Sociodemographic Heterogeneity in the Associations of Social Isolation With Mortality.

Importance: There are limited data on whether the vulnerabilities and impacts of social isolation vary across populations. Objective: To explore the association between social isolation and mortality due to all causes, cardiovascular diseases (CVD), and malignant neoplasms focusing on heterogeneity by sociodemographic factors. Design, Setting, and Participants: This cohort study used a moderator-wide approach to examine the heterogeneity in the association of social isolation with all-cause, CVD, and malignant neoplasm mortality using baseline data from the Japan Gerontological Evaluation Study in 2010 and 2011. Eligible participants were adults aged 65 years or older without heart disease, stroke, cancer, or impaired activity of daily living across 12 Japanese municipalities. Follow-up continued until December 31, 2017, identifying 6-year all-cause, cardiovascular disease (CVD), and malignant neoplasm mortality. Logistic regression assessed effect modification by age, gender, education, income, population density, marital status, and employment on mortality associations. Data analysis was performed from September 13, 2023, to March 17, 2024. Exposure: Social isolation, determined by a 3-item scale (scores of 2 or 3 indicating isolation) was the primary exposure variable. Main Outcomes and Measures: Six-year all-cause, CVD, and malignant neoplasms mortality. Results: This study included 37 604 older adults, with a mean (SD) age of 73.5 (5.9) years (21 073 women [56.0%]). A total of 10 094 participants (26.8%) were classified as experiencing social isolation. Social isolation was associated with increased all-cause (odds ratio [OR], 1.20 [95% CI, 1.09-1.32]), CVD (OR, 1.22 [95% CI, 0.98-1.52]), and malignant neoplasm mortality (OR, 1.14 [95% CI, 1.01-1.28]). Stratified analysis showed associations of social isolation with all-cause and malignant neoplasm mortality among people with high income (highest tertile all cause: OR, 1.27 [95% CI, 1.06-1.53]; malignant neoplasm: OR, 1.27 [95% CI, 1.02-1.60]), living in areas with high population density (highest tertile all cause: OR, 1.47 [95% CI, 1.26-1.72]; malignant neoplasm: OR, 1.38 [95% CI, 1.11-1.70]), not married (all cause: OR, 1.33 [95% CI, 1.15-1.53]; malignant neoplasm: OR, 1.25 [95% CI, 1.02-1.52]), and retirees (all cause: OR, 1.27 [95% CI, 1.14-1.43]; malignant neoplasm: OR, 1.27 [95% CI, 1.10-1.48]). Formal testing for effect modification indicated modification by population density and employment for all-cause mortality and by household income and employment for neoplasm mortality. Conclusions and Relevance: Social isolation was associated with increased risks of all-cause, CVD, and malignant neoplasm mortality, with associations varying across populations. This study fills an important gap in research on social isolation, emphasizing its varied associations across demographic and socioeconomic groups.

Community-level group sports participation and all-cause, cardiovascular disease, and cancer mortality: a 7-year longitudinal study.

BACKGROUND: Community-level group sports participation is a structural aspect of social capital that can potentially impact individual health in a contextual manner. This study aimed to investigate contextual relationship between the community-level prevalence of group sports participation and the risk of all-cause, cardiovascular disease (CVD), and cancer mortality in older adults. METHODS: In this 7-year longitudinal cohort study, data from the Japan Gerontological Evaluation Study, a nationwide survey encompassing 43,088 functionally independent older adults residing in 311 communities, were used. Cause of death data were derived from the Japanese governmental agency, The Ministry of Health, Labour and Welfare, for secondary use. "Participation" was defined as engaging in group sports for one or more days per month. To analyze the data, a two-level survival analysis was employed, and hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated. RESULTS: Among the participants, 5,711 (13.3%) deaths were identified, with 1,311 related to CVD and 2,349 to cancer. The average group sports participation rate was 28.3% (range, 10.0-52.7%). After adjusting for individual-level group sports participation and potential confounders, a higher community-level group sports participation rate was found to be significantly associated with a lower risk of both all-cause mortality (HR: 0.89, 95% CI: 0.83-0.95) and cancer mortality (HR: 0.89, 95% CI: 0.81-0.98) for every 10% point increase in the participation rate. For CVD mortality, the association became less significant in the model adjusted for all covariates (HR: 0.94, 95% CI: 0.82-1.09). CONCLUSIONS: Our findings support the existence of a preventive relationship between community-level group sports participation and the occurrence of all-cause and cancer mortality among older individuals. Promoting group sports within communities holds promise as an effective population-based strategy for extending life expectancy, regardless of individual participation in these groups.

Community-level educational attainment and dementia: a 6-year longitudinal multilevel study in Japan.

BACKGROUND: As the understanding of the association between community-level education and dementia is insufficient, this study examined the contextual association of community-level prevalence of low educational attainment on the risk of dementia incidence. With this study, we further explored the potential differences in the aforementioned associations for urban and non-urban areas. METHODS: We analyzed 6 years of prospective cohort data from the Japan Gerontological Evaluation Study, beginning with the baseline data collected between 2010 and 2012, for 51,186 physically and cognitively independent individuals aged ≥65 years (23,785 men and 27,401 women) from 346 communities in 16 municipalities across 7 prefectures. We assessed dementia incidence using available data from the long-term care insurance system in Japan. We dichotomized education years as ≤9 and ≥ 10 years and aggregated individual-level educational attainment as a community-level independent variable. Model 1 covariates were age and sex. Income, residential years, disease, alcohol, smoking, social isolation, and population density were added in Model 2. We conducted multiple imputation to address the missing data. We performed a two-level (community and individual) survival analysis to calculate hazard ratios (HRs) and 95% confidence intervals (CIs). RESULTS: The results indicate that the cumulative incidence of dementia during the follow-up period was 10.6%. The mean proportion with educational attainment of ≤9 years was 40.8% (range: 5.1-87.3%). Low community-level educational attainment was significantly associated with higher dementia incidence (HR: 1.04; 95% CI: 1.01-1.07), estimated by 10 percentage points of low educational attainment after adjusting for individual-level educational years and covariates. While the association was significant in non-urban areas (HR: 1.07; 1.02-1.13), there was no association in urban areas (HR: 1.03; 0.99-1.06). CONCLUSIONS: Older people living in communities with low educational attainment among their age demographic develop dementia more often compared with those living in areas with high educational attainment after adjusting for individual-level educational attainment and covariates; the association was pronounced in non-urban areas. Securing education for adolescents as a life course and population approach could thus be crucial in preventing dementia later in life among older people living in non-urban areas.

Potential causal effect of physical activity on reducing the risk of dementia: a 6-year cohort study from the Japan Gerontological Evaluation Study.

BACKGROUND: The causal effect of physical activity on reducing dementia risk has been questioned due to the possibility of reverse causation. This study examined the potential causal effects of physical activity on reducing dementia risk using residency in a snowy area as an instrumental variable (IV) representing the physical activity of older adults. METHODS: We used cohort data from the Japan Gerontological Evaluation Study, a longitudinal cohort enrolling people aged 65 or older who were physically and cognitively independent in 2013; study participants were followed for an average of 5.7 years. Participants in the present study included 73,260 individuals living in 19 municipalities in Japan. Physical activity was measured by self-report questionnaires and the incidence of dementia was ascertained by linking participants to the public registries of long-term care insurance. IV estimation was obtained from a piecewise Cox proportional hazard model using a two-stage regression procedure. RESULTS: During the study period, we ascertained 8714 cases (11.9%) of dementia onset. In the IV analysis, we found that the frequency of physical activity per week was negatively associated with dementia risk, though the association weakened over time (Year 1: hazard ratio = 0.53, 95% confidence interval: 0.39-0.74; Year 4: 0.69, 0.53-0.90; Year 6: 0.85, 0.66-1.10). CONCLUSIONS: Our IV analysis indicated a potential causal effect of physical activity on reducing dementia risk that persisted for at least 4 years of follow-up. Thus, we conclude that physical activity should be recommended for older adults to reduce dementia risk.

Community-Level Sports Group Participation and the Risk of Cognitive Impairment.

PURPOSE: Community-level group participation is a structural aspect of social capital that may have a contextual influence on individual health. We investigated the contextual effect of community-level prevalence of sports group participation on the risk of cognitive impairment among older individuals. METHODS: We analyzed prospective cohort data from the Japan Gerontological Evaluation Study, a nationwide survey of 40,308 functionally independent older individuals from 346 communities. Cognitive impairment was assessed by the nationally standardized dementia scale proposed by the Ministry of Health, Labour and Welfare of Japan. Participation in a sports group 1 d per month or more frequently was defined as "participation." We applied a two-level multilevel survival analysis to calculate hazard ratios (HR) and 95% confidence intervals (CI). RESULTS: The cumulative incidence of cognitive impairment during the 6-yr follow-up period was 9.8%. The mean proportion of sports group participation was 25.2% (range, 0.0%-56.5%). Higher prevalence of community-level sports group participation was associated with a lower risk of cognitive impairment (HR, 0.92; 95% CI, 0.86-0.99, estimated by 10 percentage points of participation proportion) after adjusting for individual-level sports group participation, sex, age, disease, obesity, social isolation, alcohol, smoking, education, income, depression, daily walking time, population density, and sunlight hours. We found cross-level interaction between individual- and community-level sports group participation (HR, 0.87; 95% CI, 0.76-0.99). CONCLUSIONS: We found a contextual preventive effect of community-level sports group participation on developing cognitive impairment among older individuals. Furthermore, the benefit may favor sports group participants. Therefore, promoting sports groups in a community setting may be effective as a population-based strategy for the prevention of dementia.

Community-level Sports Group Participation and Older Individuals' Depressive Symptoms.

PURPOSE: Community-level group participation is a structural aspect of social capital that may have a contextual influence on an individual's health. Herein, we sought to investigate a contextual relationship between community-level prevalence of sports group participation and depressive symptoms in older individuals. METHODS: We used data from the 2010 Japan Gerontological Evaluation Study, a population-based, cross-sectional study of individuals 65 yr or older without long-term care needs in Japan. Overall, 74,681 participants in 516 communities were analyzed. Depressive symptoms were diagnosed as a 15-item Geriatric Depression Scale score of ≥5. Participation in a sports group 1 d·month or more often was defined as "participation." For this study, we applied two-level multilevel Poisson regression analysis stratified by sex, calculated prevalence ratios (PR), and 95% confidence intervals (CI). RESULTS: Overall, 17,420 individuals (23.3%) had depressive symptoms, and 16,915 (22.6%) participated in a sports group. Higher prevalence of community-level sports group participation had a statistically significant relationship with a lower likelihood of depressive symptoms (male: PR, 0.89 (95% CI, 0.85-0.92); female: PR, 0.96 (95% CI, 0.92-0.99), estimated by 10% of participation proportion) after adjusting for individual-level sports group participation, age, diseases, family form, alcohol, smoking, education, equivalent income, and population density. We found statistically significant cross-level interaction terms in male participants only (PR, 0.86; 95% CI, 0.77-0.95). CONCLUSIONS: We found a contextual preventive relationship between community-level sports group participation and depressive symptoms in older individuals. Therefore, promoting sports groups in a community may be effective as a population-based strategy for the prevention of depression in older individuals. Furthermore, the benefit may favor male sports group participants.