Toru Tsuboya

Independent Association Between Improvement of Nonalcoholic Fatty Liver Disease and Reduced Incidence of Type 2 Diabetes

OBJECTIVE Only a few studies have evaluated the long-term effects of nonalcoholic fatty liver disease (NAFLD) on type 2 diabetes mellitus (T2DM), and none have examined whether NAFLD improvement reduces T2DM incidence. We investigated the association between NAFLD improvement and T2DM incidence. RESEARCH DESIGN AND METHODS Between 2000 and 2012, 4,604 participants who underwent a health check twice with >10 years between were enrolled. Exclusion criteria were positive hepatitis B surface antigen, positive hepatitis C antibody, ethanol intake >20 g/day, and diabetes. The 3,074 eligible participants were divided into an NAFLD group (n = 728) and a non-NAFLD group (n = 2,346) according to ultrasonography-detected fatty liver. The NAFLD group was categorized into an improved group (n = 110) and a sustained NAFLD group (n = 618) based on fatty liver disappearance at the second visit. Incident T2DM odds ratios (ORs) were estimated by logistic regression models adjusted for age, sex, BMI, impaired fasting glucose, family history of diabetes, dyslipidemia, hypertension, and physical exercise. RESULTS T2DM occurred in 117 participants (16.1%) in the NAFLD group and 72 (3.1%) in the non-NAFLD group. NAFLD at baseline was associated with T2DM incidence (multivariate OR 2.37 [95% CI 1.60–3.52]). T2DM occurred in 7 participants (6.4%) in the improved group and in 110 (17.8%) in the sustained NAFLD group. NAFLD improvement was associated with reduced T2DM incidence (multivariate OR 0.27 [95% CI 0.12–0.61]). CONCLUSIONS NAFLD improvement is associated with T2DM incidence reduction.

Green tea consumption and the risk of incident functional disability in elderly Japanese: the Ohsaki Cohort 2006 Study

Background: Previous studies have reported that green tea consumption is associated with a lower risk of diseases that cause functional disability, such as stroke, cognitive impairment, and osteoporosis. Although it is expected that green tea consumption would lower the risk of incident functional disability, this has never been investigated directly. Objective: The objective was to determine the association between green tea consumption and incident functional disability in elderly individuals. Design: We conducted a prospective cohort study in 13,988 Japanese individuals aged ≥65 y. Information on daily green tea consumption and other lifestyle factors was collected via questionnaire in 2006. Data on functional disability were retrieved from the public Long-term Care Insurance database, in which subjects were followed up for 3 y. We used Cox proportional hazards regression analysis to investigate the association between green tea consumption and functional disability. Results: The 3-y incidence of functional disability was 9.4% (1316 cases). The multiple-adjusted HR (95% CI) of incident functional disability was 0.90 (0.77, 1.06) among respondents who consumed 1–2 cups green tea/d, 0.75 (0.64, 0.88) for those who consumed 3–4 cups/d, and 0.67 (0.57, 0.79) for those who consumed ≥5 cups/d in comparison with those who consumed <1 cup/d (P-trend < 0.001). Conclusion: Green tea consumption is significantly associated with a lower risk of incident functional disability, even after adjustment for possible confounding factors.

Can Community Social Cohesion Prevent Posttraumatic Stress Disorder in the Aftermath of a Disaster? A Natural Experiment From the 2011 Tohoku Earthquake and Tsunami

In the aftermath of a disaster, the risk of posttraumatic stress disorder (PTSD) is high. We sought to examine whether the predisaster level of community social cohesion was associated with a lower risk of PTSD after the earthquake and tsunami in Tohoku, Japan, on March 11, 2011. The baseline for our natural experiment was established in a survey of older community-dwelling adults who lived 80 kilometers west of the epicenter 7 months before the earthquake and tsunami. A follow-up survey was conducted approximately 2.5 years after the disaster. We used a spatial Durbin model to examine the association of community-level social cohesion with the individual risk of PTSD. Among our analytic sample (n = 3,567), 11.4% of respondents reported severe PTSD symptoms. In the spatial Durbin model, individual- and community-level social cohesion before the disaster were significantly associated with lower risks of PTSD symptoms (odds ratio = 0.87, 95% confidence interval: 0.77, 0.98 and odds ratio = 0.75, 95% confidence interval: 0.63, 0.90, respectively), even after adjustment for depression symptoms at baseline and experiences during the disaster (including loss of loved ones, housing damage, and interruption of access to health care). Community-level social cohesion strengthens the resilience of community residents in the aftermath of a disaster.

A tomato-rich diet is related to depressive symptoms among an elderly population aged 70 years and over: a population-based, cross-sectional analysis.

BACKGROUND Enhanced oxidative stress or defective anti-oxidant defenses are related to the pathogenesis of depressive symptoms. Lycopene is the most powerful antioxidant amongst the carotenoids. The aim of this study was to investigate the relationship between different vegetables, including tomatoes/tomato products (a major source of lycopene), and depressive symptoms in a community-based elderly population. METHODS We analyzed a cross-sectional survey including 986 community-dwelling elderly Japanese individuals aged 70 years and older. Dietary intake was assessed using a valid self-administered diet-history questionnaire, and depressive symptoms were evaluated using the 30-item Geriatric Depression Scale with 2 cut-off points: 11 (mild and severe) and 14 (severe) or use of anti-depressive agents. RESULTS The prevalence of mild and severe and severe depressive symptoms was 34.9% and 20.2%, respectively. After adjustments for potentially confounding factors, the odds ratios of having mild and severe depressive symptoms by increasing levels of tomatoes/tomato products were 1.00, 0.54, and 0.48 (p for trend <0.01). Similar relationships were also observed in the case of severe depressive symptoms. In contrast, no relationship was observed between intake of other kinds of vegetables and depressive symptoms. LIMITATIONS This is a cross-sectional study, and not for making a clinical diagnosis of depressive episodes. CONCLUSIONS This study demonstrated that a tomato-rich diet is independently related to lower prevalence of depressive symptoms. These results suggest that a tomato-rich diet may have a beneficial effect on the prevention of depressive symptoms. Further studies are needed to confirm these findings.

Relationship Between Serum Adiponectin Levels and Disability-Free Survival Among Community-Dwelling Elderly Individuals: The Tsurugaya Project

BACKGROUND Mortality risk tends to be higher among elderly individuals with higher serum adiponectin levels. The objective of this study was to clarify whether the relationship between adiponectin and a higher risk of disability or death can be explained by physical function, bone mineral density, depression, and malnutrition. METHODS We analyzed 505 individuals who underwent comprehensive geriatric assessment and who agreed to provide information on long-term care insurance. The endpoint was the composite outcome of death and incident disability defined as a first certification for any level of care need. Relationships between adiponectin and incident disability or death were estimated using the Cox proportional hazards model. RESULTS During 6 years of follow-up, 179 incident disabilities or deaths occurred. Among them, 20 and 23 died with and without disability, respectively. The risk of incident disability or death was significantly higher among participants with adiponectin greater than or equal to 22.4 (90%) than 8.0 or less (25%) mg/L (Hazard ratio: 95% confidence interval, 1.92: 1.01-3.64) in the model adjusted for age, sex, and metabolic risk factors. Adjustment for N-terminal pro-B-type natriuretic peptide and nutritional status did not substantially alter this risk estimate, although the association ceased to be statistically significant. Adjustment for physical function did attenuate the relationship, however, which ceased to be apparent upon exclusion of disability or death occurring within 3 years of follow-up. CONCLUSION The relationship between adiponectin and the composite outcome of incident disability and death was at least partly explained by reduced physical function and wasting in participants with higher adiponectin levels.

Lack of Independent Association Between Fatty Pancreas and Incidence of Type 2 Diabetes: 5-Year Japanese Cohort Study

OBJECTIVE Previous cross-sectional studies have shown that attenuation in the pancreas seen on unenhanced computed tomography (CT) scans was inversely correlated with histologic pancreatic fat, and that fatty pancreas was associated with type 2 diabetes mellitus (T2DM). However, no longitudinal study has evaluated whether fatty pancreas increases the incidence of T2DM. We conducted a cohort study to investigate the association between fatty pancreas and the incidence of T2DM. RESEARCH DESIGN AND METHODS A total of 813 participants without diabetes underwent health checks by unenhanced CT scanning in 2008 and 2009, and were observed for a median follow-up period of 5.06 (interquartile range 3.01–5.92) years. Attenuation in three regions of the pancreas seen on an unenhanced CT scan was measured, and the mean pancreatic attenuation was calculated to evaluate fatty pancreas at baseline; the more severe the fatty pancreas, the lower the mean pancreatic attenuation. The incident T2DM hazard ratios (HRs) for the association between fatty pancreas and T2DM incidence were estimated by Cox proportional hazards models adjusted for age, sex, BMI, liver attenuation seen on unenhanced CT scan, and alcohol intake of ≥20 g/day. RESULTS T2DM occurred in 62 participants (7.6%) during the follow-up period. The higher pancreas attenuation (i.e., less pancreatic fat) at baseline was associated with decreased T2DM incidence in a univariate analysis (crude HR 0.97 [95% CI 0.96–0.99]); and fatty pancreas (lower pancreas attenuation) was positively associated with increased T2DM incidence. However, the association was substantially explained by the confounders (multivariate HR 1.00 [95% CI 0.98–1.02]). CONCLUSIONS Fatty pancreas was not independently associated with future T2DM.

Change in psychological distress following change in workplace social capital: results from the panel surveys of the J-HOPE study

Purpose Research on the longitudinal association of workplace social capital and mental health is limited. The purpose of the present study was to investigate the prospective association of social capital in the workplace with mental distress, measured by K6, adjusting for individuals factors as well as workplace-related factors among employees in Japan. Methods The participants included 6387 men and 1825 women from 12 private companies in Japan. Questionnaires, inquiring about workplace social capital, K6, job strain and effort-reward imbalance were administered at the baseline survey between October 2010 and December 2011 (response rate=77.4%). At 1-year follow-up, social capital and K6 were assessed again (follow-up rate=79.5%), and a generalised linear model was used to estimate the association between changes in workplace social capital and change in K6. Results After adjusting for baseline demographic characteristics and workplace-related factors (Job Content Questionnaire (JCQ), Effort-Reward Imbalance Questionnaire (ERIQ)), increased workplace social capital between waves was associated with improved psychological distress (β=−0.2327, p<0.0001). An inverse association was found in both men and women, all age groups, and among employees with high or low baseline mental health. The association was stronger among those who reported higher stress at baseline. Conclusions Boosting workplace social capital may promote mental health in the workplace.

Increased risk of dementia in the aftermath of the 2011 Great East Japan Earthquake and Tsunami

Significance Recovery after major disaster poses potential risks of dementia for the elderly population. However, no previous studies have examined exposure to natural disaster and changes in risk factors as predictors of deterioration in cognitive function. We prospectively examined whether housing damage and loss of relatives or friends were associated with cognitive decline in the aftermath of the 2011 Great East Japan Earthquake and Tsunami. In this study, which included 3,566 survivors who are 65 y old or older, the severity of housing damage was significantly associated with cognitive decline after controlling changes of covariates and risk factors during the follow-up period. The cognitive decline should be listed as a health risk of older survivors in the aftermath of natural disasters. No previous study has been able to examine the association by taking account of risk factors for dementia before and after the disaster. We prospectively examined whether experiences of a disaster were associated with cognitive decline in the aftermath of the 2011 Great East Japan Earthquake and Tsunami. The baseline for our natural experiment was established in a survey of older community-dwelling adults who lived 80 km west of the epicenter 7 mo before the earthquake and tsunami. Approximately 2.5 y after the disaster, the follow-up survey gathered information about personal experiences of disaster as well as incidence of dementia from 3,594 survivors (82.1% follow-up rate). Our primary outcome was dementia diagnosis ascertained by in-home assessment during the follow-up period. Among our analytic sample (n = 3,566), 38.0% reported losing relatives or friends in the disaster, and 58.9% reported property damage. Fixed-effects regression indicated that major housing damage and home destroyed were associated with cognitive decline: regression coefficient for levels of dementia symptoms = 0.12, 95% confidence interval (CI): 0.01 to 0.23 and coefficient = 0.29, 95% CI: 0.17 to 0.40, respectively. The effect size of destroyed home is comparable to the impact of incident stroke (coefficient = 0.24, 95% CI: 0.11 to 0.36). The association between housing damage and cognitive decline remained statistically significant in the instrumental variable analysis. Housing damage appears to be an important risk factor for cognitive decline among older survivors in natural disasters.

Relationship Between Serum Isoflavone Levels and Disability-Free Survival Among Community-Dwelling Elderly Individuals: Nested Case–Control Study of the Tsurugaya Project

BACKGROUND The longer healthy life expectancy observed in Japan may be partly attributed to the Japanese diet. The researchers sought to examine whether serum isoflavone levels are associated with disability and death. METHODS The researchers used a nested case-control study to compare serum isoflavones (daidzein, genistein, glycitein, and equol) levels between 165 participants that died or were certificated as disabled (cases) and 177 controls. Disability was defined by certification of long-term care insurance. Conditional logistic regression models were used to calculate the risk of isoflavones for the composite outcome. RESULTS The proportion of cases was lower in the group with the highest levels of equol (34/91, 37%) compared with equol nonproducers (84/161, 52%). The risk of disability or death among equol producers remained reduced after adjusting for age and sex (odds ratio: 0.55, 95% confidence interval: 0.33-0.93). In a multivariate model, this risk was also unchanged (odds ratio: 0.51, 95% confidence interval: 0.27-0.96). There were no significant associations between daidzein, genistein, and glycitein with the composite endpoint. CONCLUSIONS Higher serum equol levels, but not any other isoflavones, were inversely associated with the composite endpoint of disability and death. Although it cannot be concluded that equol per se has preventive effects on disability or death, higher equol levels appear associated with better health.

Social capital and cognitive decline in the aftermath of a natural disaster: a natural experiment from the 2011 Great East Japan Earthquake and Tsunami

Background We examined prospectively whether social capital mitigates the adverse effects of natural disaster on cognitive decline. Methods The baseline for our study was established seven months before the 2011 Great East Japan Earthquake and Tsunami in a survey of older community-dwelling adults who lived 80 kilometers west of the epicenter (59.0% response rate). Approximately two and a half years after the disaster, the follow-up survey gathered information about personal experiences of disaster as well as incidence of cognitive disability (82.1% follow-up rate). Our primary outcome was cognitive disability (measured on an 8-level scale) assessed by in-home assessment. Findings The experience of housing damage was associated with risk of cognitive impairment (coefficient = 0.04, 95% confidence interval: 0.02 to 0.06). Factor analysis of our analytic sample (n = 3,566) established two sub-scales of social capital: a cognitive dimension (perceptions of community social cohesion) and a structural dimension (informal socializing and social participation). Fixed effects regression showed that informal socializing and social participation buffered the risk of cognitive decline resulting from housing damage. Interpretation Informal socializing and social participation may prevent cognitive impairment following natural disaster. Funding National Institutes of Health (R01AG042463-04), the Japan Society for the Promotion of Science, the Japanese Ministry of Health, Labour and Welfare and the Japanese Ministry of Education, Culture, Sports, Science and Technology.