Yu Kaiho

Green Tea Consumption and the Risk of Incident Dementia in Elderly Japanese: The Ohsaki Cohort 2006 Study

OBJECTIVE Biologic studies have shown that certain components of green tea may have protective effects on neurocognition. However, because of the lack of human epidemiologic studies, the impact of green tea consumption on the incidence of dementia has never been confirmed. The objective of this cohort study was to clarify the association between green tea consumption and incident dementia. METHODS In this 5.7-year prospective cohort study, using a questionnaire, information on daily green tea consumption and other lifestyle factors was collected from elderly Japanese individuals aged 65 years or more. Data on incident dementia were retrieved from the public Long-term Care Insurance Database. RESULTS Among 13,645 participants, the 5.7-year rate of incident dementia was 8.7%. More frequent green tea consumption was associated with a lower risk of incident dementia (hazard ratio for ≥5 cups/day versus <1 cup/day: 0.73; 95% confidence interval: 0.61-0.87). The lower risk of incident dementia was consistent even after selecting participants who did not have subjective memory complaints at the baseline. CONCLUSION Green tea consumption is significantly associated with a lower risk of incident dementia.

Defecation frequency and cardiovascular disease mortality in Japan: The Ohsaki cohort study

BACKGROUND It has been suggested that constipation is associated with cardiovascular disease (CVD). The association between defecation frequency and CVD mortality in a large population has not been reported hitherto. The aim of this study was to examine whether defecation frequency is related to CVD mortality. METHODS AND RESULTS A total of 45,112 eligible Japanese men and women aged 40-79 years participated in the Ohsaki Cohort study. Defecation frequency was evaluated at the baseline using a self-administered questionnaire. Hazard ratios (HRs) and 95% confidence intervals (CIs) for cardiovascular disease mortality were calculated according to defecation frequency (≥ 1 time/day, 1 time/2-3 days, ≤ 1 time/4 days) by the Cox proportional hazards model. During 13.3 years of follow-up, 2028 participants died due to CVD. Compared with those in the ≥ 1 time/day group, the risk of overall CVD mortality was significantly higher in the 1 time/2-3 days and ≤ 1 time/4 days groups; the multivariate HR (95%CI) for 1 time/2-3 days and ≤ 1 time/4 days was 1.21 (95% CI: 1.08-1.35) and 1.39 (95% CI: 1.06-1.81), respectively. CONCLUSION A lower defecation frequency was associated with risk of CVD mortality in this Japanese population. Future studies, aiming at elucidating the mechanisms underlying the associations between chronic constipation and risk of CVD mortality, may be facilitated by our findings.

Dietary Patterns and Incident Dementia in Elderly Japanese: The Ohsaki Cohort 2006 Study

BACKGROUND Although it has been speculated that the Japanese dietary pattern has a preventive effect against incident dementia, no reported study has yet investigated this issue. The present prospective cohort study investigated the association between dietary patterns and incident dementia in elderly Japanese subjects. METHODS We analyzed follow-up data covering a 5.7-year period for 14,402 older adults (≥65 years) participating in a community-based, prospective cohort study. Three dietary patterns (Japanese pattern, animal food pattern, and high-dairy pattern) were derived using principal component analysis of the consumption of 39 food and beverage items assessed using a food frequency questionnaire. Data on incident dementia were retrieved from the public Long-term Care Insurance database. RESULTS With 71,043 person-years of follow-up, incidence of dementia was 9.0%. The score for the Japanese dietary pattern was associated with a lower risk of incident dementia (hazard ratio of the highest quartile vs the lowest, 0.80; 95% confidence interval: 0.66-0.97; p-trend = .016). The animal food pattern and the high-dairy pattern showed no significant association with incident dementia. CONCLUSIONS In this population of elderly Japanese individuals, the Japanese dietary pattern was associated with a decreased risk of incident dementia.

Predictive ability of a simple subjective memory complaints scale for incident dementia: Evaluation of Japan's national checklist, the "Kihon Checklist".

Subjective memory complaints scales are expected to be useful for the prediction of future cognitive decline. In Japan, the “Kihon Checklist‐Cognitive Function” (KCL‐CF), which consists of three items, is used for primary screening of high‐risk older adults. However, the predictive validity of the KCL‐CF remains unknown. The aim of the present cohort study was to examine whether the KCL‐CF can predict the incidence of dementia.

Association between Coffee Consumption and Incident Risk of Disabling Dementia in Elderly Japanese: The Ohsaki Cohort 2006 Study

Epidemiological studies of the association between coffee consumption and dementia have yielded inconsistent results. Therefore, we investigated the association between coffee consumption and incident risk of dementia in an elderly Japanese population. 23,091 subjects aged ≥65 y living in Ohsaki City, northeastern Japan, responded to the baseline survey in 2006. Of these, we analyzed 13,137 subjects who gave informed consent and were not disabled at baseline. The outcome was the incidence of disabling dementia defined by usage of the Long-term Care Insurance database. We used the Cox proportional hazards regression model for multivariate analysis. During 5.7 y of follow-up period, we identified 1,107 cases of incident dementia. Overall, coffee consumption was significantly associated with a lower risk of incident dementia. The multivariate-adjusted HRs for the incidence of dementia according to coffee consumption categories (never, occasionally, 1-2 cups/d, and ≥3 cups/d) were 1.00, 0.73 (95% CI, 0.62-0.86), 0.72 (95% CI, 0.61-0.84), and 0.82 (95% CI, 0.65-1.02; p for trend = 0.009), respectively. In addition, this significant inverse association was more remarkable among women, non-smokers, and non-drinkers. Coffee consumption is significantly associated with a lower risk of incident dementia.

Sense of life worth living (ikigai) and incident functional disability in elderly Japanese: The Tsurugaya Project

OBJECTIVE To test the hypothesis that elderly persons who feel ikigai (a sense of life worth living) have a lower risk of incident functional disability than those who do not. Recent studies have suggested that ikigai impacts on mortality. However, its impact upon disability is unknown. The aim of the present study was to investigate the association between ikigai and incident functional disability among elderly persons. METHODS We conducted a prospective cohort study of 830 Japanese elderly persons aged ≥70 years as a comprehensive geriatric assessment in 2003. Information on ikigai was collected by self-reported questionnaire. Data on functional disability were retrieved from the public Long-term Care Insurance database in which participants were followed up for 11 years. Hazard ratios (HRs) and 95% confidence intervals (CIs) for incidence of functional disability were calculated for three groups delineated according to the presence of ikigai (“no”, “uncertain” or “yes”) using the Cox proportional hazards regression model. RESULTS The 11-year incidence of functional disability was 53.3% (442 cases). As compared with the “no” group, the multiple-adjusted HR (95% CI) of incident functional disability was 0.61 (0.36–1.02) for the “uncertain” group and 0.50 (0.30–0.84) for the “yes” group. CONCLUSION A stronger degree of ikigai is significantly associated with a lower risk of incident functional disability.

Psychological distress and the incident risk of functional disability in elderly survivors after the Great East Japan Earthquake

BACKGROUND We conducted a prospective cohort study to investigate whether psychological distress would have increased the incident risk of functional disability after the 2011 Great East Japan Earthquake. METHODS First phase data pertaining to psychological distress and other lifestyle factors were collected from 1037 subjects aged ≥ 65 years, from June to December 2011, in four affected areas of Miyagi prefecture in Japan. Psychological distress was measured by the Kessler 6-item psychological distress scale (K6), and classified into three categories (K6 score ≤ 9, 10-12, ≥ 13). Outcome data on functional disability were collected from the public Long-term Care Insurance database. Participants were followed up for about 2.6 years. The Cox model was used to calculate the multivariate hazard ratios (HRs) and 95% confidence intervals (CIs). RESULTS During the follow-up period, 118 participants were certified as incident disability (43.8 disability events per 1000 person-years). Compared with the lowest category (K6 score ≤ 9), participants in the highest category (K6 score ≥ 13) had a significantly higher risk of functional disability (HR = 2.65, 95% CI = 1.35-5.18, p = 0.002). In order to consider reverse causality, we conducted analysis excluding all incidents and deaths that occurred within the first year of follow-up, but our findings remained unchanged. LIMITATIONS We did not consider all potential confounders and use of appropriate medication. CONCLUSIONS The present study has demonstrated that psychological distress was associated with an increased risk of functional disability among elderly survivors of a natural disaster.

Body mass index and the risk of incident functional disability in elderly Japanese: The OHSAKI Cohort 2006 Study.

Abstract The relationship between the body mass index (BMI) and the incidence of cause-specific disability remains unclear. We conducted a prospective cohort study of 12,376 Japanese individuals aged ≥65 years who were followed up for 5.7 years. Information on BMI and other lifestyle factors was collected via a questionnaire in 2006. Functional disability data were retrieved from the public Long-term Care Insurance database. BMI was divided into 6 groups (<21, 21–<23, 23–<25, 25–<27[reference], 27–<29 and ≥29). Hazard ratios and 95% confidence intervals for cause-specific disability were estimated using Cox proportional hazards regression models. A U-shaped relationship between BMI and functional disability was observed, with a nadir at 26. The nadir BMI values with the lowest disability risk were 28 for dementia, 25 for stroke, and 23 for joint disease. A low BMI (<23) was a risk factor for disability due to dementia, the HR values (95% CI) being 2.48 (1.70–3.63) for BMI <21 and 2.25 (1.54–3.27) for BMI 21 to <23; a high BMI (≥29) was a risk factor for disability due to joint disease, the HR value (95% CI) being 2.17 (1.40–3.35). There was no significant relationship between BMI and disability due to stroke. The BMI nadirs for cause-specific disability differed: a low BMI (<23) was a risk factor for disability due to dementia, and a high BMI (≥29) was a risk factor for disability due to joint disease. Because BMI values of 23 to <29 did not pose a significantly higher risk for each cause of disability, this range should be regarded as the optimal one for the elderly population.

Impact of Pain on Incident Risk of Disability in Elderly Japanese: Cause-specific Analysis

Background: Although several cross-sectional studies have reported that pain is associated with functional disability in the elderly, data regarding a longitudinal association between pain and disability are inconsistent. This study aimed to investigate the association of pain severity with subsequent functional disability due to all causes as well as stroke, dementia, and joint disease/fracture. Methods: The authors conducted a prospective cohort study of 13,702 Japanese individuals aged 65 yr or older. Information regarding pain severity during the previous 4 weeks and other lifestyle factors was collected via questionnaire in 2006. Data on the incidence of functional disability were retrieved from the Long-term Care Insurance database. Cox proportional hazards regression analysis was used to estimate the multivariate-adjusted hazard ratios for incident functional disability. Results: The authors documented 2,686 (19.6%) cases of incident functional disability. The multivariate hazard ratio of functional disability was 1.15 (95% CI, 1.02 to 1.31) among respondents with moderate pain and 1.31 (95% CI, 1.12 to 1.54) among respondents with severe pain in comparison with those without pain (P trend < 0.001). These positive associations were particularly remarkable for disability due to joint disease/fracture: the multivariate hazard ratio was 1.88 (95% CI, 1.37 to 2.58) for moderate pain and 2.76 (95% CI, 1.93 to 3.95) for severe pain (P trend < 0.001). There was a negative association between pain severity and disability due to dementia (P trend = 0.041) and no significant association between pain severity and disability due to stroke. Conclusions: Among elderly Japanese individuals, the authors found a significant positive association between pain severity and future incident functional disability.

Changes in time spent walking and the risk of incident dementia in older Japanese people: the Ohsaki Cohort 2006 Study

Background the impact of long-term changes in physical activity during adulthood in the context of primary prevention of dementia has not been addressed previously. Objective to study the relationship between changes in time spent walking after middle age and incident dementia in older Japanese individuals. Methodology we conducted a cohort study of 6,909 disability-free Japanese individuals aged ≥65 years who lived in Ohsaki City, Japan. In both 1994 and 2006, the individual amount of time spent walking per day was assessed using a self-reported questionnaire (<0.5 h, 0.5-1 h or ≥1 h). Based on these three categories of exposure at the two points, participants were categorised into nine groups according to changes in time spent walking. Data on incident dementia were retrieved from the public Long-term Care Insurance (LTCI) Database, in which participants were followed up for 5.7 years (between April 2007 and November 2012). The Cox model was used for estimating the multivariate-adjusted hazard ratios (HRs) of incident dementia. Results the 5.7-year incidence of dementia was 9.2%. Compared with persons who remained in the lowest category of time spent walking (<0.5 h/day in both 1994 and 2006), persons who remained in the highest category (≥1 h/day in both 1994 and 2006) had a significantly lower risk of incident dementia: the multivariate-adjusted HR (95% confidence intervals) was 0.72 (0.53 and 0.97). Conclusions these results suggest that maintaining a higher level of physical activity after middle age may be a key strategy for prevention of dementia in older age.