining rats were exposed to IH during P45-P48 (IH-Adult). Masticatory ability was evaluated based on the rats' ability to chew pellets and bite pasta throughout the growth period (P21-P70). Intraoral chemical and mechanical sensitivities were assessed using two-bottle preference drinking tests, and hind paw pain thresholds were measured in adulthood (after P60).No differences were found in body weight, grip force, and hind paw sensitivity in MS, IH-Infancy, and IH-Adult rats compared with naïve rats. Masticatory ability was lower in MS and IH-Infancy rats from P28 to P70 than in naïve rats. MS and IH-Infancy rats exhibited intraoral hypersensitivity to capsaicin and mechanical stimulations in adulthood. The IH-Adult rats did not display inferior masticatory ability or intraoral hypersensitivity.In conclusion, short-term early-life stress during the suckling-mastication transition period potentially causes a persistent decrease in masticatory ability and intraoral hypersensitivity in adulthood. The period is a "critical window" for the maturation of oral motor and sensory functions.

A Cluster Analysis of Oral and Cognitive Health Indicators in the CLSA: An Exploratory Study on Cholinergic Activity as the Link

INTRODUCTION

Poor oral health has been suggested as a risk factor for cognitive decline. Yet, biologically plausible mechanisms explaining this relationship remain unknown.

OBJECTIVES

We aimed (1) to identify oral and cognitive health clustering patterns among middle-aged to elderly Canadians and (2) to investigate the extent to which these patterns could be explained by bone mineral density (BMD), a proxy measure of the cholinergic neurons' activity.

METHODS

This cross-sectional study used baseline data from the Comprehensive cohort of the Canadian Longitudinal Study of Aging (CLSA). Oral health was assessed by a self-report questionnaire, and 7 task-based instruments measured cognitive health. We identified oral and cognitive health clusters, our outcome variables, using latent class analysis. Two sets of multivariate logistic regression and 95% confidence intervals were used to investigate whether BMD explains the odds of membership in a certain oral and cognitive health group. The final models were adjusted for socioeconomic, health, and lifestyle factors.

RESULTS

Our study sample (N = 25,444: 13,035 males, 12,409 females) was grouped into 5 and 4 clusters based on the oral health status and performance on the cognitive tasks, respectively. After adjusting for all potential covariates, increase in BMD was not associated with higher odds of membership in classes with better oral health (odds ratio [OR] = 1.58 [95% confidence interval {CI}: 0.85-2.92]) and cognitive health (OR = 1.61 [95% CI: 1-2.6]) compared with the groups with the least favorable oral and cognitive health status, respectively.

CONCLUSION

Middle-aged and elderly Canadians show different oral and cognitive health profiles, based on their denture-wearing status and performance on cognitive tests. No evidence could be found to support BMD in place of cholinergic neurons' activity as the common explanatory factor behind the association between oral health and cognitive health.

KNOWLEDGE TRANSFER STATEMENT

This study is probably the first of its kind to shed light on the cholinergic system as a potential pathway influencing oral and cognitive health. Our findings may support the notion that any potential association between poor oral health and cognitive health might be explained by common contributors, helping clinicians to find the common risk factors for both conditions.

Factors associated with intrinsic capacity impairment in hospitalized older adults: a latent class analysis

BACKGROUND

Intrinsic capacity (IC) is proposed by the World Health Organization (WHO) to promote healthy aging. Although some studies have examined the factors influencing IC, few studies have comprehensively confirmed lifestyle factors on IC, especially IC impairment patterns. The present study aimed to identify the patterns of IC impairment and explore the lifestyle and other factors associated with different patterns of IC impairment.

METHODS

This cross-sectional study was conducted in a Chinese geriatric hospital. IC was evaluated in five domains according to the recommendations of WHO: cognition, locomotion, vitality, sensory and psychological domains. The sociodemographic and health-related characteristics of participants were assessed.The health promoting lifestyle was evaluated using the Health-Promoting Lifestyle Profile-II scale, including nutrition, health responsibility, interpersonal relationships, physical activity, spiritual growth and stress management. We applied latent class analysis to identify IC impairment patterns and compared basic activities of daily living, instrumental activities of daily living, frailty, quality of life and falls among different IC impairment patterns. Multinomial logistic regression analysis was conducted to identify factors influencing the IC impairment patterns.

RESULTS

Among 237 participants included, the latent class analysis identified three patterns of IC impairment: 44.7% high IC (Class 1), 31.2% intermediate IC mainly locomotor impairment (Class 2) and 24.1% low IC mainly cognitive impairment (Class 3). Older adults in class 1 had the best function ability and quality of life, while class 3 had the highest levels of disability and frailty, the poorest quality of life and a higher prevalence of falls. Compared with class 1, older adults with advanced age (OR = 22.046, 95%CI:1.735-280.149), osteoporosis (OR = 3.377, 95%CI:1.161-9.825), and lower scores in physical activity (OR = 0.842, 95%CI:0.749-0.945), stress management (OR = 0.762, 95%CI:0.585-0.993) and social support (OR = 0.897, 95%CI:0.833-0.965) were more likely to belong to the class 2. Simultaneously, compared with class 1, older adults with advanced age (OR = 104.435, 95%CI:6.038-1806.410), stroke (OR = 3.877, 95%CI:1.172-12.823) and lower scores in physical activity (OR = 0.784, 95%CI:0.667-0.922) and social support (OR = 0.909, 95%CI:0.828-0.998) were more likely to be class 3. In addition, compared with class 2, older adults with a lower score in nutrition (OR = 0.764, 95%CI:0.615-0.950) were more likely to belong to the class 3.

CONCLUSIONS

This study provides evidence that there are heterogeneous IC impairment patterns in older adults and identifies various associated factors in each pattern, including age, stroke, osteoporosis, social support and lifestyle behaviors such as nutrition, physical activity and stress management. It informs stakeholders on which modifiable factors should be targeted through public health policy or early intervention to promote IC and healthy aging in older adults.

Hidden dangers: Does multisensory impairments accompanying visual impairment increase dementia risk

BACKGROUND

Growing evidence suggests that sensory impairment, particularly in the form of visual impairment, may contribute to the development of dementia. However, it remains unclear whether experiencing concurrent visual impairment in combination with other types of multisensory impairments may further increase this risk.

METHODS

The study used data from the UK Biobank cohort study, which recruited 500,000 adults. With meticulous screening procedures in place, individuals with visual impairment, hearing impairment, and oral health issues were identified for further follow-up evaluations. A multivariable regression analysis was conducted to investigate the relationship between multisensory impairments concurrent with visual impairment and cognitive function. Cox proportional hazard models were used to estimate hazard ratios and 95% confidence intervals to evaluate the association between multisensory impairments concurrent with visual impairment and dementia risk.

RESULTS

Subjects experiencing multisensory impairments concurrent with visual impairment demonstrated a negative association with cognitive function. Notably, individuals who have both vision and hearing impairments had a significantly higher risk of developing dementia (HR 1.28, 95% CI [1.01-1.63]). Additionally, individuals who experience vision impairment and oral health issues simultaneously were also at higher risk for dementia (HR 1.61, 95% CI [1.32-1.97]). Furthermore, the risk of dementia among individuals with vision impairment, hearing impairment, and oral health issues further escalated to an even higher level (HR 1.63, 95% CI [1.19-2.24]).

CONCLUSIONS

The correlation between the presence of multisensory impairments concurrent with visual impairment and cognitive decline is highly significant. Those with multisensory impairments concurrent with visual impairment are at a significantly increased risk of developing dementia.

Short-term data suggests cognitive benefits in the elderly with single-implant overdentures

DESIGN

This study was an extension of a randomized crossover clinical trial approved by the institutional ethics committee (approval number: D2014-148) and adhered to the CONSORT guidelines. The original study juxtaposed patient contentment with single-implant overdentures (1-IODs) against conventional complete dentures (CCDs), with patient satisfaction being the primary focus. In this follow-up study, the cognitive function of edentulous patients receiving 1-IODs was assessed, specifically monitoring for the emergence of mild cognitive impairment (MCI) throughout a three-year period. Patient outcomes were systematically recorded at predetermined intervals: initially, two months post-1-IOD placement, after one year (with groups alternated between denture types at eight-month marks), then after two and three years. A prosthodontist with a decade of expertise performed all denture-related procedures. This follow-up emphasized the cognitive outcomes using the Montreal Cognitive Assessment (MoCA-J), considering it alongside previously documented results on masticatory function, bone resorption, survival rates, and patient-reported outcomes.

CASE SELECTION

Between 2015 and 2016, a follow-up study enrolled edentulous patients over 50 years of age who were proficient in Japanese, had sufficient mandibular bone for implants, and were free of systemic health issues and habits that could impact oral health. The participants were randomly divided into two groups after receiving a central mandibular implant. Group 1 initially used 1-IODs, and Group 2 used unloaded CCDs. After two months and subsequent periods, they swapped denture types. Eventually, all patients chose 1-IODs for continued use. Implant success was monitored over three years. The design featured block randomization and accounted for a sample size of 22, determined to be sufficient for evaluating the primary outcome of patient satisfaction. All patients underwent careful allocation and received customized dental interventions, with detailed radiographic planning and surgical precision guiding the implantation process.

DATA ANALYSIS

Multivariable linear mixed models were used to assess within-group changes in both overall and specific cognitive function scores across five timepoints. Age, assessment interval, and upper jaw denture status were incorporated as consistent variables, while individual participants were considered variable elements in the analysis. SPSS software version 22.0 was utilized to conduct the statistical tests, and a p value threshold of 0.05 was predetermined to establish statistical significance.

RESULTS

Twenty-two patients with edentulous mandibles received 1-IODs. Memory and executive functions saw significant score increases at multiple timepoints over the three-year period, with statistical significance. Though one participant dropped out and another passed away, and two did not complete the 3-year follow-up, the remaining 18 participants provided comprehensive data. Age and type of maxillary denture were significant factors, influencing MoCA-J scores with older participants and those with fixed dentures showing lower scores in certain domains. Overall, the findings illustrated the positive correlation between 1-IODs and cognitive function in older adults.

CONCLUSIONS

Older adults with no natural teeth left in their mandible showed improved cognitive function after one and three years of using 1-IODs, as reflected by their total and specific cognitive domain scores. The study suggests that such implant therapy may offer protective benefits against cognitive decline, demonstrating clinical relevance for patient care, regardless of the maxillary arch (antagonist) condition.

Association of tooth location, occlusal support and chewing ability with cognitive decline and incident dementia

AIM

Emerging evidence suggests association of tooth loss with impaired cognition. However, the differential effects of anterior versus posterior tooth loss, occlusal support loss and chewing ability are not considered comprehensively.

MATERIALS AND METHODS

We conducted cross-sectional (N = 4036) and longitudinal analyses (N = 2787) on data from Health 2000 and 2011 Surveys for associations of posterior occlusal support loss, anterior versus posterior tooth loss, and chewing ability with baseline cognition and 11-year cognitive decline. Additionally, 15-year incident dementia risk was investigated (N = 4073).

RESULTS

After considering relevant confounders and potential reverse causality bias, posterior occlusal support loss significantly increased dementia risk across all categories indicative of posterior occlusal support loss (hazard ratios [HRs] between 1.99 and 2.89). Bilateral inadequate posterior occlusal support was associated with 11-year decline in overall cognition (odds ratio [OR] = 1.48:1.00-2.19), and unilateral inadequate posterior occlusal support with total immediate (OR = 1.62:1.14-2.30) and delayed recall decline (OR = 1.45:1.03-2.05). Moreover, posterior tooth loss was associated with dementia (HR = 2.23:1.27-3.91) and chewing ability with total immediate decline (OR = 1.80:1.04-3.13).

CONCLUSIONS

Posterior tooth and occlusal support loss significantly increases dementia risk. The impact of posterior occlusal support loss appears to be dose-dependent, and this effect is distinct from that of dentures. Dental healthcare services should be particularly attentive to the state of posterior dentition. Further studies exploring possible mechanisms are warranted.

Longitudinal association of oral functions and dementia in Japanese older adults

The relationship between oral functions and dementia was examined in 7384 older adults (age ≥ 75 years) who visited a dental clinic in Gifu, Japan. Participants without dementia in a baseline survey in April 2018 were followed until March 2021. As oral functions, chewing function, tongue and lip function, and swallowing function were assessed by self-administered questionnaire, by oral diadochokinesis test, and by repetitive saliva swallowing test, respectively. The presence of systemic diseases was based on data obtained from the National Database of Health Insurance of Japan. At follow-up, 415 (6%) participants were diagnosed with dementia. Multivariate logistic regression analyses showed the presence of dementia at follow-up was associated with female (odds ratio [OR] 1.386; 95% confidence interval [CI] 1.117-1.719), age (OR 1.078; CI 1.056-1.101), regular dental checkups (absence; OR 1.452; CI 1.180-1.788), brushing frequency ≥ twice/day (absence; OR 1.510; CI 1.194-1.911), decayed teeth (presence; OR 1.328; CI 1.071-1.648), swallowing function (poor; OR 1.484; CI 1.135-1.939) at baseline. It was found that poor swallowing function was associated with the future onset of dementia.

Structural brain feature is associated with changes of masticatory performance in healthy elderly people: Evidence from longitudinal neuroimaging research over two years

BACKGROUND

Human neuroimaging studies have revealed the association between brain structure and masticatory function. However, the majority of the studies adopted a cross-sectional design, which hardly reveals the change in masticatory function and brain structure between different timepoints, and the dynamical association between changes in masticatory function and changes in brain structure has not been elucidated.

OBJECTIVE

With a longitudinal design, we assessed the association between changes in masticatory performance (MP) and regional brain volume.

METHODS

Twenty-two elderly participants received assessments of the number of missing teeth and MP (via colour-changeable chewing gum) when they entered the study (i.e. the initial stage, T0 ), approximately 6 months later (T0.5 ), and approximately 1-2 years later (T1 ). Difficulty of food intake was assessed using a questionnaire. The participants received magnetic resonance imaging (MRI) at T0 and T1 . The brain volume of the motor-related area was estimated using FreeSurfer for MRI data. The associations between different stages were analysed using Spearman's rho correlation coefficients.

RESULTS

(1) Individually, a smaller volume of right primary motor cortex at T0 was associated with increased MP from T0 to T1 , suggesting the brain's role in changing oral functions; (2) higher MP at T0 was associated with an increased volume of the left superior frontal cortex from T0 to T1 p, suggesting a potential effect on brain plasticity, and (3) increased difficulty to eat was associated with decrease MP but not brain volume of motor-related area.

CONCLUSIONS

The preliminary findings revealed a complicated pattern of structural brain features and masticatory function in elderly people, and either the hypothesis that the brain predisposes masticatory function or the hypothesis that mastication reshapes the brain is oversimplified.

From teeth to brain: dental caries causally affects the cortical thickness of the banks of the superior temporal sulcus

OBJECTIVES

Dental caries is one of the most prevalent oral diseases and causes of tooth loss. Cross-sectional studies observed epidemiological associations between dental caries and brain degeneration disorders, while it is unknown whether dental caries causally affect the cerebral structures. This study tested whether genetically proxied DMFS (the sum of Decayed, Missing, and Filled tooth Surfaces) causally impacts the brain cortical structure using Mendelian randomization (MR).

METHODS

The summary-level GWAS meta-analysis data from the GLIDE consortium were used for DMFS, including 26,792 participants. ENIGMA (Enhancing NeuroImaging Genetics through Meta Analysis) consortium GWAS summary data of 51,665 patients were used for brain structure. This study estimated the causal effects of DMFS on the surface area (SA) and thickness (TH) of the global cortex and functional cortical regions accessed by magnetic resonance imaging (MRI). Inverse-variance weighted (IVW) was used as the primary estimate, the MR pleiotropy residual sum and outlier (MR-PRESSO), the MR-Egger intercept test, and leave-one-out analyses were used to examine the potential horizontal pleiotropy.

RESULTS

Genetically proxied DMFS decreases the TH of the banks of the superior temporal sulcus (BANSSTS) with or without global weighted (weighted, β = - 0.0277 mm, 95% CI: - 0.0470 mm to - 0.0085 mm, P = 0.0047; unweighted, β = - 0.0311 mm, 95% CI: - 0.0609 mm to - 0.0012 mm, P = 0.0412). The causal associations were robust in various sensitivity analyses.

CONCLUSIONS

Dental caries causally decrease the cerebral cortical thickness of the BANKSSTS, a cerebral cortical region crucial for language-related functions, and is the most affected brain region in Alzheimer's disease. This investigation provides the first evidence that dental caries causally affects brain structure, proving the existence of teeth-brain axes. This study also suggested that clinicians should highlight the causal effects of dental caries on brain disorders during the diagnosis and treatments, the cortical thickness of BANKSSTS is a promising diagnostic measurement for dental caries-related brain degeneration.

Association between timed up-and-go test and subsequent pneumonia: A cohort study

BACKGROUND

Sarcopenia is a risk factor for pneumonia in the elderly, and the timed up-and-go test (TUG) can be used as a screening tool for sarcopenia in this population. This study aimed to evaluate the association between TUG test results and future pneumonia or ventilator care.

MATERIALS AND METHODS

From the National Health Insurance Service-Senior Cohort database, we identified 19,804 people without neurological diseases who underwent the TUG test in the National Screening Program for Transitional Ages at the age of 66 years during 2007-2008. Gait abnormality was defined as taking 10 s or longer to perform the TUG test. Pneumonia occurrence was defined using the International Classification of Diseases 10th Revision (ICD-10) code for pneumonia (J12-J18, J69), and ventilator care was defined by procedure codes (M5830, M5850, M5867, M5858, M5860, M5859) according to the Healthcare Common Procedure Coding system codes from 2007 to 2015.

RESULTS

The mean follow-up period was 7.4 years (standard error, SE 0.02). The incidence rates of pneumonia in the normal and slow TUG groups were 38 and 39.5/1000 person-years, respectively. The slow TUG group did not show a higher risk of pneumonia (adjusted hazard ratio [aHR], 1.042; 95% confidence interval [95% CI], 0.988-1.107]). Regarding ventilator care, the incidence was 4.7 and 5.2 cases per 1,000 person-years in the normal and slow TUG groups, respectively. Slow TUG groups also did not show an increased risk of ventilator occurrence (aHR, 1.136, [95% CI = 0.947-1.363]).

CONCLUSION

The TUG test result was not associated with future pneumonia or ventilator care and may not be useful for predicting pneumonia in community-dwelling elderly individuals. Further studies are needed to identify additional functional tools for sarcopenia associated with future pneumonia occurrences.

Experimental tooth loss affects spatial learning function and blood-brain barrier of mice

OBJECTIVE

This study aims to investigate how experimental tooth loss affected learning, memory function, and brain pathophysiology in mice.

MATERIALS AND METHODS

The mice (C57BL/6 J, 2-month-old, male) were divided into tooth loss and control groups. The behavioral test battery was performed at 6 and 12 months after tooth extraction. The protein levels of the tight junctions in the brains of the mice were analyzed. Hippocampal astrocyte was measured using immunohistochemical staining.

RESULTS

The results of behavioral tests and biochemical analysis performed during the 6 months observation period did not show significant differences between the groups. However, the escape latency in the tooth loss group was significantly longer than that in the control group at the 12 months after tooth extraction. The level of claudin-5 decreased in the tooth loss group. Additionally, hippocampal astrogliosis was found in the tooth loss group.

CONCLUSIONS

Experimental tooth loss reduced the level of claudin-5 and caused astrogliosis in the brains of mice, which was accompanied by deterioration of learning functions. This study may provide a new insight about the association between tooth loss and cognitive dysfunction.

Care-resistant behaviour during oral examination in Dutch nursing home residents with dementia

OBJECTIVE

To assess the occurrence and associations of verbal and non-verbal care-resistant behaviour (CRB) during oral examination by a dental hygienist in nursing home residents with dementia.

BACKGROUND

CRB is a barrier to providing professional oral care and daily oral hygiene care. Understanding the predictors of CRB might help care professionals in learning to anticipate this behaviour.

METHODS

In this multicentre cross-sectional study signs of verbal and non-verbal CRB were reported during the oral examination. Data collection occurred in the psychogeriatrics wards of 14 different nursing homes in the Netherlands (N = 367).

RESULTS

A total of 367 residents were included. CRB was evident in 82 residents (22.3%), of whom 45 (55%) showed verbal and 37 (45%) non-verbal CRB. Associated with CRB were age >85 years, duration of residential stay longer than 2 years, and having Korsakov dementia. Other factors associated with CRB were duration of residential stay (categories ">2 and ≤4 years" or ">4 years") and having a natural dentition (P = .043-.005, OR = 1.20-1.33, 95% CI = 1.00-8.48). Significant associations for verbal and non-verbal CRB were age between 76 and 85 years, vascular dementia and Korsakov dementia (P = .031-.006, OR = .020-1.49, 95% CI = 0.43-2.15).

CONCLUSION

The occurrence of CRB was 22.3% and was associated with older age and longer duration of residential stay, Vascular and Korsakov dementia and natural dentition.

Clinical efficacy of assessment of swallowing ability for pneumonia and other assessment tools for occurrence and mortality from pneumonia among older inpatients in a long-term care hospital

BACKGROUND

Aspiration pneumonia is an important condition in elderly patients and detecting dysphagia early can help clinicians identify patients with a high risk of aspiration pneumonia. We previously reported the usefulness of the Assessment of Swallowing Ability for Pneumonia (ASAP) in predicting the occurrence of and mortality from pneumonia in patients in acute care hospitals; however, there are very few reports on the utility of this screening test for patients in stable condition.

METHODS

Elderly patients in stable condition (n = 133) without pneumonia were prospectively enrolled. Associations between ASAP, Functional Independence Measure (FIM), Controlling Nutrition Status (CONUT), and Charlson Co-morbidity Index (CCI) scores and occurrence of/mortality from pneumonia during hospitalization were evaluated.

RESULTS

The occurrence of pneumonia was observed in 27 (20.3%) patients, and 18 (13.5%) died during hospitalization. Multivariate analysis showed that low ASAP score and low FIM motor were independent predictors for the occurrence of pneumonia, and low ASAP score was an independent predictor for mortality from pneumonia. Areas under the curve for ASAP, FIM motor, FIM cognition, and CONUT scores were 0.895 (95% confidence interval [CI], 0.829-0.960), 0.913 (95% CI, 0.860-0.968), 0.841 (95% CI, 0.761-0.921), and 0.753 (95% CI, 0.649-0.858), respectively, for occurrence, and 0.881 (95% CI, 0.807-0.955), 0.904 (95% CI, 0.860-0.949), 0.829 (95% CI, 0.727-0.931), 0.746 (95% CI, 0.617-0.874), respectively, for mortality.

CONCLUSION

The ASAP and FIM motor are useful for predicting the occurrence of and mortality from pneumonia in elderly inpatients in long-term care hospitals.

Increased vertical dimension of occlusion for varying periods differentially impairs learning and memory in guinea pigs

There is an increasing number of studies showing that occlusal dysfunction impairs learning and memory. We previously demonstrated that the brain has a mechanism to calibrate between the activities of spindle afferents and periodontal-mechanoreceptor afferents for controlling the chewing movement, and the accurate calibration can be done only at the proper vertical dimension of occlusion (VDO). Then, the chewing at an inappropriate VDO may induce a severe mental stress due to a mal-calibration. However, it is not clear how the impairment of learning/memory progresses over the period of stress induced by occlusal dysfunction. We investigated by passive avoidance test how the behavior and learning/memory are altered in guinea pigs in which the VDO was raised by 2-3 mm over the period up to 8 weeks. We found that the guinea pigs reared under the raised occlusal-condition (ROC) for 1 week showed a very high sensitivity to electrical stimulation whereas this did not cause the memory consolidation in the 1st-day retention trial, suggesting that such hypersensitivity rather hampered the fear learning. In the guinea pigs reared under the ROC for 2 and 8 weeks, the learning ability was not largely affected and memory consolidation occurred similarly whereas the memory retention deteriorated more severely in the latter guinea pigs than in the former ones. In the guinea pigs reared under the ROC for 3 and 4 weeks, learning was severely impaired, and memory consolidation did not occur. These results suggest that the occlusal dysfunction for varying periods differentially impairs learning and memory.

Trigeminal Stimulation and Visuospatial Performance: The Struggle between Chewing and Trigeminal Asymmetries

Chewing improves visuospatial performance through locus coeruleus (LC) activation. The effects of bilateral and unilateral mastication were investigated in subjects showing different degrees of asymmetry in masseter electromyographic (EMG) activity during clenching and in pupil size at rest (anisocoria), which is a proxy of LC imbalance. Correlations between performance changes and asymmetry values were found in males, but not in females. Among males, subjects with low asymmetry values (balanced-BAL) were more sensitive than those with high asymmetry values (imbalanced-IMB) to bilateral and unilateral chewing on the side with higher EMG activity (hypertonic). The opposite was true for hypotonic side chewing. BAL subjects were sensitive to unilateral chewing on both sides, while in IMB subjects, hypertonic side chewing did not influence performance in either males or females. Bilateral chewing elicited larger effects in BAL subjects than in IMB subjects, exceeding the values predicted from unilateral chewing in both groups. Finally, pupil size and anisocoria changes elicited by chewing were correlated with asymmetry values, independent of sex. Data confirmed the facilitation of visuospatial performance exerted by chewing. Trigeminal asymmetries modulate the chewing effects, making occlusal rebalancing an appropriate strategy to improve performance.

Assessment and Improvement of Masticatory Performance in Frail Older People: A Narrative Review

According to the World Health Organization (WHO), the estimated number of older adults is around 962 million and is projected to increase to 2.1 billion by 2050. The oral frailty concept is associated with gradual oral function loss in relation to aging. There is a need to emphasize the improvement of oral function based on an evaluation of masticatory performance in patients with various oral conditions or systemic diseases and especially in the frail elderly. The present narrative review presents an overview of the current state of the assessment and improvement of masticatory performance in frail older people. To fully encompass oral frailty, oro-facial hypofunction, or oro-facial fitness, dental Patient Reported Outcomes (dPROs) should be included; nevertheless, there are limited evidence-based rehabilitation approaches. The concept of oral frailty, oro-facial hypofunction, or oro-facial fitness should involve dental Patient Reported Outcomes (dPROs), and in this sense, there are only a few evidence-based rehabilitation procedures to improve oro-facial hypofunction besides prosthodontics. It must be considered that reduced neuroplastic capacity in old individuals might preclude a positive outcome of these strategies that might need to be accompanied by functional training and nutritional counseling.

Longitudinal assessment of the eating pattern of people with dementia and its association with problems for feeding and malnutrition: a prospective follow-up study protocol

INTRODUCTION

Dementia conditions the patient's nutrition from the beginning and vice versa. Generating difficulties for feeding (FEDIF) will influence its evolution. There are currently few nutritional longitudinal studies in people with dementia. Most focus on problems already established. The Edinburgh Feeding Evaluation in Dementia (EdFED) Scale identifies FEDIF of patients with dementia by studying their behaviours while eating or being fed. It also indicates areas of potential clinical interventions.

METHODS AND ANALYSIS

Prospective multicentre observational study carried out in nursing homes, Alzheimer's day care centres and primary healthcare centres. The study population will be dyads composed by the patient (diagnosed of dementia, over 65 years of age and who have feeding difficulties) and their family caregiver. Sociodemographic variables and nutritional status (body mass index, Mini Nutritional Assessment, blood test and calf and arm circumference) will be assessed. The Spanish version of the EdFED Scale will be completed and the presence of nursing diagnoses related to feeding behaviours will be collected. Follow-up will take place for 18 months.

ETHICS AND DISSEMINATION

All data will be carried out respecting European legislation 2016/679 in data protection, and the Spanish 'Organic Law 3/2018 of December 2005'. The clinical data will be kept segregated and encrypted. The informed consent has been obtained. The research has been authorised by the Costa del Sol Health Care District on 27 February 2020 and the Ethics Committee on 2 March 2021. It has obtained funding from the Junta de Andalucía on 15 February 2021. Findings of the study will be presented at provincial, national and international conferences and published in peer-reviewed journals.

Pre-Adolescent Diet Normalization Restores Cognitive Function in Young Mice

Mastication is a fundamental function critical for human health. Controlled by the central nervous system (CNS), it influences CNS development and function. A poor masticatory performance causes cognitive dysfunction in both older adults and children. Improving mastication may prevent cognitive decline. However, no study has determined the period of masticatory dysfunction that impairs children's later acquisition of cognitive function. Herein, we developed an animal model wherein a soft diet was switched to a normal diet at early and late time points in young mice. We aimed to investigate the impact of restored mastication on learning and memory function. Behavioral studies were conducted to evaluate learning and memory. Micro-CT was used to evaluate orofacial structural differences, while histological and biochemical approaches were employed to assess differences in the hippocampal morphology and function. Correction to a hard-textured diet before adolescence restored mastication and cognitive function through the stimulation of neurogenesis, extracellular signal-regulated kinases, the cyclic adenosine monophosphate-response element-binding protein pathway, and the brain-derived neurotrophic factor, tyrosine receptor B. In contrast, post-adolescent diet normalization failed to rescue full mastication and led to impaired cognitive function, neuronal loss, and decreased hippocampal neurogenesis. These findings revealed a functional linkage between the masticatory and cognitive function in mice during the juvenile to adolescent period, highlighting the need for adequate food texture and early intervention for mastication-related cognitive impairment in children.

Advanced materials and technologies for oral diseases

Oral disease, as a class of diseases with very high morbidity, brings great physical and mental damage to people worldwide. The increasing burden and strain on individuals and society make oral diseases an urgent global health problem. Since the treatment of almost all oral diseases relies on materials, the rapid development of advanced materials and technologies has also promoted innovations in the treatment methods and strategies of oral diseases. In this review, we systematically summarized the application strategies in advanced materials and technologies for oral diseases according to the etiology of the diseases and the comparison of new and old materials. Finally, the challenges and directions of future development for advanced materials and technologies in the treatment of oral diseases were refined. This review will guide the fundamental research and clinical translation of oral diseases for practitioners of oral medicine.

Association between occlusal support and cognitive impairment in older Chinese adults: a community-based study

Introduction

The loss of occlusal support due to tooth loss is associated with systemic diseases. However, there was little about the association between occlusal support and cognitive impairment. The cross-sectional study aimed to investigate their association.

Methods

Cognitive function was assessed and diagnosed in 1,225 community-dwelling adults aged 60 years or older in Jing'an District, Shanghai. Participants were diagnosed with mild cognitive impairment (MCI) by Peterson's criteria, or dementia, according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition. We determined the number of functional occlusal supporting areas according to Eichner classifications. We used multivariate logistic regression models to analyze the relationship between occlusal support and cognitive impairment and mediation effect models to analyze the mediation effect of age.

Results

Six hundred sixty participants were diagnosed with cognitive impairment, averaging 79.92 years old. After adjusting age, sex, education level, cigarette smoking, alcohol drinking, cardiovascular disease, and diabetes, individuals with poor occlusal support had an OR of 3.674 (95%CI 1.141-11.829) for cognitive impairment compared to those with good occlusal support. Age mediated 66.53% of the association between the number of functional occlusal supporting areas and cognitive impairment.

Discussion

In this study, cognitive impairment was significantly associated with the number of missing teeth, functional occlusal areas, and Eichner classifications with older community residents. Occlusal support should be a significant concern for people with cognitive impairment.

Association between adverse oral conditions and cognitive impairment: A literature review

Oral environment deterioration results from a lack of self-cleaning ability in patients with cognitive dysfunction but is also a risk factor for cognitive dysfunction. Adverse oral conditions can be alleviated and improved through a self-management and medical examination. In this review, the epidemiological evidence of previous studies is integrated to highlight the relationship between periodontitis, tooth loss, oral flora, oral dysfunction and cognitive dysfunction, emphasizing the importance of oral health for cognition. The results show that poor oral condition is associated with cognitive impairment. Although many previous studies have been conducted, there is a lack of higher-level research evidence, different judgment criteria, and conflicting research results. There is a bidirectional relationship between oral health and cognitive dysfunction. A comprehensive analysis of the relationship between oral health and cognitive dysfunction that explores the relationship and takes measures to prevent cognitive dysfunction and control the progression of such diseases is warranted in the future.

Tooth loss and the risk of cognitive decline and dementia: A meta-analysis of cohort studies

Introduction

Epidemiological studies have shown that tooth loss may be associated with an increased risk of cognitive decline and dementia. However, some results do not show a significant association. Therefore, we performed a meta-analysis to evaluate this association.

Methods

Relevant cohort studies were searched in PubMed, Embase, Web of Science (up to May 2022), and the reference lists of retrieved articles. The pooled relative risk (RR) and 95% confidence intervals were computed using a random-effects model (CI). Heterogeneity was evaluated using the I ² statistic. Publication bias was evaluated using the Begg's and Egger's tests.

Results

Eighteen cohort studies met the inclusion criteria. Original studies with 356,297 participants with an average follow-up of 8.6 years (ranging from 2 to 20 years) were included in this study. The pooled RRs of tooth loss on dementia and cognitive decline were 1.15 (95% CI: 1.10-1.20; P < 0.01, I ² = 67.4%) and 1.20 (95% CI: 1.14-1.26; P = 0.04, I ² = 42.3%), respectively. The results of the subgroup analysis showed an increased association between tooth loss and Alzheimer's disease (AD) (RR = 1.12, 95% CI: 1.02-1.23) and vascular dementia (VaD) (RR = 1.25, 95% CI: 1.06-1.47). The results of the subgroup analysis also showed that pooled RRs varied by geographic location, sex, use of dentures, number of teeth or edentulous status, dental assessment, and follow-up duration. None of the Begg's and Egger's tests or funnel plots showed evidence of publication bias.

Discussion

Tooth loss is associated with a significantly increased risk of cognitive decline and dementia, suggesting that adequate natural teeth are important for cognitive function in older adults. The likely mechanisms mostly suggested include nutrition, inflammation, and neural feedback, especially deficiency of several nutrients like vitamin D.

Molar loss further exacerbates 2-VO-induced cognitive impairment associated with the activation of p38MAPK/NFκB pathway

Background

Vascular dementia is characterized by reduced cognitive function due to chronic cerebral hypoperfusion and has become a significant public health challenge as the global population ages. Recent studies suggested that molar loss, a common problem among the elderly, may trigger the development of cognitive decline. Our previous study found that the molar loss affected cognitive dysfunction, and the astrocytes in the hippocampus of chronic cerebral ischemia rats were affected, but the underlying mechanism is unclear.

Methods

In this study, we established the animal model of molar loss with 2-VO rats and the Morris water maze was used to test the cognitive ability of rats in each group. The damage to neurons was observed via Nissl staining, and neuronal apoptosis was analyzed by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay in the hippocampus of the rats. Quantitative Real-Time PCR and immunohistochemistry and histology (IHC) were used to detect the expression of p38MAPK, NFκB, caspase 3, and iNOS in the hippocampus. The astrocytes were detected by IHC and Immunofluorescence analysis for GFAP. After 2-VO MO surgery, rats were administered DMSO or p38MAPK inhibitor (SB203580) by intrathecal injection.

Results

The Morris water maze test showed that the molar loss aggravated spatial memory learning ability with chronic cerebral ischemia decreased in the rats. The neuronal damage and more apoptotic cells were observed in the hippocampus of 2-VO rats. After the molar loss, the mRNA and protein expression of iNOS, p38MAPK, NFκB, and caspase 3 were further upregulated in 2-VO rats. Molar loss upregulated GFAP expression, and the p38MAPK-positive cells were labeled with the astrocyte marker GFAP. SB203580 reduced cognitive impairment and apoptosis of hippocampal neurons in 2-VO rats following the molar loss.

Conclusion

Molar loss can aggravate cognitive impairment in 2-VO rats to a certain extent. The mechanism of molar loss exacerbating the cognitive decline in 2-VO rats may be associated with the activation of the p38MAPK-NFκB-caspase 3 signaling pathway, which induces neuronal apoptosis.

The Risk of Cardiovascular Disease According to Chewing Status Could Be Modulated by Healthy Diet in Middle-Aged Koreans

To assess whether a healthy diet could change the risk of cardiovascular disease (CVD)-related chewing difficulty (CD) in relation to age distribution. In a cross-sectional study of 9411 middle-aged Koreans from the KNHANES VII. In this study, the Framingham 10-year general CVD risk prediction equations and the Korean Heathy Eating index (KHEI) were used to assess the 10-year estimated risk of CVD and dietary quality, respectively. CD was experienced by 16.7% of the total subjects. Among subjects with CD, the 10-year estimated CVD risk was 8.71% of the subjects in the 30−49 years age group and 30.38% of those in the 50−64 years age group, which is a difference of approximately 3.5 times. Regardless of age distribution, the total score of the KHEI in subjects who had CD was significantly lower than in those who had no CD (NCD) (p = 0.004 for the 30−49 years age group and p < 0.001 for the 50−64 years age group, respectively). Among the subjects with poor KHEI in the 30−49-year age group, the adjusted odds ratio for the 10-year estimated CVD risk of the subjects with CD was 2.204-fold (95% CI = 1.385−3.506) higher using NCD as a reference. The findings showed that dietary quality could modify the risk for CVD according to chewing status.

Development of a system to analyze oral frailty associated with Alzheimer's disease using a mouse model

The rapid aging of the population makes the detection and prevention of frailty increasingly important. Oral frailty has been proposed as a novel frailty phenotype and is defined as a decrease in oral function coexisting with a decline in cognitive and physical functions. Oral frailty has received particular attention in relation to Alzheimer's disease (AD). However, the pathomechanisms of oral frailty related to AD remain unknown. It is assumed that the mesencephalic trigeminal nucleus (Vmes), which controls mastication, is affected by AD pathology, and as a result, masticatory function may be impaired. To investigate this possibility, we included male 3 × Tg-AD mice and their non-transgenic counterpart (NonTg) of 3-4 months of age in the present study. Immunohistochemistry revealed amyloid-β deposition and excessive tau phosphorylation in the Vmes of 3 × Tg-AD mice. Furthermore, vesicular glutamate transporter 1-immunopositive axon varicosities, which are derived from Vmes neurons, were significantly reduced in the trigeminal motor nucleus of 3 × Tg-AD mice. To investigate whether the AD pathology observed in the Vmes affects masticatory function, we analyzed electromyography of the masseter muscle during feeding. The 3 × Tg-AD mice showed a significant delay in masticatory rhythm compared to NonTg mice. Furthermore, we developed a system to simultaneously record bite force and electromyography of masseter, and devised a new method to estimate bite force during food chewing in mice. Since the muscle activity of the masseter showed a high correlation with bite force, it could be accurately estimated from the muscle activity. The estimated bite force of 3 × Tg-AD mice eating sunflower seeds was predominantly smaller than that of NonTg mice. However, there was no difference in masseter weight or muscle fiber cross-sectional area between the two groups, suggesting that the decreased bite force and delayed mastication rhythm observed in 3 × Tg-AD mice were not due to abnormality of the masseter. In conclusion, the decreased masticatory function observed in 3 × Tg-AD mice was most likely caused by AD pathology in the Vmes. Thus, novel quantitative analyses of masticatory function using the mouse model of AD enabled a comprehensive understanding of oral frailty pathogenesis.

The Sedentary Lifestyle and Masticatory Dysfunction: Time to Review the Contribution to Age-Associated Cognitive Decline and Astrocyte Morphotypes in the Dentate Gyrus

As aging and cognitive decline progresses, the impact of a sedentary lifestyle on the appearance of environment-dependent cellular morphologies in the brain becomes more apparent. Sedentary living is also associated with poor oral health, which is known to correlate with the rate of cognitive decline. Here, we will review the evidence for the interplay between mastication and environmental enrichment and assess the impact of each on the structure of the brain. In previous studies, we explored the relationship between behavior and the morphological features of dentate gyrus glial fibrillary acidic protein (GFAP)-positive astrocytes during aging in contrasting environments and in the context of induced masticatory dysfunction. Hierarchical cluster and discriminant analysis of GFAP-positive astrocytes from the dentate gyrus molecular layer revealed that the proportion of AST1 (astrocyte arbors with greater complexity phenotype) and AST2 (lower complexity) are differentially affected by environment, aging and masticatory dysfunction, but the relationship is not straightforward. Here we re-evaluated our previous reconstructions by comparing dorsal and ventral astrocyte morphologies in the dentate gyrus, and we found that morphological complexity was the variable that contributed most to cluster formation across the experimental groups. In general, reducing masticatory activity increases astrocyte morphological complexity, and the effect is most marked in the ventral dentate gyrus, whereas the effect of environment was more marked in the dorsal dentate gyrus. All morphotypes retained their basic structural organization in intact tissue, suggesting that they are subtypes with a non-proliferative astrocyte profile. In summary, the increased complexity of astrocytes in situations where neuronal loss and behavioral deficits are present is counterintuitive, but highlights the need to better understand the role of the astrocyte in these conditions.

Risk Factors for Aspiration Pneumonia among Elderly Patients in a Community-Based Integrated Care Unit: A Retrospective Cohort Study

We aimed to clarify the physical factors associated with the incidence of aspiration pneumonia in a community-based integrated care unit. This retrospective cohort study included 412 patients aged 65 years or older admitted to a community-based integrated care unit. A new diagnosis of aspiration pneumonia made by the attending physician based on physical examination, imaging findings, and blood test data after 48 h of admission was considered as an incidence of aspiration pneumonia. Basic patient information, activities of daily living, swallowing function, nutritional status, cognitive function, oral health-related factors, and energy intake were retrospectively investigated. We classified the patients into a pneumonia group and a non-pneumonia group, and examined the factors associated with the development of aspiration pneumonia. The mean age was 86.9 ± 8.1 years, and the pneumonia group comprised 49 participants. Comparison between the groups showed significant differences in oral environment, denture use, cognitive functional independence measure, and discharge to home. In multivariate logistic regression analysis, oral environment (odds ratio (OR) = 0.229, 95% confidence interval (CI): 0.070–0.753, p = 0.015) and use of dentures (OR = 0.360, 95% CI: 0.172–0.754, p = 0.007) were independently associated with aspiration pneumonia. Oral care and the use of dentures may be effective in preventing aspiration pneumonia.

Speech and the swallowing threshold in single implant overdenture wearers: A paired control study

BACKGROUND

Single implant mandibular overdentures (SIMOs) can improve mastication in edentulous elderly people. However, little attention has been paid to their effects on articulation disorders and the swallowing threshold relative to those of conventional complete dentures (CDs).

OBJECTIVE

To compare the effects of new conventional CD set and SIMOs on articulation disorders, mandibular movements during speech and swallowing threshold using a paired study design.

METHODS

Twenty-two edentulous Brazilian Portuguese-speaking elderly people (mean age 66.7 ± 4.6 years) were first evaluated whilst wearing their old conventional CDs. Articulation disorders were analysed by audio and video recordings, mandibular movements during speech were measured by kinesiography, and the swallowing threshold was assessed by masticatory cycle counting and medium particle size (X₅₀ ) calculation. Participants then received new conventional CDs, and evaluations were repeated 2 months later. Subsequently, single implants were installed in the midlines of subjects' mandibles, and the conventional CDs were converted to SIMOs. After 2 months of SIMOs use, the evaluations were repeated. Data were submitted to the Cochran-Mantel-Haenszel and ANOVA.

RESULTS

No difference in articulation disorders was found between new conventional CD and SIMO use. The frequency of anterior lisp during /s/ and /z/ phoneme pronunciation was reduced with new conventional CD use relative to old conventional CD use (p < .05). The X₅₀ decreased progressively with new conventional CD and SIMO use (both p < .05).

CONCLUSION

SIMOs do not alter speech relative to new well-fitted conventional CDs, but improved the swallowing threshold, in edentulous elderly people.

Changes in oral and cognitive functions among older Japanese dental outpatients: A 2-year follow-up study

BACKGROUND

The relationship between oral and cognitive functions among older people is highly debated.

OBJECTIVE

To examine whether oral functions are related to changes in the levels of mild cognitive impairment (MCI) biomarkers in older Japanese outpatients.

METHODS

This observational study included 52 outpatients aged ≥65 years who underwent dental examinations at the Fukuoka Dental College Hospital. The Mini-Mental State Examination (MMSE) was performed, and MCI blood biomarker levels were assessed at baseline and after 2 years. The present dental and periodontal conditions and the oral functions (tongue pressure and masticatory performance) were evaluated. Changes in parameters from baseline to follow-up were compared using the Wilcoxon signed-rank test, McNemar test or chi-squared test. Associations among changes in the parameters were analysed using Spearman's rank correlation coefficient.

RESULTS

The follow-up rate in this study was 67%. The masticatory performance was improved (p < 0.001), whereas gingival inflammation was decreased (p < 0.001) over the 2-year period. A significant increase in the MMSE score (p < 0.001) and a decrease in MCI risk (p < 0.001) were noted. The decrease in MCI risk was correlated with the increase in both masticatory performance (ρ = -0.34; p < 0.05) and MMSE score (ρ = -0.56; p < 0.01).

CONCLUSION

A decrease in MCI risk, as demonstrated by the levels of the blood biomarkers, was correlated with an increase in the masticatory performance in Japanese outpatients.

Low Tongue Strength and the Number of Teeth Present Are Associated with Cognitive Decline in Older Japanese Dental Outpatients: A Cross-Sectional Study

To mitigate the impact of dementia, initiating early intervention is important. This study aims to investigate the associations between deterioration in oral function and cognitive decline in older outpatients whose oral health was maintained in the dental clinic. This study included 50 outpatients aged ≥65 years. We used the Japanese version of the Montreal Cognitive Assessment (MoCA-J) to assess cognitive decline. Oral function was evaluated by tongue pressure, masticatory performance, and swallowing ability. A full-mouth periodontal examination was conducted, and the occlusal support and number of teeth were recorded. Odds ratios (ORs) and 95% confidence intervals (CIs) for cognitive decline (MoCA-J score ≤ 25 points) were calculated using logistic regression models. The age, number of teeth, tongue pressure, and masticatory performance were significantly correlated with cognitive decline (p < 0.05). Logistic regression analyses revealed that cognitive decline was independently associated with age (OR: 1.25; 95% CI: 1.03-1.52; p = 0.024), number of teeth (OR = 0.83; 95% CI: 0.76-1.00; p = 0.047), and lower tongue pressure (OR: 0.87; 95% CI: 0.77-0.98; p = 0.022). Lower tongue pressure and a small number of remaining teeth may be associated with cognitive decline in Japanese outpatients.