Dietary fiber intake and cognitive impairment in older patients with chronic kidney disease in the United States: A cross-sectional study

Feiyan Li; Hongxi Chen; Nan Mao; Hong Liu

doi:10.1371/journal.pone.0291690

Abstract

Background

High-fiber diet has been associated with better cognitive performance. However, the association between dietary fiber intake and cognition in older patients with chronic kidney disease (CKD) remains unknown. Hence, this study aimed to investigate the effect of dietary fiber intake on cognition in older patients with CKD.

Methods

This study included participants aged ≥60 years who provided data on social demography, cognitive tests (Consortium to Establish a Registry for Alzheimer’s disease Word Learning [CERAD-WL], CERAD Delayed Recall [CERAD-DR], Animal Fluency Test [AFT], and Digit Symbol Substitution Test [DSST]), diet, and other potential cognition-related variables from the National Health and Nutrition Examination Survey 2011–2014. Fully-adjusted multivariate logistic regression subgroup models were performed, and multiple linear regression analyses were employed to examine the association between dietary fiber intake and cognition in patients with CKD.

Results

A total of 2461 older adults were included, with 32% who suffered from CKD. Participants with CKD scored lower in CERAD-WL, CERAD-DR, AFT, and DSST. Patients with CKD consuming low dietary fiber (≤25 g/day) had a higher risk of CERAD-WL and DSST impairments. High dietary fiber intake eliminated the differences in CERAD-WL and DSST impairments between the CKD and non-CKD participants. However, no associations were observed between CKD and CERAD-DR and AFT impairments regardless of dietary fiber intake. A positive linear relationship between dietary fiber intake and AFT score was observed in older patients with CKD.

Conclusion

High dietary fiber intake may benefit cognitive function in older patients with CKD. High-fiber diet management strategies could potentially mitigate cognitive impairment in this group of patients.

Citation: Li F, Chen H, Mao N, Liu H (2023) Dietary fiber intake and cognitive impairment in older patients with chronic kidney disease in the United States: A cross-sectional study. PLoS ONE 18(10): e0291690. https://doi.org/10.1371/journal.pone.0291690

Editor: Yee Gary Ang, National Healthcare Group, SINGAPORE

Received: May 28, 2023; Accepted: September 2, 2023; Published: October 4, 2023

Copyright: © 2023 Li et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Data Availability: Publicly available datasets are available online for this study. The repository/repositories name and accession numbers are available online at http://www.cdc.gov/nchs/nhanes.htm

Funding: This research was funded by Sichuan Applied Psychology Research Center (No. CSXL-202B11) and Health Commission of Sichuan Province (No. 20PJ172). The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing interests: The authors have declared that no competing interests exist.

Introduction

Approximately 10% of adults worldwide suffer from some form of chronic kidney disease (CKD), causing 1.2 million deaths each year, and it is projected to become the fifth leading cause of death globally by 2040 [1]. As a systemic disease, CKD also involves the central nervous system and is complicated by cognitive impairment [2]. CKD is considered one of the strongest risk factors for cognitive impairment, which refers to comprehensive deficits of brain processes for learning, memory, and sensory function that varies in severity, from moderate cognition decline to severe dementia [3]. A substantial proportion of patients with CKD suffer from cognitive impairment, even in the early stages of the disease [4], and the prevalence of CKD and cognitive impairment increase with age [5].

Albuminuria and estimated glomerular filtration rate (eGFR) are the extensively researched risk factors for cognitive impairment in CKD. While studies have consistently shown that albuminuria is associated with worse cognitive performance [6, 7], the effect of eGFR on cognitive impairment remains unclear. A large prospective study in older adults showed that a declined eGFR was associated with the incidence of dementia independent of stroke even in participants with baseline eGFR ≥60 mL/min/1.73 m² [8]. In addition, numerous factors, including age, education level, CKD duration, hypertension, diabetes, hemoglobin, albumin, glycemia, serum parathyroid hormone, uric acid, acidosis, electrolyte disorders, poor nutrition/protein energy wasting, disturbed sleep, and polypharmacy were reported as CKD-specific risk factors for cognitive impairment [9–12].

Despite medical advancements, there has been very limited success in the improvement of cognitive impairment in CKD. However, in recent years, the significance of dietary or nutritional changes in older adults with cognitive impairment has received great attention[13, 14]. A study suggested that low fiber intake is associated with cognitive impairments [15]. Studies suggested that high dietary fiber intake can help improve some aspects of cognitive function in the general adult population and the hypertensive population aged >60 years [16, 17].

A high-fiber, plant-dominant and low-protein diet, which reportedly modulates the gut microbiome, reduces uremic toxin, controls uremia without renal replacement therapy, and enhances cardiovascular health, has been proposed in CKD [1]. However, at present, studies investigating the effect of dietary fiber intake on the cognitive function of patients with CKD are scarce. Given that older adults are at a higher risk for cognitive impairment compared to their younger counterparts, the association between dietary fiber intake and cognition in older adults with and without CKD in the United States (US) was evaluated using data obtained from National Health and Nutrition Examination Survey (NHANES) 2011–2014. Based on the stratification of fiber intake and CKD status among the participants, we hypothesized that high dietary fiber intake contributes to reduced cognitive impairment in patients with CKD. We believe that these findings can provide insights into reduced cognition levels in CKD.

Materials and methods

Study participants

The data of participants in this cross-sectional study were obtained from NHANES 2011–2014, which is a stratified, multistage survey conducted in US civilian, non-institutionalized population. The study protocol was approved by the National Center for Health Statistics Institutional Review Board (https://www.cdc.gov/nchs/nhanes/irba98.htm) and all participants provided written informed consents upon the application to the NHANES. The secondary data analysis did not require additional institutional review board approval. This study recruited adults aged ≥60 years with complete cognitive function test data in the 2011–2014 survey cycles. The participants with incomplete data on CKD status, dietary fiber intake, and other covariates were excluded.

CKD status

In early-stage CKD, the urinary albumin:creatinine ratio (UACR) is ≥30 mg/g; however, the eGFR remains normal. With CKD progression and the accumulation of uremic toxins, eGFR falls below 60 ml/min/ 1.73m². eGFR and UACR thresholds are usually used to define CKD [5]. In the present study, we defined CKD based on the above standards by the test value of UACR and the calculated value of eGFR. eGFR was estimated using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) 2021 creatinine-based equation recommended by the National Kidney Foundation and the American Society of Nephrology [18].

Cognitive function

A series of cognitive function assessments, including word learning and recall modules from the Consortium to Establish a Registry for Alzheimer’s Disease (CERAD), Animal Fluency test (AFT), and Digit Symbol Substitution test (DSST), were performed in 2011–2014 NHANES among participants aged ≥60 years. The CERAD tests were used to assess immediate and delayed learning ability for new verbal information [19]; there were three immediate recalls (CERAD-WL) and a delayed recall (CERAD-DR). In the immediate recalls, participants were instructed to read 10 unrelated words. Immediately following the presentation of the words, participants were asked to recall as many words as possible three times. After completing the AFT and DSST tests, delayed word recall occurred (approximately 8–10 min from the start of the word learning trials). The maximum score possible on each recall was 10. The AFT investigates categorical verbal fluency, a component of executive function [20]. Participants were asked to name as many animals as possible in 1 min and a point was given for each named animal. The total scores ranged from 1 to 40. The DSST was used to evaluate the abilities of processing speed, sustained attention, and working memory. In the DSST, nine numbers paired with symbols were provided, and the participants were required to copy the corresponding symbols in the 133 boxes that adjoin the numbers in 2 min. The score was the total number of correct matches.

In the above cognitive function tests, higher scores indicated better cognitive function. In accordance with the criteria for cognitive impairment in the previous literature, the lowest quartile of the CERAD-WL, CERAD-DR, AFT, and DSST scores were used as the cutoff points. As cognitive function declines with age, the cutoff points for different age groups were calculated (Table 1) [17,21]. The participants with scores below or equal to the cutoff points of the corresponding age group were defined as having cognitive impairment.

Download:

Table 1. Cutoff points of cognitive function test scores adjusted by age.

https://doi.org/10.1371/journal.pone.0291690.t001

Measurement of dietary data

The dietary data of participants were obtained from the NHANES database through two 24-h recall surveys. The first 24-h dietary recall was conducted in the mobile examination center, and the second dietary recall proceeded over the phone 3–10 days later. The dietary nutrients were calculated as the average of data from both times if those data were available. Otherwise, the first 24-h dietary recall was used. As the main dietary components, protein and carbohydrate intakes were reported to associated with cognition in previous studies [13,14]. In this study, in addition to dietary fiber intake, we included energy, protein, and carbohydrate as covariates.

The European Food Safety Authority and the UK Scientific Advisory Committee on Nutrition recommend a daily fiber intake of 25 g/day and 30 g/day for adults, respectively [22]. The American Heart Association recommends a dietary fiber intake of at least 25 g/day for adults [23]. In this study, we divided the participants into two groups based on the fiber intake value of 25 g/day: low-level group (≤25 g/day) and high-level group (>25 g/day).

Covariates

Potential cognition-related covariates, including age, sex, ethnicity, education level, marital status, smoking status, body mass index, hypertension, diabetes, coronary heart disease, stroke, malignancy, depression, sleep disorder, UACR, eGFR, hemoglobin, albumin, blood urea nitrogen, creatinine, uric acid, total dietary intake of energy, carbohydrates, and protein, were analyzed in this study.

Race/ethnicity was classified as Mexican American, non-Hispanic white, non-Hispanic black, or other races. Educational level was categorized as <9 years, 9–12 years, and >12 years. Marital status was classified as married/living with a partner or widowed/divorced/separated/never married. Smoking status was defined as never smokers (smoked<100 cigarettes), current smokers, and former smokers (quit smoking after smoking>100 cigarettes). Disease history (such as hypertension, diabetes, coronary heart disease, stroke, malignancy, and sleep disorder) was determined by self-report of whether the disease was diagnosed by a physician in the past. Depression status was based on mental health questionnaire (DPQ020). Total energy, carbohydrates, and protein intakes were obtained from the participants’ 24-h nutritional information. In addition, the kidney conditions questionnaire (KIQ025) was used to determine whether the participants received dialysis treatment.

Statistical analyses

The Kolmogorov–Smirnov normality test was performed to determine the normality of the distribution of continuous variables. Mean ± standard deviation was used for normal variables, and median (interquartile range) for non-normally distributed variables. Categorical variables were expressed as absolute numbers with percentages. Differences in continuous values with a normal distribution were compared using an independent samples t-test. For non-normally distributed data, the groups were compared using the Mann–Whitney U test. The chi-square test was performed to compare categorical variables. We investigated the difference in cognitive scores and cognitive impairments between CKDs and non-CKD participants. A multivariate logistic regression subgroup analysis was performed to analyze the odds ratios (OR) and 95% confidence intervals (95% CIs) of cognitive impairment between low and high dietary fiber intake groups and in participants with and without CKD. The models were fully adjusted by age, sex, ethnicity, education level, marital status, smoking status, body mass index, hypertension, diabetes, coronary heart disease, stroke, malignancy, depression, sleep disorder, UACR, eGFR, hemoglobin, albumin, blood urea nitrogen, creatinine, uric acid, total dietary intake of energy, carbohydrates, and protein. The interaction between CKD status and dietary fiber intake was inspected by the likelihood ratio test. Stratified analyses of the relationship between dietary fiber intake and cognitive impairment were performed, including the following variables: sex, marital status (married/living with a partner vs. living alone), education level (≤12 years vs. >12 years), smoking status (never smoking vs. Current/former smoker), and history of hypertension and diabetes (absence vs. presence). Multiple linear regression analyses were performed to examine the association between dietary fiber intake and cognition in patients with CKD. Furthermore, a restricted cubic spline (RCS) with four knots was performed to assess the potential nonlinear relationship between dietary fiber intake and cognitive impairment. To assess the robustness of our findings, we performed sensitivity analyses using fully-adjusted logistic regression subgroup analysis after excluding participants with extreme fiber intake <4.7g/day (2.5%) or >38.7 g/day (97.5%). In addition, considering the possible effect of dialysis treatment on cognitive impairment, patients with CKD on dialysis treatment were excluded from the sensitivity analyses. All statistical analyses were performed using the statistical software packages R 4.1.1 (http://www.R-project.org) and Free Statistics software version 1.7 [24]. A two-tailed p-value <0.05 was considered statistically significant.

Results

Study population

Overall, 2934 adults aged ≥60 years with complete cognitive function tests from the 2011–2014 survey cycles of NHANES were included. Participants with incomplete CKD status (n = 204), dietary fiber intake (n = 192), and other covariates data (n = 77) were excluded. A total of 2461 participants were included in the final analysis (Fig 1).

Download:

Fig 1. Flow diagram of the study.

Abbreviation: NHANES, National Health and Nutrition Examination Survey; CKD, chronic kidney disease.

https://doi.org/10.1371/journal.pone.0291690.g001

Baseline characteristics

The baseline characteristics of the participants according to CKD status are shown in Table 2. Of 2461, 787 (32%) participants had CKD. The average age was 69.3 (6.7) years and 49.7% were male. Individuals with CKD were older; had a lower education level; were widowed, divorced, separated, or never married; were current or former smokers; had a higher incidence of hypertension, diabetes, coronary heart disease, stroke, and depression; and had lower consumption of energy, protein, carbohydrate, and fiber.

Download:

Table 2. Characteristics of NHANES 2011-2014 US participants aged ≥60 years.

https://doi.org/10.1371/journal.pone.0291690.t002

Cognitive function of the participants with and without CKD

Table 3 shows the cognitive function of the participants. Participants with CKD showed lower scores in all four cognitive function tests (CERAD-WL, CERAD-DR, AFT, and DSST) as compared to those without CKD (p < 0.001). Cognitive impairment was determined when the scores were lower than the cutoff points adjusted by age. The incidence of cognitive impairment was higher in the CKD group.

Download:

Table 3. Cognitive function of US older adults in NHANSE 2011–2014.

https://doi.org/10.1371/journal.pone.0291690.t003

Dietary fiber intake affects the association between CKD and cognitive impairment

As shown in Fig 2, there was an inverse association between dietary fiber intake and cognitive impairment in the CKD group after adjusting for potential confounders. Compared to non-CKD participants, CKD participants consuming low dietary fiber (≤25g/day) tended to have a higher risk of CERAD-WL and DSST impairments. The adjusted OR values for the CKD group in CERAD-WL and DSST impairments were 1.38 (95% CI: 1.06–1.80, p = 0.018) and 1.41 (95% CI: 1.04–1.92, p = 0.028), respectively. In the high dietary fiber intake group, the differences in CERAD-WL and DSST impairments between the CKD and non-CKD groups were not significant. In addition, there were no associations between CKD and CERAD-DR and AFT impairments regardless of dietary fiber intake. There were no significant interactions by fiber intake on the association between CKD and cognition in any subgroup.

Download:

Fig 2. Association between CKD and cognitive function impairment in older adults with different dietary fiber intake levels in the US.

The models were adjusted by age, sex, ethnicity, education, marital status, smoking, body mass index, hypertension, diabetes, coronary heart disease, stroke, malignancy, depression, sleep disorder, UACR, eGFR, hemoglobin, albumin, blood urea nitrogen, creatinine, uric acid, dietary energy, dietary protein, and dietary carbohydrate. Abbreviations: CKD, chronic kidney disease; UACR, urinary albumin:creatinine ratio; eGFR, estimated glomerular filtration rate; CERAD-WL, Consortium to Establish a Registry for Alzheimer’s Disease Word Learning; CERAD-DR, Consortium to Establish a Registry for Alzheimer’s Disease Delayed Recall; AFT, Animal Fluency test; DSST, Digit Symbol Substitution test.

https://doi.org/10.1371/journal.pone.0291690.g002

Stratified analyses on the association between dietary fiber intake and cognitive impairment

Stratified analyses were performed to assess the potential effect of dietary fiber intake on cognitive impairment in the subgroups. Given the effects of different dietary fiber intakes on CERAD-WL and DSST impairments, the two types of cognitive impairment were analyzed in the subgroups stratified by sex, marital status, education level, smoking status, and history of hypertension and diabetes. In the low dietary fiber intake group, CERAD-WL (Fig 3) or DSST impairment (Fig 4) were prominent in CKD patients who were male, living alone, had a higher education level, never smoked, had diabetes, and had no hypertension. No difference in CERAD-WL or DSST impairment was observed between CKD and non-CKD patients in the high fiber intake group.

Download:

Fig 3. Stratified analysis of the relationship between CKD and CERAD-WL impairment in older adults with different dietary fiber intake levels in the US.

The models were adjusted by age, sex, ethnicity, education, marital status, smoking, body mass index, hypertension, diabetes, coronary heart disease, stroke, malignancy, depression, sleep disorder, UACR, eGFR, hemoglobin, albumin, blood urea nitrogen, creatinine, uric acid, dietary energy, dietary protein, and dietary carbohydrate, except for the stratification factor itself. Abbreviations: CKD, chronic kidney disease; CERAD-WL, Consortium to Establish a Registry for Alzheimer’s Disease Word Learning; UACR, urinary albumin:creatinine ratio; eGFR, estimated glomerular filtration rate.

https://doi.org/10.1371/journal.pone.0291690.g003

Download:

Fig 4. Stratified analysis of the relationship between CKD with DSST impairment in older adults with different dietary fiber intake levels in the US.

The models were adjusted by age, sex, ethnicity, education, marital status, smoking, body mass index, hypertension, diabetes, coronary heart disease, stroke, malignancy, depression, sleep disorder, UACR, eGFR, hemoglobin, albumin, blood urea nitrogen, creatinine, uric acid, dietary energy, dietary protein, and dietary carbohydrate, except for the stratification factor itself. Abbreviations: CKD, chronic kidney disease; DSST, Digit Symbol Substitution Test; UACR, urinary albumin:creatinine ratio; eGFR, estimated glomerular filtration rate.

https://doi.org/10.1371/journal.pone.0291690.g004

Association between dietary fiber intake and cognition in older patients with CKD

The multiple linear regression analyses showed that dietary fiber intake was positively correlated to the AFT score (β = 0.147, p = 0.001) after adjustment for the full set of covariates. A linear relationship between dietary fiber intake and AFT score was observed in older patients with CKD (Fig 5). No associations were found between dietary fiber intake and CERAD-WL (β = 0.046, p = 0.324), CERAD-DR (β = 0.073, p = 0.119), and DSST (β = 0.049, p = 0.229) scores. In addition, nonlinear relationships were not observed between dietary fiber intake and cognitive impairment (S1 Fig).

Download:

Fig 5. Dose-response curve between dietary fiber intake and AFT score after adjusting for full covariates in older patients with CKD.

Abbreviations: AFT, Animal Fluency Test; CKD, chronic kidney disease.

https://doi.org/10.1371/journal.pone.0291690.g005

Sensitivity analysis

Participants with dietary fiber intake <4.7g/day and >38.7g/day were excluded for sensitivity analysis. We found that the effect of dietary fiber intake on the relationship between cognitive impairment and CKD was stable (S1 Table). The results were also similar when CKD patients receiving dialysis treatment were excluded from the analysis (S2 Table).

Discussion

This cross-sectional study assessed the cognitive function of older adults in the US by CERAD-WL, CERAD-DR, AFT, and DSST, which embodies immediate and delayed learning ability, executive function, processing speed, sustained attention, and working memory. The results indicated that global cognitive performance was worse in patients with CKD. CKD patients with low dietary fiber intake showed a higher risk of cognitive impairment in CERAD-WL and DSST as compared to those without CKD, implying the worse immediate learning ability, processing speed, sustained attention, and working memory of CKD patients. In the high-fiber diet group, the differences in cognitive impairment between the CKD and non-CKD participants were not significant. A positively linear relationship between dietary fiber intake and AFT score was observed in older patients with CKD. Despite the lack of robust data, high dietary fiber intake might benefit cognitive function in older patients with CKD.

The prevalence of cognitive impairment in patients with CKD ranged from 10% to an astonishing 87% [25–27], depending on the testing methods of cognitive assessment and CKD stage. In our study, the incidence of cognitive impairment in older patients with CKD was at 32%-35%. A similar result was found in a cross-sectional study that included 825 adults with CKD aged ≥55 years [27], which showed a 4%–28% prevalence of cognitive impairment; however, a negative correlation was observed between eGFR and the prevalence of cognitive impairment. The slightly higher rate in our study may be attributed to the age differences between the study populations. Executive function and attention are most impaired in mild CKD, whereas in severe CKD, cognitive impairment is more global and more severe, which may be because individuals are older by the time they reach a severe stage of CKD [28]. A previous study based on NHANES III showed that moderate CKD patients aged 20–59 years were significantly related to poorer cognitive performance in visual attention and learning/concentration [29]. Specific to older patients with CKD, the participants scored lower in all four tests: CERAD-WL, CERAD-DR, AFT, and DSST. This suggested that CKD could influence immediate and delayed learning ability, executive function, processing speed, sustained attention, and working memory. A meta-analysis showed that patients with CKD performed worse than the control groups on Global Cognition tests, including Orientation & Attention, Memory, Language, Concept Formation & Reasoning, and Executive Function assessment, in line with our study [30]. Some potential mechanisms contributing to cognitive impairment in CKD were cerebrovascular diseases, particularly small-vessel cerebrovascular disease, and other CKD-specific risk factors, such as uremic metabolites, dialysis factors, anemia, and aluminum [31].

Furthermore, we found that CKD participants with low dietary fiber intake had a higher risk of CERAD-WL and DSST impairments, resulting in worse immediate learning ability, processing speed, sustained attention, and working memory than the non-CKD participants. However, high dietary fiber intake eliminates the differences between CKD and non-CKD participants, thus preventing older patients with CKD from cognitive impairment. A positive linear relationship was also found between dietary fiber intake and AFT score in patients with CKD, suggesting the benefit of high-fiber diets on cognition in CKD. Similarly, a result was also observed in the general older adults, whose consumption of dietary fiber was positively associated with DSST score and a plateau in DSST score was suggested at a dietary fiber intake of 34 g per day [16]. A plant-based diet characterized by high fiber and polyunsaturated fat intake and low saturated fat and protein intake is related to better cognitive performance on memory and executive function in US older adults [32]. Researchers also established a consistent effect of high dietary fiber intake on the association between hypertension and cognitive impairment [17]. In the past few decades, many studies have suggested that the Mediterranean diet (MedDiet) can reduce the risk of cardiovascular disease and improve cognition [33, 34]. The MedDiet includes plenty of vegetables, fruits, and cereals, which provide 33 g of dietary fiber per day [35]. On the contrary, a large cross-sectional study involving 48749 participants in the United Kingdom suggested that better cognitive ability was associated with moderate intake of fiber, not with high and low fiber intake. There was no reasonable explanation for the U-shaped relationship between cognition and fiber intake [36]. Considering the possibility of a non-linear relationship, we also need a large clinical study to validate our findings regarding the association between dietary fiber intake and cognition in CKD.

Emerging evidence has shown that diet plays a crucial role in shaping the gut microbiome and modulating the structure and function of the brain through the microbiota-gut-brain axis, which is made up of neuroendocrine, neural, and immune communication channels and has emerged as a key conduit for the effects of nutrition on the brain [37]. Reportedly, dietary fiber regulates the gut microbiome and provides the crucial substrate to the community of microbes in the distal gut. Dietary fiber is fermented by the gut microbiome in the intestines, and short-chain fatty acid (SCFA) is generated as a major metabolite, which is often considered a key candidate mediator of the microbiota-gut-brain axis and involved in psychological functioning [38]. Animal experiments proved that high-fiber intake in the maternal diet restores maternal obesity-induced cognitive and social deficits in offspring by reshaping the gut microbiome via the microbiota-gut-brain axis and SCFA in both mother and offspring mice [39]. On the contrary, mice with long-term dietary fiber deficiency exhibited impaired cognition, gut microbiota dysbiosis, and reduced SCFA production [15]. A randomized, double-blind, placebo-controlled, crossover-design study demonstrated that supplementation with dietary fiber, polydextrose, resulted in a modest improvement in cognition by affecting gut-to-brain communication [40]. In short, SCFA and the microbiota-gut-brain axis are the major contributors and pathways to the benefit of a high-fiber diet on cognitive impairment.

This study has some important limitations that should be acknowledged. First, although NHANES included large representative health and nutrition data, this study showed the correlation between high fiber intake and improved cognition in older patients with CKD due to its cross-sectional nature. Nonetheless, verification of the causal relationship still requires a large longitudinal study. Second, the diagnostic criteria of CKD are structural or functional abnormalities of the kidney for at least 3 months. However, the values of serum creatinine and UACR were measured only once in each participant in NHANES 2011–2014. The duration of the disease could not be determined, which may lead to a slight overestimation of the prevalence of CKD. Reportedly, an estimated 47% of individuals aged > 70 years in the US are affected by CKD [41], which is similar to that of our study, suggesting that 32% of individuals aged ≥60 years had CKD. Third, according to a study, CKD-EPI 2021 eGFR equation with creatinine and cystatin C is more accurate than the equation with creatinine alone [42]. However, cystatin C was not examined in NHANES 2011–2014, which prevented us from estimating GFR more precisely. Therefore, we chose CKD-EPI 2021 creatinine-based equation to calculate GFR, which is also recommended by the National Kidney Foundation. Fourth, although numerous related covariates were adjusted in the regression models, perhaps some potential confounders were not excluded in this study.

In summary, we found that older patients with CKD are associated with cognitive impairment across multiple domains, especially in the immediate learning ability, processing speed, attention, and working memory after adjustment for numerous sociodemographic and clinical confounders. High dietary fiber intake might benefit the association between CKD and cognitive impairment in this group of patients. Nonetheless, future longitudinal studies are warranted to validate our findings and facilitate clinical interventions that implement high-fiber diet management strategies to mitigate cognitive impairment in older patients with CKD.

Supporting information

S1 Fig. Nonlinear relationship between dietary fiber intake and cognitive impairment in older patients with CKD.

Solid and dashed lines represent the predicted value and 95% confidence intervals. The models were fully adjusted by age, sex, ethnicity, education, marital status, smoking, body mass index, hypertension, diabetes, coronary heart disease, stroke, malignancy, depression, sleep disorder, UACR, eGFR, hemoglobin, albumin, blood urea nitrogen, creatinine, uric acid, dietary energy, dietary protein, and dietary carbohydrate. Abbreviations: CKD, chronic kidney disease; UACR, urinary albumin:creatinine ratio; eGFR, estimated glomerular filtration rate; CERAD-WL, Consortium to Establish a Registry for Alzheimer’s Disease Word Learning; CERAD-DR, Consortium to Establish a Registry for Alzheimer’s Disease Delayed Recall; AFT, Animal Fluency test; DSST, Digit Symbol Substitution test.

https://doi.org/10.1371/journal.pone.0291690.s001

(TIF)

S1 Table. CKD and cognitive function impairment by levels of fiber intake among older adults without extreme dietary fiber intake in the US, NHANES 2011–2014.

The logistic regression models were adjusted by age, sex, ethnicity, education, marital status, smoking, body mass index, hypertension, diabetes, coronary heart disease, stroke, malignancy, depression, sleep disorder, UACR, eGFR, hemoglobin, albumin, blood urea nitrogen, creatinine, uric acid, dietary energy, dietary protein, and dietary carbohydrate. Abbreviations: CKD, chronic kidney disease; NHANES, National Health and Nutrition Examination Survey; UACR, urinary albumin:creatinine ratio; eGFR, estimated glomerular filtration rate; CERAD-WL, Consortium to Establish a Registry for Alzheimer’s Disease Word Learning; CERAD-DR, Consortium to Establish a Registry for Alzheimer’s Disease Delayed Recall; AFT, Animal Fluency test; DSST, Digit Symbol Substitution test.

https://doi.org/10.1371/journal.pone.0291690.s002

(DOCX)

S2 Table. CKD and cognitive function impairment by levels of fiber intake among older adults after excluding CKD patients receiving dialysis treatment in the US, NHANES 2011–2014.

The logistic regression models were adjusted by age, sex, ethnicity, education, marital status, smoking, body mass index, hypertension, diabetes, coronary heart disease, stroke, malignancy, depression, sleep disorder, UACR, eGFR, hemoglobin, albumin, blood urea nitrogen, creatinine, uric acid, dietary energy, dietary protein, and dietary carbohydrate. Abbreviations: CKD, chronic kidney disease; NHANES, National Health and Nutrition Examination Survey; UACR, urinary albumin:creatinine ratio; eGFR, estimated glomerular filtration rate; CERAD-WL, Consortium to Establish a Registry for Alzheimer’s Disease Word Learning; CERAD-DR, Consortium to Establish a Registry for Alzheimer’s Disease Delayed Recall; AFT, Animal Fluency test; DSST, Digit Symbol Substitution test.

https://doi.org/10.1371/journal.pone.0291690.s003

(DOCX)

References

1. Kalantar-Zadeh K, Jafar TH, Nitsch D, Neuen BL, Perkovic V. Chronic kidney disease. Lancet. 2021;398(10302):786–802. pmid:34175022
- View Article
- PubMed/NCBI
- Google Scholar
2. Zoccali C, Vanholder R, Massy ZA, Ortiz A, Sarafidis P, Dekker FW, et al. The systemic nature of CKD. Nat Rev Nephrol. 2017;13(6):344–58. pmid:28435157
- View Article
- PubMed/NCBI
- Google Scholar
3. Viggiano D, Wagner CA, Martino G, Nedergaard M, Zoccali C, Unwin R, et al. Mechanisms of cognitive dysfunction in CKD. Nat Rev Nephrol. 2020;16(8):452–69. pmid:32235904
- View Article
- PubMed/NCBI
- Google Scholar
4. Brodski J, Rossell SL, Castle DJ, Tan EJ. A Systematic Review of Cognitive Impairments Associated With Kidney Failure in Adults Before Natural Age-Related Changes. J Int Neuropsychol Soc. 2019;25(1):101–14. pmid:30463631
- View Article
- PubMed/NCBI
- Google Scholar
5. Ortiz A, Mattace-Raso F, Soler MJ, Fouque D. Ageing meets kidney disease. Clin Kidney J. 2022;15(10):1793–6. pmid:36158151
- View Article
- PubMed/NCBI
- Google Scholar
6. Martens RJ, Kooman JP, Stehouwer CD, Dagnelie PC, van der Kallen CJ, Koster A, et al. Estimated GFR, Albuminuria, and Cognitive Performance: The Maastricht Study. Am J Kidney Dis. 2017;69(2):179–91. https://doi.org/10.1053/j.ajkd.2016.04.017
- View Article
- Google Scholar
7. Weiner DE, Gaussoin SA, Nord J, Auchus AP, Chelune GJ, Chonchol M, et al. Cognitive Function and Kidney Disease: Baseline Data From the Systolic Blood Pressure Intervention Trial (SPRINT). Am J Kidney Dis. 2017;70(3):357–67. https://doi.org/10.1053/j.ajkd.2017.04.021
- View Article
- Google Scholar
8. Singh-Manoux A, Oumarou-Ibrahim A, Machado-Fragua MD, Dumurgier J, Brunner EJ, Kivimaki M, et al. Association between kidney function and incidence of dementia: 10-year follow-up of the Whitehall II cohort study. Age Ageing. 2022;51(1): afab259. pmid:35061870
- View Article
- PubMed/NCBI
- Google Scholar
9. Afsar B, Elsurer R, Covic A, Johnson RJ, Kanbay M. Relationship between uric acid and subtle cognitive dysfunction in chronic kidney disease. Am J Nephrol. 2011;34(1):49–54. pmid:21659739
- View Article
- PubMed/NCBI
- Google Scholar
10. Nicholas P, Green T, Purtell L, Bonner A. A cross-sectional study exploring cognitive impairment in kidney failure. J Ren Care. 2022;48(2):93–101. pmid:34227741
- View Article
- PubMed/NCBI
- Google Scholar
11. Puy L, Bugnicourt JM, Liabeuf S, Desjardins L, Roussel M, Diouf M, et al. Cognitive Impairments and Dysexecutive Behavioral Disorders in Chronic Kidney Disease. J Neuropsychiatry Clin Neurosci. 2018;30(4):310–7. pmid:30045680
- View Article
- PubMed/NCBI
- Google Scholar
12. Viggiano D, Wagner CA, Blankestijn PJ, Bruchfeld A, Fliser D, Fouque D, et al. Mild cognitive impairment and kidney disease: clinical aspects. Nephrol Dial Transplant. 2020;35(1):10–7. pmid:31071220
- View Article
- PubMed/NCBI
- Google Scholar
13. Li Y, Li S, Wang W, Zhang D. Association between Dietary Protein Intake and Cognitive Function in Adults Aged 60 Years and Older. J Nutr Health Aging. 2020;24(2):223–9. pmid:32003415
- View Article
- PubMed/NCBI
- Google Scholar
14. Zhao S, Han T, Pei X, Song Y, Zhang Y, Liu L, et al. The association of diet carbohydrates consumption with cognitive function among US older adults modification by daily fasting duration. Front Aging Neurosci. 2022;14:991007. pmid:36225887
- View Article
- PubMed/NCBI
- Google Scholar
15. Shi H, Ge X, Ma X, Zheng M, Cui X, Pan W, et al. A fiber-deprived diet causes cognitive impairment and hippocampal microglia-mediated synaptic loss through the gut microbiota and metabolites. Microbiome. 2021;9(1):223. pmid:34758889
- View Article
- PubMed/NCBI
- Google Scholar
16. Prokopidis K, Giannos P, Ispoglou T, Witard OC, Isanejad M. Dietary Fiber Intake is Associated with Cognitive Function in Older Adults: Data from the National Health and Nutrition Examination Survey. Am J Med. 2022;135(8):e257–e262. pmid:35367443
- View Article
- PubMed/NCBI
- Google Scholar
17. Zhang H, Tian W, Qi G, Sun Y. Hypertension, dietary fiber intake, and cognitive function in older adults [from the National Health and Nutrition Examination Survey Data (2011–2014)]. Front Nutr. 2022;9:1024627. pmid:36337616
- View Article
- PubMed/NCBI
- Google Scholar
18. Miller WG, Kaufman HW, Levey AS, Straseski JA, Wilhelms KW, Yu HE, et al. National Kidney Foundation Laboratory Engagement Working Group Recommendations for Implementing the CKD-EPI 2021 Race-Free Equations for Estimated Glomerular Filtration Rate: Practical Guidance for Clinical Laboratories. Clin Chem. 2022;68(4):511–20. pmid:34918062
- View Article
- PubMed/NCBI
- Google Scholar
19. Morris JC, Heyman A, Mohs RC, Hughes JP, van Belle G, Fillenbaum G, et al. The Consortium to Establish a Registry for Alzheimer’s Disease (CERAD). Part I. Clinical and neuropsychological assessment of Alzheimer’s disease. Neurology. 1989;39(9):1159–65. pmid:2771064
- View Article
- PubMed/NCBI
- Google Scholar
20. Canning SJ, Leach L, Stuss D, Ngo L, Black SE. Diagnostic utility of abbreviated fluency measures in Alzheimer disease and vascular dementia. Neurology. 2004;62(4):556–62. pmid:14981170
- View Article
- PubMed/NCBI
- Google Scholar
21. Wang A, Zhao M, Luo J, Zhang T, Zhang D. Association of Dietary Vitamin K Intake With Cognition in the Elderly. Front Nutr. 2022;9:900887. pmid:35811956
- View Article
- PubMed/NCBI
- Google Scholar
22. Reimer RA, Soto-Vaca A, Nicolucci AC, Mayengbam S, Park H, Madsen KL, et al. Effect of chicory inulin-type fructan-containing snack bars on the human gut microbiota in low dietary fiber consumers in a randomized crossover trial. Am J Clin Nutr. 2020;111(6):1286–96. pmid:32320024
- View Article
- PubMed/NCBI
- Google Scholar
23. King DE, Xiang J. A Relationship Between Mortality and Eating Breakfast and Fiber. J Am Board Fam Med. 2021;34(4):678–87. pmid:34312261
- View Article
- PubMed/NCBI
- Google Scholar
24. Yang Q, Zheng J, Chen W, Chen X, Wen D, Chen W, et al. Association Between Preadmission Metformin Use and Outcomes in Intensive Care Unit Patients With Sepsis and Type 2 Diabetes: A Cohort Study. Front Med (Lausanne). 2021;8:640785. pmid:33855034
- View Article
- PubMed/NCBI
- Google Scholar
25. Murray AM, Tupper DE, Knopman DS, Gilbertson DT, Pederson SL, Li S, et al. Cognitive impairment in hemodialysis patients is common. Neurology. 2006;67(2):216–23. pmid:16864811
- View Article
- PubMed/NCBI
- Google Scholar
26. Post JB, Jegede AB, Morin K, Spungen AM, Langhoff E, Sano M. Cognitive profile of chronic kidney disease and hemodialysis patients without dementia. Nephron Clin Pract. 2010;116(3):c247–55. pmid:20606486
- View Article
- PubMed/NCBI
- Google Scholar
27. Yaffe K, Ackerson L, Kurella Tamura M, Le Blanc P, Kusek JW, Sehgal AR, et al. Chronic kidney disease and cognitive function in older adults: findings from the chronic renal insufficiency cohort cognitive study. J Am Geriatr Soc. 2010;58(2):338–45. pmid:20374407
- View Article
- PubMed/NCBI
- Google Scholar
28. Zammit AR, Katz MJ, Bitzer M, Lipton RB. Cognitive Impairment and Dementia in Older Adults With Chronic Kidney Disease: A Review. Alzheimer Dis Assoc Disord. 2016;30(4):357–66. pmid:27861179
- View Article
- PubMed/NCBI
- Google Scholar
29. Hailpern SM, Melamed ML, Cohen HW, Hostetter TH. Moderate chronic kidney disease and cognitive function in adults 20 to 59 years of age: Third National Health and Nutrition Examination Survey (NHANES III). J Am Soc Nephrol. 2007;18(7):2205–13. pmid:17554148
- View Article
- PubMed/NCBI
- Google Scholar
30. Berger I, Wu S, Masson P, Kelly PJ, Duthie FA, Whiteley W, et al. Cognition in chronic kidney disease: a systematic review and meta-analysis. BMC Med. 2016;14(1):206. pmid:27964726
- View Article
- PubMed/NCBI
- Google Scholar
31. Drew DA, Weiner DE, Sarnak MJ. Cognitive Impairment in CKD: Pathophysiology, Management, and Prevention. Am J Kidney Dis. 2019;74(6):782–90. pmid:31378643
- View Article
- PubMed/NCBI
- Google Scholar
32. Ramey MM, Shields GS, Yonelinas AP. Markers of a plant-based diet relate to memory and executive function in older adults. Nutr Neurosci. 2022;25(2):276–85. pmid:32297555
- View Article
- PubMed/NCBI
- Google Scholar
33. Guasch-Ferré M, Willett W C. The Mediterranean diet and health: a comprehensive overview. J Intern Med. 2021;290(3):549–566. pmid:34423871
- View Article
- PubMed/NCBI
- Google Scholar
34. Jay Widmer R, Flammer Andreas J, Lerman Lilach O, Amir Lerman. The Mediterranean diet, its components, and cardiovascular disease. Am J Med. 2015;128(3):229–38. pmid:25447615
- View Article
- PubMed/NCBI
- Google Scholar
35. Davis C, Bryan J, Hodgson J, Murphy K. Definition of the Mediterranean Diet; a Literature Review. Nutrients. 2015;7(11):9139–53. pmid:26556369
- View Article
- PubMed/NCBI
- Google Scholar
36. Hepsomali P, Groeger JA. Diet and general cognitive ability in the UK Biobank dataset. Sci Rep. 2021;11(1):11786. pmid:34083695
- View Article
- PubMed/NCBI
- Google Scholar
37. Horn J, Mayer DE, Chen S, Mayer EA. Role of diet and its effects on the gut microbiome in the pathophysiology of mental disorders. Transl Psychiatry. 2022;12(1):164. pmid:35443740
- View Article
- PubMed/NCBI
- Google Scholar
38. Dalile B, Van Oudenhove L, Vervliet B, Verbeke K. The role of short-chain fatty acids in microbiota-gut-brain communication. Nat Rev Gastroenterol Hepatol. 2019;16(8):461–78. pmid:31123355
- View Article
- PubMed/NCBI
- Google Scholar
39. Liu X, Li X, Xia B, Jin X, Zou Q, Zeng Z, et al. High-fiber diet mitigates maternal obesity-induced cognitive and social dysfunction in the offspring via gut-brain axis. Cell Metab. 2021;33(5):923–38.e6. pmid:33651981
- View Article
- PubMed/NCBI
- Google Scholar
40. Berding K, Long-Smith CM, Carbia C, Bastiaanssen TFS, van de Wouw M, Wiley N, et al. A specific dietary fibre supplementation improves cognitive performance-an exploratory randomised, placebo-controlled, crossover study. Psychopharmacology (Berl). 2021;238(1):149–63. pmid:32951067
- View Article
- PubMed/NCBI
- Google Scholar
41. Coresh J, Selvin E, Stevens LA, Manzi J, Kusek JW, Eggers P, et al. Prevalence of chronic kidney disease in the United States. JAMA. 2007;298(17):2038–47. pmid:17986697
- View Article
- PubMed/NCBI
- Google Scholar
42. Inker LA, Eneanya ND, Coresh J, Tighiouart H, Wang D, Sang Y, et al. New Creatinine- and Cystatin C-Based Equations to Estimate GFR without Race. N Engl J Med. 2021;385(19):1737–49. pmid:34554658
- View Article
- PubMed/NCBI
- Google Scholar

[ref1] 1. Kalantar-Zadeh K, Jafar TH, Nitsch D, Neuen BL, Perkovic V. Chronic kidney disease. Lancet. 2021;398(10302):786–802. pmid:34175022
View Article
PubMed/NCBI
Google Scholar

[2] View Article

[3] PubMed/NCBI

[4] Google Scholar

[ref2] 2. Zoccali C, Vanholder R, Massy ZA, Ortiz A, Sarafidis P, Dekker FW, et al. The systemic nature of CKD. Nat Rev Nephrol. 2017;13(6):344–58. pmid:28435157
View Article
PubMed/NCBI
Google Scholar

[6] View Article

[7] PubMed/NCBI

[8] Google Scholar

[ref3] 3. Viggiano D, Wagner CA, Martino G, Nedergaard M, Zoccali C, Unwin R, et al. Mechanisms of cognitive dysfunction in CKD. Nat Rev Nephrol. 2020;16(8):452–69. pmid:32235904
View Article
PubMed/NCBI
Google Scholar

[10] View Article

[11] PubMed/NCBI

[12] Google Scholar

[ref4] 4. Brodski J, Rossell SL, Castle DJ, Tan EJ. A Systematic Review of Cognitive Impairments Associated With Kidney Failure in Adults Before Natural Age-Related Changes. J Int Neuropsychol Soc. 2019;25(1):101–14. pmid:30463631
View Article
PubMed/NCBI
Google Scholar

[14] View Article

[15] PubMed/NCBI

[16] Google Scholar

[ref5] 5. Ortiz A, Mattace-Raso F, Soler MJ, Fouque D. Ageing meets kidney disease. Clin Kidney J. 2022;15(10):1793–6. pmid:36158151
View Article
PubMed/NCBI
Google Scholar

[18] View Article

[19] PubMed/NCBI

[20] Google Scholar

[ref6] 6. Martens RJ, Kooman JP, Stehouwer CD, Dagnelie PC, van der Kallen CJ, Koster A, et al. Estimated GFR, Albuminuria, and Cognitive Performance: The Maastricht Study. Am J Kidney Dis. 2017;69(2):179–91. https://doi.org/10.1053/j.ajkd.2016.04.017
View Article
Google Scholar

[22] View Article

[23] Google Scholar

[ref7] 7. Weiner DE, Gaussoin SA, Nord J, Auchus AP, Chelune GJ, Chonchol M, et al. Cognitive Function and Kidney Disease: Baseline Data From the Systolic Blood Pressure Intervention Trial (SPRINT). Am J Kidney Dis. 2017;70(3):357–67. https://doi.org/10.1053/j.ajkd.2017.04.021
View Article
Google Scholar

[25] View Article

[26] Google Scholar

[ref8] 8. Singh-Manoux A, Oumarou-Ibrahim A, Machado-Fragua MD, Dumurgier J, Brunner EJ, Kivimaki M, et al. Association between kidney function and incidence of dementia: 10-year follow-up of the Whitehall II cohort study. Age Ageing. 2022;51(1): afab259. pmid:35061870
View Article
PubMed/NCBI
Google Scholar

[28] View Article

[29] PubMed/NCBI

[30] Google Scholar

[ref9] 9. Afsar B, Elsurer R, Covic A, Johnson RJ, Kanbay M. Relationship between uric acid and subtle cognitive dysfunction in chronic kidney disease. Am J Nephrol. 2011;34(1):49–54. pmid:21659739
View Article
PubMed/NCBI
Google Scholar

[32] View Article

[33] PubMed/NCBI

[34] Google Scholar

[ref10] 10. Nicholas P, Green T, Purtell L, Bonner A. A cross-sectional study exploring cognitive impairment in kidney failure. J Ren Care. 2022;48(2):93–101. pmid:34227741
View Article
PubMed/NCBI
Google Scholar

[36] View Article

[37] PubMed/NCBI

[38] Google Scholar

[ref11] 11. Puy L, Bugnicourt JM, Liabeuf S, Desjardins L, Roussel M, Diouf M, et al. Cognitive Impairments and Dysexecutive Behavioral Disorders in Chronic Kidney Disease. J Neuropsychiatry Clin Neurosci. 2018;30(4):310–7. pmid:30045680
View Article
PubMed/NCBI
Google Scholar

[40] View Article

[41] PubMed/NCBI

[42] Google Scholar

[ref12] 12. Viggiano D, Wagner CA, Blankestijn PJ, Bruchfeld A, Fliser D, Fouque D, et al. Mild cognitive impairment and kidney disease: clinical aspects. Nephrol Dial Transplant. 2020;35(1):10–7. pmid:31071220
View Article
PubMed/NCBI
Google Scholar

[44] View Article

[45] PubMed/NCBI

[46] Google Scholar

[ref13] 13. Li Y, Li S, Wang W, Zhang D. Association between Dietary Protein Intake and Cognitive Function in Adults Aged 60 Years and Older. J Nutr Health Aging. 2020;24(2):223–9. pmid:32003415
View Article
PubMed/NCBI
Google Scholar

[48] View Article

[49] PubMed/NCBI

[50] Google Scholar

[ref14] 14. Zhao S, Han T, Pei X, Song Y, Zhang Y, Liu L, et al. The association of diet carbohydrates consumption with cognitive function among US older adults modification by daily fasting duration. Front Aging Neurosci. 2022;14:991007. pmid:36225887
View Article
PubMed/NCBI
Google Scholar

[52] View Article

[53] PubMed/NCBI

[54] Google Scholar

[ref15] 15. Shi H, Ge X, Ma X, Zheng M, Cui X, Pan W, et al. A fiber-deprived diet causes cognitive impairment and hippocampal microglia-mediated synaptic loss through the gut microbiota and metabolites. Microbiome. 2021;9(1):223. pmid:34758889
View Article
PubMed/NCBI
Google Scholar

[56] View Article

[57] PubMed/NCBI

[58] Google Scholar

[ref16] 16. Prokopidis K, Giannos P, Ispoglou T, Witard OC, Isanejad M. Dietary Fiber Intake is Associated with Cognitive Function in Older Adults: Data from the National Health and Nutrition Examination Survey. Am J Med. 2022;135(8):e257–e262. pmid:35367443
View Article
PubMed/NCBI
Google Scholar

[60] View Article

[61] PubMed/NCBI

[62] Google Scholar

[ref17] 17. Zhang H, Tian W, Qi G, Sun Y. Hypertension, dietary fiber intake, and cognitive function in older adults [from the National Health and Nutrition Examination Survey Data (2011–2014)]. Front Nutr. 2022;9:1024627. pmid:36337616
View Article
PubMed/NCBI
Google Scholar

[64] View Article

[65] PubMed/NCBI

[66] Google Scholar

[ref18] 18. Miller WG, Kaufman HW, Levey AS, Straseski JA, Wilhelms KW, Yu HE, et al. National Kidney Foundation Laboratory Engagement Working Group Recommendations for Implementing the CKD-EPI 2021 Race-Free Equations for Estimated Glomerular Filtration Rate: Practical Guidance for Clinical Laboratories. Clin Chem. 2022;68(4):511–20. pmid:34918062
View Article
PubMed/NCBI
Google Scholar

[68] View Article

[69] PubMed/NCBI

[70] Google Scholar

[ref19] 19. Morris JC, Heyman A, Mohs RC, Hughes JP, van Belle G, Fillenbaum G, et al. The Consortium to Establish a Registry for Alzheimer’s Disease (CERAD). Part I. Clinical and neuropsychological assessment of Alzheimer’s disease. Neurology. 1989;39(9):1159–65. pmid:2771064
View Article
PubMed/NCBI
Google Scholar

[72] View Article

[73] PubMed/NCBI

[74] Google Scholar

[ref20] 20. Canning SJ, Leach L, Stuss D, Ngo L, Black SE. Diagnostic utility of abbreviated fluency measures in Alzheimer disease and vascular dementia. Neurology. 2004;62(4):556–62. pmid:14981170
View Article
PubMed/NCBI
Google Scholar

[76] View Article

[77] PubMed/NCBI

[78] Google Scholar

[ref21] 21. Wang A, Zhao M, Luo J, Zhang T, Zhang D. Association of Dietary Vitamin K Intake With Cognition in the Elderly. Front Nutr. 2022;9:900887. pmid:35811956
View Article
PubMed/NCBI
Google Scholar

[80] View Article

[81] PubMed/NCBI

[82] Google Scholar

[ref22] 22. Reimer RA, Soto-Vaca A, Nicolucci AC, Mayengbam S, Park H, Madsen KL, et al. Effect of chicory inulin-type fructan-containing snack bars on the human gut microbiota in low dietary fiber consumers in a randomized crossover trial. Am J Clin Nutr. 2020;111(6):1286–96. pmid:32320024
View Article
PubMed/NCBI
Google Scholar

[84] View Article

[85] PubMed/NCBI

[86] Google Scholar

[ref23] 23. King DE, Xiang J. A Relationship Between Mortality and Eating Breakfast and Fiber. J Am Board Fam Med. 2021;34(4):678–87. pmid:34312261
View Article
PubMed/NCBI
Google Scholar

[88] View Article

[89] PubMed/NCBI

[90] Google Scholar

[ref24] 24. Yang Q, Zheng J, Chen W, Chen X, Wen D, Chen W, et al. Association Between Preadmission Metformin Use and Outcomes in Intensive Care Unit Patients With Sepsis and Type 2 Diabetes: A Cohort Study. Front Med (Lausanne). 2021;8:640785. pmid:33855034
View Article
PubMed/NCBI
Google Scholar

[92] View Article

[93] PubMed/NCBI

[94] Google Scholar

[ref25] 25. Murray AM, Tupper DE, Knopman DS, Gilbertson DT, Pederson SL, Li S, et al. Cognitive impairment in hemodialysis patients is common. Neurology. 2006;67(2):216–23. pmid:16864811
View Article
PubMed/NCBI
Google Scholar

[96] View Article

[97] PubMed/NCBI

[98] Google Scholar

[ref26] 26. Post JB, Jegede AB, Morin K, Spungen AM, Langhoff E, Sano M. Cognitive profile of chronic kidney disease and hemodialysis patients without dementia. Nephron Clin Pract. 2010;116(3):c247–55. pmid:20606486
View Article
PubMed/NCBI
Google Scholar

[100] View Article

[101] PubMed/NCBI

[102] Google Scholar

[ref27] 27. Yaffe K, Ackerson L, Kurella Tamura M, Le Blanc P, Kusek JW, Sehgal AR, et al. Chronic kidney disease and cognitive function in older adults: findings from the chronic renal insufficiency cohort cognitive study. J Am Geriatr Soc. 2010;58(2):338–45. pmid:20374407
View Article
PubMed/NCBI
Google Scholar

[104] View Article

[105] PubMed/NCBI

[106] Google Scholar

[ref28] 28. Zammit AR, Katz MJ, Bitzer M, Lipton RB. Cognitive Impairment and Dementia in Older Adults With Chronic Kidney Disease: A Review. Alzheimer Dis Assoc Disord. 2016;30(4):357–66. pmid:27861179
View Article
PubMed/NCBI
Google Scholar

[108] View Article

[109] PubMed/NCBI

[110] Google Scholar

[ref29] 29. Hailpern SM, Melamed ML, Cohen HW, Hostetter TH. Moderate chronic kidney disease and cognitive function in adults 20 to 59 years of age: Third National Health and Nutrition Examination Survey (NHANES III). J Am Soc Nephrol. 2007;18(7):2205–13. pmid:17554148
View Article
PubMed/NCBI
Google Scholar

[112] View Article

[113] PubMed/NCBI

[114] Google Scholar

[ref30] 30. Berger I, Wu S, Masson P, Kelly PJ, Duthie FA, Whiteley W, et al. Cognition in chronic kidney disease: a systematic review and meta-analysis. BMC Med. 2016;14(1):206. pmid:27964726
View Article
PubMed/NCBI
Google Scholar

[116] View Article

[117] PubMed/NCBI

[118] Google Scholar

[ref31] 31. Drew DA, Weiner DE, Sarnak MJ. Cognitive Impairment in CKD: Pathophysiology, Management, and Prevention. Am J Kidney Dis. 2019;74(6):782–90. pmid:31378643
View Article
PubMed/NCBI
Google Scholar

[120] View Article

[121] PubMed/NCBI

[122] Google Scholar

[ref32] 32. Ramey MM, Shields GS, Yonelinas AP. Markers of a plant-based diet relate to memory and executive function in older adults. Nutr Neurosci. 2022;25(2):276–85. pmid:32297555
View Article
PubMed/NCBI
Google Scholar

[124] View Article

[125] PubMed/NCBI

[126] Google Scholar

[ref33] 33. Guasch-Ferré M, Willett W C. The Mediterranean diet and health: a comprehensive overview. J Intern Med. 2021;290(3):549–566. pmid:34423871
View Article
PubMed/NCBI
Google Scholar

[128] View Article

[129] PubMed/NCBI

[130] Google Scholar

[ref34] 34. Jay Widmer R, Flammer Andreas J, Lerman Lilach O, Amir Lerman. The Mediterranean diet, its components, and cardiovascular disease. Am J Med. 2015;128(3):229–38. pmid:25447615
View Article
PubMed/NCBI
Google Scholar

[132] View Article

[133] PubMed/NCBI

[134] Google Scholar

[ref35] 35. Davis C, Bryan J, Hodgson J, Murphy K. Definition of the Mediterranean Diet; a Literature Review. Nutrients. 2015;7(11):9139–53. pmid:26556369
View Article
PubMed/NCBI
Google Scholar

[136] View Article

[137] PubMed/NCBI

[138] Google Scholar

[ref36] 36. Hepsomali P, Groeger JA. Diet and general cognitive ability in the UK Biobank dataset. Sci Rep. 2021;11(1):11786. pmid:34083695
View Article
PubMed/NCBI
Google Scholar

[140] View Article

[141] PubMed/NCBI

[142] Google Scholar

[ref37] 37. Horn J, Mayer DE, Chen S, Mayer EA. Role of diet and its effects on the gut microbiome in the pathophysiology of mental disorders. Transl Psychiatry. 2022;12(1):164. pmid:35443740
View Article
PubMed/NCBI
Google Scholar

[144] View Article

[145] PubMed/NCBI

[146] Google Scholar

[ref38] 38. Dalile B, Van Oudenhove L, Vervliet B, Verbeke K. The role of short-chain fatty acids in microbiota-gut-brain communication. Nat Rev Gastroenterol Hepatol. 2019;16(8):461–78. pmid:31123355
View Article
PubMed/NCBI
Google Scholar

[148] View Article

[149] PubMed/NCBI

[150] Google Scholar

[ref39] 39. Liu X, Li X, Xia B, Jin X, Zou Q, Zeng Z, et al. High-fiber diet mitigates maternal obesity-induced cognitive and social dysfunction in the offspring via gut-brain axis. Cell Metab. 2021;33(5):923–38.e6. pmid:33651981
View Article
PubMed/NCBI
Google Scholar

[152] View Article

[153] PubMed/NCBI

[154] Google Scholar

[ref40] 40. Berding K, Long-Smith CM, Carbia C, Bastiaanssen TFS, van de Wouw M, Wiley N, et al. A specific dietary fibre supplementation improves cognitive performance-an exploratory randomised, placebo-controlled, crossover study. Psychopharmacology (Berl). 2021;238(1):149–63. pmid:32951067
View Article
PubMed/NCBI
Google Scholar

[156] View Article

[157] PubMed/NCBI

[158] Google Scholar

[ref41] 41. Coresh J, Selvin E, Stevens LA, Manzi J, Kusek JW, Eggers P, et al. Prevalence of chronic kidney disease in the United States. JAMA. 2007;298(17):2038–47. pmid:17986697
View Article
PubMed/NCBI
Google Scholar

[160] View Article

[161] PubMed/NCBI

[162] Google Scholar

[ref42] 42. Inker LA, Eneanya ND, Coresh J, Tighiouart H, Wang D, Sang Y, et al. New Creatinine- and Cystatin C-Based Equations to Estimate GFR without Race. N Engl J Med. 2021;385(19):1737–49. pmid:34554658
View Article
PubMed/NCBI
Google Scholar

[164] View Article

[165] PubMed/NCBI

[166] Google Scholar

Figures

Abstract

Background

Methods

Results

Conclusion

Introduction

Materials and methods

Study participants

CKD status

Cognitive function

Measurement of dietary data

Covariates

Statistical analyses

Results

Study population

Baseline characteristics

Cognitive function of the participants with and without CKD

Dietary fiber intake affects the association between CKD and cognitive impairment

Stratified analyses on the association between dietary fiber intake and cognitive impairment

Association between dietary fiber intake and cognition in older patients with CKD

Sensitivity analysis

Discussion

Supporting information

S1 Fig. Nonlinear relationship between dietary fiber intake and cognitive impairment in older patients with CKD.

S1 Table. CKD and cognitive function impairment by levels of fiber intake among older adults without extreme dietary fiber intake in the US, NHANES 2011–2014.

S2 Table. CKD and cognitive function impairment by levels of fiber intake among older adults after excluding CKD patients receiving dialysis treatment in the US, NHANES 2011–2014.

References