Tooth loss mediates the association between smoking and an increased risk of dementia among older adults: The JAGES prospective cohort study.

AIM: Tooth loss has various causes; however, its cause-specific effects on health outcomes remain unclear. This study evaluated whether the association between past/current smoking and risk of dementia was mediated by tooth loss. MATERIALS AND METHODS: This 9-year-follow-up prospective cohort study targeted adults aged ≥65 years. Dementia incidence during 2013-2019, smoking status (never, past/current) in 2010 and the number of remaining teeth (≤19, ≥20) in 2013 were the outcome, exposure and mediator, respectively. We used causal mediation analysis to fit the Cox proportional hazards model and estimated the hazard ratio (HR) and 95% confidence interval (CI) of the natural indirect effect (NIE) of smoking on dementia incidence through tooth loss and their mediated proportions. RESULTS: Among 32,986 participants (mean age 72.6 years [1 SD = 5.4]; men 48.4%), the dementia incidence during follow-up was 2.11/100 person-years. Tooth loss significantly mediated the association between past/current smoking and dementia incidence; the NIE of fewer remaining teeth for past/current smokers compared to never smokers was HR = 1.03 (95% CI: 1.02-1.05), and the mediated proportion was 18.0%. CONCLUSIONS: Tooth loss significantly mediates the association between past/current smoking and an increased risk of dementia among older adults.

Associations between school-based fluoride mouth-rinse program, medical-dental expense subsidy policy, and children's oral health in Japan: an ecological study.

BACKGROUND: Dental caries are a common non-communicable disease among children. As a public health measure at the prefectural level, school-based fluoride mouth-rinse (S-FMR) program, medical/dental expense subsidy policies, and other factors may reduce the incidence of dental caries and tooth loss. Prefectures focusing on promoting oral health policies may promote both, but the interaction effect of implementing both subsidy policies and S-FMR at the prefectural level on caries prevention has not yet been examined. METHODS: We conducted an ecological study using two-wave panel data, prefecture-level aggregated data in Japan for 2016 and 2018. Coefficient and 95% confidence intervals (CI) were calculated for the dependent variables for oral health using mixed-effects linear regression analysis adjusted for possible confounders. Two dependent variables were used; the standardized claim ratio (SCR) of deciduous tooth extraction and 12-year-olds' decayed, missing, or filled permanent teeth (DMFT). Four independent variables were S-FMR, the SCR of dental sealants, prefectural income per person, and subsidy policy in three models: co-payment until children enter elementary school (n = 23), no co-payment until children enter elementary school (n = 7), and co-payment continuing beyond elementary school (n = 17). The effects of six interaction terms, each representing a unique pairing from the four independent variables, were individually calculated. RESULTS: S-FMR was negatively associated with the SCR of deciduous tooth extractions and DMFT (coefficient = -0.11, 95% CI -0.20; -0.01 and coefficient = -0.003, 95% CI -0.005; -0.001, respectively). No co-payment until children enter elementary school was positively associated with the SCR of deciduous tooth extraction compared to co-payment until children enter elementary school(coefficient = 11.42, 95% CI 3.29; 19.55). SCR of dental sealants was positively associated with the SCR of deciduous tooth extractions (coefficient = 0.12, 95% CI 0.06; 0.19) but negatively associated with DMFT (coefficient = -0.001, 95% CI -0.003; -0.0001). Per capita prefectural income was positively associated with the SCR of deciduous tooth extractions(coefficient = 0.01, 95% CI 0.001; 0.02). No interaction was found between S-FMR and the subsidy policy at both outcomes. CONCLUSION: High S-FMR utilization and no co-payment until children enter elementary school were associated with fewer deciduous tooth extractions. Also, S-FMR and dental sealant were associated with decreased DMFT.

The association between objective and subjective oral health conditions and the presence of anorexia of aging among Japanese older Adults1.

Anorexia of aging is a risk factor for malnutrition among older adults. This study aimed to evaluate the association between objective and subjective oral health and anorexia among independent older adults. This cross-sectional study targeted independent older adults aged ≥65 years who participated in the Japan Gerontological Evaluation Study conducted in 2022. The outcome variable was the presence of anorexia, as assessed by the Simplified Nutritional Appetite Questionnaire. Exposure variables were dental status (≥20 teeth, 10-19 teeth with/without dentures, and 0-9 teeth with/without dentures) as objective oral health and oral health-related quality of life measured by five items of the short version of the Oral Impacts on Daily Performances (OIDP) (eating, speaking, smiling, emotional stability, and enjoying with others) as subjective oral health. We fitted the Poisson regression model, including possible confounders, and estimated prevalence ratios (PRs) and 95% confidence intervals. Among 19,787 participants (mean age: 74.6 years [1SD = 6.2], male: 48.5%), 9.0% were classified as having anorexia. After adjusting possible confounders, those with ≤19 teeth had a higher proportion of experiencing anorexia compared to those with ≥20 teeth; however, the association was less pronounced among those with dentures (0-9 teeth with dentures: PR = 1.48 [1.31-1.68], and 0-9 teeth without dentures: PR = 2.08 [1.65-2.63]). Even after adjusting for dental status, each item of OIDP was significantly associated with the presence of anorexia (all p < 0.05). The results showed that both objective and subjective poor oral health were significantly associated with a higher probability of developing anorexia of aging. Therefore, improving both objective and subjective oral health through appropriate dental care could contribute to maintaining appetite in later life.

Compliance Trajectory and Patterns of COVID-19 Preventive Measures, Japan, 2020-2022.

COVID-19 remains a global health threat. Compliance with nonpharmaceutical interventions is essential because of limited effectiveness of COVID-19 vaccines, emergence of highly contagious variants, and declining COVID-19 antibody titers over time. We evaluated compliance with 14 nonpharmaceutical intervention-related COVID-19 preventive behaviors, including mask wearing, ventilation, and surface sanitation, in a longitudinal study in Japan using 4 waves of Internet survey data obtained during 2020-2022. Compliance with most preventive behaviors increased or remained stable during the 2-year period, except for surface sanitation and going out behaviors; compliance with ventilation behavior substantially decreased in winter. Compliance patterns identified from latent class analysis showed that the number of persons in the low compliance class decreased, whereas those in the personal hygiene class increased. Our findings reflect the relaxation of mobility restriction policy in Japan, where the COVID-19 pandemic continues. Policymakers should consider behavioral changes caused by new policies to improve COVID-19 prevention strategies.

Oral status and homebound status: A 6-year bidirectional exploratory prospective cohort study.

OBJECTIVES: Little is known about the association between oral status and homebound status, and there is a possibility of a bidirectional relationship between them. In this exploratory prospective cohort study, we examined the association between four oral status measurements and being homebound bidirectionally. METHODS: We used 2010-2016 panel data gathered from the Japan Gerontological Evaluation Study. All functionally independent participants aged 65 years or older (n = 26,579) were included in this study. Multiple imputation and Poisson regression were used for analyses. We adjusted for age, sex, education, comorbidity, and depressive symptoms. RESULTS: In the fully adjusted model, the prevalence ratio (PR) of being homebound at follow-up was 1.42 for having <20 remaining teeth, 1.28 for having chewing difficulty, 0.99 for having choking experience, and 0.94 for having dry mouth at baseline. Reversely, being homebound at baseline predicted having chewing difficulty at follow-up (PR = 1.17), while no significant association was demonstrated with having <20 teeth (PR = 1.00), choking experience (PR = 1.06), and dry mouth (PR = 1.02). CONCLUSION: Chewing difficulty and having <20 remaining teeth predicted homebound status after 6 years. Reversely, homebound status at baseline only predicted having chewing difficulty at follow-up. These findings may help to determine the oral frailty assessment measures for older people.

Dental prosthesis use is associated with higher protein intake among older adults with tooth loss.

BACKGROUND: Tooth loss is associated with reduced protein intake, which leads to sarcopenia and frailty in older adults. OBJECTIVE: To evaluate the protective effect of dental prostheses on decreased protein intake in older adults with tooth loss. METHODS: This cross-sectional study was based on a self-reported questionnaire targeting older adults. Data were obtained from the Iwanuma Survey of the Japan Gerontological Evaluation Study. We used % energy intake (%E) of total protein as the outcome and the use of dental prostheses and number of remaining teeth as explanatory variables. We estimated the controlled direct effects of tooth loss by fixing the use/non-use of dental prostheses based on a causal mediation analysis, including possible confounders. RESULTS: Among 2095 participants, the mean age was 81.1 years (1SD = 5.1), and 43.9% were men. The average protein intake was 17.4%E (1SD = 3.4) of the total energy intake. Among participants with ≥20, 10-19 and 0-9 remaining teeth, the average protein intake was 17.7%E, 17.2%E/17.4%E and 17.0%E/15.4%E (with/without a dental prosthesis), respectively. Compared to participants with ≥20 remaining teeth, those with 10-19 remaining teeth without a dental prosthesis did not have a significantly different total protein intake (p > .05). Among those with 0-9 remaining teeth without a dental prosthesis, total protein intake was significantly low (-2.31%, p < .001); however, the use of dental prostheses mitigated the association by 79.4% (p < .001). CONCLUSION: Our results suggest that prosthodontic treatment could contribute to maintaining protein intake in older adults with severe tooth loss.

Lower socio-economic status in adolescence is associated with poor oral health at an older age: Mediation by social and behavioural factors.

AIM: To examine the mediators between lower socio-economic status (SES) in adolescence and oral health at an older age to uncover the underlying mechanisms of the association. METHODS: Participants (n = 21 536) aged ≥65 years from the Japan Gerontological Evaluation Study were evaluated. The dependent variables were self-rated chewing difficulty and having ≤19 remaining teeth. The main independent variable was self-perceived SES in adolescence. The Karlson-Holm-Breen method was used for mediation analysis. RESULTS: Mean age of the participants was 74.8 years (standard deviation = 6.4), and 51.5% were female. Overall, 5598 (26.0%) participants reported chewing difficulty and 9404 (43.7%) had ≤19 remaining teeth. Lower SES in adolescence was associated with a higher prevalence of chewing difficulty (odds ratio [OR] = 1.38, 95%confidence interval [CI] = 1.29-1.48; total effect). After controlling for mediators, OR for lower SES in adolescence was 1.22 (95%CI = 1.13-1.30; direct effect) and 1.13 (95%CI = 1.11-1.16; indirect effect). Mediators, prominently the number of teeth and income, explained 39.3% of the associations. Lower SES in adolescence increased the odds of ≤19 remaining teeth by OR = 1.23 (95% CI = 1.16-1.31; total effect). After controlling for mediators, the OR for lower SES in adolescence was 1.03 (95%CI = 0.97-1.10; direct effect) and 1.19 (95%CI = 1.16-1.23; indirect effect). Mediators, prominently educational attainment, explained 85.0% of the associations. CONCLUSIONS: Lower SES in adolescence was associated with poor oral health at an older age through mediators. Approaches that consider social determinants from the beginning of the life course are required.

Longitudinal Association Between Oral Status and Cognitive Decline Using Fixed-effects Analysis.

BACKGROUND: Although the feasibility of randomized trials for investigating the long-term association between oral health and cognitive decline is low, deriving causal inferences from observational data is challenging. We aimed to investigate the association between poor oral status and subjective cognitive complaints (SCC) using fixed-effects model to eliminate the confounding effect of unobserved time-invariant factors. METHODS: We used data from Japan Gerontological Evaluation Study (JAGES) which was conducted in 2010, 2013, and 2016. ß regression coefficients and 95% confidence intervals [CIs] were calculated using fixed-effects models to determine the effect of deteriorating oral status on developing SCC. Onset of SCC was evaluated using the Kihon Checklist-Cognitive function score. Four oral status variables were used: awareness of swallowing difficulty, decline in masticatory function, dry mouth, and number of teeth. RESULTS: We included 13,594 participants (55.8% women) without SCC at baseline. The mean age was 72.4 (standard deviation [SD], 5.1) years for men and 72.4 (SD, 4.9) years for women. Within the 6-year follow-up, 26.6% of men and 24.9% of women developed SCC. The probability of developing SCC was significantly higher when participants acquired swallowing difficulty (ß = 0.088; 95% CI, 0.065-0.111 for men and ß = 0.077; 95% CI, 0.057-0.097 for women), decline in masticatory function (ß = 0.039; 95% CI, 0.021-0.057 for men and ß = 0.030; 95% CI, 0.013-0.046 for women), dry mouth (ß = 0.026; 95% CI, 0.005-0.048 for men and ß = 0.064; 95% CI, 0.045-0.083 for women), and tooth loss (ß = 0.043; 95% CI, 0.001-0.085 for men and ß = 0.058; 95% CI, 0.015-0.102 for women). CONCLUSION: The findings suggest that good oral health needs to be maintained to prevent the development of SCC, which increases the risk for future dementia.

The lack of opportunity to eat together is associated with an increased risk of weight loss among independent older adults: a prospective cohort study based on the JAGES.

OBJECTIVE: the present study aimed to investigate the relationship between the frequency of eating together and the risk of weight loss in older adults. METHODS: this was a three-year follow-up prospective cohort study based on a self-reported questionnaire. We used data from the Japan Gerontological Evaluation Study (JAGES) conducted in 2016 and 2019. The participants were independent older adults aged ≥65 years in Japan. We used >5% weight loss during follow-up as the outcome variable and frequency of eating together as the explanatory variable. The relative risks (RRs) and 95% confidence intervals (95% CIs) were estimated based on the Poisson regression model with a Huber-White sandwich estimator for standard errors, including possible confounders. RESULTS: among 56,919 participants, the mean age was 73.0 years (1SD = 5.5) at baseline, and 47.9% were male. About 15.1% (n = 8,596) of the participants experienced >5% weight loss during follow-up. The proportion of each category of the eating together frequency was 36.6% for 'every day', 10.3% for 'several times a week', 26.8% for 'several times a month', 20.5% for 'several times a year' and 5.8% for 'seldom'. Compared to 'every day', only 'several times a year (RR = 1.07, 95% CI = 1.01-1.13)' and 'seldom (RR = 1.17, 95% CI = 1.08-1.27)' were significantly associated with the increased risk of >5% weight loss. CONCLUSION: there is a temporal association between less frequent opportunities to eat together and the increased risk of weight loss among independent older adults.

Association of poor dental status with eating alone: A cross-sectional Japan gerontological evaluation study among independent older adults.

Eating alone is reported to deteriorate health; however, the relationship between eating alone and poor dental health remains unclear. This cross-sectional study aimed to investigate the association between poor dental health and eating alone. Data of participants (n = 156,287) aged ≥65 years from the Japan Gerontological Evaluation Study were evaluated using logistic regression to estimate adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for the association between dental status, including prosthesis use, and eating status. Differences in these associations according to living status were also examined. The mean age of participants was 73.7 (SD = 6.0) years. The percentages of participants eating alone with 20 or more teeth, 10-19 teeth with dental prostheses, 0-9 teeth with dental prostheses, 10-19 teeth without dental prostheses, and 0-9 teeth without dental prostheses were 13.8%, 16.0%, 18.6%, 18.9%, and 27.0%, respectively. After adjusting for covariates, participants with 0-9 teeth without any dental prosthesis showed a significantly higher odds ratio for eating alone (OR = 1.81, 95% CI = 1.58-2.07) than those with 20 or more teeth. Among participants with poorer dental status, the probability of eating alone was higher in those living alone than in those living with others. Among older adults, poor dental status was significantly associated with eating alone, and this association was stronger among those living alone. Maintaining better dental status by using a dental prosthesis might reduce the risk of eating alone, especially for those living alone.

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

BACKGROUND: Bidirectional association between oral health, including tooth loss and oral hypofunction, and cognitive impairment can induce time-varying confounding in association with dementia. This study aimed to investigate the association between oral health and the development of dementia among older adults, considering cognitive impairment as a time-varying confounder. METHODS: This nine-year follow-up cohort study targeted independent older adults aged ≥65 years who participated in the Japan Gerontological Evaluation Study. The exposure variables were self-reported poor oral health (≤19 remaining teeth, edentulousness, chewing difficulty, swallowing problems, and xerostomia), which were assessed in 2010 and 2013. The outcome variable was the incidence of dementia between 2013 and 2019, which was obtained from the municipalities' administrative database. Furthermore, in 2010 and 2013, we considered cognitive impairment as a time-varying confounder and treated it based on a marginal structural model (MSM), including possible baseline confounders. Oral health and cognitive impairment were assessed using the items of Kihon checklist. We employed a Cox proportional hazards model with a stabilized inverse probability weight and estimated hazard ratios (HRs) and 95% confidence intervals (CIs). RESULTS: Among 37,556 participants (mean age: 72.8 years [1 SD = 5.5], males: 46.8%), the dementia incidence rate was 2.2/100 person-year. The proportions of those with ≤19 remaining teeth, edentulousness, chewing difficulty, swallowing problems, and xerostomia were 61.3%, 11.0%, 24.4%, 14.7%, and 19.2%, respectively. From the regression analysis based on MSM, ≤19 remaining teeth (HR = 1.12, 95% CI = 1.03-1.23), edentulousness (HR = 1.20, 95% CI = 1.09-1.32), chewing difficulty (HR = 1.11, 95% CI = 1.02-1.21), and xerostomia (HR = 1.10, 95% CI = 1.01-1.20) were significantly associated with an increased risk of dementia; however, swallowing problems were not significantly associated with dementia onset (p > 0.05). CONCLUSIONS: Even after considering time-varying confounding by cognitive function at baseline and follow-up, we observed significant associations between poor oral health and increased risk of dementia among older adults.

Dental prosthesis use moderates association between tooth loss and risk of depressive symptoms in older adults with severe tooth loss: The JAGES cohort trial.

PURPOSE: Depression is a leading cause of disability. Although tooth loss increases the risk of depressive symptoms, it is unclear whether dental prosthesis use moderates this risk. This study aimed to investigate whether dental prosthesis use moderates the association between tooth loss and new depressive symptoms in older adults. METHODS: This cohort study used data from the 2016 and 2019 Japan Gerontological Evaluation Study (JAGES). The participants were independent older adults aged ≥65 years without depressive symptoms in 2016. The onset of depressive symptoms in 2019 was the outcome variable. The explanatory variables were dental status (≥20 teeth, 10-19 teeth with or without dental prostheses, and 0-9 teeth with or without dental prostheses) in 2016. Risk ratios (RRs) and 95% confidence intervals (CIs) were estimated using Poisson regression models with potential confounders as covariates. RESULTS: The analysis included 50,169 participants (mean age: 72.8 [standard deviation, 5.4] years). During follow-up, the incidence of depressive symptoms was 11.3%. Compared to those who had ≥20 teeth, the RR of depressive symptom onset was highest among those who had 0-9 teeth without dental prostheses (RR, 1.27; 95% CI, 1.04-1.56), after the adjustment for confounders. However, this risk was lower in those with 0-9 teeth and dental prostheses (RR, 1.08; 95% CI, 1.01-1.15). CONCLUSIONS: These data highlight the potential of dental prostheses as an important factor in reducing the risk of depressive symptoms among individuals with severe tooth loss.

Exposure to household dysfunction at childhood and later number of teeth among older Japanese adults: A life course study from the Japan Gerontological Evaluation Study.

OBJECTIVES: The aim of this retrospective cohort study was to investigate the life course association between exposure to two household dysfunctions (father violence against mother and parental divorce) at childhood (≤18 years) with later number of remaining teeth (≥65 years) in functionally independent older Japanese population. This was the first study to investigate this research question in the Asian context. METHODS: The Japan Gerontological Evaluation study (JAGES) self-reported retrospective data gathered in 2013 was used (n = 21,604). Each household dysfunction was binary variable (Yes/No), while the five categories of the number of remaining teeth were ≥20, 10-19, 5-9, 1-4, and no teeth. Sex-stratified ordered logistic regression models were used to calculate the odds ratios (OR) of having fewer teeth. The models were adjusted for age, economic adversity in childhood, educational attainment, comorbidities, and smoking status. RESULTS: Overall, 46.4% were men and a total of 1149 participants (5.3%) experienced household dysfunction at childhood [men = 642 (6.4%), women = 507 (4.4%)]. The regression models showed higher OR of having fewer teeth among men who experienced a household dysfunction [OR = 1.16; 95% Confidence interval (CI) = 1.00-1.36] than men who did not. This association was not observed among women [OR = 0.94; 95% CI = 0.79-1.13]. Similar magnitude and direction of the association was observed among men but not among women when the two components of household dysfunction were used separately and aggregately as exposure variables. CONCLUSION: An exposure to a household dysfunction at childhood was associated with having fewer teeth in later life among men but not among women.

Oral Hypofunction and Risk of Weight Change among Independent Older Adults.

Oral health is essential for nutritional status; however, little is known about its association with weight change. This study aimed to investigate whether the risk of weight change differs according to the presence of each important component of oral hypofunction (fewer remaining teeth, low chewing efficiency, swallowing problems, and xerostomia) among independent older adults. This was a three-year follow-up cohort study based on self-reported questionnaires. The participants were independent older adults aged ≥65 from the Japan Gerontological Evaluation Study (JAGES). We used >5% weight loss/gain during follow-up as the outcome variables, and the number of remaining teeth (≥20/10-19/0-9), the presence of chewing difficulty, swallowing problems, and xerostomia (yes/no) as the exposure variables. We fitted the Poisson regression model, including possible confounders to estimate the risk ratios (RRs) and 95% confidence intervals (CIs). For weight loss, RRs were significantly higher among those with 0-9 remaining teeth (RR = 1.17; 95% CI = 1.11-1.23), chewing difficulty (RR = 1.12; 95% CI = 1.07-1.16), and xerostomia (RR = 1.11; 95% CI = 1.06-1.16), but there was no significant association with swallowing problems (RR = 1.01; 95% CI = 0.97-1.06). For weight gain, we also found similar associations with oral hypofunction. Oral hypofunction among older adults could have non-negligible health impacts on nutritional status.

Co-Payments and Inequality in Gingival Bleeding and Dental Visits.

OBJECTIVES: Japan's universal health insurance covers a wide range of dental treatments, and the co-payment rates differ by age. We investigated whether the inequality in gingival bleeding and dental visits was smaller amongst those with lower co-payment rates. METHODS: This cross-sectional study used data from the 2019 Japan Gerontological Evaluation Study. The participants were functionally independent adults aged 65 years or older. The dependent variables were current gingival bleeding as a symptom of periodontal diseases and dental nonattendance for treatment in the past year. The independent variables were ridit scores of equivalent income and educational status. For covariates, we used age, sex, and the number of remaining teeth. To evaluate the inequalities, we used the slope index of inequality (SII) and the relative index of inequality (RII). We also conducted stratified analyses by co-payment rates (30%, 20%, and 10%) to clarify the difference in inequalities by co-payment rate. RESULTS: A total of 15,389 participants were included in the analysis; their mean age was 71.8 (SD = 4.1) and 51.8% were women. There were significant absolute and relative inequalities in gingival bleeding and dental visits by equivalent income and education. With regards to educational status, inequalities were lower with a decrease in the co-payment rate. In particular, relative inequality by education in gingival bleeding was the largest amongst the 30% co-payment group (RII, 1.918; 95% confidence interval [CI], 1.386 to 2.656). For gingival bleeding, the absolute and relative inequality by equivalent income were not significant amongst the 10% co-payment group (SII, -0.003; 95% CI, -0.003 to 0.028; RII, 1.006; 95% CI = 0.676 to 1.498). CONCLUSIONS: A low co-payment rate was associated with smaller inequalities in gingival bleeding and dental visits by equivalent income and educational status.

Education-related inequalities in oral health among older adults: Comparing Singapore and Japan.

OBJECTIVES: Oral health inequalities exist worldwide, and cross-country comparisons can provide valuable insights into country-level characteristics contributing to such inequalities. However, comparative studies in Asian countries are limited. This study examined the magnitude of education-related oral health inequalities in older adults in Singapore and Japan. METHODS: Longitudinal data for older adults, aged ≥65 years, from the Panel on Health and Ageing of Singaporean Elderly (PHASE; 2009, 2011-2012, and 2015) and Japan Gerontological Evaluation Study (JAGES; 2010, 2013, and 2016) were used. Dependent variables were being edentate and having a minimal functional dentition (MFD; i.e. ≥20 teeth). The absolute and relative inequalities were calculated using the slope index of inequality (SII) and relative index of inequality (RII) for educational level [low (<6 years); middle (6-12 years); high (>12 years)] in each country. RESULTS: A total of 1032 PHASE participants and 35 717 JAGES participants were included. At baseline among PHASE participants, 35.9% were edentate and 24.4% had MFD, while among JAGES participants, 8.5% were edentate and 42.4% had MFD. The prevalence of low, middle and high educational levels for PHASE was 76.5%, 18.0% and 5.5%, and for JAGES were 0.9%, 78.1% and 19.7%, respectively. Older adults in Japan had lower education-related inequalities for being edentate [for both SII (-0.53, 95% CI = -0.55 to -0.50) and RII (0.40, 95% CI = 0.33-0.48)] and for not having MFD for both SII (-0.24, 95% CI = -0.27 to -0.20) and RII (0.83, 95% CI = 0.79-0.87) compared to Singapore. CONCLUSIONS: Education-related inequalities for being edentate and not having MFD were higher among older adults in Singapore compared to Japan.

Does online communication mitigate the association between a decrease in face-to-face communication and laughter during the COVID-19 pandemic? A cross-sectional study from JACSIS study.

Laughter has a protective effect on human health. The spread of coronavirus disease 2019 (COVID-19) has changed opportunities for face-to-face communication and might decrease opportunities for laughter. This cross-sectional study aimed to investigate whether the decrease in face-to-face communication during the COVID-19 pandemic is associated with a decrease in laughter. Additionally, we investigated whether an increase in online communication mitigates this association. Data from the "Japan COVID-19 and Society Internet Survey (JACSIS)," conducted between August and September 2020, were used. Participants aged 15-79 years were included in this study. The outcome was a decrease in laughter before the onset of the COVID-19 pandemic. The explanatory variables were decreased face-to-face communication with friends and increased online communication (text message, telephone, and video contact). Causal mediation analysis was used to calculate prevalence ratios (PRs) and 95 % confidence intervals (CIs) of the controlled direct effects of increased online communication. Furthermore, the proportions eliminated (PEs) by an increase in online communication were calculated. Among the 25,482 participants, 40.4 % had decreased face-to-face communication and 21.4 % had a decreased frequency of laughter. After adjusting for confounders, a decrease in face-to-face communication was significantly associated with a decrease in laughter (PR = 1.62, 95 %CI = 1.55-1.70). PEs for decrease in laughter were 27.2 % (95 %CI = -2.0 to 56.4) for text-based communication, 36.1 % (95 %CI = 12.3-59.8) for telephone-based communication, and 28.6 % (95 %CI = 0.6-56.6) for video-based communication. Although a decrease in face-to-face communication was associated with a decrease in laughter during the COVID-19 pandemic, online communication, particularly telephone-based communication, mitigated this association.

Large Contribution of Oral Status for Death Among Modifiable Risk Factors in Older Adults: The Japan Gerontological Evaluation Study (JAGES) Prospective Cohort Study.

BACKGROUND: Oral diseases are preventable and modifiable, but highly prevalent, and cause worse oral status. Particularly, tooth loss has increased in aging societies. However, studies on population-attributable risks of modifiable risk factors for mortality have neglected oral status. This study aimed to investigate the impact of modifiable risk factors on mortality, including oral status. METHODS: This cohort study used the Japan Gerontological Evaluation Study data, including participants aged ≥65 years. The outcome was death between August 2010 and March 2017. We calculated the hazard ratios (HRs) and population attributable fraction (PAF) of modifiable risk factors (oral status, hypertension, depression, heart disease, diabetes, physical activity, smoking status, and alcohol drinking history) for mortality. RESULTS: Analyses included 24 175 men and 27 888 women (mean age: 73.8 [6.0] and 74.2 [6.1], respectively). In men, after adjusting for covariates, having no teeth showed the highest hazard ratio (HR = 1.67, 95% confidence interval [CI] = 1.51-1.86) among the modifiable risk factors, and the PAF for the number of teeth (18.2%) was the second largest following age. In women, having no teeth had the third largest HR (HR = 1.37, 95% CI = 1.19-1.56) following current and former smoking. The PAF for the number of teeth (8.5%) was the sixth largest, which was larger than that of smoking status (4.8%). CONCLUSIONS: In the older population, the HR and PAF of the number of teeth on mortality were sufficiently large compared with other modifiable risk factors, especially in men. Therefore, maintaining good oral status should be included more in global health policies.

Oral status and incident functional disability: A 9-year prospective cohort study from the JAGES.

INTRODUCTION: The population-attributable risk of oral status for incident functional disability remains unknown. We investigated the impact of a range of oral statuses (number of remaining teeth, chewing difficulty, dry mouth, and choking) on incident functional disability. METHODS: Participants (n = 44,083) aged ≥ 65 years from the Japan Gerontological Evaluation Study were evaluated. The outcome variable was incident functional disability, and the explanatory variables were four select oral statuses. The possible confounders were included as covariates. Using the Cox proportional hazards model, we calculated hazard ratios (HRs), 95% confidence intervals (CIs), and their population-attributable fractions (PAFs). RESULTS: The mean age of the participants was 73.7 (standard deviation=6.0) years at baseline, and 53.2% were women. A total of 8,091 participants (18.4%) developed functional disabilities during the follow-up period. Among the four oral statuses, the incidence rate of functional disability was the highest in those with chewing difficulty (3.27/100 person-years), followed by those with dry mouth (3.20/100 person-years), choking (3.10/100 person-years), and ≤19 remaining teeth (2.89/100 person-years). After adjusting for all covariates, chewing difficulty showed the highest risk of functional disability (HR=1.22, 95%CI=1.16-1.28), followed by ≤19 remaining teeth (HR=1.18, 95%CI=1.12-1.25), dry mouth (HR=1.18, 95%CI=1.12-1.24), and choking (HR=1.10, 95%CI=1.04-1.17). Regarding PAF, ≤19 remaining teeth (12.0%) were the largest, followed by chewing difficulty (7.2%), dry mouth (4.6%), and choking (1.9%). CONCLUSIONS: Maintaining a good oral status may reduce the risk of functional disability later in life. Given its population contribution, tooth loss had the largest impact among the four oral conditions.

Association between dietary pattern and insomnia symptoms among independent older adults: A cross-sectional study based on JAGES.

BACKGROUND: Poor diet can cause sleep disorders; however, this association has not been established in older populations. This study investigated the association between dietary patterns and insomnia symptoms in independent older adults. METHODS: This cross-sectional study targeted independent older Japanese adults aged ≥74 years. We used insomnia symptoms classified into three domains: difficulty initiating sleep (DIS), difficulty maintaining sleep (DMS), and insomnia. These symptoms were assessed as dependent variables by a self-reported questionnaire. Dietary patterns (DP), identified by principal component analysis of a self-administered diet history questionnaire, were used as independent variables. Poisson regression analysis was used to estimate the prevalence ratios and 95% confidence intervals with adjustment for potential confounders. RESULTS: Among 1,311 participants (mean age = 80.1; women, 48.5%), we identified three dietary patterns: DP1 was characterized by a high intake of vegetables, soy products, and fruits and a low intake of rice; DP2 was characterized by a high intake of fish, chicken, processed meat, and noodles and a low intake of soy products; and DP3 was characterized by a lower intake of fruits and confectionaries. Higher DP1 scores were significantly associated with a lower prevalence of DIS (p-for-trend = 0.012). A higher DP2 score was significantly associated with a higher prevalence of insomnia (p-for-trend = 0.032). There was no significant association between DP3 and insomnia symptoms (p-for-trend >0.05). CONCLUSION: Our results highlighted that a dietary pattern with a high intake of vegetables, soy products, and fruits may contribute to reducing insomnia symptoms among independent older adults.