Prevalence of and Risk Factors for Post-COVID-19 Condition during Omicron BA.5-Dominant Wave, Japan.

The increased risk for post-COVID-19 condition after the Omicron-dominant wave remains unclear. This population-based study included 25,911 persons in Japan 20-69 years of age with confirmed SARS-CoV-2 infection enrolled in the established registry system during July-August 2022 and 25,911 age- and sex-matched noninfected controls who used a self-reported questionnaire in January-February 2023. We compared prevalence and age- and sex-adjusted odds ratios of persistent COVID-19 symptoms (lasting ≥2 months). We evaluated factors associated with post-COVID-19 condition by comparing cases with and without post-COVID-19 condition. We analyzed 14,710 (8,392 cases and 6,318 controls) of 18,183 respondents. Post-COVID-19 condition proportion among cases was 11.8%, higher by 6.3% than 5.5% persistent symptoms among controls. Female sex, underlying medical conditions, mild to moderate acute COVID-19, and vaccination were associated with post-COVID-19 condition. Approximately 12% had post-COVID-19 condition during the Omicron-dominant wave, indicating the need for longer follow-up.

Association of depressive symptoms with incident fractures: the Japan Public Health Center-based Prospective Study for the Next Generation (JPHC-NEXT).

This 5-year longitudinal study investigated the relationship between depressive symptoms and fracture risk in a large Japanese cohort. Depressive symptoms were a significant risk factor for hip fractures in women. PURPOSE: A relationship between depressive symptoms and fractures has not been clearly demonstrated. We aimed to investigate the relationship between depressive symptoms and 5-year fracture risk in the Japan Public Health Center-based Prospective Study for the Next Generation. METHODS: From 2011 to 2016, 114,092 participants were enrolled, and a follow-up survey was conducted 5 years later. We analyzed 30,552 men and 38,063 women aged 40-74 years who had no past fractures at baseline. Presence of depressive symptoms was defined as a modified 11-item Center for Epidemiological Studies Depression Scale score of 8 or higher, a history of depression, or use of antidepressants. Subjects were asked to report vertebral, upper limb, and/or hip fractures, except for traffic or work accidents, that occurred during the follow-up period. The adjusted odds ratios (AORs) and 95% confidence intervals (CIs) for fracture were analyzed via logistic regression analysis to evaluate the relationship between depressive symptoms and fracture. RESULTS: Women with depressive symptoms demonstrated a high AOR for hip fractures (AOR: 2.78, 95% CI: 1.30 - 5.92); this result was consistent in post menopause women. In men, this association was not found for any age group or any type of fracture. CONCLUSIONS: Depressive symptoms in women may increase the risk of hip fractures. Further studies are required to explore this relationship in more detail.

Sleep duration, its change, and risk of dementia among Japanese: The Japan Public Health Center-based Prospective Study.

OBJECTIVE: Previous findings on the association between sleep duration, changes in sleep duration, and long-term dementia risk were mixed. Thus, we aimed to investigate the association between midlife sleep duration, its change, and dementia. METHODS: We recruited 41,731 Japanese (40-71 years) and documented their habitual sleep duration at baseline (1990-1994) and a 5-year follow-up survey. Changes in sleep duration were calculated as differences between baseline and 5-year measurements. We identified dementia using the Long-Term Care Insurance system (2007-2016). Hazard ratios (HRs) and 95% confidence intervals (CIs) of dementia were calculated using the area-stratified Cox model. RESULTS: During 360,389 person-years, 4621 participants exhibited dementia. The multivariable HRs of dementia compared with 7 h of sleep were 1.13 (95% CI: 0.98-1.30) for 3-5 h, 0.93 (0.85-1.02) for 6 h, 1.06 (0.99-1.14) for 8 h, 1.13 (1.01-1.27) for 9 h, and 1.40 (1.21-1.63) for 10-12 h with a J-shaped fashion (p for linear < 0.001 and quadratic < 0.001). For its change, the HRs compared with no change were 1.02 (0.90-1.16) for decreased ≥2 h, 0.95 (0.88-1.03) for decreased 1 h, 1.00 (0.91-1.09) for increased 1 h, and 1.37 (1.20-1.58) for increased ≥2 h. The positive association for decreased sleep duration was observed in individuals with an initial sleep duration of ≤7 h, but not in those with ≥8 h (p for interaction = 0.007). CONCLUSIONS: Long and increased sleep duration was associated with a higher risk of dementia.

Mushroom intake and risk of incident disabling dementia: the Circulatory Risk in Communities Study (CIRCS).

It is uncertain whether dietary intake of mushrooms rich in dietary fibre and several antioxidants is associated with a lower risk of dementia. We sought to examine prospectively the association between mushroom intake and the risk of disabling dementia. We performed a prospective study involving 3750 people aged 40 to 64 years residing in three communities who participated in an annual cardiovascular risk survey from 1985 to 1999. Cases of incident disabling dementia were surveyed from 1999 to 2020. We calculated the hazard ratios (HR) and 95 % CI for incident total dementia according to mushroom intake among participants with or without a history of stroke. During a mean 16·0 years' follow-up in 3739 eligible participants, 670 people developed disabling dementia. For women, mushroom intake was inversely associated with the risk of total dementia and the association was confined to dementia without a history of stroke. The multivariable HR (95 % CI) for total dementia in women were 0·81 (0·62, 1·06) for mushroom intake of 0·1-14·9 g/d and 0·56 (0·42, 0·75) for mushroom intake above 15·0 g/d (Pfor trend = 0·003) compared with no intake. The corresponding HR (95 % CI) for dementia without a history of stroke were 0·66 (0·47, 0·93) and 0·55 (0·38, 0·79) (Pfor trend = 0·01). In men, no associations were observed between mushroom intake and the risk of disabling dementia. Among Japanese women, dietary mushroom intake was associated with a lower risk of disabling dementia.

Validity of self-reported participation in cancer screenings and health checkups in Japan.

BACKGROUND: The participation rate for screening is regarded as a useful indicator for preventing cancer and cardio-metabolic disease. However, the validity of self-reported screening participation has not yet been thoroughly evaluated in Japan. We aimed to examine its validity using the municipal screening records among the Japanese population. METHODS: We included 3,060 men and 3,860 women insured by the National Health Insurance for residents aged <75 years or the Medical Care System for the Elderly aged ≥75 years in the Chikusei area of the Japan Public Health Center-based Prospective Study for the Next Generation. They were asked about their participation in cancer screenings and health checkups during the previous year. We compared their responses to the municipal records and calculated the sensitivity and specificity of self-reported screening participation. RESULTS: The sensitivity and specificity of self-reported participation were 0.49 and 0.86 for lung cancer screening; 0.67 and 0.85 for colorectal cancer screening; 0.77 and 0.79 for stomach cancer screening; and 0.86 and 0.65 for health checkup, respectively. Among women, the sensitivity and specificity were 0.83 and 0.81 for breast cancer and 0.85 and 0.90 for cervical cancer, respectively. CONCLUSION: Self-reported cancer screening participation for colorectal, stomach, breast, and cervical cancers had moderate-high sensitivity and specificity. Self-reported participation, especially for lung cancer screening and health checkups, should be carefully interpreted when assessing the performance of preventive measures.

Serum folate and risk of disabling dementia: a community-based nested case-control study.

PURPOSE: The aim of this study was to examine associations between serum folate levels and risk of disabling dementia that required care under the national insurance (disabling dementia). METHODS: We performed a nested case-control study in a community-based cohort, the Circulatory Risk in Communities Study, involving 13,934 Japanese individuals aged 40-84 years at the baseline period of 1984-2005. Serum folate was measured in 578 cases of incident disabling dementia, and in 1,156 controls whose age (±1 years), sex, area of residence, and baseline year were matched with the cases. The diagnosis of disabling dementia was performed by attending physicians under the National Long-Term Care Insurance System in Japan. Conditional odds ratios of disabling dementia according to quintiles of serum folate were calculated using conditional logistic regression models. RESULTS: After a 20.8-year follow-up, serum folate was inversely associated with risk of disabling dementia. The respective multivariable odds ratios (95% CIs) were 0.71 (0.51-0.99), 0.76 (0.54-1.06), 0.70 (0.49-1.00), and 0.62 (0.43-0.90) for persons with the second, third, fourth, and highest quintiles of serum folate as compared with the lowest quintile (P for trend = 0.03). A similar association was observed for dementia with or without stroke. CONCLUSION: In this nested case-control study with a long follow-up, low serum folate levels were associated with an increased risk of disabling dementia among Japanese individuals.

The effect of age on the relationship between body mass index and risks of incident stroke subtypes: The JPHC study.

OBJECTIVE: The associations between body mass index (BMI) and stroke subtypes, particularly intracerebral hemorrhage, have not been consistent. Such inconsistencies may be due to differences in the age at which BMI was obtained. We examined the possible age modifications in the association between BMI and stroke risk. MATERIALS AND METHODS: We followed 88,754 participants, aged 40-69 years at baseline (1990-1994), of the Japan Public Health Center-based prospective (JPHC) study for stroke incidence. BMI was obtained using self-reported body weight and height, which were categorized using the following cut-off points: 18.5, 21, 23, 25, 27.5, and 30 kg/m2. Time-dependent Cox proportional hazards models that updated BMI and covariates using 5- and 10-year questionnaire responses were used to estimate hazard ratios and 95 % confidence intervals. The analyses were stratified by age group (40-59 and ≥60 years) and the age of the individuals was updated. RESULTS: During the median follow-up period of 19 years, we documented 4,690 strokes, including 2,781 ischemic strokes and 1,358 intracerebral hemorrhages. After adjusting for sex, age, smoking, alcohol consumption, leisure-time physical activity, history of hypertension, dyslipidemia, and diabetes mellitus, we observed a positive linear association between BMI and ischemic stroke (linear trend, p < 0.001) in both age groups (interaction p>0.05). In contrast, a curvilinear association between BMI and intracerebral hemorrhage was observed in both the middle (curvilinear trend, p=0.017) and the older group (curvilinear trend, p=0.098) (interaction p>0.05). CONCLUSION: BMI and stroke associations did not vary significantly with age, although the association may differ according to subtype.

Modifying Effect of Outdoor Recreational Activity on the Association Between Anger Expression and Cardiovascular Disease Risk: The Circulatory Risk in Communities Study.

OBJECTIVE: Outdoor recreational activity (ORA) has been suggested as a practical strategy for anger management to moderate the risk of cardiovascular disease (CVD). However, there is a lack of evidence pertaining to this topic. Our aim was to examine whether ORA modified the association between anger expression and the risk of CVD. METHODS: A community-based cohort study was conducted among 1877 Japanese individuals aged 40 to 79 years at baseline in 1997. The anger expression was measured using the Spielberger Anger Expression Scale. Stratified into low and high ORA (0 and ≥1 of the four behaviors), a Cox proportional hazards model was used to assess the anger expression-related risk of incident CVD (ischemic heart disease and stroke). RESULTS: We identified 76 incident CVDs during a median follow-up of 18.8 years. Among participants with low ORA, anger expression was associated with an increased risk of CVD, whereas no association was identified among those with high ORA. The standardized hazard ratios were 1.53 (95% confidence interval, 1.23-1.91) and 0.77 (0.51-1.15) among those with low and high ORA, respectively ( p for interaction = .004). Similar associations were observed regarding the risk of total and ischemic stroke, and ischemic CVD. CONCLUSIONS: We found an elevated risk of CVD associated with anger expression among participants with low ORA but not among those with high ORA, suggesting that ORA use may mitigate the association between anger expression and CVD risk.

Longitudinal trajectories of smoking status using 25 year annually-updated data and all-cause mortality followed over 30 years: A community-based prospective cohort study.

We aimed to evaluate the long-term risk of smoking for all-cause mortality according to smoking status trajectories using 25-year annually-repeated input, traced by group-based trajectory modeling with an extension to account for non-random participant attrition or truncation due to death. We examined 2682 men and 4317 women aged 40 to 59 years who participated in annual health checks for the community-based prospective cohort study, 1975-1984 enrollment in Japan. The main outcome measure was all-cause mortality (follow-up period: median 30.2 years in men and 32.2 years in women). We traced annual smoking trajectories, stratified by sex and smoking status at baseline. For smokers at baseline, we identified five trajectories in both sexes, with different patterns of smoking cessation (e.g., early quitters and lifelong smokers). We calculated HRs and 95% CI of all-cause mortality using Cox proportional hazards regression modeling adjusted for age, body mass index, alcohol intake, blood pressure category, dyslipidemia and glucose category. Compared with one-time-point-based smokers, trajectory-based lifelong smokers had an increased risk of all-cause mortality; HRs were 1.31 (95% CI, 1.18-1.46) in men and 1.26 (95% CI, 0.91-1.73) in women. Among community residents aged 40 to 59 years, 25-year-trajectory-based lifelong smokers had an approximately 30% increased risk for all-cause mortality compared to one-time-point-based smokers. Risk of all-cause mortality among smokers with earlier cessation varied materially. It is necessary to consider the trajectories of smoking status to clarify the long-term excess risk of smoking.

Prospective cohort study on potato intake and mortality from cardiovascular diseases: the Japan Collaborative Cohort Study (JACC study).

PURPOSE: The association between potato intake and risk of cardiovascular diseases is unknown. This study aimed to examine the association between potatoes intake and mortality from stroke and coronary heart disease among Japanese. METHODS: The study included 74,750 participants of the Japan Collaborative Cohort Study, aged 40-79, who were initially free of cardiovascular diseases or cancer at baseline (1988-1990) and provided information on their potato intake. Hazard ratios and 95% confidence intervals were estimated by fitting a Cox proportional hazards model according to the frequency of potatoes intake (0, 0.4, 1.5, 3.5 and 7 servings per week) adjusting for geographic location, age, body mass index, drinking status, smoking status, perceived mental stress, education level, walking time, dietary intakes of total energy, meat, fish, vegetables, fruit, dairy products, cakes, and salt. RESULTS: Over a median of 19.2 years of follow-up, 4908 deaths from cardiovascular diseases were identified: 1019 from coronary heart diseases and 2153 from strokes (738 ischemic strokes and 495 hemorrhagic strokes). After adjustment for potential confounding factors, the hazard ratio of mortality from cardiovascular diseases for daily potato intake compared with no potato intake was 0.82 (95% confidence interval: 0.70, 0.95) among women, and 1.01 (0.88, 1.16) among men. Among women, the multivariable hazard ratios were 0.67 (0.48, 0.96) for coronary heart disease, 0.83 (0.66-1.05) for total stroke, 0.70 (0.43-1.15) for hemorrhagic stroke, and 0.75 (0.49-1.13) for ischemic stroke. CONCLUSION: We found an inverse association of potato intake with mortality from total cardiovascular diseases, especially that from coronary heart disease, among Japanese women. To our knowledge, this is the first report to show an inverse association between potato intake and total cardiovascular diseases.

Sleep Duration and Daytime Napping and Risk of Type 2 Diabetes Among Japanese Men and Women: The Japan Collaborative Cohort Study for Evaluation of Cancer Risk.

BACKGROUND: Little is known about the impacts of sleep duration and daytime napping on the risk of type 2 diabetes mellitus (T2DM). METHODS: In this study, 20,318 participants (7,597 men, 12,721 women) aged 40-79 years without a history of T2DM, stroke, coronary heart disease, or cancer at baseline (1988-1990), completed the baseline survey and the 5-year follow-up questionnaires, which included average sleep duration, napping habits, and self-reports of physician-diagnosed diabetes. The multivariable odds ratios (ORs) with 95% confidence intervals (CIs) were calculated using a logistic regression model. RESULTS: During the 5-year follow-up, 531 new cases of T2DM (266 men and 265 women) were documented. Sleep duration ≥10 hours was associated with higher risk of T2DM compared to sleep duration of 7 hours (OR 1.99; 95% CI, 1.28-3.08). The excess risk was observed for both sexes and primarily found among the non-overweight; the multivariable ORs of sleeping ≥10 hours compared to 7 hours were 2.05 (95% CI, 1.26-3.35) for the non-overweight (BMI <25 kg/m2) and 1.38 (95% CI, 0.49-3.83) for the overweight (BMI ≥25 kg/m2). The respective ORs of nappers versus non-nappers were 1.30 (95% CI, 1.03-1.63) and 0.92 (95% CI, 0.65-1.29). Among the non-overweight, nappers who slept ≥10 hours had the highest risk of T2DM (OR 2.84; 95% CI, 1.57-5.14), non-nappers who slept ≥10 hours (OR 2.27; 95% CI, 1.27-4.06), and nappers who slept <10 hours (OR 1.30; 95% CI, 1.03-1.64), compared with non-nappers who slept <10 hours. CONCLUSION: Long sleep duration was associated with the risk of T2DM in both sexes, which was confined to the non-overweight.

Impact of Perceived Social Support on the Association Between Anger Expression and the Risk of Stroke: The Circulatory Risk in Communities Study (CIRCS).

BACKGROUND: Anger has been suggested as a risk factor for stroke. Perceived social support (PSS) may relieve anger, thus reducing the risk of stroke; however, evidence supporting this is limited. We aimed to examine whether PSS modifies the risk of stroke associated with anger expression. METHODS: A cohort study was conducted among 1,806 community residents aged 40-74 years who received a cardiovascular risk survey, including anger expression, in 1997. A Cox proportional hazards model was applied to the participants with low and high PSS to calculate the hazard ratios (HRs) and 95% confidence intervals (CIs) of the risks of total stroke and its subtypes based on total anger expression after adjusting for known stroke risk factors. RESULTS: The median follow-up duration was 18.8 years, with 51 incident strokes. Among the participants with low PSS, anger expression had a positive association with the total stroke risk: The multivariable HR per standard deviation increment of total anger expression was 1.43 (95% CI, 1.13-1.82). In contrast, no association was identified among those with high PSS. The corresponding HR was 0.83 (95% CI, 0.49-1.40), with a significant interaction between low and high PSS (P = 0.037). Similar associations regarding the risk of ischemic stroke were found. CONCLUSION: We found an increased risk of stroke associated with anger expression among the participants with low PSS, but not among those with high PSS. Our results suggest that PSS might mitigate the risk of stroke associated with anger.

Hobby Engagement and Risk of Disabling Dementia.

BACKGROUND: The association between hobby engagement and risk of dementia reported from a short-term follow-up study for individuals aged ≥65 years may be susceptible to reverse causation. We examined the association between hobby engagement in age of 40-69 years and risk of dementia in a long-term follow-up study among Japanese, including individuals in mid-life, when the majority of individuals have normal cognitive function. METHODS: A total of 22,377 individuals aged 40-69 years completed a self-administered questionnaire in 1993-1994. The participants answered whether they had hobbies according to the three following responses: having no hobbies, having a hobby, and having many hobbies. Follow-up for incident disabling dementia was conducted with long-term care insurance data from 2006 to 2016. RESULTS: During a median of 11.0 years of follow-up, 3,095 participants developed disabling dementia. Adjusting for the demographic, behavioral, and psychosocial factors, the multivariable hazard ratios of incident disabling dementia compared with "having no hobbies" were 0.82 (95% confidence interval [CI], 0.75-0.89) for "having a hobby" and 0.78 (95% CI, 0.67-0.91) for "having many hobbies". The inverse association was similarly observed in both middle (40-64 years) and older ages (65-69 years). For disabling dementia subtypes, hobby engagement was inversely associated with the risk of dementia without a history of stroke (probably non-vascular type dementia), but not with that of post-stroke dementia (probably vascular type dementia). CONCLUSION: Hobby engagement in both mid-life and late life was associated with a lower risk of disabling dementia without a history of stroke.

Risk and population attributable fraction of stroke subtypes in Japan.

BACKGROUND: Associations of major risk factors for stroke with total and each type of stroke as well as subtypes of ischemic stroke and their population attributable fractions had not been examined comprehensively. METHODS: Participants of the Japan Public Health Center-based prospective (JPHC) Study Cohort II without histories of cardiovascular disease and cancer (n=14,797) were followed from 1993 through 2012. Associations of current smoking, hypertension, diabetes, overweight (body mass index ≥ 25 kg/m2), non-high-density lipoprotein cholesterol (non-HDLC) categories, low HDLC (< 40 mg/dL), urine protein, and history of arrhythmia were examined in a mutually-adjusted Cox regression model that included age and sex. Population attributable fraction (PAF) was estimated using the hazard ratios and the prevalence of risk factors among cases. RESULTS: Subjects with hypertension were 1.63 to 1.84 times more likely to develop any type of stroke. Diabetes, low HDLC, current smoking, overweight, urine protein, and arrhythmia were associated with risk of overall and ischemic stroke. Hypertension and urine protein were associated with risk of intracerebral hemorrhage while current smoking, hypertension, and low non-HDLC were associated with subarachnoid hemorrhage. Hypertension alone accounted for more than a quarter of stroke incidence, followed by current smoking and diabetes. High non-HDLC, current smoking, low HDLC, and overweight contributed mostly to large-artery occlusive stroke. Arrhythmia explained 13.2% of embolic stroke. Combined PAFs of all the modifiable risk factors for total, ischemic and large-artery occlusive strokes were 36.7 and 44.5% and 61.5%, respectively. CONCLUSION: Although there are differences according to the subtypes, hypertension could be regarded as the most crucial target for preventing strokes in Japan.

Long-term Response of Helicobacter pylori Antibody Titer After Eradication Treatment in Middle-aged Japanese: JPHC-NEXT Study.

BACKGROUND: Helicobacter pylori (H. pylori) is an established causative factor of gastric cancer. Although the expansion of insurance coverage has led to an increase in the number of patients treated for H. pylori, the population impact of eradication treatment for H. pylori has been scarcely investigated. This study aimed to clarify the long-term responses of H. pylori antibody titer after eradication treatment using large scale cross-sectional data from the Japan Public Health Center-based Prospective Study for the Next Generation (JPHC-NEXT Study). METHODS: A total of 55,282 Japanese participants aged 40 to 74 years residing in 16 areas provided blood samples from 2011 through 2016. From these, treated (n = 6,276) and untreated subjects who were seropositive for H. pylori or had serological atrophy (n = 22,420) formed the study population (n = 28,696). Seropositivity was defined as an anti-H. pylori IgG titer of ≥10 U/mL. Antibody level was compared among subjects according to self-reported treatment history as untreated, and treated for less than 1 year (<1Y), 1 through 5 years (1-5Y), and 6 or more years ago (6Y+). RESULTS: Median serum antibody titer was 34.0 U/mL, 7.9 U/mL, 4.0 U/mL, and 2.9 U/mL for the untreated, <1Y, 1-5Y, and 6Y+ groups, respectively. While those treated for H. pylori within the previous year had a 76.8% lower antibody titer compared to untreated subjects, approximately 41% of subjects were still seropositive. CONCLUSION: A significant reduction in H. pylori antibody titer occurs within 1 year after eradication treatment, but that a long period is needed to achieve complete negative conversion.

Association between birth weight and prevalence of cardiovascular disease and other lifestyle-related diseases among Japanese population: JPHC-NEXT Study.

BACKGROUND: An association between birth weight and cardiovascular disease (CVD) in adulthood has been observed in many countries; however, only a few studies have been conducted in Asian populations. METHODS: We used data from the baseline survey (2011-2016) of the Japan Public Health Center-based Prospective Study for the Next Generation Cohort, which included 114,105 participants aged 40-74 years. Adjusted prevalence ratios (aPRs) and 95% confidence intervals (CIs) were calculated from the prevalence of present and past histories of CVD and other lifestyle-related diseases, including hypertension, diabetes, hyperlipidemia, and gout, by birth weight, using Poisson regression. RESULTS: The prevalence of CVD increased with lower birth weight, with the highest prevalence among those with birth weight under 1,500 grams (males 4.6%; females 1.7%) and the lowest one among those with birth weight at or over 4,000g (males 3.7%: females 0.8%). Among 88.653 participants (41,156 males and 47,497 females) with complete data on possible confounders, birth weight under 1,500g was associated with a higher prevalence of CVD (aPR 1.76 [95%CI 1.37-2.26]), hypertension (aPR 1.29 [95%CI 1.17-1.42]), and diabetes (aPR 1.53 [95%CI 1.26-1.86]) when a birth weight of 3,000-3,999 grams was used as the reference. Weaker associations were observed for birth weight of 1500-2499 grams and 2500-2999 grams, while no significant associations were observed for birth weight at or over 4000 g. The association between birth weight and the prevalence of hyperlipidemia was less profound, and no significant association was observed between birth weight and gout. CONCLUSION: Lower birth weight was associated with a higher prevalence of CVD, hypertension, and diabetes in the Japanese population.

Dietary fiber intake and risk of incident disabling dementia: the Circulatory Risk in Communities Study.

OBJECTIVES: It has been hypothesized that dietary fiber intake has a beneficial impact on prevention of dementia, but the epidemiological evidence is scant. We sought to examine whether dietary fiber intake is inversely associated with risk of dementia requiring care under the national insurance (disabling dementia). METHODS: The study setting was the Circulatory Risk in Communities Study, involving 3739 Japanese individuals aged 40-64 years at the dietary surveys (1985-99). Dietary fiber intake was estimated using the 24-hour dietary recall method. Incident disabling dementia was followed up from 1999 through 2020. Disabling dementia was further classified into that with or without a history of stroke. Hazard ratios of disabling dementia according to quartiles of total, soluble, and insoluble fiber intake were calculated using the Cox proportional hazards model. RESULTS: During a median 19.7-year follow-up, a total of 670 cases of disabling dementia developed. Dietary fiber intake was inversely associated with risk of dementia: the multivariate hazards ratios (95% confidence intervals) were 0.83 (0.67-1.04), 0.81 (0.65-1.02), and 0.74 (0.57-0.96) for individuals with the second, third, and highest quartiles of dietary fiber intake, respectively, as compared with the lowest quartile (P for trend = 0.03). The inverse association was more evident for soluble fiber intake and was confined to dementia without a history of stroke. As for fiber-containing foods, potatoes, but not vegetables or fruits, showed a similar association. CONCLUSIONS: Dietary fiber intake, especially soluble fiber, was inversely associated with risk of disabling dementia in a general Japanese population.

Dietary behaviours and related lifestyles according to the presence or absence of skipping breakfast in Japanese adults: the JPHC-NEXT study.

OBJECTIVE: To assess dietary behaviours and related lifestyles according to the presence or absence of skipping breakfast. DESIGN: We analysed the cross-sectional data from a baseline survey of a large-scale population-based cohort study in Japan conducted in 2011-2016. Participants provided information on dietary behaviours and lifestyles through a self-administered questionnaire. Skipping breakfast was defined as not eating breakfast at least once a week and was classified according to the frequency of skipping breakfast as 1-2, 3-4 or ≥5 times/week. SETTING: Sixteen municipalities in seven prefectural areas across Japan under the Japan Public Health Centre-based prospective study for the Next Generation. PARTICIPANTS: 112 785 residents (51 952 males and 60 833 females) aged 40-74 years. RESULTS: After adjustment for age, socio-demographic status, drinking status and smoking status, individuals who skipped breakfast at least once a week, compared with those who ate breakfast every day, were more likely to have adverse dietary behaviours such as frequent eating out (multivariable OR = 2·08, 95 % CI (1·96, 2·21) in males and 2·15, 95 % CI (1·99, 2·33) in females), frequent eating instant foods (1·89, 95 % CI (1·77, 2·01) in males and 1·72, 95 % CI (1·56, 1·89) in females). They had late bedtime (1·85, 95 % CI (1·75, 1·95) in males and 1·98, 95 % CI (1·86, 2·11) in females) and living alone (2·37, 95 % CI (2·17, 2·58) in males and 2·02, 95 % CI (1·83, 2·21) in females), using the logistic regression model. CONCLUSIONS: Both adult males and females who skipped breakfast were likely to eat out, to have a dietary habit of eating instant foods and have lifestyles such as late bedtime and living alone than those who ate breakfast.

Childhood secondhand smoke exposure and respiratory disease mortality among never-smokers: the Japan collaborative cohort study for evaluation of cancer risk.

BACKGROUND: The main source of secondhand smoke (SHS) exposure during childhood occurs at home due to close family members who smoke. This study examined the association between childhood SHS exposure and the risk of respiratory disease mortality among non-smoking adults. METHODS: Data from 44 233 never-smoking Japanese men and women aged 40-79 years who participated in the JACC study between 1988 and 1990 were analyzed. The Cox proportional hazards model was used to calculate hazard ratios and 95% confidence intervals of respiratory disease mortality according to the number of smoking family members during childhood. Subdistribution HRs (SHRs) were calculated as a competing risk analysis. RESULTS: A total of 735 deaths from respiratory diseases were documented in a median follow-up of 19.2 years. Living with three or more smoking family members during childhood was associated with a higher risk of respiratory disease mortality in adulthood among women; multivariable SHR compared with participants with no family member smokers during childhood was 1.60 (1.01-2.54) for participants with three or more family members who smoked during their childhood. CONCLUSIONS: SHS exposure from three or more family members during childhood was associated with an increased risk of respiratory disease-related mortality in adulthood.

Daytime napping and risk of liver cancer: A large population-based prospective cohort study.

INTRODUCTION AND OBJECTIVES: Liver cancer is a major cause of morbidity and mortality in Japan and worldwide. Daytime napping is a common behavior, especially among older adults, that was related in previous research to unfavorable health conditions. Herein, we investigated the association between daytime napping and liver cancer risk. MATERIALS AND METHODS: In this prospective cohort study, data from 51,185 participants aged 40-79 years and registered in the Japan Collaborative Cohort Study (JACC Study) were analyzed. Incident cases of liver cancer were diagnosed using cancer registries, hospital records, and death certificates. Daytime napping was assessed using the JACC baseline self-administered questionnaire. We used the Cox regression to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) of incident liver cancer among participants in the age categories of the 40s, 50s, 60s, and 70s who reported daytime napping compared with their counterparts who did not. RESULTS: Within 669,734 person-years of follow-up, 341 participants developed liver cancer. Daytime napping was associated with a higher risk of liver cancer among participants who were in their 60s and 70s of age after adjusting for sex: HRs (95% CIs) 1.88 (1.35-2.61) and 1.96 (1.18-3.26), lifestyle and medical history: 1.76 (1.27-2.47) and 1.82 (1.07-3.09), and history of liver diseases: 1.66 (1.18-2.34) and 1.72 (1.01-2.94), respectively. No associations were detected among participants from the 40s and 50s age groups. CONCLUSIONS: Daytime napping was associated with a higher risk of liver cancer among older adults.