Associations of dietary patterns and longitudinal brain-volume change in Japanese community-dwelling adults: results from the national institute for longevity sciences-longitudinal study of aging.

BACKGROUND: The association of dietary patterns and longitudinal changes in brain volume has rarely been investigated in Japanese individuals. We prospectively investigated this association in middle-aged and older Japanese community-dwelling adults. METHODS: Data with a 2-year follow-up from the sixth wave (July 2008 to July 2010; baseline) to the seventh (July 2010 to July 2012; follow-up) of the National Institute for Longevity Sciences-Longitudinal Study of Aging project were analyzed. Dietary intake was assessed using a 3-day dietary record, and longitudinal volume changes (%) in the total gray matter (TGM), total white matter, and frontal, parietal, occipital, temporal, and insular lobes were assessed using 3-dimensional T1 magnetic resonance imaging scans. Multiple factor analysis and hierarchical clustering revealed sex-specific dietary patterns. Associations between dietary patterns and annual brain-volume changes (%) were evaluated using general linear models adjusted for age, apoprotein E genotype, body mass index, medical history, lifestyle behaviors, socioeconomic factors, and energy intake. RESULTS: Among the 1636 participants (age: 40.3-89.2 years), three dietary patterns were determined for men (n = 815; Western; Vegetable-Fruit-Dairy; and Traditional Japanese diets) and women (n = 821; Western; Grain-Vegetable-Fruit; and Traditional Japanese diets). Compared to women following the Western diet, those on the Traditional Japanese diet had less TGM atrophy. Multivariable-adjusted ß (95% confidence interval) of the annual change (%) of TGM was - 0.145 (-0.287 to -0.002; P = 0.047), which correlated with reduced parietal lobe atrophy. No association between dietary pattern and brain atrophy was observed in men. CONCLUSIONS: Adherence to healthy dietary patterns, with higher consumption of whole grains, seafood, vegetables, fruits, mushrooms, soybean products, and green tea, potentially confers a protective effect against brain atrophy in middle-aged and older Japanese women but not in men. Further research to confirm these results and ascertain the underlying mechanisms is required. This study highlights the importance of sex-specific effects on the relationship between dietary patterns and brain health in diverse populations.

No Appreciable Effect of Education on Aging-Associated Declines in Cognition: A 20-Year Follow-Up Study.

Education has been claimed to reduce aging-associated declines in cognitive function. Given its societal relevance, considerable resources have been devoted to this research. However, because of the difficulty of detecting modest rates of change, findings have been mixed. These discrepancies may stem from methodological shortcomings such as short time spans, few waves, and small samples. The present study overcame these limitations (N = 1,892, nine waves over a period of 20 years). We tested the effect of education level on baseline performance (intercept) and the rate of change (slope) in crystallized and fluid cognitive abilities (gc and gf, respectively) in a sample of Japanese adults. Albeit positively related to both intercepts, education had no impact on either the gc or the gf slope. Furthermore, neither intercept exhibited any appreciable correlation with either slope. These results thus suggest that education has no substantial role (direct or mediated) in aging-related changes in cognition.

Twenty-year prospective cohort study of the association between a Japanese dietary pattern and incident dementia: the NILS-LSA project.

PURPOSE: Evidence has suggested that adherence to a Japanese diet may be beneficial for health. However, its association with incident dementia remains unclear. The aim was to explore this association in older Japanese community-dwellers, taking apoprotein E genotype into consideration. METHODS: A 20-year follow-up cohort study involving 1504 dementia-free older Japanese community-dwellers (aged 65-82 years) living in Aichi Prefecture, Japan, was conducted. Based on a previous study, a 9-component-weighted Japanese Diet Index (wJDI9) score (range - 1 to 12) was calculated using 3-day dietary record data and used as an indicator of adherence to a Japanese diet. Incident dementia was confirmed by the Long-term Care Insurance System certificate, and dementia events occurring within the first 5 years of follow-up were excluded. A multivariate-adjusted Cox proportional hazards model was used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for incident dementia, and Laplace regression was used to estimate percentile differences (PDs) and 95% CIs (expressed in months) in age at incident dementia (i.e., dementia-free duration differences), according to tertiles (T1-T3) of wJDI9 scores. RESULTS: The median (IQR) follow-up duration was 11.4 (7.8-15.1) years. During the follow-up period, 225 (15.0%) cases of incident dementia were identified. Because the smallest prevalence of incident dementia was 10.7% for the T3 group of wJDI9 scores, to avoid inaccurately estimating the dementia-free duration of participants in the T3 group, the 11th PDs in age at incident dementia between the T1 and T3 groups of wJDI9 scores were estimated. A higher wJDI9 score was associated with a lower risk of incident dementia and a longer dementia-free duration difference. The multivariate-adjusted HR (95% CI) and 11th PDs (95% CI) in age at incident dementia for participants in the T1 vs. T3 group were 1.00 (reference) vs. 0.58 (0.40, 0.86), and 0 (reference) vs. 36.7 (9.9, 63.4) months, respectively. Each 1-point increase of the wJDI9 score was associated with a 5% lower risk of incident dementia (P value = 0.033) and 3.9 (0.3, 7.6) additional months of dementia-free duration (P value = 0.035). No differences were seen in sex or smoking status (current smoker vs. non-current smoker) at baseline. CONCLUSION: These findings suggest that adherence to a Japanese diet defined by wJDI9 is associated with a lower risk of incident dementia in older Japanese community-dwellers, suggesting the benefit of the Japanese diet for dementia prevention.

Mushroom consumption and hyperuricemia: results from the National Institute for Longevity Sciences-Longitudinal Study of Aging and the National Health and Nutrition Examination Survey (2007-2018).

BACKGROUND: Prior study reported that mushroom consumption was associated with a lower incidence of hyperuricemia, but there is limited evidence on this association. We conducted a collaborative study to investigate the association between mushroom intake and hyperuricemia in middle-aged and older populations. METHODS: We used data from the National Health and Nutrition Examination Survey (NHANES) in the U.S. (2007-2018) and the National Institute for Longevity Sciences-Longitudinal Study of Aging (NILS-LSA) in Japan (1997-2012). Consumption of mushroom (g/day) were measured by one- or two-day dietary recall in NHANES and by 3-day dietary records in the NILS-LSA. Hyperuricemia was defined using uric acid levels as > 420 µmol/L and > 350 µmol/L in NHANES for men and women, respectively; in the NILS-LSA, serum uric acid was repeatedly measured at baseline and follow-up surveys. Hyperuricemia was defined as uric acid levels > 416.4 µmol/L for men and ≥ 356.9 µmol/L for women. Logistic regression models in NHANES (cross-sectionally) and Generalized Estimation Equations in NILS-LSA (longitudinally) were performed. RESULTS: A total of 5,778 NHANES participants (mean (SD) age: 53.2 (9.6) years) and 1,738 NILS-LSA (mean (SD) age: 53.5 (11.2) years) were included. Mushrooms were consumed by 5.7% of participants in NHANES and 81.2% in NILS-LSA. We did not observe a significant association between mushroom intakes and hyperuricemia in the NHANES men and women. However, in the NILS-LSA, compared to non-consumers, a higher mushroom intake was associated with a lower risk of incident hyperuricemia in men under 65 years old. The adjusted odds ratio (95% CI) for non-consumers, participants with middle, and the highest consumption of mushrooms were 1.00 (Ref.), 0.77 (0.44, 1.36), and 0.55 (0.31, 0.99), respectively (P-trend = 0.036). No association was found in women in NILS-LSA. CONCLUSIONS: Mushroom consumption was associated with a lower risk of incident hyperuricemia in Japanese men.

Dietary amino acid intake and sleep duration are additively involved in future cognitive decline in Japanese adults aged 60 years or over: a community-based longitudinal study.

BACKGROUND: Sleep duration and amino acid intake are independently associated with cognitive decline. This study aimed to determine the longitudinal association between sleep duration and cognitive impairment incidence and to examine the involvement of diet, particularly amino acid intake, in these associations in community dwellers. METHODS: In this longitudinal study in a community-based setting, we analyzed data from 623 adults aged 60-83 years without cognitive impairment at baseline. Sleep duration was assessed using a self-report questionnaire. Amino acid intake was assessed using 3-day dietary records. Cognitive impairment was defined as a Mini-Mental State Examination score ≤ 27. Participants were classified into short-, moderate-, and long-sleep groups according to baseline sleep duration (≤ 6, 7-8, and > 8 h, respectively). Using moderate sleep as a reference, odds ratios (ORs) and 95% confidence intervals (CIs) of short- and long-sleep for cognitive-impairment incidence were estimated using the generalized estimating equation. Participants were classified according to sex-stratified quartiles (Q) of 19 amino acid intake: Q1 and Q2-Q4 were low- and middle to high-intake groups, respectively. Using middle- to high-intake as a reference, ORs and 95% CIs of low intake for cognitive impairment incidence were estimated using the generalized estimating equation in each sleep-duration group. Follow-up period, sex, age, body mass index, depressive symptoms, education, smoking status, employment status, sleep aids use, physical activity, medical history, and Mini-Mental State Examination score at baseline were covariates. RESULTS: Mean follow-up period was 6.9 ± 2.1 years. Adjusted ORs (95% CIs) for cognitive impairment in short- and long-sleep groups were 0.81 (0.49-1.35, P = 0.423) and 1.41 (1.05-1.87, P = 0.020), respectively. Particularly in long sleepers (i.e., > 8 h), cognitive impairment was significantly associated with low cystine, proline, and serine intake [adjusted ORs (95% CIs) for cognitive impairment were 2.17 (1.15-4.11, P = 0.017), 1.86 (1.07-3.23, P = 0.027), and 2.21 (1.14-4.29, P = 0.019), respectively]. CONCLUSIONS: Community-dwelling adults aged ≥ 60 years who sleep longer are more likely to have cognitive decline, and attention should be paid to the low cystine, proline, and serine intake.

Basic lifestyle habits and volume change in total gray matter among community dwelling middle-aged and older Japanese adults.

The brain controls human behavior, and the gray matter is the main resource of neuronal cells. We examined the longitudinal relationship between six basic lifestyle habits (diet, exercise, sleep, alcohol consumption, smoking, and social activity including employment) and total gray matter volume in community-dwelling adults in Japan. This two-year follow-up study with data derived from the National Institute for Longevity Sciences, Longitudinal Study of Aging, Aichi, Japan, included adults aged 40-87 years (n = 1665, men: 51%). Lifestyle habits were assessed at baseline (2008-2010) using self-reported questionnaires and three-day dietary records. Total gray matter volume at baseline and after two years was estimated using T1-weighted brain magnetic resonance imaging and FreeSurfer software. The association between each lifestyle factor, the total number of healthy lifestyle habits, and gray matter volume change was determined via a multiple linear regression analysis adjusting for baseline age, total gray matter volume, and other confounders. The mean ± standard deviation decrease in total gray matter volume during the two-year follow-up period was 0.94 ± 1.86% in men and 0.61 ± 2.27% in women. In the multiple regression analysis, volume loss in total gray matter positively correlated with male smoking, while it was negatively correlated with male social activity and employment, female dietary diversity, and the total number of healthy lifestyle habits (standardized beta coefficient; -0.061 in men [p = 0.07], -0.113 in women [p < 0.05]). Therefore, engaging in social activities, non-smoking, a diverse diet, or adopting one healthy lifestyle habit may help prevent gray matter volume loss.

Interaction between cognitive leisure activity and long-chain polyunsaturated fatty acid intake on global cognitive decline in a Japanese longitudinal cohort study: National Institute for Longevity Sciences-Longitudinal Study of Aging.

BACKGROUND: There is a growing interest in the significance of adopting a variety of lifestyle habits for maintaining cognitive function among older adults. A lifestyle that is easy to modify, simple, and less burdensome for older people is ideal. We investigated the longitudinal association between global cognitive decline and cognitive leisure activities (CLAs) combined with long-chain polyunsaturated fatty acids (LCPUFAs) intake. METHODS: The National Institute for Longevity Sciences-Longitudinal Study of Aging (NILS-LSA) enrolled community-dwelling middle-aged and older men and women who were randomly selected from Obu-City and Higashiura Town, Aichi, Japan. Baseline data (2006-2008), including CLAs and dietary intake, were obtained from 517 participants (aged 60-84 years) with normal cognition. Global cognitive decline, defined as the Mini-Mental State Examination (MMSE) score ≤ 27, was assessed at baseline and four years later. Interaction between CLAs and LCPUFAs on cognitive decline was investigated using a multiple logistic analysis with adjustment for confounders. CLA engagement and LCPUFA intake were divided into high and low groups according to the frequency at which each participant engaged in the activity and the median intake level according to sex, respectively. RESULTS: A significant interaction was detected for the combination of CLA engagement and LCPUFA intake. Logistic regression coefficients revealed significant interactions when participants engaged in more than five CLA varieties. One of the CLAs, art appreciation, produced a significant main effect against cognitive decline and a significant interaction in combination with LCPUFA intake. The major LCPUFAs-docosahexaenoic acid and arachidonic acid-also exhibited a significant interaction. The combination of high LCPUFA intake and high art appreciation frequency yielded a lower adjusted odds ratio for cognitive decline than the combination of low LCPUFA and low art appreciation [0.25 (95 % confidence intervals, 0.11-0.56)]. CONCLUSIONS: Preserving cognitive function might be associated with a combination of varied and high-frequency engagement in CLAs combined with high LCPUFA intake.

Vasomotor symptoms, sleep problems, and depressive symptoms in community-dwelling Japanese women.

AIM: To assess prevalence and characteristics of vasomotor symptoms in community-dwelling Japanese women. METHODS: These were cross-sectional analyses using data from the National Institute for Longevity Sciences-Longitudinal Study of Aging. The main outcome measures were prevalence and severity of hot flashes and sweating. Associations between hot flashes/sweating (slight, moderate, or severe vs none) and sleep problems were explored using logistic regression, with and without adjustment for age, daily physical activity, and number of urinations/night. Associations between hot flashes/sweating and sleep problems, depressive symptoms, and dietary variables were explored in logistic regression models or general linear models. RESULTS: A total of 1152 women between 40 and 91 years of age were enrolled. Hot flashes were reported by 24.5% of participants; with prevalence and severity highest in those 50-54 years or 2-5 years postmenopause. Sleep problems were reported 15 percentage points more frequently by women who reported hot flashes than by those without hot flashes. Adjusted odds ratios [95% CI] for difficulty in falling asleep and difficulty in sleeping through were 2.09 [1.565-2.796] and 2.07 [1.549-2.763]), respectively. Also, hot flashes were associated with higher risk of depressive symptoms (adjusted odds ratio [95% CI]: 2.99 [2.07-4.32]) and lower life satisfaction, self-esteem, and self-rated health status. A similar pattern was observed in women with and without sweating. No associations were found between hot flashes and dietary factors. CONCLUSIONS: Clear associations were found between hot flashes and sleeping problems, even after adjusting for potential confounding factors. Women who reported hot flashes also reported worse mental and physical health than those who did not report hot flashes.

[Cross-sectional association between the amino acid intake and episodic memory in middle- and old-aged community dwellers].

AIM: The specific amino acid intake has been suggested to be positively associated with the cognitive function. However, few reports have investigated the association between the amino acid intake and episodic memory (EM). Therefore, we investigated this association. METHODS: Data were obtained from the fourth survey (2004-2006) of the National Institute for Longevity Sciences - Longitudinal Study of Aging. We analyzed 2,082 participants 40-85 years old (50.1% male). The dietary intake was assessed by the three-day dietary records, and participants were classified into sex- and age-specific tertiles of protein and amino acid intakes. EM was assessed using the Logical Memory II of the Wechsler Memory Scale. The association of protein and amino acid intakes with EM was analyzed using the general linear model. Covariates were sex, age, body mass index, education, depressive symptoms, smoking status, employment status, living alone, and medical history in model 1. The energy intake was added to model 1 in model 2. The protein intake was added to model 2 in model 3. RESULTS: The mean (standard deviation) age was 59.4 (12.3) years old. After adjusting for the energy intake, the EM tended to be higher with a higher protein intake (p=0.053 for group differences and p=0.015 for trends). Furthermore, after adjusting for energy and protein intake, EM was significantly higher with higher intakes of isoleucine, leucine, lysine, methionine, phenylalanine, tyrosine, tryptophan, valine, and histidine (p< 0.05, both for group differences and trends). CONCLUSION: Our findings suggest a positive association between EM and the intake of essential and semi-essential amino acids, independent of the protein and energy intake.

Green tea and coffee intake and risk of cognitive decline in older adults: the National Institute for Longevity Sciences, Longitudinal Study of Aging.

OBJECTIVE: To examine the association between green tea and coffee intake and cognitive decline in older adults. DESIGN: A prospective cohort study. The average intake of green tea and coffee in the previous year was assessed through a dietitian interview using a dietary questionnaire. A Mini-Mental State Examination (MMSE) was conducted up to six times biennially. Cognitive decline was screened using the MMSE; its incidence was defined as the first time a score of <27 points was obtained in a biennial test from the baseline. Hazard ratios for incidence of cognitive decline were estimated according to the intake of the two beverages using multivariable Cox proportional hazard regression, controlling for sociodemographic and lifestyle factors. SETTING: The National Institute for Longevity Sciences, Longitudinal Study of Aging (NILS-LSA) in Japan. PARTICIPANTS: Men (n 620) and women (n 685), aged 60-85 years, from the NILS-LSA. RESULTS: During a mean of 5·3 (sd 2·9) years of follow-up, 432 incident cases of cognitive decline were observed. Compared with participants who consumed green tea

Protein intake per day and at each daily meal and skeletal muscle mass declines among older community dwellers in Japan.

OBJECTIVE: To examine associations between protein intake per day and at different meals and skeletal muscle mass declines. DESIGN: Two-year prospective cohort study among older community dwellers. SETTING: National Institute for Longevity Sciences-Longitudinal Study of Aging (NILS-LSA) in Japan. PARTICIPANTS: Older men (n 292) and women (n 363) aged 60-87 years who participated in the baseline (2006-2008) and follow-up studies (2008-2010) of NILS-LSA and did not exhibit low skeletal muscle mass at baseline. Muscle mass was assessed using dual-energy X-ray absorptiometry at baseline and follow-up. Low muscle mass was defined as skeletal muscle mass index <7·0 kg/m2 for men and <5·4 kg/m2 for women at follow-up. Daily protein intake and protein intake at each meal were calculated from 3 d dietary records at baseline and sex-stratified tertiles were determined. RESULTS: Mean (sd) protein intake at breakfast, lunch and dinner was 22·7 (7·8), 26·7 (9·3) and 37·4 (10·5) g for men and 19·3 (6·3), 23·2 (7·3) and 28·5 (7·0) g for women, respectively. After adjusting for age, baseline skeletal muscle mass and other confounders in logistic modelling, greater total protein intake was associated with lower prevalence of skeletal muscle mass decline among men at follow-up (P = 0·024). Particularly, the OR (95 % CI) for high lunchtime protein intake was low (0·11 (0·02, 0·61); P = 0·01). No significant association between total protein intake and prevalence of skeletal muscle mass decline was found among women. CONCLUSIONS: High total protein intake, particularly at lunchtime, is associated with retention of skeletal muscle mass in men.

A cross-sectional study of the associations between the traditional Japanese diet and nutrient intakes: the NILS-LSA project.

BACKGROUND: Although our previous study using a food frequency questionnaire simulated nutritional characteristics of the traditional Japanese diet, this issue has not been sufficiently evaluated. This study was conducted to examine the relationship between the traditional Japanese diet and nutrient density (ND). METHODS: A cross-sectional study employing the dietary record method was conducted among 2221 community-dwelling Japanese adults (40-88 years) living in Aichi Prefecture, Japan, in 2006-2008. Based on previous studies, a 9-component Japanese Diet Index (JDI) and a 12-component modified JDI (mJDI12) were defined. To develop a new weighted index, a multiple linear regression model was used to select food components which were significantly associated with an ND score (integrated by 11 nutrient components) from the mJDI12 and weight them. Correlation analyses were performed between JDI, mJDI12, the new weighted JDI score and the ND score and its 11 nutrient components. The findings were validated with data from 2008 to 2010 by assessing the associations between the JDIs scores and the ND score. RESULTS: Scores of the JDI and mJDI12 were positively correlated with the ND score (corresponding Spearman's ρ [95% confidence interval; CI], 0.34 [0.31, 0.38] and 0.44 [0.41, 0.48], respectively; P < 0.05 for both). Among the mJDI12, 9 food components (rice, fish and shellfish, green and yellow vegetables, seaweed, green tea, beef and pork, soybeans and soybean foods, fruit, and mushrooms) significantly associated with the ND score. All of these 9 components were weighted and a new weighted JDI (wJDI9) was developed. The wJDI9 score was also positively correlated with the ND score (Spearman's ρ [95% CI] = 0.61 [0.58, 0.64]; P < 0.05). However, scores for all 3 indices were positively correlated with sodium intake. The wJDI9 score obtained using dietary record data from 2008 to 2010 was also positively correlated with the ND score (Spearman's ρ [95% CI] = 0.61 [0.58, 0.64]; P < 0.05). CONCLUSIONS-: Adhering to a traditional Japanese diet as defined by the JDI was associated with good ND. Furthermore, the modified indices (mJDI12 and wJDI9) had a higher performance for ND. However, all of the indices were correlated with high sodium intake.

Role of gait speed and grip strength in predicting 10-year cognitive decline among community-dwelling older people.

BACKGROUND: The gait speed and handgrip strength represented the core determinants of physical frailty and sarcopenia, which were reported to be associated with cognitive impairment and decline. Different physical measures might differentially affect cognitive changes, such as higher-level cognitive change and global cognitive decline. This study examined the differential associations of gait speed and handgrip strength with 10-year cognitive changes among community-dwelling older people. METHODS: Participants aged 60 years and over living in the community were invited for study. Gait speed and handgrip strength were classified into 5 groups based on quintiles at baseline. Cognitive functions were assessed using the Mini-Mental State Examination (MMSE) and Digit Symbol Substitution Test (DSST) every 2 years from baseline for a period of 10 years. Linear mixed effects models were used to determine the role of gait speed and handgrip strength in the prediction of 10-year cognitive changes by adjusting covariates, including age, gender, education, depressive symptoms, marital status, smoking status, instrumental activities of daily life (IADL), Charlson Comorbidity Index (CCI), and body mass index (BMI) at baseline. RESULTS: A total of 1096 participants were enrolled in the study. The mean age was 69.4 ± 5.8 years and 50.9% were male. The slowest gait speed group showed a significantly greater decline in the DSST scores over 10 years than the highest group (estimate = 0.28 and P = 0.003), but not in the MMSE scores (estimate = 0.05 and P = 0.078). The lowest handgrip strength group showed a significantly greater decline in the MMSE scores than the highest group (estimate = 0.06 and P = 0.039) and in the DSST scores than the highest two quintiles (estimate = 0.20 and P = 0.033 for the fourth quintile; estimate = 0.20 and P = 0.040 for the highest quintile) over 10-year follow-up. CONCLUSIONS: A slow gait speed could predict 10-year cognitive decline using DSST, and a low handgrip strength could predict 10-year cognitive decline using MMSE in addition to DSST. Thus both physical measures are lined to cognitive decline but there may be different mechanisms between brain and physical functions.

Hemoglobin A1c and 10-year information processing speed in Japanese community dwellers.

BACKGROUND: Hyperglycemia is believed to be a risk factor for cognitive decline, but the longitudinal relationship between hyperglycemia and cognitive decline in the Japanese population is unclear. The present study aimed to clarify the association between blood glucose levels and information processing ability in middle-aged and older adults. METHODS: The subjects were 866 men and 815 women aged 40-79 years not taking medication for diabetes who participated in the first study wave (1997-2000) and then participated at least once in the subsequent six study waves (2000-2012) of the National Institute for Longevity Sciences-Longitudinal Study of Aging, Japan. Hemoglobin A1c (HbA1c) levels were categorized into four groups (< 5.6, 5.6 to < 6.0, 6.0 to < 6.5, ≥ 6.5%), and a mixed-effects model was used to evaluate the effects of the HbA1c level (four groups) on repeated measures of information processing speed. The models also included baseline age, body mass index, ethanol intake, smoking status, educational level, family income, and history of stroke, hypertension, heart disease, and dyslipidemia as covariates. RESULTS: Mean (standard deviation) HbA1c and follow-up time in participants were 5.2 (0.5) % and 10.0 (3.6) years, respectively. A linear mixed model showed that the main effect of the four HbA1c groups on information processing ability was not significant in either men or women, but the interaction of HbA1c and time with information processing speed in the higher HbA1c level groups (≥ 6.5% group in men, 6.0 to < 6.5% and ≥ 6.5% groups in women) was significant compared to the lower HbA1c level (< 5.6%) group (P < 0.05). When the slope of information processing speed by HbA1c level at baseline was examined, the slope of information processing speed in the higher HbA1c level (≥ 6.5%) group was higher than in the lower HbA1c level (< 5.6%) group, both in men (- 0.31/year) and in women (- 0.30/year), as well as in women with an HbA1c level of 6.0 to < 6.5% (- 0.40/year). CONCLUSIONS: Higher baseline HbA1c was associated with greater subsequent decline in information processing ability in Japanese community dwellers, even with the pre-clinical HbA1c level (6.0 to < 6.5%) in women. The results suggest that good glycemic control or prevention of hyperglycemia may contribute to maintaining information processing ability.

What is the best adjustment of appendicular lean mass for predicting mortality or disability among Japanese community dwellers?

BACKGROUND: Age-related declines in skeletal muscle mass and strength, representing "sarcopenia," are a growing concern in aging societies. However, the prevalence of low muscle mass based on the height2-adjustment has been shown to be extremely low, and a more appropriate definition of low muscle mass is needed, particularly for Asian women. The aim of this study was to explore the most appropriate adjustment of appendicular lean mass (ALM) for predicting mortality or disability risk using ALM or any of 5 adjustments of ALM among community-dwelling Japanese. METHODS: Subjects comprised 1026 men and 952 women between 40 and 79 years old at baseline (1997-2000) who participated in the National Institute for Longevity Sciences - Longitudinal Study of Aging, Japan. ALM (kg) and 5 adjusted indices of ALM (ALM/leg length, ALM/height, ALM/height2, ALM/weight, and ALM/body mass index [BMI]) were assessed at baseline. Disability was defined by long-term care insurance certification based on responses to a survey mailed in 2013, and death records were obtained as vital statistics until December 2014. Crude and adjusted Cox proportional hazard models were used to estimate hazard ratios for mortality or disability by sex-stratified quintiles of each ALM index (ALM and adjusted ALM) or sarcopenia-related indices. The area under the curve (AUC) was calculated with the multivariate-adjusted logistic regression model. Additionally, mixed-effects analyses were used to clarify the age-related ALM indices decline over 12 years (n = 1838). RESULTS: Crude Cox proportional hazard models and multivariate-adjusted logistic model (AUC) indicated that higher ALM and ALM/BMI in women, and higher ALM, ALM/leg length, ALM/height, and ALM/BMI in men were associated with lower risks for mortality or disability than ALM/height2. The mixed effect model indicated all ALM indices in men, and ALM, ALM/leg length, and ALM/height in women could better predict age-related lean muscle mass decline. CONCLUSIONS: Unadjusted ALM in women, and ALM/leg length, ALM/height, ALM/BMI, and ALM in men may be more appropriate for predicting future mortality or disability than ALM/height2. Considering the age-related muscle mass decline, unadjusted ALM would be the first variable to assess, regardless of sex, in this Japanese cohort study.

Cross-sectional association between serum concentrations of n-3 long-chain PUFA and depressive symptoms: results in Japanese community dwellers.

The effect of n-3 long-chain PUFA (n-3 LCPUFA) on depression in healthy subjects is unclear, and most of the previous studies have focused on populations eating Western diets with lower fish intake. The present study investigated the association between blood levels of n-3 LCPUFA and depressive symptoms in Japanese community dwellers with higher n-3 LCPUFA blood levels. A cross-sectional study was conducted from 2006 to 2008, including 1050 men and 1073 women aged 40 years or older from the National Institute for Longevity Sciences--the Longitudinal Study of Aging. The Center for Epidemiologic Studies Depression Scale (CES-D) was used to assess depressive symptoms. Multiple logistic regression analysis was performed to estimate the OR and 95% CI for a CES-D score ≥ 16. Serum concentrations of n-3 PUFA, but not n-6 PUFA, were inversely associated with depressive symptoms. Compared with the lowest quintile, the adjusted OR for serum EPA at the fourth and fifth quintiles were 0·55 (95% CI 0·35, 0·85) and 0·64 (95% CI 0·42, 0·98), respectively, and at the fifth quintile for DHA it was 0·58 (95% CI 0·37, 0·92), for the presence of depressive symptoms (P for trend=0·013 and 0·011, respectively). Serum levels of EPA and DHA were inversely associated with depressive symptoms in Japanese community dwellers with higher blood levels of n-3 LCPUFA, suggesting that n-3 LCPUFA intakes corresponding to higher levels in a Japanese population may have implications for a lower prevalence of depression.

Implication of grip strength assessment for the management of body weight in disability prevention in older adults.

BACKGROUND: Although body mass index (BMI) and grip strength (GS) are both predictors of disability, their joint effect on predicting incident disability remains uncertain. We examined whether the effect of BMI on incident disability can be modulated by GS in community-dwelling older people in Japan. METHODS: A total of 1486 community-dwellers in Japan (731 men and 755 women, aged 65-82 years) who participated in the 2nd to 7th waves of the National Institute for Longevity Sciences-Longitudinal Study of Aging (NILS-LSA) project, were followed up to 20 years. Twelve subgroups were created according to the intersections of GS (sex-specific tertiles: low, intermediate, and high) and BMI (underweight 1, <18.5; underweight 2, 18.5-<21.5; normal, 21.5-<25.0; and overweight/obese, ≥25.0 kg/m2 ). Incident disability was defined as requiring care need level 1 or higher, as per the long-term care insurance system in Japan. The hazard ratios (HR) and corresponding 95% confidence intervals (CI) of incident disability (the 'high GS-normal BMI' subgroup was used as the reference) were calculated using a multivariable-adjusted Cox proportional hazards model. The model was adjusted for baseline characteristics on sex, participation wave, smoking, depressive symptoms, total physical activity, disease history, education level, residential status, and energy intake. RESULTS: Compared with that for participants in the 'high GS-normal BMI' group, the risk of incident disability was higher for participants in the 'low GS-normal BMI', 'low GS-overweight/obese', 'intermediate GS-underweight 1' and 'intermediate GS-overweight/obese' groups. The multivariable-adjusted HR (95% CI) were 1.72 (1.27-2.32, P value<0.001), 1.81 (1.27-2.58, P value = 0.001), 2.42 (1.35-4.32, P value = 0.003) and 1.53 (1.06-2.20, P value = 0.023), respectively. The results did not change substantially when participants with disability occurring within 1 and 2 years of follow-up were excluded, or when the competing events were death without incident disability or dementia. CONCLUSIONS: The joint effect of BMI and GS was more pronounced in those of normal weight or overweight/obese status and low GS, along with underweight or overweight/obese status and intermediate GS in predicting disability. The lack of observed joint effect for those underweight with low GS was likely due to insufficient sample size. GS consideration is necessary for weight management in older adults, and interventions for individuals who are underweight or overweight/obese with adequate GS need not be prioritized for disability prevention.

Differential Longitudinal Associations Between Domains of Cognitive Function and Physical Function: A 20-Year Follow-Up Study.

OBJECTIVES: Cognitive and physical functions are both associated with disability and death. Recent studies have addressed the relationship between cognitive declines and physical declines; however, whether various facets of cognition are diversely associated with specific physical functions is yet to be ascertained. The present work examines the longitudinal associations between fluid and crystallized cognitive functions (Gf and Gc) and physical functions. METHODS: The sample consisted of 863 community-dwelling older adults (baseline age 60-79 years) from the National Institute for Longevity Sciences-Longitudinal Study of Aging. The participants were tested on a set of Gf and Gc tests and physical tests (grip strength and gait speed). We ran a series of Multivariate Latent Growth Curve models. Specifically, we tested the relationship between cognitive and physical functions in terms of baseline performance (intercept) and rate of change (slope). RESULTS: The slope-slope correlations between Gf and physical function were large (grip strength r = 0.64 and gait speed r = 0.68, ps < .001). By contrast, the slope correlations between Gc and physical functions were weak (rs ≤ 0.31) and barely or marginally significant (ps ≤ .06). DISCUSSION: The results show that distinct domains of cognitive functions have different associations with physical functions. Namely, the aging-associated declines in the tested physical functions are robustly correlated with the declines in Gf, but are only weakly correlated with the declines in Gc. Therefore, Gc measures may be poor proxies for the patient's frailty and should be considered with caution in clinical assessment.

Association of taurine intake with changes in physical fitness among community-dwelling middle-aged and older Japanese adults: an 8-year longitudinal study.

Introduction: Taurine has diverse valuable biological functions, including antioxidant activity and regulation of osmotic pressure. Maintaining physical fitness from middle age is important for healthy life expectancy. Although taurine administration improves muscle endurance and strength, its role in maintenance remains unclear. We aimed to clarify the longitudinal taurine intake association with fitness changes. Methods: Participants comprised men and women aged ≥40 years who participated in the third (2002-2004; Baseline) and seventh (2010-2012; Follow-up) waves of the National Institute for Longevity Sciences-Longitudinal Study of Aging (NILS-LSA) and completed a 3-day dietary weights recording survey at baseline. A table of taurine content was prepared for 751 foods (including five food groups: Seaweed; Fish and shellfish; Meat; Eggs; and Milk and dairy products) from the Standard Tables of Food Composition in Japan (1,878 foods) 2010. Four physical fitness items (knee extension muscle strength, sit-and-reach, one-leg standing with eyes closed, and maximum walking speed) were measured at baseline and follow-up. We analyzed the association of taurine intake with physical fitness change, employing a general linear model (GLM) and trend tests for baseline taurine intake and follow-up fitness change. Adjustments included baseline variables: sex, age, height, weight, educational level, self-rated health, smoking status, depressive symptoms, and clinical history. Results: The estimated average daily taurine intake (standard deviation) was 207.5 (145.6) mg/day at the baseline. When examining the association with the four physical fitness parameters, higher taurine intake positively increased the change in knee extension muscle strength (T1; 0.1, T2; 0.8, T3; 1.1 (kgf) GLM, p < 0.05; p for trend <0.05) and reduced the decline in knee extension muscle strength in the subgroup analysis of participants aged ≥65 years (T1: -1.9, T2: -1.7, T3: -0.4 kgf; GLM p < 0.05, p for trend <0.05). No relationship was found between taurine intake and the remaining three fitness factors. Conclusion: Estimation of taurine intake showed that dietary taurine intake potentially contributes to the maintenance of knee extension muscle strength over 8 years among Japanese community-dwelling middle-aged and older individuals. This is the first study to investigate the association of dietary taurine intake with muscle strength.

Effects of cigarette smoking and secondhand smoke exposure on physical frailty development among community-dwelling older adults in Japan: Evidence from a 10-year population-based cohort study.

AIM: This study explored longitudinally the relationship between smoking and secondhand smoke and the incidence of physical frailty in community-dwelling Japanese older people. METHODS: Data collected from the National Institute for Longevity Sciences-Longitudinal Study of Aging database from 2002 to 2012 (third to seventh wave) among older adults aged ≥65 years were analyzed. Participants with physical frailty at baseline, as determined by the Cardiovascular Health Study criteria, missing data or who failed to attend follow ups were excluded. Data on current cigarette smoking and secondhand smoke exposure were collected from the third wave results. The generalized estimating equation model was used to examine the longitudinal relationships between smoking, secondhand smoke and subsequent frailty. RESULTS: The final analysis included 540 participants with a mean age of 71.4 years (standard deviation 4.6). The generalized estimating equation analysis showed that, compared with non-smokers, smokers were at significant risk of physical frailty (odds ratio [OR] 2.39, 95% confidence interval [CI] 1.21-4.74) after adjustment for multiple covariates; especially men (OR 3.75, 95% CI 1.76-8.00) and older adults aged ≥75 years (OR 4.12, 95% CI 1.43-11.87). Participants exposed to both smoking and secondhand smoke had a higher risk of physical frailty (OR 3.47, 95% CI 1.56-7.73) than non-smokers without secondhand smoke exposure. Smokers exposed to secondhand smoke were associated with more risk of physical frailty (OR 9.03, 95% CI 2.42-33.77) compared with smokers without secondhand smoke exposure. CONCLUSIONS: Smoking, especially when combined with secondhand smoke exposure, is associated with future physical frailty among older adults. Geriatr Gerontol Int 2024; 24: 142-149.