Does eating with others promote happiness among older adults living alone? A 3-year longitudinal study of the Japan gerontological evaluation study

OBJECTIVE

Living a happy life is an essential issue for old adults. However, how eating with others contributes to happiness and whether this association is different by living arrangements or not is unknown. The current study examined the relationship between the frequency of eating with others and happiness among older adults according to their living arrangements using 3-year longitudinal data.

METHODS

The analyzed sample comprised 18,727 people (10,920 males and 7807 females) with low happiness (0-7 points on score of 0-10 points) from Japan Gerontological Evaluation Study (JAGES) in 2016. Our exposure was the frequency of eating with others: rarely, a few times a year, a few times a month, and a few times a week or more. We performed Modified Poisson Regression to examine the association between the frequency of eating with others and high happiness (8-10 points) in 2019 stratified by living arrangement (living alone/with others).

RESULTS

A total of 4352 (23.2%) people showed high happiness in 2019. After adjusting for age, sex, marital status, education, household income, social participation, illnesses under treatment, and depressive symptoms in 2016, the cumulative incidence ratio (CIR) for high happiness in 2019 among people living alone was more significant, that is, 1.28 (95% confidence intervals: 0.88-1.87), 1.50 (1.05-2.14), and 1.82 (1.26-2.63), than 1.28 (1.11-1.48), 1.30 (1.12-1.50), and 1.33 (1.16-1.52) among people living with others for those who ate with others a few times a year, a few times a month, and a few times a week or more compared to those who rarely ate with others, respectively. The interaction between the frequency of eating with others and living arrangements was statistically significant. The trend test showed that higher frequency of eating with others was significantly associated with high happiness.

CONCLUSIONS

Eating with others was associated with improved happiness among older adults, with such an association being stronger among people living alone.

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.

Cooking skills, living alone, and mortality: JAGES cohort study

BACKGROUND

Living alone without someone to cook meals for them can happen more frequently in aging due to bereavement, divorce, or other family changes. Health risks to older adults due to poor cooking skills may be more pronounced among those living alone. We aimed to examine whether cooking skills are associated with mortality according to cohabitation status in older Japanese people.

METHODS

Participants in the Japan Gerontological Evaluation Study, a population-based cohort of independent older adults, were followed for three years (n = 10,647). Cooking skill was assessed using a scale with good validity and modified for Japanese people in the baseline survey. After stratification by living alone or together, participants with high and low cooking skills were matched on demographic, socioeconomic, health-related factors, and availability of food stores using propensity score matching. All-cause mortality risks were compared between high and low cooking skills using Cox regression models.

RESULTS

During the follow-up, 520 of the 10,647 participants died. One hundred and seventy-one pairs of high and low cooking skills were matched among those living alone, and 2,161 pairs among those living with others were matched as well. The hazard ratio of the low level of cooking skills (vs. high) was 2.50 (95% confidence interval [CI]: 1.10-5.68) among those living alone, while 1.05 (95% CI: 0.82-1.33) among those living with others.

CONCLUSION

Lower cooking skills were associated with a higher risk of mortality only among those living alone. Cooking skills may be important for older adults who live alone to reduce mortality risk.

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.

Do disasters exacerbate socioeconomic inequalities in health among older people?

Disasters can exacerbate socioeconomic health disparities because of differential exposure (e.g., socioeconomically disadvantaged groups are more likely to be exposed to disaster-related trauma) and differential vulnerability (disadvantaged groups are more likely to suffer health consequences of exposure to trauma). We sought to test whether health disparities among older adults widened in the area which was directly affected by the 2011 Great East Japan Earthquake & Tsunami compared to areas which largely escaped tsunami damage. We used data from a cohort of community-dwelling older adults who were directly affected by the 2011 disaster (the Iwanuma Study) and municipalities that were not directly affected (the JAGES parent cohort excluding Iwanuma city). The Iwanuma Study gathered pre-disaster information from participants in 2010 (seven months before the disaster) as well as post-disaster information in 2013, 2016 and 2019 (2.5, 5.5 and 8.5 years after the disaster). Our outcomes were depressive symptoms (GDS) and instrumental activities of daily living (IADL). We examined the pre- versus post-disaster trends in socioeconomic health disparities using the slope index and relative index of inequality. We then conducted a difference-in-difference analysis comparing the pre/post disaster change in health disparities in the "exposed" city (Iwanuma) compared to "control" cities. We found clear pre-disaster socioeconomic inequalities in both GDS and IADL in both the exposed and control cities. However, the magnitude of these inequalities did not change after the disaster on either the absolute or relative scales. The 2011 disaster in northeastern Japan did not exacerbate pre-existing patterns of health inequalities in the older population.

Moderating effect of country-level health determinants on the association between hobby engagement and mental health: cross-cohort multi-level models, meta-analyses, and meta-regressions

BACKGROUND

Theories from anthropology, evolutionary psychology, and sociology have focused on the potential adaptive benefits of hobby engagement for mental health in older adults. However, previous studies have used data from single countries, potentially biased by specific measurement and methodological approaches, cohort effects, or cultural specificities. Whether there are genuine benefits for mental health in older adults cross-culturally remains unknown. This study explored the consistency of this association across 16 different nations.

METHODS

For this epidemiological study, we used data from adults aged 65 years or older across 16 countries in the USA, Europe, and Asia, represented in five longitudinal studies (ELSA, JAGES, HRS, SHARE and CHARLS; N=93 263, 45-62% female, mean age 72-76 years, data collected 2008-20). We harmonised measures of self-reported engagement in hobbies and past-times, depressive symptoms (validated scales), and Likert scale responses for self-reported health, happiness, and life satisfaction. We conducted fixed-effects models and longitudinal regression models of hobbies and mental health for each country and then pooled in multinational meta-analyses. We accounted for all time-constant factors including those unobserved (eg, genetics, past leisure behaviour, medical history, psychological traits) and identified time-varying factors (eg, sociodemographic background, clinical conditions, daily functioning). We tested the potential moderating effects of country-level determinants of health in meta-regressions and multilevel models.

FINDINGS

Meta-analytic fixed-effects findings showed that having a hobby was associated with fewer depressive symptoms (pooled coefficient -0·10, 95% CI -0·13 to -0·07, I2=69·5%, H2=3·28), and higher levels of self-reported health (0·06, 0·03 to 0·08, I2=48·1%, H2=1·93), happiness (0·09, 0·06 to 0·13, I2=67·0%, H2=3·03), and life satisfaction (0·10, 0·08 to 0·12, I2=33·6%, H2=1·51). Results were consistent in meta-analyses of longitudinal regression models testing directionality of findings. Macro-level factors such as life expectancy, world happiness index, country wealth, and income inequality predicted prevalence of hobby engagement, but they showed only marginal moderating effects on the association between hobbies and mental health.

INTERPRETATION

Despite some heterogeneity in measurement between the cohorts, the apparent universality of the health benefits of hobbies internationally suggests that facilitating greater opportunities for engagement across demographic groups and between countries could be an important part of multidisciplinary care. Findings have implications for social prescribing schemes (currently in trial in many countries) and multidisciplinary work on origins and human behavioural patterns of hobby engagement.

FUNDING

National Endowment for the Arts, Wellcome Trust, Belgian Nnational Scientific Fund (FNRS).

Association between adverse childhood experiences and social integration among older people in Japan: Results from the JAGES study

Social integration, network, and support are beneficial to health. However, there is little evidence of the association between adverse childhood experiences (ACEs) and social integration in later life. This study investigates the association between ACE history and social integration in older people. We used data from the Japan Gerontological Evaluation Study (JAGES) 2013, which conducted a self-reported survey of functionally independent people aged ≥ 65 years from 30 municipalities across Japan and yielded information on ACE history. We conducted a Poisson regression analysis with robust error variances to assess the association between ACE history and social integration, adjusting for sex, age, childhood economic hardship, adult socioeconomic status, health status, living status, and trust in others. The number of respondents with at least one incident of ACE was approximately 36.8%. The prevalence ratios for those who reported a history of ACEs were as follows: housebound 1.495 (95% confidence interval [CI]: 1.19-1.88), small network size 1.146 (95% CI: 1.10-1.19), low network contact 1.059 (95% CI: 1.00-1.059), non-membership sports group 1.038 (95% CI: 1.00-1.07), and non-membership hobby group 1.06 (95% CI: 1.03-1.09). Among older people in Japan, a history of ACEs is inversely associated with social integration. These findings support the life course approach and suggest that adverse events in early life may have an impact on social life in old age. In order to promote healthy aging, it is important to recognize the significant impact of early-life adversities that can extend into later life.

Built Environments and Frailty in Older Adults: The JAGES Longitudinal Study Using Mediation Analysis

OBJECTIVES

The purpose of this study was to investigate the association between subjective built environment and the onset of frailty in older adults living in the community. In addition, we examined whether daily walking time, depressive symptoms, and social support from neighbors and friends are mediating factors.

DESIGN

This was a longitudinal study using prospective cohort data from the 2013 Japan Gerontological Evaluation Study.

SETTING AND PARTICIPANTS

Participants included 38,829 older adults who were not frail recruited from 22 cities and towns.

METHODS

The dependent variable, frailty, was assessed using the Kihon checklist. The explanatory variables were 5 items for the subjective built environment. The mediating variables were walking time of at least 30 minutes per day, a Geriatric Depression Scale (GDS) score of at least 5 points, and social support from neighbors and friends. We performed a causal mediation analysis of mediating effects between each built environment and frailty onset. Furthermore, the proportion of mediation was estimated.

RESULTS

After 3 years of follow-up, frailty emerged in 2232 adults (6.7%) in 2016. Access to parks and sidewalks, access to fresh food stores, houses or facilities where people feel free to drop in, and fascinating views, or buildings reduced the onset of frailty. Mediators significantly associated with the built environment and onset of frailty were access to parks and sidewalks (walking time: 5.9%, GDS: 22.9%, social support: 5.9%), access to fresh food stores (GDS: 31.9%, social support: 4.0%), hills and steps (GDS: 20.6%), houses or facilities where people feel free to drop in (walking time: 4.0%, GDS 28.0%, social support: 10.4%), and fascinating views, or buildings (walking time: 7.8%, GDS: 42.1%, social support: 12.0%).

CONCLUSIONS AND IMPLICATIONS

We found that walking time, depression, and social support were mediating factors in the relationship between built environment and the onset of frailty.

[Association between use of the "health-supportive" roadside station and self-rated health: A three-wave longitudinal study]

Objective　Mutsuzawa town, Chiba Prefecture, relocated a "health-supportive" roadside station in 2019. The underlying hypothesis is that older people who use the roadside station will have better self-rated health than those who do not use it. We aimed to verify whether roadside station use was associated with a decrease in poor self-rated health.Method　This was a longitudinal study that compared and evaluated the roadside station use and non-use groups using three-wave panel data before and after relocation of the roadside station in September 2019. To obtain three-wave panel data, self-administered questionnaires were mailed three times: in July 2018 (FY 2018) before the station was relocated and in November 2020 (FY 2020) and January 2022 (FY 2021) after the relocation in 2019. The dependent variable was poor self-rated health in FY 2021, and the independent variable was use of the roadside station as of FY 2020. Covariates included basic characteristics from FY 2018, as well as going out, social participation, and interacting on social networks in FY 2018 and FY 2020. A multivariate analysis was conducted using multiple imputation to complete missing values for the Crude model, which included the basic attributes of FY 2018 (Model 1); going out, social participation, and interacting on social networks in FY 2018 (Model 2); and going out, social participation, and interacting on social networks in FY 2020 (Model 3). The cumulative incidence rate ratio (CIRR), 95% confidence intervals, and P-values were calculated using a modified Poisson regression analysis for each model.Results　Of the 576 participants, 344 (59.8%) were roadside station users. The multivariate analysis adjusted for basic attributes revealed that the number of people with poor self-rated health in the user group was significantly lower than that in the non-user group, with a CIRR of 0.67 (95% confidence interval: 0.45-0.99, P=0.043). However, the adjusted model showed a CIRR of 0.71 (95% confidence interval: 0.48-1.06, P=0.096) for going out, social participation, and interacting on social networks in FY2020 after the roadside station opened.Conclusion　Findings of this study revealed that, after adjusting for confounding factors prior to relocation of the roadside station, the number of people with poor self-rated health decreased in the user group. Thus, such commercial facilities as roadside stations, which give users an opportunity to go out and meet people, can provide a "naturally healthy" environment.

Oral Self-Care, Pneumococcal Vaccination, and Pneumonia Among Japanese Older People, Assessed With Machine Learning

BACKGROUND

Pneumonia is a leading cause of death worldwide. It is a particularly serious burden in older people, as they tend to have a weakened immune response. Identifying the role of oral self-care and pneumococcal vaccination in healthy, independent older people can aid pneumonia prevention among them. This study investigated the associations between oral self-care, pneumococcal vaccination, and pneumonia experience among independent older people.

METHODS

This cross-sectional study used data from the 2016 Japan Gerontological Evaluation Study. We used machine learning to examine the association between oral self-care and the experience of pneumonia over the previous year, stratified by pneumococcal vaccination. The covariates were sex, age, years of education, equivalent annual income, medical history of stroke, oral health status (choking, dryness, number of teeth), and smoking status. The analysis included 17 217 independent older people aged 65 and over.

RESULTS

The prevalence of pneumonia experienced among those who brushed their teeth once or less per day was 4.5% and 5.3% for those with and those without pneumococcal vaccinations, respectively. In the unvaccinated group, the odds ratio of pneumonia experience for those who brushed their teeth once or less a day was 1.57 (95% confidence interval: 1.15-2.14) compared to those who brushed their teeth 3 or more times a day. By contrast, there was no significant association between the frequency of toothbrushing and the experience of pneumonia among people who received pneumococcal vaccination.

CONCLUSIONS

Oral care influenced the experience of pneumonia among independent older people who did not receive pneumococcal vaccination.

Association between adverse childhood experiences and marital status among Japanese older adults

BACKGROUND

Marital status is a well-known social determinant of health. Adverse childhood experiences (ACEs) affect attachment, critical to establishing and maintaining intimate relationships, such as marital status.

OBJECTIVE

This study examined the association between ACEs and marital status among older Japanese adults.

PARTICIPANTS AND SETTING

This research used data from a nationwide population-based study among functionally independent people aged 65 and above in Japan.

METHODS

ACEs were assessed by self-reported questionnaires on the following experiences before 18 years old: parental death, parental divorce, parental mental disease, exposure to intimate partner violence, physical abuse, psychological neglect, psychological abuse, and poverty. Marital status was asked as currently having a spouse (including common-law marriage), widowed, divorced, or unmarried. Associations between the total number of ACEs and marital status were analyzed by multinomial logistic regression.

RESULTS

Three or more ACEs showed higher risks of being widowed, divorced, or unmarried. Psychological neglect led to higher divorce risks among males (RRR, 95%CI = 1.41, 1.13-1.76) and females (RRR, 95%CI = 1.56, 1.28-1.89). Childhood poverty showed higher risks of unmarried among males (RRR, 95%CI = 1.25, 1.02-1.53) and females (RRR, 95%CI = 1.41, 1.18-1.69). Association between ACEs and divorce risks showed gender differences (RRR, 95%CI of having three or more ACEs in males: 2.19, 1.66-2.90; in females: 3.45, 2.71-4.38; p for interaction = 0.034).

CONCLUSIONS

ACEs showed higher risks of being widowed, divorced, and unmarried among older Japanese people. Policy to tackle ACEs and research investigating how ACEs, attachment, and relationship quality influence marital status are required to promote well-being in later life.

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.

[Association between social participation and frailty among older adults: A longitudinal study from Japan Gerontological Evaluation Study]

Objective　In Japan, measures to prevent frailty among older adults have been implemented. Promotion of social participation is a key measure, but few longitudinal studies have examined the relationship between the types and number of social participation and frailty onset. In this study, we aimed to clarify the relationship between the types and number of social participation and frailty onset using longitudinal data from a large sample of older adults in municipalities in Japan.Methods　We used the 2016 and 2019 panel survey data from the Japan Gerontological Evaluation Study (JAGES). The analysis included 59,545 individuals from 28 municipalities who responded to the JAGES survey in both 2016 (at baseline) and 2019 (at follow-up). We excluded individuals who were dependent on activities of daily living at baseline and non-responders, and those who were frail or with no information about frailty. The dependent variable was frailty onset (≥8 out of 25 points on the basic checklist) at follow-up, and the independent variables were the types and number of types of social participation at baseline. We included 11 variables as potential confounders. We used multiple imputations to complete the missing values and used modified Poisson regression to examine the association between social participation and risk of frailty onset.Results　Of the 59,545 participants, 6,431 (10.8%) were frail onset at follow-up. After multiple imputations (minimum 64,212, maximum 64,287), the risk of frailty onset at follow-up was lower for eight types of social participation, excluding senior citizens' clubs, (nursing care [risk ratio; 0.91], paid work [0.90], volunteer groups [0.87], neighborhood associations [0.87], learning or cultural groups [0.87], activities intended to teach skills or pass experiences to others [0.85], hobby groups [0.81], and sports groups or clubs [0.80]; P<0.05), than no social participation. Additionally, individuals who participated in more types of social participation were at a lower risk of frailty than those with no social participation (P for trend <0.001).Conclusions　The risk of frailty onset was lower among individuals who participated in eight types of social participation at baseline and among those who participated in more types of social participation than those with no social participation. The results suggest that social participation is a useful measure to prevent frailty for extending healthy life expectancy.

Association between sense of coherence and health and well-being among older survivors of a natural disaster: a prospective outcome-wide study

We examined whether pre-disaster Sense of Coherence (SOC) mitigated the impact of housing damage on health and well-being of older survivors after the 2011 Japan Earthquake and Tsunami. A panel survey was conducted in a city located 80 km west of the epicenter seven months before and three years after the disaster (3594 respondents). Among respondents with lighter property damage, higher SOC was inversely associated with mental distress (coefficient - 0.29, 95% CI (confidence interval) - 0.39, - 0.19, p < .01), unhappiness (coefficient - 0.33, 95% CI - 0.43, - 0.23, p < .01), low expectation of mutual help (coefficient - 0.17, 95% CI - 0.27, - 0.07, p < .01), and weak community attachment (coefficient - 0.20, 95% CI - 0.30, - 0.11, p < .01). Conversely, among those who experienced housing loss, higher SOC was no longer protectively associated with health and well-being. Loss of generalized resistance resources due to serious damage led to difficulties in stress coping.

Association between diversity levels of member composition in group activities of older adults and the occurrence of need for care: the JAGES 2013-2019 longitudinal study

BACKGROUND

Participating in groups with diverse members is associated with improved health among older adults. The study examined the relationship between diversity of group members and needed support or long-term care.

METHODS

We conducted a longitudinal study for the Japan Gerontological Evaluation Study with 61,281 participants aged ≥ 65 years who were surveyed in 2013 and followed-up for six years. We assessed three dimensions of the diversity of the participating members (sex, age, and region of residence). We then graded the diversity level into four categories: level 0 (not in any group), level 1 (in a group without diversity or in a group with diversity in one of the three factors), level 2 (in a group with diversity in two of the three factors), or level 3 (in a group with diversity across all factors). We adjusted for 12 covariates using Cox hazard survival analysis models with hazard ratios (HRs) and 95% confidence intervals (CIs) estimated for the association between group members' diversity levels and needed support or long-term care. The same study was conducted when stratified by employment status at baseline.

RESULTS

Participants in social participation groups with more diverse group members had a lower incidence of needed support or long-term care as compared to their counterparts. Compared to those with no participation group, HR decreased by 14% to 24% with increasing levels of diversity. The HR for the level of care needed for participants in the social participation group with high residential diversity was 0.89 (95% CI: 0.84-0.94). For participants who were currently unemployed, HR reductions ranged from 16%-28% with increasing levels of diversity compared to the non-participating group. No association was found for employed participants.

CONCLUSIONS

The reason the HRs of Japanese elderly people certified as needing support or care are lower when the diversity of participating groups is higher could be owing to the presence of a variety of people and the diversification of social networks, which facilitates the building of bridging social relational capital. Public health policies that encourage participation in diverse organizations will be important in the future.

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.

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.

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.