Frequency of social participation by types and functional decline: A six-year longitudinal study

Social participation is effective for preventing functional decline in older people. However, researchers have not fully explored how different frequencies of social participation by type. We aimed to clarify the relationship between the frequency of social participation by type and functional decline. We used data from the Japan Gerontological Evaluation Study, which consists of individuals aged 65 years and older who were not eligible to receive public long-term-care insurance benefits. From 13 municipalities, 51,968 respondents who met the criteria were included in the analysis. We used a sex-stratified Cox proportional hazards model. The outcome was the new incidence of functional decline during a six-year follow-up, and the exposure was the frequency of social participation of one of the following six types: sports, hobbies, volunteering, neighborhood, senior clubs, and industry groups. The frequency was categorized as "never," "a few times a year," "once or twice a month," and "once a week or more." We set non-participation in each activity as the reference, and we adjusted for 12 potential confounders (i.e., sociodemographic and health-related factors). After we adjusted for confounders, participation in sports and hobbies once or twice a month, once a week or more was protectively associated with functional decline. We found a similar association for participation in neighborhood a few times a year. Our findings demonstrate the importance of considering the effects of different types and frequencies of activities when promoting social participation among older people as part of public health policies.

Cooking skills modify the association between oral health and mortality

Poor oral health has been linked to an increased risk of mortality. People with good cooking skills may be able to cope with problems caused by oral dysfunction, such as restricted food choice. This study investigated whether cooking skills modified the association between oral health status and mortality. A 3-year follow-up was conducted among participants of the Japan Gerontological Evaluation Study, a population-based cohort study of Japanese adults aged 65-101 years. Oral health assessment comprised number of teeth and three oral functions (awareness of swallowing difficulty, decline in masticatory function, and dry mouth). Cooking skills were assessed using a valid scale adapted for Japanese participants. Mortality from 2016 to 2019 was analysed for 10,121 respondents. Cox regression models were used to estimate hazard ratios for mortality risk adjusting for potential confounders, including sociodemographic factors and health status. During the follow-up, there were 488 deaths (4.8% of all participants). Both fewer teeth and poor oral function were associated with a greater mortality risk. Cooking skills modified the association only for oral function. Stratification by cooking skill score showed that the hazard ratios for ≥2 oral difficulties (vs. none) was 2.06 (95% confidence interval: 1.43-2.96) among those with low cooking skills and 1.25 (95% confidence interval: 0.92-1.71) among those with high cooking skills after adjusting for potential confounders. Improving cooking skills may be key to mitigating health risks owing to poor oral functions.

Hobby engagement and mental wellbeing among people aged 65 years and older in 16 countries

Growing aging populations pose a threat to global health because of the social and psychological challenges they experience. To mitigate this, many countries promote hobby engagement to support and improve mental health. Yet, it remains unclear whether there is consistency in benefits across different national settings. We harmonized measures of hobby engagement and multiple aspects of mental wellbeing across 16 nations represented in five longitudinal studies (N = 93,263). Prevalence of hobby engagement varied substantially across countries, from 51.0% of Spanish respondents to 96.0% of Danish respondents. Fixed effects models and multinational meta-analyses were applied to compare the longitudinal associations between hobbies and mental wellbeing. Independent of confounders, having a hobby was associated with fewer depressive symptoms (pooled coefficient = -0.10; 95% confidence intervals (CI) = -0.13, -0.07), and higher levels of self-reported health (pooled coefficient = 0.06; 95% CI = 0.03, 0.08), happiness (pooled coefficient = 0.09; 95% CI = 0.06, 0.13) and life satisfaction (pooled coefficient = 0.10; 95% CI = 0.08, 0.12). Further analyses suggested a temporal relationship. The strength of these associations, and prevalence of hobby engagement, were correlated with macrolevel factors such as life expectancy and national happiness levels but overall, little variance in findings was explained by country-level factors (<9%). Given the relative universality of findings, ensuring equality in hobby engagement within and between countries should be a priority for promoting healthy aging.

Participation in Community Gathering Places and Subsequent Health and Well-Being: An Outcome-Wide Analysis

Background and Objectives

Evidence remains inadequate regarding the benefits of participation in community gathering places, which is Japan's primary strategy for preventing functional disability in older adults, in other domains of health and well-being. This longitudinal study examined the associations of participation in community gathering places with an array of subsequent health and well-being outcomes among older adults.

Research Design and Methods

We used 3-wave data (2013, 2016, and 2019) from Japan Gerontological Evaluation Study (n = 5 879 or 4 232 depending on the outcome). Our exposure was participation in community gathering places in 2016. We assessed 34 health/well-being outcomes in 2019 across 6 domains. We adjusted for pre-baseline covariates including prior outcome values in 2013.

Results

Compared with nonparticipation, participation in community gathering places was associated with some outcomes in the following 3 domains: physical/cognitive health (better higher-level functional capacity), social well-being (more frequent participation in hobby groups, senior citizens clubs, learning or cultural groups, and seeing more friends within a month), and prosocial/altruistic behaviors (more frequent participation in volunteering; after Bonferroni correction as p < .0015, .05/34).

Discussion and Implications

Evidence was mixed and more modest for the outcomes in three other domains, mental health, psychological well-being, and health behaviors. Promoting participation in community gathering places may not only fulfill its original goal (ie, preventing functional disability) but also enhance other domains of human well-being, potentially by increasing social interactions.

Group leisure activities are associated with a lower risk of dementia than individual leisure activities: A 6-year longitudinal study from the Japan Gerontological Evaluation Study (JAGES)

Participating in group leisure activities may lower the risk of dementia compared with doing leisure activities alone. However, only some studies have examined the differences. In this study, we sought to determine whether the incidence of dementia risk differs according to the implementation status of leisure activities (participation in a group or alone). The association between the implementation status of leisure activities and the risk of dementia was examined using Cox proportional hazards models in the 6-year (2010-2016) cohort data of 50,935 participants (23,533 males and 27,402 females) aged 65 years or older of the Japan Gerontological Evaluation Study. Over six years of follow-up, 5395 respondents (10.6%) developed dementia. After adjusting for potential confounders, such as depression and social support, the implementation status of leisure activities was associated with a lower dementia risk in participants who engaged in group leisure activities (hazard ratio [HR], 0.79; 95% confidence interval [CI], 0.73-0.85) and a higher dementia risk in those without leisure activity (HR, 1.30; 95% CI, 1.22-1.39), in comparison with those engaging in leisure activities alone. Engagement in group leisure activities may be associated with a reduced risk of dementia.

Machine Learning-Based Prediction of Functional Disability: a Cohort Study of Japanese Older Adults in 2013-2019

BACKGROUND

It is important to identify older adults at high risk of functional disability and to take preventive measures for them at an early stage. To our knowledge, there are no studies that predict functional disability among community-dwelling older adults using machine learning algorithms.

OBJECTIVE

To construct a model that can predict functional disability over 5 years using basic machine learning algorithms.

DESIGN

A cohort study with a mean follow-up of 5.4 years.

PARTICIPANTS

We used data from the Japan Gerontological Evaluation Study, which involved 73,262 people aged  ≥ 65 years who were not certified as requiring long-term care. The baseline survey was conducted in 2013 in 19 municipalities.

MAIN MEASURES

We defined the onset of functional disability as the new certification of needing long-term care that was ascertained by linking participants to public registries of long-term care insurance. All 183 candidate predictors were measured by self-report questionnaires.

KEY RESULTS

During the study period, 16,361 (22.3%) participants experienced the onset of functional disability. Among machine learning-based models, ridge regression (C statistic = 0.818) and gradient boosting (0.817) effectively predicted functional disability. In both models, we identified age, self-rated health, variables related to falls and posture stabilization, and diagnoses of Parkinson's disease and dementia as important features. Additionally, the ridge regression model identified the household characteristics such as the number of members, income, and receiving public assistance as important predictors, while the gradient boosting model selected moderate physical activity and driving. Based on the ridge regression model, we developed a simplified risk score for functional disability, and it also indicated good performance at the cut-off of 6/7 points.

CONCLUSIONS

Machine learning-based models showed effective performance prediction over 5 years. Our findings suggest that measuring and adding the variables identified as important features can improve the prediction of functional disability.

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.

"What Did You Do in the War, Daddy?": Paternal Military Conscription During WWII, Economic Hardship and Family Violence in Childhood, and Health in Late Life in Japan

Childhood adversity is a risk factor for poor health in late life and includes economic hardship and family violence, whose prevalence is high among offspring of military conscripted father. We assessed the association between paternal military conscription (PMC) and paternal war death (PWD) during Second World War and self-rated health (SRH) among older adults in Japan. Data were obtained from a population-based cohort of functionally independent people aged 65 years or older from 39 municipalities across Japan in 2016. Information on PMC and SRH was obtained through a self-report questionnaire. A total of 20,286 participants were analyzed with multivariate logistic regression to investigate the association between PMC, PWD, and poor health. Causal mediation analysis was performed to see whether childhood economic hardship and family violence mediated the association. Among participants, 19.7% reported PMC (including 3.3% PWD). In the age- and sex-adjusted model, older people with PMC showed higher risk of poor health (odds ratio [OR]: 1.16, 95% confidence interval [CI] [1.06, 1.28]), while those with PWD were not associated (OR: 0.96, 95% CI [0.77, 1.20]). Causal mediation showed a mediation effect of childhood family violence exposure on the association between PMC and poor health (proportion mediated: 6.9%). Economic hardship did not mediate the association. PMC, but not PWD, increased the risk of poor health in older age, which was partially explained by the exposure to family violence in childhood. There appears to be a transgenerational health impact of war which continues to affect the health of offspring as they age.

Association between housing damage, present bias and delayed-onset post-traumatic stress symptoms among older adults 9 years after a natural disaster

BACKGROUND

Previous studies suggest that experience of natural disasters may heighten present bias. Research also suggests that impaired self-control (in particular, heightened present bias) could be linked to delayed-onset post-traumatic stress symptoms (PTSS) among survivors of natural disasters. We examined a hypothesis that the association between disaster experiences and delayed-onset PTSS is mediated through present bias among older survivors of the 2011 Japan earthquake and tsunami.

METHODS

The baseline survey was conducted for older adults who lived in a city located 80 km west of the epicentre 7 months before the disaster. Approximately 2.5 and 8.5 years after the disaster, we surveyed older survivors to assess the trajectory of PTSS (2230 participants). We implemented analyses by three analytical groups: (1) resilient versus delayed-onset, (2) resilient versus improved and (3) resilient versus persistent.

RESULTS

Logistic regression models showed that major housing damage was linked to raised present bias in all analytical groups (OR 2.47, 95% CI 1.04 to 5.87; OR 2.75, 95% CI 1.20 to 6.29; OR 2.65, 95% CI 1.15 to 6.10, respectively). The present bias, however, was significantly associated with only delayed-onset PTSS (OR 2.05, 95% CI 1.14 to 3.69). In the group of resilient versus delayed onset, housing destruction was also associated with delayed-onset PTSS (OR 2.44, 95% CI 1.11 to 5.37), and the association was attenuated by present bias (OR 2.36, 95% CI 1.07 to 5.18).

CONCLUSIONS

Present bias could mediate the association between housing damage and delayed-onset PTSS among older survivors of a natural disaster.

Social participation and incident disability and mortality among frail older adults: A JAGES longitudinal study

BACKGROUND

Frailty is the highest risk factor for incident disability and mortality. Social participation is a modifiable factor for reducing adverse outcomes among independent older adults. However, the association between social participation and incident disability and mortality among frail older adults remains unclear. Therefore, we examined the association between various social activities and incident disability and mortality.

METHODS

This nationwide prospective cohort study (The Japan Gerontological Evaluation Study) recruited older adults with frailty, aged 65 years and older (N = 9090) who were followed up for 6 years (2010-2016). We examined incident disability and all-cause mortality at the end of the follow-up period. Frailty was assessed using the Kihon Checklist. The independent variable was social participation in 2010, grouped into the following seven categories: hobby groups, sports groups or clubs, volunteer groups, senior citizens' clubs, industries, neighborhood communities, and paid work.

RESULTS

The incidence of disability among participants was 19.5% (1770) and that of mortality was 19.2% (1753). Belonging to sports groups or clubs (Hazard Ratios [HR] = 0.74; 95% Confidence Interval [CI] = 0.57, 0.98) or hobby groups (HR = 0.77; 95% CI = 0.60, 0.98) was significantly associated with a lower risk of incident disability. Meanwhile, hobby groups (HR = 0.68; 95% CI = 0.56, 0.83), sports groups or clubs (HR = 0.71; 95% CI = 0.57, 0.88), volunteer groups (HR = 0.69; 95% CI = 0.54, 0.88), and senior citizens' club (HR = 0.75; 95% CI = 0.61, 0.90) were associated with lower risk of incident mortality.

CONCLUSIONS

Social participation was associated with a lower risk of incident disability and mortality, not only in healthy older adults but also in frail older adults who are at higher risk of incident disability and mortality. This suggests that frail older adults should be encouraged to participate in all the seven types of social participation examined in this study, as this may lower the risk of subsequent disability and mortality.

Does social participation foster social support among the older population in Japan? A three-year follow-up study from the Japan gerontological evaluation study

•Whether social participation has generated new, healthier social support is unclear.•We prospectively examined whether social participation fosters social support.•Social support was dose-responsive to the number of types of social participation.•Social support was fostered by participating in some type of group at any frequency.•Support to encourage social participation may be effective to enhance social support.

Change in Geographic Accessibility to Dental Clinics Affects Access to Care

Access to dental clinics is a feature of the neighborhood service environment that may influence oral health care utilization. However, residential selection poses a challenge to causal inference. By studying the involuntary relocation of survivors of the 2011 Great East Japan Earthquake and Tsunami (GEJE), we examined the association between changes in geographic distance to dental clinics and dental visits. Longitudinal data from a cohort of older residents in Iwanuma City directly impacted by the GEJE were analyzed in this study. The baseline survey was conducted in 2010, 7 mo before the occurrence of GEJE, and a follow-up was conducted in 2016. Using Poisson regression models, we estimated the incidence rate ratios (IRR) and 95% confidence intervals (CIs) for the uptake of denture use (as a proxy for dental visits) according to changes in distance from the nearest dental clinic to their house. Age at baseline, housing damage by the disaster, deteriorating economic conditions, and worsened physical activity were used as confounders. Among the 1,098 participants who had not worn dentures before the GEJE, 495 were men (45.1%), with a mean ± SD age at baseline of 74.0 ± 6.9 y. During the 6-year follow-up, 372 (33.9%) participants initiated denture use. Compared to those who experienced a large increase in distance to dental clinics (>370.0-6,299.1 m), a large decrease in distance to dental clinics (>429.0-5,382.6 m) was associated with a marginally significantly higher initiation of denture use among disaster survivors (IRR = 1.28; 95% CI, 0.99-1.66). The experience of major housing damage was independently associated with higher initiation of denture use (IRR = 1.77; 95% CI, 1.47-2.14). Improved geographic access to dental clinics may increase dental visits of disaster survivors. Further studies in non-disaster-affected areas are needed to generalize these findings.

Subjective Happiness, Frequency of Laughter, and Hypertension: A Cross-Sectional Study Based on the Japan Gerontological Evaluation Study (JAGES)

In recent years, positive psychological factors, such as subjective happiness and laughter, have been reported to be associated with cardiovascular disease. In this study, we examined the relationship of hypertension with subjective happiness and frequency of laughter using the data from the Japan Gerontological Evaluation Study (JAGES). Of the 138,294 respondents, 26,368 responded to a version of the self-administered questionnaire that included a question about the frequency of laughter in the JAGES 2013. In total, 22,503 (10,571 men and 11,932 women) were included in the analysis after excluding those with missing responses regarding a history of hypertension, frequency of laughter, and subjective happiness. The prevalence of hypertension in this study was 10,364 (46.1%). Multivariate logistic regression analysis showed that age, female sex, obesity, infrequent chewing, former and current drinker, seeing three to five friends, and the absence of hobbies were positively associated with hypertension. However, infrequent laughter/high level of subjective happiness, frequent laughter/high level of subjective happiness, being underweight, and current smoker were negatively associated with hypertension. As per the findings of this study, it was determined that subjective happiness was negatively associated with hypertension. Therefore, this study suggests that having more opportunities to feel happiness may be important in preventing hypertension.

Social isolation and subsequent health and well-being in older adults: A longitudinal outcome-wide analysis

BACKGROUND

Social isolation has become a serious public health issue. However, most previous studies examine the relationship between social isolation and a single outcome. We aimed to conduct holistic assessments to understand the multidimensional impacts of social isolation on health and well-being.

METHODS

We used the three-wave data (2013, 2016, and 2019) obtained from the Japan Gerontological Evaluation Study. Our exposure, obtained from the 2016 survey, was the Social Isolation Index (SII) comprising five components: no partner, poor interaction with children, poor interaction with relatives, poor interaction with friends, and no social participation). We assessed 36 health and well-being outcomes across six dimensions obtained from the 2019 survey: physical/cognitive health, health behaviours, mental health, subjective well-being, social isolation, and cognitive social capital. Pre-exposure characteristics and prior outcome levels in 2013 were adjusted. We included 47,318 respondents for 4 outcomes (death, dementia, and functional disability) and 34,187 respondents for 32 other outcomes. The Bonferroni correction was used to correct for multiple tests.

RESULTS

The total SII scores were associated with a wide range of health and well-being outcomes across the six dimensions. Specifically, we found a robust association between an SII score of four or greater with mortality (Odds ratio: 1.89; 95% CI: 1.46-2.43). Among the five components of the SII, poor interaction with friends and no social participation showed robust associations with a wide range of health and well-being. We also found some robust evidence regarding effect modification by gender and age in the associations between the components of the SII and health and well-being.

CONCLUSIONS

Social isolation, specifically social interaction with friends and social participation, may affect a wide range of health and well-being among older adults.

Association of frailty with influenza and hospitalization due to influenza among independent older adults: a longitudinal study of Japan Gerontological Evaluation Study (JAGES)

BACKGROUND

It is unknown that whether frailty is a risk factor of influenza and the hospitalization among older adults, although it has been shown that frailty was associated with poor recovery from the hospitalization among those. We examined the association of frailty with influenza and the hospitalization and the effect by sex among independent older adults.

METHODS

We used the longitudinal data from the Japan Gerontological Evaluation Study (JAGES), performed in 2016 and 2019 and conducted in 28 municipalities in Japan. The target population comprised 77,103 persons aged ≥ 65 years who did not need assistance from the public long-term care insurance. Primary outcome measures were influenza and hospitalization due to influenza. Frailty was evaluated with the Kihon check list. We estimated the risk of influenza, the hospitalization, those risks by sex, and the interaction for frailty and sex using Poisson regression adjusting for covariates.

RESULTS

Frailty was associated with both influenza and the hospitalization among the older adults compared with nonfrail individuals after adjusting for covariates (influenza, frail: risk ratio {RR}: 1.36, 95% confidence interval {95% CI}: 1.20 - 1.53, and prefrail: RR: 1.16, 95% CI: 1.09 - 1.23; the hospitalization, frail: RR: 3.18, 95% CI: 1.84 - 5.57, and prefrail: RR: 2.13, 95% CI: 1.44 - 3.16). Male was associated with the hospitalization, but not associated with influenza compared to female (the hospitalization: RR: 1.70, 95% CI: 1.15 - 2.52 and influenza: RR: 1.01, 95% CI: 0.95 - 1.08). The interaction for frailty and sex was significant neither in influenza nor in the hospitalization.

CONCLUSION

These results suggest that frailty is a risk of influenza and the hospitalization, that risks of the hospitalization are different by sex, but that the sex difference does not cause the effect heterogeneity of frailty on the susceptibility and severity among independent older adults.

Impact of Teeth on Social Participation: Modified Treatment Policy Approach

Social participation prevents social isolation and loneliness among older adults while having numerous positive effects on their health and well-being in rapidly aging societies. We aimed to estimate the effect of retaining more natural teeth on social participation among older adults in Japan. The analysis used longitudinal data from 24,872 participants in the Japan Gerontological Evaluation Study (2010, 2013, and 2016). We employed a longitudinal modified treatment policy approach to determine the effect of several hypothetical scenarios (preventive scenarios and tooth loss scenarios) on frequent social participation (1 = at least once a week/0 = less than once a week) after a 6-y follow-up. The corresponding statistical parameters were estimated using targeted minimum loss-based estimation (TMLE) method. Number of teeth category (edentate/1-9/10-19/≥20) was treated as a time-varying exposure, and the outcome estimates were adjusted for time-varying (income, self-rated health, marital status, instrumental activities of daily living, vision loss, hearing loss, major comorbidities, and number of household members) and time-invariant covariates (age, sex, education, baseline social participation). Less frequent social participation was associated with older age, male sex, lower income, low educational attainment, and poor self-rated health at the baseline. Social participation improved when tooth loss prevention scenarios were emulated. The best preventive scenario (i.e., maintaining ≥20 teeth among each participant) improved social participation by 8% (risk ratio [RR] = 1.08; 95% confidence interval [CI], 1.05-1.11). Emulated tooth loss scenarios gradually decreased social participation. A hypothetical scenario in which all the participants were edentate throughout the follow-up period resulted in a 11% (RR = 0.89; 95% CI, 0.84-0.94) reduction in social participation. Subsequent tooth loss scenarios showed 8% (RR = 0.92; 95% CI, 0.88-0.95), 6% (RR = 0.94; 95% CI, 0.91-0.97), and 4% (RR = 0.96; 95% CI, 0.93-0.98) reductions, respectively. Thus, among Japanese older adults, retaining a higher number of teeth positively affects their social participation, whereas being edentate or having a relatively lower number of teeth negatively affects their social participation.

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.

Does remaining teeth and dental prosthesis associate with social isolation? A six-year longitudinal study from the Japan Gerontological Evaluation Study (JAGES)

OBJECTIVES

Social isolation was associated with increased mortality and numerous adverse health outcomes. However, the longitudinal association between oral health and social isolation has not been studied. In this longitudinal prospective cohort study, the association between the number of remaining teeth and dental prosthesis use with social isolation after 6-years follow-up was examined.

METHODS

Functionally independent adults aged 65 years or older, who were not socially isolated in 2010, were followed up until 2016 in the Japan Gerontological Evaluation Study. Data from 26 417 participants were analysed after random forest imputation to address missing data. Logistic regression models were used to calculate the odds ratio (OR) for incident social isolation in 2016 after adjusting for age, sex, educational attainment, income, activities of daily living, living area and having depressive symptoms.

RESULTS

The mean age of the participants at baseline was 72.3 (SD = 5.0). A total of 1,127 (4.3%) participants were socially isolated at follow-up. Of these, 338 (3.2%) had ≥20 teeth (with or without using dental prosthesis), 171 (3.9%) had 10-19 teeth and used dental prosthesis, 112 (4.2%) had 10-19 teeth and did not use the dental prosthesis, 338 (5.1%) had 0-9 teeth and used dental prosthesis, and 168 (7.6%) had 0-9 teeth and did not use the dental prosthesis. Fully adjusted logistic regression models showed that the OR of incident social isolation was higher for those with fewer teeth; OR = 1.13 (95%CI = 0.96-1.33) for those with 10-19 teeth and OR = 1.36 (95%CI = 1.17-1.58) for those with 0-9 teeth, compared to those with ≥20 teeth. The OR of incident social isolation was lower for those who used a dental prosthesis [OR = 0.90, 95%CI = 0.80-1.02)] compared to those who did not use a dental prosthesis. The interaction between the number of teeth and dental prosthesis use demonstrated that the latter mitigated the incidence of social isolation for participants with tooth loss. Compared to those with ≥20 teeth (with or without prosthesis use), participants with 0-9 teeth that did not use a dental prosthesis were 79% [OR = 1.79, 95%CI = 1.49-2.19] more likely to be socially isolated, whereas participants with 0-9 teeth that used a dental prosthesis were only 23% [OR = 1.23, 95%CI = 1.05-1.45] more likely to be socially isolated.

CONCLUSION

Tooth loss was the main predictor for social isolation at follow-up, while no dental prostheses use was an additional risk factor. Dental prosthesis use may reduce the risk of social isolation especially in those with severe tooth loss.

Associations of Cooking Skill with Social Relationships and Social Capital among Older Men and Women in Japan: Results from the JAGES

The health benefits of social relationships and social capital are well known. However, little research has examined the determinants of social relationships and social capital. We examined whether cooking skill was associated with social relationships and social capital in older Japanese people. We used 2016 Japan Gerontological Evaluation Study data on a population-based sample of men and women aged ≥ 65 years (n = 21,061). Cooking skill was assessed using a scale with good validity. Social relationships were evaluated by assessing neighborhood ties, frequency and number of meetings with friends, and frequent meals with friends. Individual-level social capital was evaluated by assessing civic participation, social cohesion, and reciprocity. Among women, high-level cooking skill was positively associated with all components of social relationships and social capital. Women with high-level cooking skill were 2.27 times (95% CI: 1.77-2.91) more likely to have high levels of neighborhood ties and 1.65 (95% CI: 1.20-2.27) times more likely to eat with friends, compared with those with middle/low-level cooking skill. Cooking skills explained 26.2% of the gender difference in social relationships. Improving cooking skills may be key to boosting social relationships and social capital, which would prevent social isolation.

Video call and depression among older adults during the COVID-19 pandemic in Japan: The JAGES one-year longitudinal study

Evidence of video call on preventing late-life depression during the COVID-19 pandemic is limited. We examined the associations of social contact (in-person, voice call, and video call) with incidence of depressive symptoms and evaluated whether specific factors (particularly, age and change in the frequency of in-person contact) affect these associations. We used longitudinal data from the 2019 and 2020 waves of the Japan Gerontological Evaluation Study, including 10,523 participants aged ≥65 years in 10 municipalities. Depressive symptoms were measured by the 15-item Geriatric Depression Scale (GDS-15) score ≥5 in main analysis, and GDS-15 score ≥4, 10, or continuous variable in sensitivity analyses. Social contact represented frequency changes before and during the pandemic: non-contact (reference), decreased-contact, maintained-contact, and increased-contact. We employed modified Poisson regression analysis. Compared to non-contact of video call, the association of increased-contact of video call with depressive symptoms was insignificant in main analysis (GDS-15 ≥ 5: risk ratio (RR) = 0.89, 95% confidence interval (CI): 0.79-1.01), whereas significant in sensitivity analyses (GDS-15 ≥ 4: RR = 0.89, 95% CI: 0.82-0.98; GDS-15 ≥ 10: RR = 0.71, 95% CI: 0.53-0.97; GDS-15 = continuous variable: Β = -0.17, 95% CI: -0.33 to -0.002). In-person contact was significantly associated with lower incidence of depressive symptoms (non-contact: reference; maintained-contact: RR = 0.92, 95% CI: 0.85-0.99; increased-contact: RR = 0.84, 95% CI: 0.77-0.91), whereas voice call was not. Age and change in the frequency of in-person contact did not show significant effect modifications on the associations of video call with incidence of depressive symptoms after Bonferroni correction for multiple testing. In conclusion, this study suggests that the evidence supporting video call as a way to protect against depressive symptoms among older adults during the pandemic appears weak compared to the evidence for in-person contact.

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.

Uncovering Heterogeneous Associations Between Disaster-Related Trauma and Subsequent Functional Limitations: A Machine-Learning Approach

This study examined heterogeneity in the association between disaster-related home loss and functional limitations of older adults, and identified characteristics of vulnerable subpopulations. Data were from a prospective cohort study of Japanese older survivors of the 2011 Japan Earthquake. Complete home loss was objectively assessed. Outcomes in 2013 (n = 3,350) and 2016 (n = 2,664) included certified physical disability levels, self-reported activities of daily living, and instrumental activities of daily living. We estimated population average associations between home loss and functional limitations via targeted maximum likelihood estimation with SuperLearning and its heterogeneity via the generalized random forest algorithm. We adjusted for 55 characteristics of survivors from the baseline survey conducted 7 months before the disaster. While home loss was consistently associated with increased functional limitations on average, there was evidence of effect heterogeneity for all outcomes. Comparing the most and least vulnerable groups, the most vulnerable group tended to be older, not married, living alone, and not working, with preexisting health problems before the disaster. Individuals who were less educated but had higher income also appeared vulnerable for some outcomes. Our inductive approach for effect heterogeneity using machine learning algorithm uncovered large and complex heterogeneity in postdisaster functional limitations among Japanese older survivors.

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.

Association between the Standardized Mortality Ratio and Healthy Life Expectancy in Japan

Introduction

Healthy life expectancy (HLE) remains the principal target of various health plans. We aimed to identify the areas of priority and determinants of mortality to extend HLE across local governments in Japan.

Methods

HLE according to secondary medical areas was calculated using the Sullivan method. People requiring long-term care of level 2 or higher were considered unhealthy. Standardized mortality ratios (SMRs) for major causes of death were calculated using vital statistics data. The association between HLE and SMR was analyzed using simple and multiple regression analyses.

Results

The average (standard deviation) HLE values were 79.24 (0.85) and 83.76 (0.62) years for men and women, respectively. A comparison of HLE revealed regional health gaps of 4.46 (76.90-81.36) and 3.46 (81.99-85.45) years for men and women, respectively. The coefficients of determination for the SMR of malignant neoplasms with HLE were the highest and were 0.402 and 0.219 among men and women, respectively, followed by those of cerebrovascular diseases, suicide, and heart diseases among men and those of heart disease, pneumonia, and liver disease among women. When all major preventable causes of death were analyzed simultaneously in a regression model, the coefficients of determination were 0.738 and 0.425 among men and women, respectively.

Conclusions

Our findings suggest that local governments should prioritize preventing cancer deaths via cancer screening and smoking cessation measures in health plans, with a special focus on men.

Associations of influenza and pneumococcal vaccinations with burdens of older family caregivers: The Japan Gerontological Evaluation study (JAGES) cross-sectional study

BACKGROUND

Influenza and pneumonia tend to be severe in older adults; thus, vaccination is necessary to prevent these illnesses. Vaccination is especially important for older family caregivers (OFCs) not only to prevent them from becoming ill, but also to prevent secondary infections in the family care receivers (FCRs), who are mostly frail older adults and have a higher risk of severe illness. Thus, we investigated whether caregiving burdens were associated with the vaccinations among older adults.

METHODS

We used cross-sectional data from the Japan Gerontological Evaluation Study (JAGES), which was conducted in 64 Japanese municipalities from November 2019 to January 2020. The target population consisted of 26,177 individuals aged 65 years or older who were independent and did not need public long-term care. The primary outcome was the uptakes of either or both influenza and pneumococcal vaccinations. Multinomial logistic regressions were performed, setting those who underwent neither vaccinations as the reference group.

RESULTS

Among the participants, 23.3 %, 25.8 %, 9.4 %, or 41.5 % underwent neither, only influenza, only pneumococcal, or the both vaccinations, respectively. The caregiving frequency, time length in a day, or dementia of FCR were negatively associated with influenza vaccination (caregiving almost every day: relative risk ratio {RRR}: 0.39, 95 % confident interval {95 % CI} [0.24-0.63]; caregiving almost all day: 0.44, 95 % CI: 0.23-0.85; caregiving for FCR: RRR:0.55, 95 % CI: 0.34-0.91). On the other hand, those caregiving burdens were not associated with pneumococcal only or the both vaccinations. Having a family physician mitigated all the negative effect of the caregiving burdens on the vaccinations.

CONCLUSION

Our results suggest that the caregiving burden is a barrier to influenza vaccination but not to pneumococcal vaccination and that having a physician mitigates the negative effect regardless of the burden kind.