Relationship between mild cognitive decline and oral motor functions in metropolitan community-dwelling older Japanese: The Takashimadaira study

Correlation during the extent of surgical resection, oral function and quality of life after tongue cancer surgery: single-institution study

INTRODUCTION

The extent of surgical resection for tongue tumors is determined by tumor size, potentially affecting oral function and quality of life (QoL). However, the relationship between oral dysfunction and QoL decline due to glossectomy extent remains unexplored. Therefore, these correlations and their predictive value for postoperative QoL decline were elucidated.

METHODS

Patients treated for tongue cancer at our hospital between 2018 and 2022 were categorized by partial, hemi, or subtotal/total glossectomy. Assessments included swallowing function (RSST), articulation (Oral Diadochokinesis (ODK)), mastication, tongue pressure, and oral moisture. QoL was measured using the Oral Health Impact Profile-14 (OHIP-14). Differences within parameters were assessed using Kruskal-Wallis tests, and between-group comparisons via Mann-Whitney U tests. Spearman's correlation analysis examined parameter relationship.

RESULTS

35 patients were evaluated. Significant differences were found in ODK [ta] (p = 0.015), [ka] (p = 0.0006), tongue pressure (p = 0.0001), moisture levels (p = 0.031), OHIP-14 domains: physical disability (p = 0.014) and social disability (p = 0.046). ODK [ta] (PG: 5.95, HG: 5.38, TG: 4.03 times), [ka] (PG: 5.56, HG: 4.78, TG: 3.23 times), and tongue pressure (PG: 32.9, HG: 21.2, TG: 10.3 mmHg) decreased with glossectomy extent, while physical (PG: 0.27, HG: 2.38, TG: 2.00) and social disability (PG: 0.18, HG: 0.94, TG: 1.43) worsened. A significant negative correlation was observed between tongue pressure and social disability (p = 0.013, r = -0.36).

CONCLUSION

Expanding resection significantly impacted postoperative oral function and QoL. Tongue pressure assessment may predict long-term social disability in patient QoL.

The predictive value of masticatory function for adverse health outcomes in older adults: a systematic review

Masticatory function is associated with a variety of health outcomes. The aim of this systematic review is to clarify the predictive value of masticatory function for adverse health outcomes, such as frailty, sarcopenia and malnutrition, in older adults. An online literature search covered articles published in English or Dutch in three databases (PubMed, Embase and CINAHL, last searched November 4th 2022). Inclusion criteria were: an observational study design, focus on adults aged ≥65 years and evaluation of the association between masticatory function and health outcomes. Reviews and articles published before the year 2000 were excluded. Methodological quality and risk of bias were assessed using the Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies of the U.S. National Institutes of Health. Study population demographics, methods for assessing masticatory function, and the association between masticatory function and adverse health outcomes were extracted. From the 34 included studies, 5 studies had a prospective design, 2 had a retrospective design, and the other 27 studies had cross-sectional design. The majority of the studies were conducted in Japan (74%, n = 26). Twenty studies (59%) used one indicator for masticatory function, the other 41% used two (n = 9) or more (n = 5) indicators. Masticatory function was most frequently assessed with the maximum occlusal force (MOF) (79%, n = 27). The identified health outcomes were clustered into 6 categories: physical parameters and sarcopenia, history of falling, nutritional status, frailty, cognitive function and mortality. Despite the complex and multidimensional character of both masticatory function and most identified adverse health outcomes, some significant associations were reported. Prospective studies showed that reduced masticatory function in older adults is associated with incidence of frailty and frailty progression, cognitive decline and all-cause mortality. Regarding the other identified adverse health outcomes, i.e., physical measures and sarcopenia, history of falling and nutritional status, only cross-sectional studies were available and results were less concordant. As all prospective studies showed that reduced masticatory function in older adults is associated with adverse health outcomes, prevention of decline of masticatory function by adequate oral care may contribute to healthy ageing.

DO ORAL CARE AND REHABILITATION IMPROVE COGNITIVE FUNCTION? A SYSTEMATIC REVIEW OF CLINICAL STUDIES

OBJECTIVES

An increasing number of studies have identified an association between oral health status and cognitive function. However, the effect of oral interventions, including oral health care, dental treatment and oral motor exercises, on cognitive function remains unclear. This systematic review examined whether oral interventions contribute to the long-term improvement of cognitive status.

METHODS

Four databases were searched (MEDLINE, Web of Science, Cochrane Library, and ICHUSHI Web) to identify randomized and nonrandomized controlled trial studies and prospective cohort studies from inception until 1 September 2023, published in English or Japanese. The Cochrane risk of bias tool for randomized controlled trials and the risk of bias assessment tool for nonrandomized studies were used to assess bias risk.

RESULTS

A total of 20 articles were included in the qualitative analysis; 13 articles were published in English, and 7 were published in Japanese. The implemented interventions were oral care in 8 studies, dental treatment in 8 studies, and oral motor exercise in 4 studies. One study found a significant effect on attention following oral care intervention. Some dental treatments influenced cognitive function, although a clear positive effect was not determined. In 1 study, attention and working memory improved in the chewing exercise group.

CONCLUSIONS

Several studies verified the improvement effects of oral interventions, such as oral care, dental treatment, and oral motor exercise, on cognitive function or impairment. However, there was still a lack of conclusive evidence that such an intervention clearly improved cognitive function. To clarify the effects of oral interventions on cognitive function, it is necessary to examine participants, interventions, and outcome measures in detail.

Can oral diadochokinesis be used as an assessment tool of oral function in older adults requiring care in nursing home?

BACKGROUND

Oral diadochokinesis (OD) test is an articulation test that analyses fine movements of the lips, cheeks and tongue. It is difficult to perform the test accurately in older people with reduced physical and cognitive functions.

OBJECTIVES

This study aimed to investigate the number of older adults who could not be tested for OD and to investigate their characteristics.

METHODS

The participants included 145 older residents of an aged care nursing home. They were divided into two groups: those who could be tested for OD and those who could not, and their characteristics were compared. The degree of requiring long-term care was classified into five levels. The degree of dementia was classified into five levels. Those having difficulty in performing daily activities alone and having degree III or higher dementia were considered to have severe dementia.

RESULTS

The participants included 41 men and 104 women with a median age of 89 years (range, 64-105 years). Sixty-eight participants failed the OD test (46.9%). In univariate and multivariate analyses, degree of dementia and oral care (among other characteristics in univariate analysis) showed statistically significant differences between the two groups. Cut-off values for older adults who could not perform OD test were level 4 or higher in need of care and degree III or higher in dementia.

CONCLUSION

This study suggests that additional assessment tools for oral function should be considered for older adults requiring a nursing care level of 4 or higher and a dementia degree of III or higher.

Current evidence on the association of tongue strength with cognitive decline in older adults and the known risk factors of frailty, sarcopenia and nutritional health: a scoping review protocol

INTRODUCTION

Evidence suggests that the pathology underlying cognitive decline leading to dementia begins 15-20 years before cognitive symptoms emerge. Thus, identifying biomarkers in this preclinical phase is critically important. Age-related decrease in muscle mass and strength, a known risk factor for sarcopenia, frailty and cognitive decline, also affects the tongue. This paper describes an a priori protocol by a multidisciplinary team to address the following questions relating to adults ≥50 years of age: (1) What is the current evidence on the association of tongue strength with cognitive decline? (2) How does tongue strength associate with frailty and sarcopenia? (3) What is the association of tongue strength with nutritional health?

METHODS AND ANALYSIS

Search terms will be identified then multiple electronic databases (PubMed, PsycINFO (Ovid), Scopus, Embase (Ovid), CINAHL and Web of Science) searched systematically for peer-reviewed articles published in English that address the following inclusion criteria: (1) human studies, (2) participants ≥50 years of age and (3) studies with tongue pressure values measured in relation to at least one of the following: frailty, sarcopenia, nutritional health, cognitive function and dementia (Alzheimer's, vascular, frontotemporal and Lewy body). Grey literature also will be searched to identify additional studies, clinical trials and policy papers appropriate for inclusion. The search will be from database inception. After removing duplicates, two research team members will independently screen abstracts and identify articles for full-text review. The team will use a data charting tool for data extraction. Data will be analysed quantitatively and qualitatively.

ETHICS AND DISSEMINATION

The scoping review does not require ethics approval as data will be from publicly available sources. Results will be disseminated in workshops and conferences and a peer-reviewed journal paper.

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.

Long-term trends in the burden of edentulism in China over three decades: A Joinpoint regression and age-period-cohort analysis based on the global burden of disease study 2019

Background

To investigate secular trends in edentulism incidence, prevalence, and years lived with disability (YLDs) rates in Chinese men and women from 1990 to 2019.

Methods

Data were obtained from the Global Burden of Disease Study 2019. The annual percentage change and average annual percentage change were calculated using Joinpoint regression analysis. The age-period-cohort (APC) analysis estimated the independent age, period, and cohort effects.

Results

From 1990 to 2019, the crude incidence, prevalence, and YLDs of edentulism in the Chinese population increased year by year, while the age-standardized incidence, prevalence, and YLDs decreased, and the latter was higher in women than in men. The APC analysis showed that the age effect increased in men and women from age 20 to 74 and decreased thereafter. The risk of tooth loss increased with age. However, the relationship was not linear. The temporal effect showed a gradual increase; the risk of missing teeth gradually increased with the changing modern living environment. The cohort effect showed a single decreasing trend, with the early birth cohort having a higher risk of tooth loss than the later birth cohort population. The age, period, and cohort effects were consistent for both sexes.

Conclusion

Although the standardized incidence, prevalence, and YLD rate and cohort effect of dentition loss in China are declining, they are still causing a severe burden to China due to the continued aging of the population and the rising period effect. Despite the decreasing trends of the standardized incidence and prevalence of dentition loss and the rate of YLDs, China should develop more effective oral disease prevention and control strategies to reduce the increasing burden of edentulism in the older adult, especially in older women.

Effect of elastic oral appliance chewing on frontal lobe activity

OBJECTIVES

Chewing increases frontal lobe activity, resulting in improved memory, learning ability, and response reaction time. This study aimed to assess the effects of elastic oral appliance chewing on the activities and functions of the frontal lobe.

METHODS

The study participants were 15 healthy men with full dentulous (mean age, 27.4 ± 4.1 years). A prospective crossover design was used to assess frontal lobe activities and functions. Changes in frontal lobe activities were measured with near-infrared spectroscopy (NIRS). At baseline, the participants were assessed in the resting state. Changes in channels #7, representing right frontal lobe activities by NIRS, and #10, representing left frontal lobe activities, during the first and second chewing periods in a total of two periods were evaluated. Frontal lobe functions were measured using the Trail Making Test Part A (TMT-A) in the resting state and after elastic oral appliance or gum chewing. These values were compared with each period.

RESULTS

Elastic oral appliance chewing caused significant differences between the baseline and first chewing periods for channel #7 (p = .032) and significant differences between the baseline and second chewing periods for channels #7 and #10 (p < .001 and p < .001, respectively) using NIRS. Moreover, significant differences were found in the TMT-A results between the resting state and elastic oral appliance chewing (p = .04).

CONCLUSIONS

Elastic oral appliance chewing improves frontal lobe activities to a level similar to that obtained with gum chewing.

Oral environment and cerebral blood flow in patients with neurodegenerative dementia: comparison of Alzheimer type dementia and dementia with Lewy bodies

BACKGROUND

The number of patients with dementia is increasing worldwide. Modifying risk factors may significantly reduce the prevalence and cost of dementia. The number of remaining teeth, occlusal force, denture use, and periodontal disease status are associated with the risk of developing dementia. The oral environment may be a risk factor for dementia. This study aimed to investigate the association between the oral environment and cerebral blood flow in patients with mild cognitive impairment and dementia (either Alzheimer type dementia (ATD) or dementia with Lewy bodies (DLB)). We aimed to identify differences in the oral environment according to the underlying neurodegenerative disease.

METHODS

The participants were 25 patients with ATD and 25 patients with DLB who visited the Department of Dementia and Geriatric Medicine, Kanagawa Dental University Hospital. Patients were diagnosed with ATD and DLB by well-trained specialists certified by the Japanese Dementia Society and categorised as Level 3 or 4 by the Functional Assessment Staging of Alzheimer Disease scale. The correlation between oral environment (number of teeth, periodontal tissue, and oral function) and cerebral blood flow in each brain area calculated by single photon emission computed tomography was examined.

RESULTS

The DLB group showed a significant correlation between masticatory performance and cerebral blood flow in some areas, while no such correlation was observed in the ATD group. Significant correlations were found between periodontal pocket depth and bleeding on probing and cerebral blood flow in some areas in both groups, although the correlation was considerable in the ATD group.

CONCLUSIONS

The results of this study suggest that the association between changes in the oral environment and cerebral blood flow may differ among patients with ATD and DLB, depending on the underlying causative disease.

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.

Assessment of subjective and objective masticatory function among elderly individuals with mild cognitive impairment

BACKGROUND

Masticatory function is known to be related to cognitive ability; therefore, factors for improving masticatory function should be identified.

AIMS

This study aimed to identify factors influencing masticatory function associated with mild cognitive impairment (MCI) in elderly individuals.

METHODS

A total of 123 elderly participants [mean age: 76.5 ± 6.5 years; 82 females (66.7%), 41 males (33.3%)] were included. Cognitive function was evaluated by the Korean version of the Mini-Mental State Examination (KMMSE). Questionnaires for subjective evaluation were administered, and dynamic objective masticatory function evaluations, including chewing tests and bite force measurements, were performed. Intergroup differences were evaluated by the Wilcoxon rank-sum and chi-square test, and correlations between cognitive ability and masticatory function were evaluated by multilinear logistic regression.

RESULTS

The number of teeth, number of posterior teeth, bite force, masticatory ability index (MAI) and posterior support status showed significant differences between the normal (KMMSE > 23) and MCI (KMMSE ≤ 23) groups. However, only the MAI, representing dynamic masticatory performance, was significantly associated with MCI regardless of age, sex and removable prostheses. The number of teeth and posterior teeth, bite force, subjective masticatory ability and posterior occlusal support showed no significant association with MCI.

DISCUSSION

These results suggested the importance of chewing function for preventing the progression of cognitive impairment.

CONCLUSIONS

Considering that only the MAI was significantly associated with MCI, it is more important to improve chewing efficiency by harmonizing therapeutic prosthetics with the surrounding masticatory system than simply increasing the number of teeth to prevent or delay cognitive impairment in elderly individuals.

Activity diversity is associated with the prevention of frailty in community-dwelling older adults: The Otassha Study

Introduction

A prior study showed an association between diversity in daily activities (type, frequency, evenness) and frailty in older adults. However, the causality of this relationship is unclear. Therefore, this study aimed to clarify the relationship between activity diversity and frailty through a 2-year longitudinal study conducted among community-dwelling older adults.

Methods

We evaluated data from the 2018 and 2020 waves of the Otassha Study. Frailty was assessed using the Cardiovascular Health Study criteria, with pre-frail and frail participants defined as frail and the other participants categorized into the robust group. We enrolled a total of 207 participants who were not frail at baseline. Activity type, frequency, and evenness scores were calculated using an Activity Diversity Questionnaire. The association between each activity diversity score and the incidence of frailty was evaluated using logistic regression modeling (each diversity score was entered the model after Z-transformation).

Results

Of the 207 enrolled participants (median age, 73 years; age range, 65-91 years; 60.4% women), 64 (30.9%) had incident frailty during the follow-up period. A logistic regression analysis adjusting for sociodemographic and psychosomatic factors revealed odds ratios for activity type and evenness scores of 0.64 and 0.61, respectively (P < 0.05). These factors were significantly associated with the incidence of frailty.

Discussion

Activity type and evenness (except frequency) within daily activities were predictors of frailty during 2 years of follow-up. Engagement in diverse activities appears to be more effective in preventing frailty than does engagement in a few activities.

Relationship between tongue pressure and handgrip strength: A systematic review and meta-analysis

OBJECTIVES

Muscle strength decreases with age, causing a decline in physical and oro-facial function. However, the impact of physiological and pathophysiological factors on tongue pressure (TP) has not been clarified. The purpose of this systematic review and meta-analysis was to compare and analyse TP and handgrip strength (HGS) between individuals aged <60 and ≥60 years, gender and need for care (independent older adults (IC) and older adults receiving nursing care (NC)). Furthermore, the effect of HGS in physical function on TP was examined.

METHODS

Human clinical studies reporting HGS and TP were searched systematically using PubMed and Ichushi-Web published from 1969 to Nov 2021. Random-effects meta-regressions were performed to compare between subgroups and to examine the association between HGS and TP (α < .05).

RESULTS

Forty-four studies with a total of 10 343 subjects were included. TP and HGS values were significantly higher in people aged <60 years relative to ≥60 years and in IC relative to NC (all p < .001). Regarding gender, there was no significant difference in TP (p = .370). However, a significant gender-dependent difference in TP was observed in people aged <60 years (p < .001), but not in aged ≥60 years in IC group (p = .118) and aged ≥60 years in NC group (p = .895). There was a significant positive correlation of HGS and TP (p < .001).

CONCLUSIONS

Similar to decrease in HGS, age-related sarcopaenia seems to have an effect on oro-facial muscles like the tongue. Research on rehabilitation measures for oro-facial muscle strength, similar to HGS might be beneficial to improve the personally acquired oro-facial potential.

Functional quantification of oral motor cortex at rest and during tasks using activity phase ratio: A zero-setting vector functional near-infrared spectroscopy study

Oral frailty associated with oral hypokinesia may cause dementia. Functional near-infrared spectroscopy (fNIRS) can be used while the participants are in seating position with few restrictions. Thus, it is useful for assessing brain function, particularly oral motor activity. However, methods for identifying oral motor cortex (OMC) activation via the scalp have not been established. The current study aimed to detect OMC activation, an indicator of activity phase ratio (APR), which reflects increased oxygen consumption (0 &lt; [deoxyhemoglobin (ΔDeoxyHb) or 0 &lt; {[ΔDeoxyHb- oxyhemoglobin (ΔOxyHb)/√2]}, via fNIRS to accurately identify local brain activity. The APR, calculated via zero-set vector analysis, is a novel index for quantifying brain function both temporally and spatially at rest and during tasks. In total, 14 healthy participants performed bite tasks for 3 s per side for 10 times while in the sitting position. Then, time-series data on concentration changes in ΔOxyHb and ΔDeoxyHb were obtained via fNIRS. The anatomical location of the OMC was determined using a pooled data set of three-dimensional magnetic resonance images collected in advance from 40 healthy adults. In the zero-set vector analysis, the average change in ΔOxyHb and ΔDeoxyHb concentrations was utilized to calculate the APR percentage in 140 trials. The significant regions (z-score of ≥2.0) of the APR and ΔOxyHb in the task were compared. During the bite task, the APR significantly increased within the estimated OMC region (56–84 mm lateral to Cz and 4–20 mm anterior to Cz) in both the right and left hemispheres. By contrast, the ΔOxyHb concentrations increased on the bite side alone beyond the OMC region. The mean APR at rest for 2 s before the task showed 59.5%–62.2% in the left and right OMCs. The average APR for 3 s during the task showed 75.3% for the left OMC and 75.7% for the right OMC during the left bite task, and 65.9% for the left OMC and 80.9% for the right OMC during the right bite task. Interestingly, the average increase in APR for the left and right OMCs for the left bite task and the right bite task was 13.9% and 13.7%, respectively, showing almost a close match. The time course of the APR was more limited to the bite task segment than that of ΔOxyHb or ΔDexyHb concentration, and it increased in the OMC. Hence, the APR can quantitatively monitor both the resting and active states of the OMC in the left and right hemispheres. Using the zero-set vector-based fNIRS, the APR can be a valid indicator of oral motor function and bite force.

Investigation of the relationship between feeding problems and cognitive functions in premature children

Children with a history of premature birth may show various problems in feeding, and these problems may continue at school age. It is necessary to examine the role of cognitive functions in children's feeding with more detailed studies.Comparison of feeding problems and cognitive functions of premature and full-term children and examining the relationship between them. The parents of 60 children aged 6-10 completed the The Screening Tool of Feeding Problems, and the cognitive functions of the children were evaluated with the Dynamic Occupational Therapy Cognitive Assessment. Results are compared and correlations betweeen feeding problems and cognitive functions were examıned. Feeding problems of premature children are statistically higher than those born at term; their cognitive functions were statistically weaker (p < 0.001). It was found that feeding problems and cognitive functions were statistically related in premature children (p < 0.05). Feeding problems seen in premature children may be related to their weaker cognitive functions compared to their peers. It is important to evaluate cognitive functions and include them in the intervention in rehabilitation programs to be prepared for premature children with feeding problems.

Oral exercises significantly improve oral functions in people with mild and moderate dementia: a randomized controlled study

BACKGROUND

There have been no standard protocols of oral exercises for maintaining and improving oral function for people with dementia.

OBJECTIVE

This study aimed to determine the effects of home-based oral exercises on the oral function of people with mild to moderate dementia.

METHODS

Twenty-two participants at King Chulalongkorn Memorial Hospital were randomly assigned to exercise group (n = 11) or control group (n = 11). The exercise group was instructed to do three home-based oral exercises, consisting of tongue-strengthening, oral diadochokinesis (ODK), and mouth-opening exercises, for 3 months, while the control group received advice on oral health care. The maximum tongue pressure (MTP) was the primary outcome. MTP, ODK rates of /pa/, /ta/, /ka/, modified water swallowing test (MWST), and oral moisture were measured at baseline, and after 1, 2, and 3 months of training. The generalized estimating equation analysis was used to evaluate the effects of oral exercises on the oral function.

RESULTS

The MTP and all ODK rates in the exercise group were significantly increased after 3 months of training. There were significant interaction effects between time and intervention in MTP and all ODK rates. No significant interaction effects between time and intervention in oral moisture were found. The MWST scores in both groups did not change through the end of study and no adverse effects were reported.

CONCLUSION

Home-based oral exercises were found to be effective for improving tongue strength and tongue-lip motor function in people with mild to moderate dementia.

Patients with mild cognitive impairment diagnosed at dementia clinic display decreased maximum occlusal force: a cross-sectional study

Background

Previous research indicates that patients with mild cognitive impairment (MCI) are more likely to have poor oral health and impairments in oral functions, which may be due to few remaining teeth and impaired tongue and lip motor function. However, the oral health of those patients following comprehensive cognitive assessment by a dementia specialist has not been sufficiently investigated. Therefore, this study aimed to clarify the oral function of patients with MCI and the association between oral health and lower cognitive function.

Methods

This cross-sectional study included 96 participants (men: 35; women: 61; mean age: 73.3 ± 8.5 years) who visited a dementia clinic between December 2017 and January 2020. Participants’ cognitive function was assessed by a dementia specialist using neuropsychological and hematological tests and neuroimaging immediately after enrollment. The participants were divided into the healthy and MCI groups according to comprehensive cognitive assessment. Participants’ age, sex, body mass index, primary disease, education level, drinking habits, smoking habits, living environment, employment status, and exercise habits were evaluated. Moreover, oral outcomes, including the number of existing teeth, number of functional teeth (natural and prosthetic teeth which were occluded with antagonists), denture use, oral dryness, tongue and lip motor function, tongue pressure, occlusal force, masticatory ability, and swallowing ability were recorded. The Mann–Whitney U test, χ², and Fisher’s exact tests were used for between-group comparisons. Furthermore, logistic regression analysis using MCI diagnosis as the target variable was performed.

Results

A comprehensive evaluation of the cognitive function of the study participants by the dementia specialist revealed that 48 participants (mean age: 69.8 ± 8.8 years) were healthy and 48 (mean age: 76.9 ± 6.7 years) had MCI. MCI participants were significantly older (p < 0.001) and had significantly fewer existing teeth (p = 0.031) and lower maximum occlusal force (p = 0.019) than healthy participants. Age (odds ratio: 1.126, p = 0.002) and maximum occlusal force (odds ratio: 0.978, p = 0.048) were significantly associated with lower cognitive function.

Conclusions

Patients with MCI had poorer oral health than healthy individuals. Decreased maximum occlusal force was independently associated with lower cognitive function, even when adjusted for age and sex.

Decline of oral functions in old-old adults and their relationship with age and sex: The SONIC study

BACKGROUND

Many physical functions decline with aging, but it is not known whether oral functions vary according to sex or decline with aging, as it occurs with physical functions. The present study aimed to examine the association of sex, age, and elapsed years with occlusal force and tongue pressure using a generalized linear mixed-effect model (GLMM) over a 3-year period among old-old Japanese adults.

METHODS

Participants were community-dwelling older adults who participated in a survey (June 2014-March 2017) and a follow-up survey (July 2017-December 2019) after 3 years (n = 951: 70-year group, n = 466; 80-year group, n = 391; 90-year group, n = 94). Dental examinations including the number of teeth, occlusal force, and tongue pressure were conducted, and a GLMM was used to estimate the association of sex, age, and elapsed years with occlusal force and tongue pressure, adjusting for the number of teeth.

RESULTS

The GLMM showed that occlusal force was significantly associated with sex (reference; male, non-standardized coefficient: B = -66.9 [female], p < 0.001), age (reference; 70-year group, B = -81.7 [80-year group], p < 0.001, B = -87.2 [90-year group], p < 0.001), and the number of teeth (B = 13.8, p < 0.001), but did not significantly decrease with elapsed years. Tongue pressure was significantly associated with sex (reference; male, B = -0.94 [female], p = 0.034) and age (reference; 70-year group, B = -1.78 [80-year group], p < 0.001, B = -5.47 [90-year group], p < 0.001). Tongue pressure decreased significantly with elapsed years (B = -0.82, p < 0.001).

CONCLUSIONS

These findings suggest that tongue pressure significantly decreased over time, but occlusal force did not. Tongue-related muscles may be more susceptible to aging than masticatory muscles.

Association of Oral Hypofunction with Frailty, Sarcopenia, and Mild Cognitive Impairment: A Cross-Sectional Study of Community-Dwelling Japanese Older Adults

Oral hypofunction is a new concept that addresses the oral function of older adults. Few studies have investigated the relationship between oral hypofunction and general health conditions such as frailty, sarcopenia, and mild cognitive impairment. This paper explores these relationships in a large-scale, cross-sectional cohort study. The relationships of oral hypofunction with frailty, sarcopenia, and mild cognitive impairment were examined using data from 832 individuals who participated in the 2018 health survey of the residents of Tarumizu City, Kagoshima Prefecture, Japan. Individuals with frailty, sarcopenia, and mild cognitive impairment had significantly higher rates of oral hypofunction. Frailty was independently associated with deterioration of the swallowing function (odds ratio 2.56; 95% confidence interval, 1.26-5.20), and mild cognitive impairment was independently associated with reduced occlusal force (odds ratio 1.48; 95% confidence interval, 1.05-2.08) and decreased tongue pressure (odds ratio 1.77; 95% confidence interval, 1.28-2.43). There was no independent association found between sarcopenia and oral function. In conclusion, early intervention for related factors such as deterioration of the swallowing function in frailty, reduced occlusal force, and decreased tongue pressure in mild cognitive impairment could lead to the prevention of general hypofunction in older adults.

Factors Associated with Denture Non-use in Older Adults Requiring Long-Term Care

BACKGROUND

Evidence suggests that denture non-use is significantly associated with activities of daily living, oral function, and cognitive decline. Few studies have focused on the possibility that the indications for denture use may differ depending on the cognitive and physical functions in older adults requiring long-term care.

OBJECTIVES

The aim of this study was to elucidate the factors associated with denture non-use in older adults requiring long-term care.

METHODS

This cross-sectional study comprised 201 older adults (45 men and 156 women; average age = 86.2 ± 7.1 years) requiring long-term care in Japan. Those who did not require denture treatment were classified by dentists into denture-use and denture non-use groups. The severity of dementia was assessed using the Clinical Dementia Rating scale. Multiple logistic regression analyses were conducted to detect the factors significantly associated with denture non-use.

RESULTS

The proportion of participants without dentures was 58.2%. Multiple logistic regression analyses revealed that a moderate dementia (odds ratio [OR], 4.44; 95% confidence interval [CI] 1.18-16.71, p=0.027) and rinsing ability (OR 3.00; 95% CI 1.12-8.06; p=0.030) were significant factors related to the non-use of dentures.

CONCLUSION

Severity of dementia and rinsing ability were significantly associated with non-use of dentures. These findings indicate the necessity of evaluating oral and cognitive functions while planning denture treatment in older adults requiring long-term care.

Association between activity diversity and frailty among community-dwelling older Japanese: A cross-sectional study

PURPOSE

Deterioration of daily activities increases frailty risk. Most of the previous research has examined the association between frailty and specific activities; nevertheless, the diversity of daily activities is also important. Although the type, frequency, and evenness of daily activities have been proposed as indicators of activity diversity, the association between these indicators and frailty remains unclear. In this study, we examined the association between activity diversity and frailty in community-dwelling older adults.

MATERIALS AND METHODS

This cross-sectional study comprised 658 community-dwelling older adults aged ≥ 65 years who participated in comprehensive health check-ups in 2018. Frailty was defined using the Japanese version of the Cardiovascular Health Study criteria. Three indicators, type, frequency, and evenness of daily activities, were used to assess activity diversity across one week. Multiple logistic regression analyses were performed, with frailty as the dependent variable and the three activity diversity indicators as independent variables. Socio-demographic, physical, and mental functioning factors were adjusted as covariates.

RESULTS

Of the 658 participants (median age: 72 years; age range: 65-91 years; 60.5% women), 27 (4.1%) met the criteria for frailty. The frail group had significantly lower scores for type, frequency, and evenness of daily activities, as well as Mini-Mental State Examination scores (all at p < 0.01). We found significant independent associations in all activity diversity indicators with frailty, in multiple logistic models.

CONCLUSION

Activity diversity is independently associated with frailty in community-dwelling older adults.

Relationship between two pressure-sensitive films for testing reduced occlusal force in diagnostic criteria for oral hypofunction

OBJECTIVE

To measure the occlusal force in the same group of patients with the Dental Prescale 50H type R and the Dental Prescale II, examine the association between them, and determine the reference value for Dental Prescale II that corresponds to the 50H type R 200 N reference value used to make a diagnosis of oral hypofunction.

BACKGROUND

Reduced occlusal force, a measure of frailty in older persons, was previously determined with Prescale 50H type R pressure-sensitive film, but it has been replaced by the Prescale II.

MATERIALS AND METHODS

The study participants were 441 men and women aged ≥ 65 (mean, 71.8 ± 5.3) years. The occlusal force was measured with the two different types of pressure-sensitive film, and their association was examined. Receiver operating characteristic curves for the Prescale II measured values were created with the 200 N reference value used for the 50H type R film as the cut-off value.

RESULTS

The analysis set included 391 participants for whom measurements were obtained using both the 50H type R and the Prescale II. Linear regression analysis produced regression equations, and a ROC curve analysis provided reference values of 500 N for the Prescale II (without pressure filter) and 350 N for the Prescale II (with pressure filter).

CONCLUSION

In occlusal force tests for making a diagnosis of oral hypofunction, reference values for the Prescale II (without pressure filter) and for the Prescale II (with pressure filter) were determined. The findings suggested that the Prescale II can be used as a diagnostic examination for oral hypofunction.

Relationship between oral function and life-space mobility or social networks in community-dwelling older people: A cross-sectional study

OBJECTIVES

This study aimed to clarify the relationship between oral function and life-space mobility or social networks in order to explore approaches that prevent a decline in oral function.

MATERIALS AND METHODS

A total of 113 community-dwelling older people (mean age; 75.7 ± 7.3 years) who participated in preventive long-term care projects aimed at the maintenance or improvement of physical and mental functions were included in this study. The life-space assessment (LSA) was used to evaluate life-space mobility, while the Lubben Social Network Scale-6 (LSNS-6) was employed to assess social networks. Oral function was measured by maximum voluntary tongue pressure, oral diadochokinesis, the repetitive saliva swallowing test, and lip pressure. Indices of frailty were grip strength and the Kihon Checklist score. Multiple regression analysis was performed to clarify whether the LSA, LSNS-6, and frailty are associated with oral function.

RESULTS

The results of the Kihon Checklist showed that 63 participants (56%) were subjectively and at least slightly aware of a decline in oral function. LSA (B = 0.222, p < .001) and grip strength (B = 0.266, p = .003) associated with maximum voluntary tongue pressure. The goodness of fit of the predictive model was an adjusted R² value of .486. Other oral functions were not associated with any factors and the goodness of fit of the model was poor (Adjusted R²  < .1). LSNS-6 was not associated with any oral function.

CONCLUSIONS

Life-space mobility and grip strength were independent factors associating maximum voluntary tongue pressure, while social networks did not directly association oral function. This study suggests the necessity of a program that approaches both oral and physical functions through guidance for securing a certain amount of daily activity for older people at risk of or exhibiting a decline in maximum voluntary tongue pressure.

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.

Effect of oral health intervention on cognitive decline in community-dwelling older adults: A randomized controlled trial

PURPOSE

The incidence of dementia is rapidly increasing worldwide, especially in developed countries. Little is known regarding the effectiveness of dental intervention to prevent dementia or a decline in cognitive functions among community-dwelling older adults, but a few studies have reported a correlation between the lack of regular dental checkups and dementia. For that reason, this study aimed to investigate the effects of oral health intervention on cognitive functions in community-dwelling subjects with a mild cognitive decline via a randomized controlled trial.

PATIENTS AND METHODS

Fifty-five community-dwelling older adults with a Mini-Mental State Examination score of ≥21 to ≤26 who had not visited a dental clinic in the previous year were randomized to an intervention group (n = 28) or a control group (n = 29). The intervention group received monthly oral health intervention by dental hygienists for 8 months while the control group did not. Data on demographics, cognitive function and oral parameters were collected before and after the intervention.

RESULTS

Twenty-five subjects in the intervention group (mean age 77.0 years) and 25 in the control group (mean age 72.8 years) completed the study. Significant improvements were observed in the Trail Making Test (TMT)-A, TMT-B, bleeding on probing rate, oral diadochokinesis, tongue pressure and chewing ability in the intervention group (P < 0.05). There were also significant interactions between the TMT-A and TMT-B scores, oral diadochokinesis, tongue pressure and chewing ability (P < 0.05).

CONCLUSION

Oral health intervention by dental hygienists may be effective for improving the oral health and executive function of cognitive function assessed via TMT.

Variability in tongue pressure among elderly and young healthy cohorts: A systematic review and meta-analysis

OBJECTIVES

Tongue pressure (TP) is used for the diagnosis of oral hypofunction; however, the impact of several variables on TP is unclear. Therefore, the current systematic review and meta-analysis aimed to analyse the variability in tongue pressure among healthy individuals aged ≥60 years vs <60 years. Secondary outcomes were the influence of gender and the type of measuring device (Iowa Oral Performance Instrument (IOPI) vs JMS tongue pressure measurement device (JMS)).

METHODS

PubMed and the Japanese database Ichushi-Web were searched systematically by two independent reviewers for studies reporting TP values in healthy populations. Clinical studies published between 1959 and June 2020 with more than 10 participants, written in English, German or Japanese, were included. A random-effects meta-regression for aggregate-level data was applied (α < 0.05).

RESULTS

Sixty-eight studies reported TP for a total of 13 773 subjects aged <60 years (n = 3265) and ≥60 years (n = 10 508). TP was significantly higher in subjects <60 years (estimated weighted mean (EWM) ± standard error = 51.9 ± 1.28 kPa; 95% CI = 49.4-54.4) relative to those ≥60 (EWM = 34.7 ± 0.94 kPa; 95% CI = 32.8-36.5) (P < .001), men (EWM = 45.9 ± 2.09 kPa; 95% CI = 41.8-50.0) relative to women (EWM = 39.3 ± 1.68 kPa; 95% CI = 36.0-42.6) (P = .015) and when assessed with the IOPI (EWM = 51.9 ± 1.32 kPa; 95% CI = 49.3-54.5) compared to the JMS (EWM = 33.5 ± 0.63 kPa; 95% CI = 32.2-34.7) (P < .001). In terms of gender, there was no significant difference in TP among subjects ≥60 years (P = .282). However, in subjects younger than 60, a significant difference was observed (P = .004).

CONCLUSIONS

Healthy populations aged <60 years showed significantly higher TP than those aged ≥60 years. TP values ascertained by the IOPI are significantly higher than those obtained with the JMS.

Are Japanese Older Adults Rejuvenating? Changes in Health-Related Measures Among Older Community Dwellers in the Last Decade

During the last three decades, Japan has become one of the world's top countries for longevity, and the increase in average life expectancy is accompanied by a sharp rise in older population 65 years of age and above to ∼28%. This study aimed to examine the changes in major health-related measures, including a physical constitution, physical function, and functional capacity of community-dwelling Japanese older people in the last decade. From the data of 13 longitudinal cohort studies on aging conducted in Japan with a total of 13,441 older subjects, this study analyzed the changes in six indices that are related to health and functioning of the older people; height, weight, body mass index, walking speed, grip strength, and instrumental activity of daily living, between 2007 (±2 years) and 2017 (±2 years). Comparison of data for the two periods between subjects matched for age group and gender evidently showed better health status and a slower decline in most of the health-related measures in 2017 compared to a decade ago. The results of this study indicate that the phenomenon of "rejuvenation" is occurring among the new generation of Japanese older adults, and the importance of this older population as a social resource in the super-aged society should be reacknowledged.

Association between oral, social, and physical frailty in community-dwelling older adults

OBJECTIVES

Oral frailty (OF) has been shown to be a predictor of disability. Therefore, it is important to be able to identify factors associated with OF in order to prevent long-term dependence. The purpose of this study was to clarify the relationships between OF, social frailty (SF), and physical frailty (PF) in community-dwelling older adults, with the overarching aim of informing the future development of effective measures to prevent frailty.

METHODS

Oral, physical, and social function, nutritional and psychological status, and medical history were examined in 682 community-dwelling individuals (267 men, 415 women) aged ≥ 65 years. Ordinal logistic regression analysis with SF and PF as independent variables was performed with pass analysis to determine the relationship between the different types of frailty.

RESULTS

Logistic regression analysis revealed significant associations between OF and decline in social function, physical function, and nutritional status, and an increase in the number of medications used. Path analysis showed that SF was directly related to OF and that OF and SF were directly related to PF.

CONCLUSIONS

These findings suggest that a decline in social function may directly influence a decline in oral and physical function. The results of this study provide initial evidence, that may guide the future development of measures that aim to prevent and manage OF.

Development and validity of the Computer-Based Cognitive Assessment Tool for intervention in community-dwelling older individuals

Aim

The Mini‐Mental State Examination is a widely used cognitive assessment tool. However, it has several limitations, including the learning effect and interrater reliability. Therefore, we developed a Computer‐Based Cognitive Assessment Tool (CompBased‐CAT), which runs on a tablet or personal computer. In this study, we examined the validity and discrimination ability of the CompBased‐CAT.

Methods

Participants were recruited from the Otasha‐Kenshin study carried out in 2016. We included 773 community‐dwelling older individuals in Japan (332 men, 441 women, aged 65–97 years). CompBased‐CAT scores were converted to z‐scores, and the correlation with Mini‐Mental State Examination scores was examined using Pearson's correlation coefficient. Furthermore, the ability to discern cognitive impairment was examined using the receiver operating characteristic curve.

Results

The Pearson's correlation coefficient for the Mini‐Mental State Examination scores and each task component of the CompBased‐CAT ranged from 0.24 to 0.41 (P < 0.001), and the correlation coefficient of the total z‐scores was 0.51 (P < 0.001). The sensitivity, specificity and area under the receiver operating characteristic curve of the discriminating ability of the CompBased‐CATool for cognitive impairment were 0.81, 0.77 and 0.85, respectively.

Conclusions

The CompBased‐CAT certainly possesses validity, discriminating ability and utility as a new cognitive assessment tool in community‐dwelling older individuals. Geriatr Gerontol Int 2020; ••: ••–••.

Are Self-Reported Masticatory Ability and Regular Dental Care Related to Mortality?

AIM

The aim of the study was to examine whether a combination of self-reported masticatory ability and regular dental care is linked to mortality and issuance of new long-term care insurance (LTCI) service certifications.

METHODS

Older residents in institutions or in need of LTCI certification requirements were excluded, and self-administered questionnaires were sent to 5,400 older adults in 2013; these participants were followed for 5 years. The total response rate was 94.3%, and our final sample comprised 4,824 older adults (89.3%). We used 3 items to assess self-reported masticatory ability and regular dental care. These included (1) decline in chewing abilities of the posterior teeth on either side, (2) not brushing one's own teeth or dentures at least once a day, and (3) not visiting the dentist at least once a year.

RESULTS

The mean age of the participants at baseline was 75.9 years, and 58.4% of them were women. Main outcomes included mortality (n = 562) or new LTCI certification requirements (n = 1187) during the 5-year period. Multivariate analyses revealed that a poor score on masticatory ability and on regular dental care produced significant adverse health outcomes leading to earlier negative outcomes. The score is considered poor as it increases relative to the 0-point reference.

DISCUSSION

Regular dental care (both self-and professional care) and maintaining masticatory ability are both important. Hence, public activities focusing on preventive oral health from middle age onward is important.