Longitudinal associations between post-traumatic stress and post-traumatic growth among older adults 11 years after a disaster.

AIMS: Previous studies have reported inconsistent findings regarding the association between post-traumatic stress (PTS) and post-traumatic growth (PTG). Three major issues could account for this inconsistency: (1) the lack of information about mental health problems before the disaster, (2) the concept of PTG is still under scrutiny for potentially being an illusionary perception of personal growth and (3) the overlooking of PTS comorbidities as time-dependent confounding factors. To address these issues, we explored the associations of PTS and PTG with trauma-related diseases and examined the association between PTS and PTG using marginal structural models to address time-dependent confounding, considering pre-disaster covariates, among older survivors of the 2011 Japan Earthquake and Tsunami. METHODS: Seven months before the disaster, the baseline survey was implemented to ask older adults about their health in a city located 80 km west of the epicentre. After the disaster, we implemented follow-up surveys approximately every 3 years to collect information about PTS and comorbidities (depressive symptoms, smoking and drinking). We asked respondents about their PTG in the 2022 survey (n = 1,489 in the five-wave panel data). RESULTS: PTG was protectively associated with functional disability (coefficient -0.47, 95% confidence interval (CI) -0.82, -0.12, P < 0.01) and cognitive decline assessed by trained investigators (coefficient -0.07, 95% CI -0.11, -0.03, P < 0.01) and physicians (coefficient -0.06, 95% CI -0.11, -0.02, P < 0.01), while PTS was not significantly associated with them. Severely affected PTS (binary variable) was associated with higher PTG scores, even after adjusting for depressive symptoms, smoking and drinking as time-dependent confounders (coefficient 0.35, 95% CI 0.24, 0.46, P < 0.01). We also found that an ordinal variable of the PTS score had an inverse U-shaped association with PTG. CONCLUSION: PTG and PTS were differentially associated with functional and cognitive disabilities. Thus, PTG might not simply be a cognitive bias among survivors with severe PTS. The results also indicated that the number of symptoms in PTS had an inverse U-shaped association with PTG. Our findings provided robust support for the theory of PTG, suggesting that moderate levels of psychological struggles (i.e., PTS) are essential for achieving PTG, whereas intense PTS may hinder the attainment of PTG. From a clinical perspective, interventions that encourage social support could be beneficial in achieving PTG by facilitating deliberate rumination.

Multifaceted ORganizational InterventiONs (M-ORION) project for prevention of depression and anxiety among workers: study protocol for a five-arm cluster randomized controlled trial.

BACKGROUND: Depression and anxiety are the most common mental health issues experienced by workers. Although organizational intervention has been extensively evaluated as a primary prevention of depression and anxiety, the corresponding scientific evidence remains limited because of the lack of cluster randomized controlled trials (cRCT) and failure to detect organizational-level effects. Therefore, the present study aims to assess the preventive effects of four types of interventions on depression and anxiety among workers in an open, five-arm, parallel-group cRCT. METHODS: Overall, 140 worksites and 18,200 nested employees will be recruited from September 2023. The eligible worksites will be randomly assigned to each of the five arms, and programs will be offered for 6-12 months. The five arms are 1) psychoeducation for workers, 2) psychoeducation for supervisors, 3) work environment improvement, 4) physical activity promotion, and 5) active control. The primary outcomes of interest are depression and anxiety. We will also assess psychosocial factors at work, work engagement, health-related quality of life, well-being, economic outcomes, physiological outcomes of health checkups, cortisol levels extracted from fingernails, and indices representing the process and implementation outcomes, including program completion rates. Follow-up surveys will be conducted at 6, 12, and 18 months from baseline, and the primary endpoint is set at the 6-month follow-up. Repeated-measures multi-level mixed modeling will be used to evaluate the effect of each intervention compared with the control. ETHICS AND DISSEMINATION: The study protocol was approved by the Research Ethics Committee of the Kitasato University Medical Ethics Organization (C22-082). The results and findings of this study will be published in a scientific journal and disseminated to companies that participate in the study. TRIAL REGISTRATION NUMBER: UMIN000050949.

Association of disaster-related damage with inflammatory diet among older survivors of the Great East Japan Earthquake and Tsunami.

Traumatic experiences from disasters have enduring effects on health, both directly and indirectly by influencing health behaviours. Among potential pathways, the impact of disaster-related trauma on dietary patterns has been understudied. This study investigated the relationship between disaster-related trauma and dietary inflammatory index (DII®), and how these relationships differed by gender and whether they prepare meal by themselves or not among older survivors of the 2011 Great East Japan Earthquake and Tsunami (n 1375). Dietary data were collected in 2020 using a brief-type self-administered diet history questionnaire, from which we derived a dietary inflammatory index (DII®) based on twenty-six food/nutrient items, where higher scores indicate pro-inflammatory (i.e. unhealthy) diet. We found that the experience of housing damage due to the earthquake and tsunami was associated with slightly higher DII scores (coef. = 0·38, 95 % CI -0·05, 0·81). Specifically, women who cooked by themselves tended to have higher DII when they experienced housing damage (coef. = 1·33, 95 %CI -0·63, 3·28). On the other hand, loss of friends was associated with a lower DII score (coef. = -0·28, 95 % CI -0·54, -0·01). These findings highlight the importance of providing support to groups who are at increased risk of deterioration in dietary quality in the aftermath of disasters.

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

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

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.

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.

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.

Bidirectional associations between post-traumatic stress symptoms and sleep quality among older survivors of the 2011 Great East Japan Earthquake and Tsunami.

STUDY OBJECTIVES: We sought to examine the bidirectional associations between post-traumatic stress symptoms (PTSS) and sleep quality in a sample of older disaster survivors. METHODS: We used 4 waves (2010, 2013, 2016, and 2020) of the Iwanuma Study, which included pre-disaster information and 9 years of follow-up data among older survivors of the 2011 Great East Japan Earthquake and Tsunami. Poisson regression analysis was used to examine the bidirectional associations between sleep problems and PTSS. RESULTS: Individuals reporting sleep problems before the disaster were more likely to develop PTSS after exposure to disaster trauma, while there was no effect modification, i.e. prevalence ratio for sleep problems did not differ by the magnitude of disaster damages. Individuals reporting sleep problems after the disaster were less likely to recover from PTSS, and more likely to develop the delayed onset of PTSS 5 years after the disaster. While individuals who recovered from PTSS 9 years after the disaster were still at slightly higher risk of having sleep problems compared to those who never had PTSS, none of the sleeping problems were found to be significantly prevalent after the Bonferroni correction. CONCLUSIONS: Pre-disaster sleep problems predicted PTSS onset independently of experiences of disaster trauma. The association between PTSS and sleep problems was bidirectional. Intervening to mitigate lingering sleep problems may benefit the recovery of disaster survivors from post-traumatic symptoms.

Longitudinal Associations Between Disaster Damage and Falls/Fear of Falling in Older Adults: 9-Year Follow-Up of Survivors of the 2011 Great East Japan Earthquake and Tsunami.

Background and Objectives: Fear of falling and falls are common in older adults. However, their associations with natural disaster exposures remain poorly understood. This study aims to examine longitudinal associations between disaster damage with fear of falling/falls among older disaster survivors. Research Design and Methods: In this natural experiment study, the baseline survey (4,957 valid responses) took place 7 months before the 2011 Great East Japan Earthquake and Tsunami, and 3 follow-ups were conducted in 2013, 2016, and 2020. Exposures were different types of disaster damage and community social capital. Outcomes were fear of falling and falls (including incident and recurrent falls). We used lagged outcomes in logistic models adjusting for covariates and further examined instrumental activities of daily living (IADLs) as a mediator. Results: The baseline sample had a mean (standard deviation) age of 74.8 (7.1) years; 56.4% were female. Financial hardship was associated with fear of falling (odds ratio (OR), 1.75; 95% confidence interval (CI) [1.33, 2.28]) and falls (OR, 1.29; 95% CI [1.05, 1.58]), especially recurrent falls (OR, 3.53; 95% CI [1.90, 6.57]). Relocation was inversely linked with fear of falling (OR, 0.57; 95% CI [0.34, 0.94]). Social cohesion was protectively associated with fear of falling (OR, 0.82; 95% CI [0.71, 0.95]) and falls (OR, 0.88; 95% CI [0.78, 0.98]) whereas social participation increased the risk of these issues. IADL partially mediated observed associations between disaster damage and fear of falling/falls. Discussion and Implications: Experiences of material damage rather than psychological trauma were associated with falls and fear of falling, and the increased risk of recurrent falls revealed a process of cumulative disadvantage. Findings could inform targeted strategies for protecting older disaster survivors.

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.

Long-Term Trend in the Association Between Disaster Damage and Happiness Before and After the Great East Japan Earthquake.

Objectives: Disasters change survivors' living circumstances, which can affect their happiness. We examined the trends in the association between disaster damage and happiness before and after a disaster. Methods: We analyzed 4,044 participants aged ≥65 years who had experienced the Great East Japan Earthquake in 2011. The baseline survey was conducted 7 months before the disaster. Follow-up surveys have been conducted every 3 years. Using a mixed model for repeated measures, we compared the prevalence ratios (PRs) for unhappiness according to the survivors' level of housing damage, which is a proxy for disaster damage. Results: The unhappiness in participants who suffered severe damage appeared to be higher than in those with no damage in 2010 (multivariate-adjusted PR: 1.18, 95% confidence interval: 0.93-1.48). A higher PR was observed after the earthquake in 2013 (1.34, 0.79-2.28), while there was no difference in 2016 (1.02, 0.53-1.97) and 2019 (1.03, 0.50-2.12). Conclusion: The prevalence of unhappiness in survivors with severe housing damage was higher before the disaster. However, the unhappiness gap between people with and without housing damage converged during the follow-up.

Workplace Social Support and Reduced Psychological Distress: A 1-Year Occupational Cohort Study.

OBJECTIVE: There is little evidence that workplace social support can relieve workers' mental health problems. Therefore, we examined whether social support from coworkers and supervisors was associated with reduced serious psychological distress among employees. METHODS: We used two-wave panel data from 13 Japanese companies. The baseline survey was conducted in 2011, and the follow-up survey 1 year later. From 9889 respondents, we selected 759 who had psychological distress at baseline, defined as ≥13 on the Kessler Psychological Distress Scale (K6). RESULTS: Increased coworker support was significantly associated with employees' reduced psychological distress (odds ratio, 3.51; 95% confidence interval, 2.17 to 5.68). The association between increased supervisor support and reduced psychological distress was nonsignificant (odds ratio, 1.32, 95% confidence interval, 0.85 to 2.04). CONCLUSION: Encouraging coworker support may contribute to the secondary prevention of mental health problems among employees.

Long-Term Associations between Disaster-Related Home Loss and Health and Well-Being of Older Survivors: Nine Years after the 2011 Great East Japan Earthquake and Tsunami.

BACKGROUND: Little research has examined associations between disaster-related home loss and multiple domains of health and well-being, with extended long-term follow-up and comprehensive adjustment for pre-disaster characteristics of survivors. OBJECTIVES: We examined the longitudinal associations between disaster-induced home loss and 34 indicators of health and well-being, assessed ∼9y post-disaster. METHODS: We used data from a preexisting cohort study of Japanese older adults in an area directly impacted by the 2011 Japan Earthquake (n=3,350 and n=2,028, depending on the outcomes). The study was initiated in 2010, and disaster-related home loss status was measured in 2013 retrospectively. The 34 outcomes were assessed in 2020 and covered dimensions of physical health, mental health, health behaviors/sleep, social well-being, cognitive social capital, subjective well-being, and prosocial/altruistic behaviors. We estimated the associations between disaster-related home loss and the outcomes, using targeted maximum likelihood estimation and SuperLearner. We adjusted for pre-disaster characteristics from the wave conducted 7 months before the disaster (i.e., 2010), including prior outcome values that were available. RESULTS: After Bonferroni correction for multiple testing, we found that home loss (vs. no home loss) was associated with increased posttraumatic stress symptoms (standardized difference=0.50; 95% CI: 0.35, 0.65), increased daily sleepiness (0.38; 95% CI: 0.21, 0.54), lower trust in the community (-0.36; 95% CI: -0.53, -0.18), lower community attachment (-0.60; 95% CI: -0.75, -0.45), and lower prosociality (-0.39; 95% CI: -0.55, -0.24). We found modest evidence for the associations with increased depressive symptoms, increased hopelessness, more chronic conditions, higher body mass index, lower perceived mutual help in the community, and decreased happiness. There was little evidence for associations with the remaining 23 outcomes. DISCUSSION: Home loss due to a disaster may have long-lasting adverse impacts on the cognitive social capital, mental health, and prosociality of older adult survivors. https://doi.org/10.1289/EHP10903.

Community intervention programs prolong the onset of functional disability among older Japanese.

AIM: This study examined the effects of a "community-based center" intervention to prevent the onset of functional disability among residents in disaster-affected areas. METHODS: We used data from a prospective cohort study conducted from 2010 to 2016 in Iwanuma City, Japan. Participants were community-dwelling independent adults aged ≥65 years. The exposure variable was the experience of using a community-based center. The outcome variable was functional disability onset. The average treatment effect on the treated (ATET) was estimated by adjusting for possible confounders. Additional analysis stratified by sex was conducted considering the sex differences in social participation rates. RESULTS: Among 3794 participants (mean ± SD age = 72.9 ±5.3 years, 46.0% men), 196 (5.2%) used the community-based center, and 849 (22.4%) exhibited disability onset. Of those with functional disabilities, 40 (20.4%) used the community-based center, while 809 (22.5%) did not. The ATET for functional disability onset with community-based center activities across all participants were not significant (ATET: 0.51 years [95% confidence interval [CI] = -0.23; 1.27]). However, the direction of the effect of community-based center activities differed by sex (ATET: -0.14, 95% CI = -2.59; 2.31 for men [n = 18], and 0.66, 95% CI = 0.18; 1.16 for women [n = 178]). Women exhibited a 15.63% (95% CI = 3.58; 27.68) increase in the time until functional disability onset. CONCLUSIONS: The use of community-based centers was associated with a longer period without functional disability in women. Geriatr Gerontol Int 2022; 22: 465-470.

Heterogeneity in cognitive disability after a major disaster: A natural experiment study.

Cognitive disability following traumatic experiences of disaster has been documented; however, little is known about heterogeneity in the association across individuals. In this natural experiment study of approximately 3000 Japanese older adults in an area directly affected by the 2011 Great East Japan Earthquake, the baseline survey was established 7 months before the 2011 earthquake. To inductively identify heterogeneity in postdisaster cognitive disability by predisaster characteristics, we applied a machine learning­based causal inference approach­generalized random forest. We identified strong evidence for heterogeneity in the association between home loss and cognitive disability objectively assessed 2.5 and 5.5 years after the 2011 earthquake. The subgroups with the strongest disaster-dementia associations tended to be from low socioeconomic backgrounds and have predisaster health problems. The study demonstrated that some subpopulations are particularly prone to experience cognitive disability after disasters, which could be overlooked in studies assessing population average associations only.

Six-year follow-up study of residential displacement and health outcomes following the 2011 Japan Earthquake and Tsunami.

Studies examining the long-term health consequences of residential displacement following large-scale disasters remain sparse. Following the 2011 Japan Earthquake and Tsunami, victims who lost their homes were resettled by two primary means: 1) group relocation to public housing or 2) individual relocation, in which victims moved into public housing by lottery or arranged for their own accommodation. Little is known about how the specific method of residential relocation affects survivors' health. We examined the association between residential relocation and long-term changes in mental and physical well-being. Our baseline assessment predated the disaster by 7 mo. Two follow-up surveys were conducted ∼2.5 y and 5.5 y after the disaster to ascertain the long-term association between housing arrangement and health status. Group relocation was associated with increased body mass index and depressive symptoms at 2.5-y follow-up but was no longer significantly associated with these outcomes at 5.5-y follow-up. Individual relocation at each follow-up survey was associated with lower instrumental activities of daily living as well as higher risk of cognitive impairment. Our findings underscore the potential complexity of long-term outcomes associated with residential displacement, indicating both positive and negative impacts on mental versus physical dimensions of health.

Parental cohabitation and mental well-being amongst young adults in the world's densest population with least affordable housing: Evidence from the FAMILY cohort.

BACKGROUND: Owing to rapidly raising property prices, living with parents is the most common living arrangement among young adults in urban areas. Studies for "full nest syndrome" or "boomerang children" have demonstrated that moving back in with parents was associated with more depressive symptoms. On the other hand, studies have suggested that living with parents was not associated with mental health in several countries where inter-generational households could potentially provide more social support among household members. We examined whether delayed residential independence might adversely impact mental health of young adults. METHODS: The cross-sectional study was conducted from 2009 to 2011 in Hong Kong SAR, China - a highly urbanized city with the least affordable housing in the world. The analytic samples were 3612 young adults. Outcomes of interest were depressive symptoms and mental well-being. RESULTS: Co-residence with parents under self headship was associated with young adults' fewer depressive symptoms (ß = -0.157, 95% confidence interval [CI] = -0.311 to -0.003) and better mental well-being (ß = 1.342, 95% CI = 0.522 to 2.162). LIMITATIONS: This is susceptible to reverse causation, whereby young adults with poorer mental health may be more likely to stay or move back into their parental home. CONCLUSIONS: Our findings showed that young adults co-residing with parents as the household head were associated with fewer depressive symptoms and better mental well-being compared to living with parents under their parental headship.

Associations Between Community Social Capital and Preservation of Functional Capacity in the Aftermath of a Major Disaster.

The strength of social connections in the community ("social capital") is hypothesized to be a crucial ingredient in disaster resilience. We examined whether community-level social capital is correlated with the ability to maintain functional capacity among older residents who experienced the 2011 Great East Japan Earthquake and Tsunami. The baseline of our cohort (mean age, 74 years) was established in 2010, 7 months before the disaster in Iwanuma, a Japanese city located 80 km from the epicenter. Disaster-related personal experiences (e.g., housing damage or relocation) were assessed through a follow-up survey (n = 3,594; follow-up rate, 82.1%) conducted in 2013, 2.5 years after the earthquake. Multiple membership multilevel models were used to evaluate the associations between functional capacity, measured by the Instrumental Activities of Daily Living scale, and 3 subscales of community-level social capital: social cohesion, social participation, and reciprocity. Community-level social participation was associated with a lower risk of functional decline after disaster exposure. The average level of social participation in the community also mitigated the adverse impact of housing damage on functional status, suggesting a buffering mechanism.

Disaster Resilience in Aging Populations: Lessons from the 2011 Great East Japan Earthquake & Tsunami.

Recovery after major disaster poses a unique set of challenges for the older population, including disruption of medical care for pre-existing conditions, functional limitations that impede recovery, and social isolation following involuntary resettlement. In this review, we summarize the lessons about disaster resilience that have been learned (so far) from a unique ongoing field study based in a community that was affected by the 2011 earthquake and tsunami in Japan. In the Iwanuma Study, baseline information about the health status and living conditions of older residents was collected seven months before the disaster. A follow-up survey was conducted 2.5 years after the disaster, allowing us investigate the risk and protective factors for a range of disaster-related health sequelae, including mental illness and cognitive disability. A consistent finding to emerge from our studies is the critical role of social connections (the "social capital" of a community) in protecting against the deleterious after-effects of psychological trauma and involuntary resettlement following the disaster. In contrast to the emphasis on investing in material infrastructure to prepare for disasters, a review of our studies suggests that repairing (or at least preserving) the social fabric of people's lives is a crucial ingredient in disaster resilience.

Community-level social capital and cognitive decline after a natural disaster: A natural experiment from the 2011 Great East Japan Earthquake and Tsunami.

We examined prospectively whether community-level social capital can mitigate the adverse effects of natural disaster on cognitive decline in the aftermath of the 2011 Great East Japan Earthquake and Tsunami. The baseline for our natural experimental study was established seven months before the disaster in a survey of older community-dwelling adults who lived in Iwanuma City, Japan, located 80 km west of the epicenter. Two and a half years after the disaster, we conducted a follow-up survey of survivors to gather information about their personal experiences during the disaster (n = 3560; 82.1% follow-up rate). Our primary outcome was the level of cognitive disability (measured on an 8-level scale) assessed within people's homes. Factor analysis established two subscales of community social capital: a cognitive dimension (perceptions of community social cohesion) and a structural dimension (informal socializing and social participation). The prevalence of cognitive decline at follow-up (11.5%) was three times higher than at baseline (4.2%). Our multiple membership multilevel model indicated that pre-versus post-disaster increases in community-level informal socializing and social participation were associated with lower risk of cognitive decline (coefficient = -0.12, 95% confidence interval: -0.20 to -0.04). In addition, social capital mitigated the risk of cognitive decline due to housing damage (interaction effect coefficient = -0.07, 95% confidence interval: -0.14 to -0.01). Community-level informal socializing and social participation buffers the impact of housing damage on cognitive decline in the aftermath of natural disaster. Relocating residents together with other community members may help to preserve community social capital and improve the cognitive resilience of older survivors.