Objective: To investigate the association between the sense of “life worth living (ikigai)” and the cause-specific mortality risk. The psychological factors play important roles in morbidity and mortality risks. However, the association between the negative psychological factors and the risk of mortality is inconclusive. Methods: The Ohsaki Study, a prospective cohort study, was initiated on 43,391 Japanese adults. To assess if the subjects found a sense of ikigai, they were asked the question, “Do you have ikigai in your life?” We used Cox regression analysis to calculate the hazard ratio of the all-cause and cause-specific mortality according to the sense of ikigai categories. Results: Over 7 years’ follow-up, 3048 of the subjects died. The risk of all-cause mortality was significantly higher among the subjects who did not find a sense of ikigai as compared with that in the subjects who found a sense of ikigai; the multivariate adjusted hazard ratio (95% confidence interval) was 1.5 (1.3–1.7). As for the cause-specific mortality, subjects who did not find a sense of ikigai were significantly associated with an increased risk of cardiovascular disease (1.6; 1.3–2.0) and external cause mortality (1.9; 1.1–3.3), but not of the cancer mortality (1.3; 1.0–1.6). Conclusions: In this prospective cohort study, subjects who did not find a sense of ikigai were associated with an increased risk of all-cause mortality. The increase in mortality risk was attributable to cardiovascular disease and external causes, but not cancer. CVD = cardiovascular disease; NHI = National Health Insurance; PHC = Public Health Center; IHD = ischemic heart disease; HR = hazard ratio; CI = confidence interval; BMI = body mass index.

The association between social isolation and psychological distress among disaster survivors is inconclusive. In addition, because these previous studies were cross-sectional in design, the longitudinal association between time-varying social isolation and psychological distress was not clear. The present study examined the longitudinal association between social isolation and psychological distress after the Great East Japan Earthquake. We analyzed longitudinal data for 959 adults who had responded to the self-report questionnaires about Lubben Social Network Scale-6 (LSNS-6) and K6 in both a community-based baseline survey (2011) and a follow-up survey (2014) after the disaster. Participants were categorized into four groups according to changes in the presence of social isolation (<12/30 of LSNS-6) at two time points (2011 and 2014): "remained socially isolated", "became not socially isolated", "remained not socially isolated", and "became socially isolated". We defined a K6 score of ≥ 10/24 as indicating the presence of psychological distress. We used multiple logistic regression analysis to estimate the adjusted odds ratios (ORs) and 95% confidence intervals (CIs) to indicate how the change in social isolation was related to changes in psychological distress over 3 years. Among the participants who had not shown psychological distress at the baseline, the rates of deterioration of psychological distress were significantly lower in participants who "became not socially isolated" (multivariate OR = 0.26, 95% CI = 0.08-0.70) and "remained not socially isolated" (multivariate OR = 0.49, 95% CI = 0.27-0.91), compared with participants who "remained socially isolated". Among the participants who had psychological distress at the baseline, the rate of improvement of psychological distress was significantly higher in participants who "remained not socially isolated" (multivariate OR = 2.61, 95% CI = 1.08-6.44). The present findings suggest that prevention of social isolation may be an effective public health strategy for preventing psychological distress after a natural disaster.

Randomized controlled trial for an effect of catechin-enriched green tea consumption on adiponectin and cardiovascular disease risk factors

To examine whether social participation affects the association between frailty and disability. A baseline survey conducted from December 1 to 15, 2006, included 11,992 participants who were classified based on the Kihon Checklist into three categories and based on the number of activities in which they socially participated into four categories. The study outcome, incident functional disability, was defined as in Long-Term Care Insurance certification. A Cox proportional hazards model was used to calculate hazard ratios (HRs) for incident functional disability according to frailty and social participation categories. Combination analysis was performed between the nine groups using the above-mentioned Cox proportional hazards model. During the 13-year follow-up (107,170 person-years), 5,732 incident cases of functional disability were certified. Compared with the robust group, the other groups had significantly higher incident functional disability. However, the HRs for those participating in social activities were lower than that for those not participating in any activity [1.52 (pre-frail + none group); 1.31 (pre-frail + one activity group); 1.42 (pre-frail + two activities group); 1.37 (pre-frail + three activities group); 2.35 (frail + none group); 1.87 (frail + one activity group); 1.85 (frail + two activities group); and 1.71 (frail + three activities group)]. The risk of functional disability for those participating in social activities was lower than that for those not participating in any activity, irrespective of being pre-frail or frail. Comprehensive social systems for disability prevention need to focus on social participation in frail older adults.

Effective social problem-solving abilities can contribute to decreased risk of poor mental health. In addition, physical activity has a favorable effect on mental health. These previous studies suggest that physical activity and social problem-solving ability can interact by helping to sustain mental health. The present study aimed to determine the association between attitude and practice of physical activity and social problem-solving ability among university students. Information on physical activity and social problem-solving was collected using a self-administered questionnaire. We analyzed data from 185 students who participated in the questionnaire surveys and psychological tests. Social problem-solving as measured by the Social Problem-Solving Inventory-Revised (SPSI-R) (median score 10.85) was the dependent variable. Multiple logistic regression analysis was employed to calculate the odds ratios (ORs) and 95% confidence intervals (CIs) for higher SPSI-R according to physical activity categories. The multiple logistic regression analysis indicated that the ORs (95% CI) in reference to participants who said they never considered exercising were 2.08 (0.69–6.93), 1.62 (0.55–5.26), 2.78 (0.86–9.77), and 6.23 (1.81–23.97) for participants who did not exercise but intended to start, tried to exercise but did not, exercised but not regularly, and exercised regularly, respectively. This finding suggested that positive linear association between physical activity and social problem-solving ability (p value for linear trend < 0.01). The present findings suggest that regular physical activity or intention to start physical activity may be an effective strategy to improve social problem-solving ability.