Interaction between APOE ε4 and dietary protein intake on cognitive decline: A longitudinal cohort study

Fish consumption, cognitive impairment and dementia: an updated dose-response meta-analysis of observational studies

BACKGROUND

Cognitive impairment is projected to affect a preponderant proportion of the aging population. Lifelong dietary habits have been hypothesized to play a role in preventing cognitive decline. Among the most studied dietary components, fish consumptionhas been extensively studied for its potential effects on the human brain.

AIMS

To perform a meta-analysis of observational studies exploring the association between fish intake and cognitive impairment/decline and all types of dementia.

METHODS

A systematic search of electronic databases was performed to identify observational studies providing quantitative data on fish consumption and outcomes of interest. Random effects models for meta-analyses using only extreme exposure categories, subgroup analyses, and dose-response analyses were performed to estimate cumulative risk ratios (RRs) and 95% confidence intervals (CIs).

RESULTS

The meta-analysis comprised 35 studies. Individuals reporting the highest vs. the lowest fish consumption were associated with a lower likelihood of cognitive impairment/decline (RR = 0.82, 95% CI: 0.75, 0.90, I2 = 61.1%), dementia (RR = 0.82, 95% CI: 0.73, 0.93, I2 = 38.7%), and Alzheimer's disease (RR = 0.80, 95% CI: 0.67, 0.96, I2 = 20.3%). The dose-response relation revealed a significantly decreased risk of cognitive impairment/decline and all cognitive outcomes across higher levels of fish intake up to 30% for 150 g/d (RR = 0.70, 95% CI: 0.52, 0.95). The results of this relation based on APOE ε4 allele status was mixed based on the outcome investigated.

CONCLUSIONS

Current findings suggest fish consumption is associated with a lower risk of cognitive impairment/decline in a dose-response manner, while for dementia and Alzheimer's disease there is a need for further studies to improve the strength of evidence.

Association between dietary diversity changes and frailty among Chinese older adults: findings from a nationwide cohort study

BACKGROUND

Dietary diversity has been suggested as a potential preventive measure against frailty in older adults, but the effect of changes in dietary diversity on frailty is unclear. This study was conducted to examine the association between the dietary diversity score (DDS) and frailty among older Chinese adults.

METHODS

A total of 12,457 adults aged 65 years or older were enrolled from three consecutive and nonoverlapping cohorts from the Chinese Longitudinal Healthy Longevity Survey (the 2002 cohort, the 2005 cohort, and the 2008 cohort). DDS was calculated based on nine predefined food groups, and DDS changes were assessed by comparing scores at baseline and the first follow-up survey. We used 39 self-reported health items to assess frailty. Cox proportional hazard models were performed to examine the association between DDS change patterns and frailty.

RESULTS

Participants with low-to-low DDS had the highest frailty incidence (111.1/1000 person-years), while high-to-high DDS had the lowest (41.1/1000 person-years). Compared to the high-to-high group of overall DDS pattern, participants in other DDS change patterns had a higher risk of frailty (HRs ranged from 1.25 to 2.15). Similar associations were observed for plant-based and animal-based DDS. Compared to stable DDS changes, participants with an extreme decline in DDS had an increased risk of frailty, with HRs of 1.38 (1.24, 1.53), 1.31 (1.19, 1.44), and 1.29 (1.16, 1.43) for overall, plant-based, and animal-based DDS, respectively.

CONCLUSIONS

Maintaining a lower DDS or having a large reduction in DDS was associated with a higher risk of frailty among Chinese older adults. These findings highlight the importance of improving a diverse diet across old age for preventing frailty in later life.

Protein intake and episodic memory: the moderating role of the apolipoprotein E ε4 status

BACKGROUND

This study investigated the correlation between protein intake and Alzheimer's disease (AD)-related cognitive decline, particularly in episodic memory, among older adults without dementia. Furthermore, we assessed the moderating effect of apolipoprotein ε4 (APOE4) on this association and analyzed its influence on other cognitive functions beyond memory.

METHODS

The study involved 196 participants who underwent assessments for protein intake, cognitive performance, APOE4 genotyping, and nutritional biomarkers. Protein intake was categorized into low, medium, and high based on the consumption of dairy, legumes, eggs, meat, and fish.

RESULTS

High protein intake was significantly associated with better episodic memory and overall cognition. Moreover, a significant interaction was found between high protein intake and APOE4, indicating that APOE4 moderates the association between high protein intake level and episodic memory. Sensitivity analysis confirmed these results among participants with stable food intake.

CONCLUSIONS

Our study results demonstrated that high protein intake is associated with better episodic memory among older adults without dementia. Furthermore, the findings highlight the significant role of APOE4 status in moderating the relationship between protein consumption and episodic memory. These results suggest that dietary interventions focusing on protein intake could be beneficial for cognitive health, particularly in individuals with a genetic predisposition to AD.

Protein-enriched and anti-inflammatory dietary patterns, healthy lifestyle index and depressive symptoms: A cross-sectional study of 287,945 adults in China

OBJECTIVES

Depressive symptoms have a considerable negative impact on mental health. This study aimed to understand the relationship between the protein-enriched and anti-inflammatory dietary index scores, modified healthy lifestyle index scores (Modified HLIS), and depressive symptoms.

METHODS

This study used convenience sampling to conduct a single-center cross-sectional survey. From January 1, 2015 to December 31, 2020, a total of 287,945 Chinese adults from a health management center of a general hospital completed an online self-reported health questionnaire, which included demographic characteristics, the Dietary Diversity Scale, the Modified Healthy Lifestyle Index Scores and the Patient Health Questionnaire-9.

RESULTS

The higher anti-inflammatory dietary index scores (POR = 0.87; 95 % CI: 0.86-0.87; p < 0.001), moderate modified healthy lifestyle index scores (POR = 0.76; 95 % CI: 0.75-0.78; p < 0.001) and sufficient modified healthy lifestyle index scores (POR = 0.53; 95 % CI: 0.52-0.54; p < 0.001) were negatively associated with depressive symptoms, while the higher protein-enriched dietary index scores (POR = 1.01; 95 % CI: 1.01-1.02; p < 0.001) was positively correlated with depressive symptoms.

CONCLUSIONS

This study demonstrated that protein-enriched and anti-inflammatory dietary index scores, and multiple healthy lifestyles are associated depressive symptoms in adults.

Genetic risk for Alzheimer's disease and adherence to the Mediterranean diet: results from the HELIAD study

Obejctives: The aim of the current study was to investigate whether genetic risk factors may moderate the association between adherence to the Mediterranean diet and AD incidence.Mehtods: The sample was drawn from the HELIAD study, a longitudinal study with a follow-up interval of 3 years. In total 537 older adults without dementia or AD at baseline were included. Adherence to the Mediterranean diet was assessed at baseline and AD diagnosis was determined at both visits. A Polygenic Index for late onset AD (PGI-AD) was constructed. Cox proportional hazard models adjusted for age, sex, education, baseline Global cognition score and APOE e-4 genotype were employed to evaluate the association between PGI-AD and Mediterranean diet with AD incidence. Next, we examined the association between adherence to the Mediterranean diet and AD risk over time across participants stratified by low and high PGI-AD.Results: Twenty-eight participants developed AD at follow-up. In fully adjusted models both the PGI-AD and the adherence to the Mediterranean diet were associated with AD risk (p < 0.05 for both). In the low PGI-AD group, those with a low adherence had a 10-fold higher risk of developing AD per year of follow-up, than did the participants with a high adherence to the Mediterranean diet (p = 0.011), whereas no such association was found for participants in the high PGI-AD group.Discussion: The association of Mediterranean diet with AD risk is more prominent in the group of older adults with a low polygenic risk for developing AD. Our findings suggest that genetic risk factors should be taken into account when planning interventions aiming to improve cognitive health.

Effect of dairy consumption on cognition in older adults: A population-based cohort study

OBJECTIVE

We aimed to assess the effect on cognitive function of adding dairy (total, fermented, non-fermented, full fat, low fat, and sugary) to the diet and of substituting some food groups for dairy.

DESIGN

Secondary analysis of a prospective population-based cohort study.

PARTICIPANTS

We analyzed data from 1334 cognitively healthy participants (median age 67 years at baseline) with a mean follow-up of 5.6 years from the CoLaus|PsyColaus cohort in Lausanne, Switzerland.

MEASUREMENTS

The participants completed a food frequency questionnaire at baseline and cognitive tests at baseline and at follow-up. Clinical dementia rating was the primary outcome. Subjective cognitive decline, memory, verbal fluency, executive and motor functions were secondary outcomes.

METHODS

Our exposure was the consumption of total and 5 sub-types of dairy products (g/d). We used marginal structural models to compute average causal effects of 1) increasing dairy consumption by 100 g/d and 2) substituting 100 g/d of meat, fish, eggs, fruits and vegetables with dairy on the outcomes. We used inverse probability of the treatment and lost to follow-up weighting to account for measured confounding and non-random loss to follow-up.

RESULTS

Overall, the effects of adding dairy products to the diet on cognition were negligible and imprecise. No substitution had a substantial and consistent effect on clinical dementia rating. The substitution of fish [11.7% (-3% to 26.5%)] and eggs [18% (2.3%-33.7%)] for dairy products could negatively impact verbal memory and neurolinguistic processes.

CONCLUSION

We found no effect of adding dairy to the diet or substituting meat, vegetables or fruit for dairy on cognitive function in this cohort of older adults. The substitution of fish and eggs for dairy could have a negative effect on some secondary outcomes, but more studies modeling food substitutions are needed to confirm these results.

APOE Genotype Modifies the Association between Midlife Adherence to the Planetary Healthy Diet and Cognitive Function in Later Life among Chinese Adults in Singapore

BACKGROUND

It remains unclear if adherence to the planetary healthy diet (PHD), designed to improve human and environmental health, is associated with better cognitive function in aging, and if this association differs by apolipoprotein E (APOE) genotype.

OBJECTIVES

We aimed to examine the association between the PHD pattern and risk of poor cognitive function, and to further assess whether the APOE ε4 allele could modify this association.

METHODS

The study included 16,736 participants from the Singapore Chinese Health Study. The PHD score was calculated using data from a validated 165-item food frequency questionnaire at baseline (1993-1998), with higher scores indicating greater adherence to the PHD. Cognitive function was assessed by the Singapore-modified Mini-Mental State Examination at follow-up 3 visits (2014-2016). A subset of 9313 participants had APOE genotype data. Logistic regression models were used to estimate the odds ratios (ORs) and 95% confidence intervals (CIs), with adjustment for potential confounders.

RESULTS

We identified 2397 (14.3%) cases of poor cognitive function. In the total population, OR (95% CI) of poor cognitive function for each one-SD increment in the PHD score was 0.89 (0.85, 0.93). Carriers of APOE ε4 allele had increased risk of poor cognitive function (OR: 1.36, 95% CI: 1.15, 1.61). There was a significant interaction between the PHD score and the APOE ε4 allele (P-interaction = 0.042). Each one-SD increment in the PHD score was significantly associated with lower risk of poor cognitive function (OR: 0.89; 95% CI: 0.83, 0.96) in non-carriers of APOE ε4 allele, but not in APOE ε4 allele carriers (OR: 1.04, 95% CI: 0.89, 1.23).

CONCLUSIONS

Midlife adherence to the PHD was associated with reduced risk of poor cognitive function in later life. However, this was not observed in carriers of APOE ε4 allele who had higher risk of poor cognitive function.

Dairy Intake and Risk of Cognitive Decline and Dementia: A Systematic Review and Dose-Response Meta-Analysis of Prospective Studies

Dairy intake may influence cognition through several molecular pathways. However, epidemiologic studies yield inconsistent results, and no dose-response meta-analysis has been conducted yet. Therefore, we performed a systematic review with a dose-response meta-analysis about the association between dairy intake and cognitive decline or incidence of dementia. We investigated prospective studies with a follow-up ≥6 mo on cognitive decline or dementia incidence in adults without known chronic conditions through a systematic search of Embase, Medline, Cochrane Library, Web of Science, and Google Scholar from inception to 11 July 2023. We evaluated the dose-response association using a random-effects model. We identified 15 eligible cohort studies with >300,000 participants and a median follow-up of 11.4 y. We observed a negative nonlinear association between cognitive decline/dementia incidence and dairy intake as assessed through the quantity of consumption, with the nadir at ∼150 g/d (risk ratio: 0.88; 95% confidence interval: 0.78, 0.99). Conversely, we found an almost linear negative association when we considered the frequency of consumption (risk ratio for linear trend: 0.84; 95% confidence interval: 0.77, 0.92 for 1 time/d increase of dairy products). Stratified analysis by dairy products showed different shapes of the association with linear inverse relationship for milk intake, whereas possibly nonlinear for cheese. The inverse association was limited to Asian populations characterized by generally lower intake of dairy products, compared with the null association reported by European studies. In conclusion, our study suggests a nonlinear inverse association between dairy intake and cognitive decline or dementia, also depending on dairy types and population characteristics, although the heterogeneity was still high in overall and several subgroup analyses. Additional studies should be performed on this topic, including a wider range of intake and types of dairy products, to confirm a potential preventing role of dairy intake on cognitive decline and identify ideal intake doses. This review was registered at PROSPERO as CRD42020192395.

APOE-Genotype and Insulin Modulate Estimated Effect of Dietary Macronutrients on Cognitive Performance: Panel Analyses in Nondiabetic Older Adults at Risk of Dementia

BACKGROUND

The apolipoprotein E gene (APOE ε-2/3/4, combined as 6 different genotypes: ε-22/23/24/33/34/44) and insulin status modulate dementia risk and play a role in the metabolism of macronutrients.

OBJECTIVES

We aimed to examine APOE-genotype and fasting insulin as effect modifiers of the slopes between dietary macronutrients and cognitive performance among older adults at risk of dementia.

METHODS

Panel analyses-with diet and cognition measured at baseline and follow-up at years 1 and 2-were performed in a sub-sample from the FINGER (Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability) trial (n = 676, 60-77 y, 46% females, all nondiabetics). The associations between macronutrients (3-d food records, z-scores) and global cognition (modified Neuropsychological Test Battery, z-score) were analyzed in mixed regression models adjusted for confounders selected a priori. After a gradient was implied by the point estimates in categorical APOE analyses, we investigated a continuous APOE variable [APOE-gradient, coded -1 (for ε-23), -0.5 (ε-24), 0 (ε-33), 1 (ε-34), 2 (ε-44)] as an effect-modifier.

RESULTS

At increasing levels of the APOE-gradient, a relatively more favorable slope between diet and cognition was observed for a lower carbohydrate/fat ratio [β = -0.040, 95% confidence interval (CI): -0.074, -0.006; P = 0.020 for interaction diet × APOE-gradient), and higher protein (β = 0.075, 95% CI: 0.042, 0.109; P = 9.4 × 10-6). Insulin concentration (log-linear) modulated the association between the carbohydrate/fat ratio and cognition by a quadratic interaction (β = -0.016, P = 0.039). Coherent findings for exploratory predictors (fiber, fat subtypes, composite score, metabolic biomarkers) were compatible with published hypotheses of differential dietary adaptation by APOE, with cognition among ε-33 being relatively independent of dietary parameters-implying "metabolic flexibility." Antagonistic slopes to cognition for ε-23 (positive) compared with ε-34 and ε-44 (negative) were found for a Higher-carbohydrates-fiber-Lower-fat-protein composite score, even as within-subjects effects.

CONCLUSIONS

APOE-based precision nutrition appears conceptually promising, but replications in wider samples are warranted, as well as support from trials. Both relative hyper- and hypoinsulinemia might modulate the effect of diet on cognition.

Socioeconomic Deprivation, Genetic Risk, and Incident Dementia

INTRODUCTION

Socioeconomic factors and genetic predisposition are established risk factors for dementia. It remains unclear whether associations of socioeconomic deprivation with dementia incidence are modified by genetic risk.

METHODS

Participants in the UK Biobank aged ≥60 years and of European ancestry without dementia at baseline (2006-2010) were eligible for the analysis, with the main exposures area-level deprivation based on the Townsend Deprivation Index and individual-level socioeconomic deprivation based on car and home ownership, housing type and income, and polygenic risk of dementia. Dementia was ascertained in hospital and death records. Analysis was conducted in 2021.

RESULTS

In this cohort study, 196,368 participants (mean [SD] age=64.1 [2.9] years, 52.7% female) were followed up for 1,545,316 person-years (median [IQR] follow-up=8.0 [7.4-8.6] years). In high genetic risk and high area-level deprivation, 1.71% (95% CI=1.44, 2.01) developed dementia compared with 0.56% (95% CI=0.48, 0.65) in low genetic risk and low-to-moderate area-level deprivation (hazard ratio=2.31; 95% CI=1.84, 2.91). In high genetic risk and high individual-level deprivation, 1.78% (95% CI=1.50, 2.09) developed dementia compared with 0.31% (95% CI=0.20, 0.45) in low genetic risk and low individual-level deprivation (hazard ratio=4.06; 95% CI=2.63, 6.26). There was no significant interaction between genetic risk and area-level (p=0.77) or individual-level (p=0.07) deprivation. An imaging substudy including 11,083 participants found a greater burden of white matter hyperintensities associated with higher socioeconomic deprivation.

CONCLUSIONS

Individual-level and area-level socioeconomic deprivation were associated with increased dementia risk. Dementia prevention interventions may be particularly effective if targeted to households and areas with fewer socioeconomic resources, regardless of genetic vulnerability.

Association of laxatives use with incident dementia and modifying effect of genetic susceptibility: a population-based cohort study with propensity score matching

BACKGROUND

Constipation was associated with incidence of dementia and cognitive decline. Laxatives are the mainstay of constipation management and are commonly used among older populations for both treatment and prevention of constipation. However, the association between use of laxatives and incident dementia, and whether laxatives use may modify the effect of genetic predisposition on dementia remains unclear.

METHODS

We applied 1:3 propensity score matching to balance the baseline characteristics of the laxative users versus non-users and to reduce potential confounders using multi-variates adjusted Cox hazards regression models. We categorized genetic risk into three groups (low, middle, and high) through a genetic risk score of common genetic variants. Information on laxatives use was assessed at baseline and categories into four varieties, including bulk forming laxatives, softeners and emollients, osmotic laxatives, and stimulant laxatives.

RESULTS

Of 486,994 participants, there were 14,422 laxatives users in UK Biobank. After propensity score matching, participants with use of laxatives (n = 14,422) and matched non-laxative (n = 43,266) exposed individuals were enrolled. Over follow-up to 15 years, there were 1377 participants developed dementia (539 for Alzheimer's disease, and 343 for vascular dementia). The use of laxatives had greater risk of dementia (HR, 1.72; 95% CI:1.54-1.92), Alzheimer's disease (HR, 1.36; 95% CI: 1.13-1.63), and vascular dementia (HR, 1.53; 95% CI: 1.23-1.92). Compared to non-laxative exposed participants, those with use of softeners and emollients drugs, stimulant laxatives, and osmotic laxatives were associated with 96% (HR, 1.96; 95 CI: 1.23-3.12; P = 0.005), 80% (HR, 1.80; 95% CI: 1.37-2.37; P < 0.001), and 107% (HR, 2.07; 95% CI: 1.47-2.92; P < 0.001) higher risk of developed incident dementia, respectively. In joint effect analysis, compared to participants with low/middle genetic susceptibility and non-laxatives use, the HR (95% CIs) of dementia was 4.10 (3.49-4.81) for those with high genetic susceptibility plus use of laxatives. There was an additive interaction between laxatives use and genetic susceptibility on dementia (RERI: 0.736, 95% CI: 0.127 to 1.246; AP: 0.180, 95% CI: 0.047 to 0.312).

CONCLUSIONS

Use of laxatives was associated with higher risk of dementia and modify the effect of genetic susceptibility on dementia. Our findings suggested that attention should be paid to the relationship between laxatives use and dementia, especially in people at high genetic susceptibility.

Association between Changes in Protein Intake and Risk of Cognitive Impairment: A Prospective Cohort Study

Little is known about the role of change in protein intake in affecting cognitive function among older adults. Therefore, we aimed to investigate the associations between the change in protein intake from various food groups and cognitive impairment among older adults in a prospective cohort study. A total of 6951 participants without cognitive impairment or dementia were included in this study. The frequency of protein intake from various food groups was measured by a food frequency questionnaire at baseline and follow-up. Multivariable Cox hazard models with time as the underlying time metric applied to calculate the hazard ratios (HRs) and 95% confidence intervals (CIs). During the 37,535 person-years of follow-up, 1202 (17.3%) participants developed cognitive impairment. The improvement in overall protein intake was negatively associated with cognitive impairment with multivariable-adjusted HR of 0.98 (95% CI = 0.97-0.99). Compared with participants with stable change, those with an extreme decline in animal-based protein intake had a 48% higher risk of cognitive impairment. The associations of changes in protein from six food groups with cognitive impairment were in a similar direction to the main result. Protective associations between improving protein intake and a reduced risk of cognitive impairment were observed.

Research gaps and opportunities in precision nutrition: an NIH workshop report

Precision nutrition is an emerging concept that aims to develop nutrition recommendations tailored to different people's circumstances and biological characteristics. Responses to dietary change and the resulting health outcomes from consuming different diets may vary significantly between people based on interactions between their genetic backgrounds, physiology, microbiome, underlying health status, behaviors, social influences, and environmental exposures. On 11-12 January 2021, the National Institutes of Health convened a workshop entitled "Precision Nutrition: Research Gaps and Opportunities" to bring together experts to discuss the issues involved in better understanding and addressing precision nutrition. The workshop proceeded in 3 parts: part I covered many aspects of genetics and physiology that mediate the links between nutrient intake and health conditions such as cardiovascular disease, Alzheimer disease, and cancer; part II reviewed potential contributors to interindividual variability in dietary exposures and responses such as baseline nutritional status, circadian rhythm/sleep, environmental exposures, sensory properties of food, stress, inflammation, and the social determinants of health; part III presented the need for systems approaches, with new methods and technologies that can facilitate the study and implementation of precision nutrition, and workforce development needed to create a new generation of researchers. The workshop concluded that much research will be needed before more precise nutrition recommendations can be achieved. This includes better understanding and accounting for variables such as age, sex, ethnicity, medical history, genetics, and social and environmental factors. The advent of new methods and technologies and the availability of considerably more data bring tremendous opportunity. However, the field must proceed with appropriate levels of caution and make sure the factors listed above are all considered, and systems approaches and methods are incorporated. It will be important to develop and train an expanded workforce with the goal of reducing health disparities and improving precision nutritional advice for all Americans.

Anti-Inflammatory Dietary Diversity and Depressive Symptoms among Older Adults: A Nationwide Cross-Sectional Analysis

The purpose of this study was to associate the anti-inflammatory dietary diversity and depressive symptoms among a nationwide sample of Chinese older adults. We used data from the 2018 wave of Chinese longitudinal healthy longevity survey (CLHLS). We assessed depressive symptoms using the 10 items of the center for epidemiologic studies depression scale (CES-D-10). Based on the dietary diversity index (DDI) generated by previous studies, we construct two novel indicators: the protein-enriched dietary diversity index diet (PEDDI) and the anti-inflammatory dietary diversity index diet (AIDDI). We used multivariate logistic models to evaluate the associations of DDI, PEDDI, and AIDDI with depressive symptoms, statistically adjusted for a range of potential confounders. A total of 12,192 participants (mean age 83.6 years) were included in the analysis. We found that participants with a higher score of DDI (OR = 0.91, 95% CI: 0.89-0.92) and PEDDI (OR = 0.91, 95% CI: 0.88-0.93) showed lower odds of having depressive symptoms, while the association between AIDDI and depressive symptoms was more marked (OR = 0.80, 95% CI: 0.78-0.83). The associations remained in subgroup analyses and sensitivity analyses. The results indicate that intaking diversified diet, particularly anti-inflammatory foods, may be associated with a lower risk of depressive symptoms. The findings of this study, if confirmed as causal, provide evidence that an intervention of adopting an anti-inflammatory diversified diet may reduce the burden of depression among older adults.

Association between outdoor artificial light at night and sleep duration among older adults in China: A cross-sectional study

BACKGROUND

Light after dusk disrupts the circadian rhythms and shifts the timing of sleep later; but it is unknown whether outdoor artificial light at night (ALAN) affects sleep quality. This study aimed to explore the association between residential outdoor ALAN and sleep duration in a nationally representative sample of Chinese older adults.

METHODS

We examined the cross-sectional associations of outdoor ALAN with self-reported sleep duration in 13,474 older adults participating in the 2017-2018 wave of the Chinese Longitudinal Healthy Longevity Survey (CLHLS). Outdoor ALAN exposure was estimated at the residence level using satellite images. We applied generalized linear mixed models to investigate the association between ALAN exposure and sleep duration. We performed stratified analyses by age, sex, education, and household income levels. Moreover, we used multi-level logistic regression models to investigate the effects of ALAN on the short sleep duration (≤6 h) and the long sleep duration (>8 h), respectively, in reference to sleep for >6-8 h per day.

RESULTS

We found a significant association between outdoor ALAN intensity and sleep duration. The highest quartile of ALAN was associated with 17.04 (95% CI: 9.42-24.78) fewer minutes of sleep as compared to the lowest quartile. The reductions in sleep duration per quartile change in ALAN were greater in the young old (≥65-85 years) and in those with higher levels of education, and those with higher household income, respectively. We did not detect a sex difference. In addition, those in the highest quartile of ALAN were more likely to report a 25% (95% CI: 10%-42%) increase in short sleep (<6 h), and a 21% (95% CI: 9%-31%) decrease in long sleep (>8 h).

CONCLUSIONS

Increasing outdoor nighttime light intensity surrounding residences was associated with shorter sleep duration in older residents in China. This finding implies the importance of urban outdoor artificial light management as a potential means to lower the public health burden of sleep disorders.

Association of Body Mass Index and Plant-Based Diet with Cognitive Impairment among Older Chinese Adults: A Prospective, Nationwide Cohort Study

To examine the association of body mass index (BMI) and a plant-based diet (PBD) with cognitive impairment in older adults, this cohort study used data from the Chinese Longitudinal Healthy Longevity Survey (CLHLS), a national, community-based, longitudinal, prospective study in China. Cognitive function was evaluated via the Mini-Mental State Examination (MMSE). Diet was assessed using a simplified food frequency questionnaire (FFQ), and PBD patterns were estimated using the overall plant-based diet index (PDI), the healthful plant-based diet index (hPDI), and the unhealthful plant-based diet index (uPDI). BMI was measured objectively during the physical examination. Cox proportional hazard models and restricted cubic spline analyses were used. A total of 4792 participants with normal cognition at baseline were included, and 1077 participants were identified as having developed cognitive impairment during the 24,156 person-years of follow-up. A reverse J-shaped association was observed between BMI and cognitive impairment (p = 0.005 for nonlinearity). Participants who were overweight (HR = 0.79; 95% CI 0.66-0.95) and obese (HR = 0.72; 95% CI 0.54-0.96) had a decreased risk of cognitive impairment, while those who were underweight (HR = 1.42; 95% CI 1.21-1.66) had an increased risk. Lower PDI, lower hPDI, and higher uPDI were associated with an increased risk of cognitive impairment (HR = 1.32; 95% CI 1.16-1.50 for PDI; HR = 1.46; 95% CI 1.29-1.66 for hPDI; HR = 1.21; 95% CI 1.06-1.38 for uPDI). The protective effect of being overweight on cognitive impairment was more pronounced among participants with a higher PDI (HR = 0.74; 95% CI 0.57-0.95) than those with a lower PDI (HR = 0.87; 95% CI 0.67-1.12), among participants with a higher hPDI (HR = 0.73; 95% CI 0.57-0.94) than those with a lower hPDI (HR = 0.93; 95% CI 0.72-1.10), and among participants with a lower uPDI (HR = 0.61; 95% CI 0.46-0.80) than those with a higher uPDI (HR = 1.01; 95% CI 0.80-1.27). Our results support the positive associations of overweight status, obesity, an overall PBD, and a healthful PBD with cognitive function in older adults. A lower adherence to an overall PBD, a healthful PBD, and a higher adherence to an unhealthful PBD may attenuate the protective effect of being overweight on cognitive function.

Associations between urinary caffeine and caffeine metabolites and cognitive function in older adults

BACKGROUND

The effects of caffeine on cognitive impairment have not been conclusively determined. This study aimed to objectively assess the correlation between the urinary caffeine and caffeine metabolites and cognitive decline in older adults.

METHODS

Data on urinary caffeine and caffeine metabolites and the cognitive performance of participants aged 60 years and older were extracted from the National Health and Nutrition Examination Surveys 2011-2014. Binary logistic regression and restricted cubic splines (RCS) analyses were used to evaluate the association between urinary caffeine and caffeine metabolites and cognitive performance.

RESULTS

Eight hundred twenty-seven individuals were enrolled in this cross-sectional study. We observed that 1-methylxanthine, 3-methylxanthine, 7-methylxanthine, 1,3-dimethylxanthine, 1,7-dimethylxanthine, and 3,7-dimethylxanthine levels were significantly and inversely associated with cognitive decline. The RCS results suggested an approximately linear dose-response relationship between the aforementioned metabolites and cognitive performance. Moreover, the effects of urinary caffeine and caffeine metabolites on cognitive function assessed using the AFT were more evident in men.

CONCLUSIONS

Our study suggested that urinary caffeine and caffeine metabolite levels were associated with a reduced risk of cognitive impairment in a linear manner, especially in men.

Individual and environmental factors associated with cognitive function in older people: a longitudinal multilevel analysis

BACKGROUND

Individual and environmental factors have been found to be related to cognitive function. However, few studies have examined the longitudinal effects of both individual and environmental factors over time. The purpose of this study was to examine the effects of individual and environmental factors over time on older people's cognitive function.

METHODS

Nationally representative panel data from the Taiwan Longitudinal Survey on Aging 1999-2015 (n = 6349 persons, observations = 12,042) were used. City-level indicator data were sourced from the government. A multilevel mixed linear model analysis was conducted.

RESULTS

Better cognitive function was significantly related to individuals' work, ethnicity, younger age, higher education level, better self-rated health, higher level of emotional support received, being more religious, higher economic satisfaction, and living in the cities with higher population densities. Education and social connectedness were protective factors over time.

CONCLUSION

Socioeconomics and social connectedness are related to cognitive function. A more social integrated lifestyle and financially secure living is suggested in the policy.

Plant-based dietary patterns in relation to mortality among older adults in China

A plant-based dietary pattern has been recommended for its potential health and environmental benefits, but its relation to mortality warrants further exploration1. We examined this association among 13,154 adults aged 65 years and older (57.4% female) in the Chinese Longitudinal Healthy Longevity Survey (CLHLS). The overall plant-based diet index (PDI), healthful plant-based diet index (hPDI) and unhealthful plant-based diet index (uPDI) were calculated using dietary data collected by a simplified food frequency questionnaire (FFQ). Compared with the lowest quintile, participants in the highest quintile of PDI and hPDI had a decreased risk of all-cause mortality (hazard ratio (HR) = 0.92; 95% confidence interval (CI) 0.86, 0.98 for PDI; HR = 0.81, 95% CI, 0.76, 0.87 for hPDI), whereas participants with the highest uPDI scores had a 17% (95% CI, 9%, 26%) increased risk. Among plant foods, fresh fruits, fresh vegetables, legumes, garlic, nuts and tea were the main protective contributors, whereas preserved vegetables and sugar were associated with a higher risk of mortality. These findings support the beneficial roles of overall and healthful plant-based dietary patterns. The quality, and not only quantity, of plant foods should be emphasized in relevant public health recommendations.

Leisure Activities, APOE ε4, and Cognitive Decline: A Longitudinal Cohort Study

Background: Both leisure activities and the ε4 allele of the apolipoprotein E (APOE ε4) have been shown to affect cognitive health. We aimed to determine whether engagement in leisure activities protects against APOE ε4-related cognitive decline.

Methods: We used the cohort data from the Chinese Longitudinal Healthy Longevity Survey. A total of 3,017 participants (mean age of 77.0 years, SD = 9.0; 49.3% female) from 23 provinces of China were recruited in 2008 and were reinterviewed in 2014. We assessed cognitive function using the Mini-Mental State Examination (MMSE). We calculated cognitive decline using subtraction of the MMSE score of each participant in 2008 and 2014. We genotyped a number of APOE ε4 alleles for each participant at baseline and determined the Index of Leisure Activities (ILAs) by summing up the frequency of nine types of typical activities in productive, social, and physical domains. We used ordinal logistic regression models to estimate the effects of leisure activities, APOE ε4, and their interaction on cognitive decline, statistically adjusted for a range of potential confounders.

Results: There were significant associations between APOE ε4 and faster cognitive decline, independent of potential confounders, and between leisure activities and mitigated cognitive decline. The odds ratios were 1.25 (95% CI: 1.03, 1.53) and 0.93 (95% CI: 0.89, 0.97), respectively. We found significant interactions of APOE ε4 with leisure activities with a P-value of 0.018. We also observed interactive effects of subtypes of leisure activities: participants who regularly engaged in productive activities were more likely to reduce the risk of APOE ε4-related cognitive decline.

Conclusion: Our findings provide support for the indication that participating in leisure activities reduces the risk of APOE ε4-related cognitive decline.