Systematic review of structural and functional neuroimaging findings in children and adults with CKD

Association of cognitive impairment with the interaction between chronic kidney disease and depression: findings from NHANES 2011-2014

BACKGROUND

Cognitive impairment (CoI), chronic kidney disease (CKD), and depression are prevalent among older adults and are interrelated, imposing a significant disease burden. This study evaluates the association of CKD and depression with CoI and explores their potential interactions.

METHOD

Data for this study were sourced from the 2011-2014 National Health and Nutritional Examination Survey (NHANES). Multiple binary logistic regression models assessed the relationship between CKD, depression, and CoI while controlling for confounders. The interactions were measured using the relative excess risk of interaction (RERI), the attributable proportion of interaction (AP), and the synergy index (S).

RESULTS

A total of 2,666 participants (weighted n = 49,251,515) were included in the study, of which 700 (16.00%) had CoI. After adjusting for confounding factors, the risk of CoI was higher in patients with CKD compared to non-CKD participants (odds ratio [OR] = 1.49, 95% confidence interval [CI]:1.12-1.99). The risk of CoI was significantly increased in patients with depression compared to those without (OR = 2.29, 95% CI: 1.73-3.03). Furthermore, there was a significant additive interaction between CKD and depression in terms of the increased risk of CoI (adjusted RERI = 2.01, [95% CI: 0.31-3.71], adjusted AP = 0.50 [95% CI: 0.25-0.75], adjusted S = 2.97 [95% CI: 1.27-6.92]).

CONCLUSION

CKD and depression synergistically affect CoI, particularly when moderate-to-severe depression co-occurs with CKD. Clinicians should be mindful of the combined impact on patients with CoI. Further research is needed to elucidate the underlying mechanisms and assess the effects specific to different CKD stages.

Neurodevelopmental profile of infants and toddlers awaiting a kidney transplant

BACKGROUND

Infants and toddlers with kidney failure are susceptible to neurodevelopmental delays due to medical comorbidities and rapid brain development in early childhood. However, research on the neuropsychological development of this patient population has been limited over the past 10 years.

METHODS

We performed a retrospective study to evaluate the neurodevelopmental functioning of infants/toddlers with kidney failure who completed the Bayley Scales of Infant and Toddler Development (3rd and 4th Edition) as part of a pretransplant evaluation between 2010 and 2022 (n = 23; Mage = 18 months, SD = 8.53; 16 males) using t-tests, linear model, and Pearson correlations.

RESULTS

Mean Bayley scores of participants were below normative means for cognition (M = 86.74, 95% CI = 80.53-92.94, p < 0.001), language (M = 79.20, 95% CI = 73.32-85.08, p < 0.001), and motor (M = 78.00, 95% CI = 70.15-85.85, p < 0.001) domains. After adjusting for prematurity and epilepsy, patients on dialysis had significantly lower cognitive (78.7 vs. 93.8; p = 0.001) and motor scores (67.1 vs. 85.5; p = 0.01) compared to no dialysis. Pretransplant cognitive scores were positively correlated with posttransplant Full-Scale IQ (r(8) = 0.65 p = 0.04), verbal comprehension (r(8) = 0.75 p = 0.02), and fluid reasoning (r(7) = 0.68 p = 0.045). Similarly, pretransplant language scores were positively correlated with posttransplant Full-Scale IQ (r(7) = 0.74 p = 0.03) and verbal comprehension (r(7) = 0.73 p = 0.03). Of the 16 participants who reached age > 5 years during the study period, seven were diagnosed with a neurodevelopmental disorder, including three with autism spectrum disorder.

CONCLUSIONS

Infants and toddlers with kidney failure are at risk of developmental delays and later neurodevelopmental disorders. Dialysis is associated with cognitive and motor delays independent of prematurity and epilepsy.

Understanding the impact of pediatric kidney transplantation on cognition: A review of the literature

BACKGROUND

Chronic kidney disease (CKD) is a relatively rare childhood disease that is associated with a wide array of medical comorbidities. Roughly half of all pediatric patients acquire CKD due to congenital anomalies of the kidneys and urinary tract, and of those with congenital disease, 50% will progress to end-stage kidney disease (ESKD) necessitating a kidney transplantation. The medical sequelae of advanced CKD/ESKD improve dramatically following successful kidney transplantation; however, the impact of kidney transplantation on neurocognition in children is less clear. It is generally thought that cognition improves following kidney transplantation; however, our knowledge on this topic is limited by the sparsity of high-quality data in the context of the relative rarity of pediatric CKD/ESKD.

METHOD

We conducted a narrative review to gauge the scope of the literature, using the PubMed database and the following keywords: cognition, kidney, brain, pediatric, neurocognition, intelligence, executive function, transplant, immunosuppression, and neuroimaging.

RESULTS

There are few published longitudinal studies, and existing work often includes wide heterogeneity in age at transplant, variable dialysis exposure/duration prior to transplant, and unaccounted cofounders which persist following transplantation, including socio-economic status. Furthermore, the impact of long-term maintenance immunosuppression on the brain and cognitive function of pediatric kidney transplant (KT) recipients remains unknown.

CONCLUSION

In this educational review, we highlight what is known on the topic of neurocognition and neuroimaging in the pediatric KT population.

Stroke Subtype Among Individuals With Chronic Kidney Disease

Background

It is widely accepted that there is a stepwise increase in the risk of acute ischemic stroke with chronic kidney disease (CKD). However, whether the risk of specific ischemic stroke subtypes varies with CKD remains unclear.

Objective

To assess the association between ischemic stroke subtypes (cardioembolic, arterial, lacunar, and other) classified using the Trial of ORG 10172 in Acute Stroke Treatment (TOAST) and CKD stage.

Design

retrospective cohort study.

Setting

Ontario, Canada.

Patients

A total of 17 434 adults with an acute ischemic stroke in Ontario, Canada between April 1, 2002 and March 31, 2013, with an estimated glomerular filtration rate (eGFR) measurement or receipt of maintenance dialysis captured in a stroke registry were included.

Measurements

Kidney function categorized as an eGFR of ≥60, 30-59, <30 mL/min/1.73 m2, or maintenance dialysis. Ischemic stroke classified by TOAST included arterial, cardioembolic, lacunar, and other (dissection, prothrombotic state, cortical vein/sinus thrombosis, and vasculitis) types of strokes.

Methods

Adjusted regression models.

Results

In our cohort, 58.9% had an eGFR of ≥60, 34.7% an eGFR of 30-59, 6.0% an eGFR of <30 and 0.5% were on maintenance dialysis (mean age of 73 years; 48% women). Cardioembolic stroke was more common in patients with non-dialysis-dependant CKD (eGFR 30-59: 50.4%, adjusted odds ratio [OR] 1.20, 95% confidence interval [CI]: 1.02, 1.44; eGFR<30: 50.6%, OR 1.21, 95% CI: 1.02, 1.44), whereas lacunar stroke was less common (eGFR 30-59: 22.7% OR 0.85, 95% CI: 0.77, 0.93; eGFR <30: 0.73, 95% CI: 0.61, 0.88) compared with those with an eGFR ≥60. In stratified analyses by age and CKD, lacunar strokes were more frequent in those aged less than 65 years, whereas cardioembolic was higher in those aged 65 years and above.

Limitations

TOAST classification was not captured for all patients.

Conclusion

Non-dialysis CKD was associated with a higher risk of cardioembolic stroke, whereas an eGFR ≥60 mL/min/1.73 m2 was associated with a higher risk of lacunar stroke. Detailed stroke subtyping in CKD may therefore provide mechanistic insights and refocus treatment strategies in this high-risk population.

The kidney-brain pathogenic axis in severe falciparum malaria

Severe falciparum malaria is a medical emergency and a leading cause of death and neurodisability in endemic areas. Common complications include acute kidney injury (AKI) and cerebral malaria, and recent studies have suggested links between kidney and brain dysfunction in Plasmodium falciparum infection. Here, we review these new findings and present the hypothesis of a pivotal pathogenic crosstalk between the kidneys and the brain in severe falciparum malaria. We highlight the evidence of a role for distant organ involvement in the development of cerebral malaria and subsequent neurocognitive impairment post-recovery, describe the challenges associated with current diagnostic shortcomings for both AKI and brain involvement in severe falciparum malaria, and explore novel potential therapeutic strategies.

Risk factors for neurocognitive impairment and the relation with structural brain abnormality in children and young adults with severe chronic kidney disease

BACKGROUND

Severe chronic kidney disease (CKD) in children and young adults has shown to be associated with abnormal brain development, which may contribute to neurocognitive impairments. We aimed to investigate risk factors for neurocognitive impairment and investigate the relation with structural brain abnormalities in young severe CKD patients.

METHODS

This cross-sectional study includes 28 patients with severe CKD (eGFR < 30), aged 8-30 years (median 18.5 years), on different treatment modalities (pre-dialysis [n = 8], dialysis [n = 8], transplanted [n = 12]). We assessed neurocognitive functioning using a comprehensive test battery and brain structure by magnetic resonance imaging metrics of brain volume and white matter integrity (fractional anisotropy [FA] and mean diffusivity [MD] measured with diffusion tensor imaging). Multivariate regression and mediation analyses were performed between clinical CKD parameters, brain structure, and neurocognitive outcome.

RESULTS

A combination of risk factors (e.g., longer time since kidney transplantation, longer dialysis duration and late CKD onset) was significantly associated with lower intelligence and/or worse processing speed and working memory. Lower FA in a cluster of white matter tracts was associated with lower intelligence and mediated the relation between clinical risk factors and lower intelligence.

CONCLUSIONS

Young severe CKD patients with a prolonged duration of kidney replacement therapy, either dialysis or transplantation are at particular risk for impairments in intelligence, processing speed, and working memory. Disrupted white matter integrity may importantly contribute to these neurocognitive impairments. Prospective, longitudinal studies are needed to elucidate the mechanisms involved in CKD and treatment that affect white matter integrity and neurocognitive outcome in young patients. A higher resolution version of the Graphical abstract is available as Supplementary information.

Covert vascular brain injury in chronic kidney disease

Chronic kidney disease (CKD) contributes to the increased risk of stroke and dementia. Accumulating evidence indicates that structural brain abnormalities, such as cerebral small vessel disease, including white matter hyperintensities, lacunes, perivascular spaces, and cerebral microbleeds, as well as brain atrophy, are common in patients with CKD. All of these imaging findings have been implicated in the development of stroke and dementia. The brain and kidney exhibit similar impairments and promote structural brain abnormalities due to shared vascular risk factors and similar anatomical and physiological susceptibility to vascular injury in patients with CKD. This indicates that kidney function has a significant effect on brain aging. However, as most results are derived from cross-sectional observational studies, the exact pathophysiology of structural brain abnormalities in CKD remains unclear. The early detection of structural brain abnormalities in CKD in the asymptomatic or subclinical phase (covert) should enable stroke risk prediction and guide clinicians on more targeted interventions to prevent stroke in patients with CKD. This article summarizes the currently available clinical evidence linking covert vascular brain injuries with CKD.

Global and Regional White Matter Fractional Anisotropy in Children with Chronic Kidney Disease

OBJECTIVE

To investigate the associations between neurocognition and white matter integrity in children with chronic kidney disease (CKD).

STUDY DESIGN

This cross-sectional study included 17 boys (age 6-16 years) with a diagnosis of mild to moderate (stages 1-3, nondialysis/nontransplant) CKD because of congenital anomalies of the kidney and urinary tract and 20 typically developing community controls. Participants underwent 3T neuroimaging and diffusion-weighted magnetic resonance imaging to assess white matter fractional anisotropy. Multivariable linear regression models were used to evaluate the impact of each group (controls vs CKD) on white matter fractional anisotropy, adjusting for age. Associations between white matter fractional anisotropy and neurocognitive abilities within the CKD group were also evaluated using regression models that were adjusted for age. The false discovery rate was used to account for multiple comparisons; wherein false discovery values <0.10 were considered significant.

RESULTS

Global white matter fractional anisotropy was reduced in patients with CKD relative to controls (standardized estimate = -0.38, 95% CI -0.69:-0.07), driven by reductions within the body of the corpus callosum (standardized estimate = -0.44, 95% CI -0.75:-0.13), cerebral peduncle (SE = -0.37, 95% CI -0.67:-0.07), cingulum (hippocampus) (standardized estimate = -0.45, 95% CI -0.75:-0.14), and posterior limb of the internal capsule (standardized estimate = -0.46, 95% CI -0.76:-0.15). Medical variables and neurocognitive abilities were not significantly associated with white matter fractional anisotropy.

CONCLUSIONS

White matter development is vulnerable in children with CKD because of congenital causes, even prior to the need for dialysis or transplantation.

Impact of Chronic Kidney Disease on Brain Structure and Function

Chronic kidney disease (CKD) affects more than 37 million American adults. Adult-onset CKD is typically attributed to acquired comorbidities such as aging, type II diabetes, and cardiovascular disease. Conversely, congenital abnormalities of the kidney and urinary tract are the most common cause of CKD in children. Both adult and pediatric patients with CKD are at risk for neurocognitive dysfunction, particularly in the domain of executive function. The exact mechanism for neurocognitive dysfunction in CKD is not known; however, it is conceivable that the multisystemic effects of CKD—including hypertension, acidosis, anemia, proteinuria, and uremic milieu—exert a detrimental effect on the brain. Quantitative neuroimaging modalities, such as magnetic resonance imaging (MRI), provide a non-invasive way to understand the neurobiological underpinnings of cognitive dysfunction in CKD. Adult patients with CKD show differences in brain structure; however, much less is known about the impact of CKD on neurodevelopment in pediatric patients. Herein, this review will summarize current evidence of the impact of CKD on brain structure and function and will identify the critical areas for future research that are needed to better understand the modifiable risk factors for abnormal brain structure and function across both pediatric and adult CKD populations.

The Similarities and Differences Between Glomerular vs. Non-glomerular Diagnoses on Intelligence and Executive Functions in Pediatric Chronic Kidney Disease: A Brief Report

Pediatric chronic kidney disease (CKD) appears to be a heterogeneous group of conditions, but this heterogeneity has not been explored with respect to its impact on neurocognitive functioning. This study investigated the neurocognitive functioning of those with glomerular (G) vs. non-glomerular (NG) diagnoses. Data from the North American CKiD Study were employed and the current study included 1,003 children and adolescents with mild to moderate CKD. The G Group included 260 participants (median age = 14.7 years) and the NG Group included 743 individuals (median age = 9.0 years). Neurocognitive measures assessed IQ, inhibitory control, attention regulation, problem solving, working memory, and overall executive functioning. Data from all visits were included in the linear mixed model analyses. After adjusting for sociodemographic and CKD-related covariates, results indicated no differences between the diagnostic groups on measures of IQ, problem solving, working memory, and attention regulation. There was a trend for the G group to receive better parent ratings on their overall executive functions (p < 0.07), with a small effect size being present. Additionally, there was a significant G group X hypertension interaction (p < 0.003) for inhibitory control, indicating that those with both a G diagnosis and hypertension performed more poorly than the NG group with hypertension. These findings suggest that the separation of G vs. NG CKD produced minimal, but specific group differences were observed. Ongoing examination of the heterogeneity of pediatric CKD on neurocognition, perhaps at a different time point in disease progression or using a different model, appears warranted.

Structural brain abnormalities in children and young adults with severe chronic kidney disease

BACKGROUND

The pathophysiology of neurological dysfunction in severe chronic kidney disease (CKD) in children and young adults is largely unknown. We aimed to investigate brain volumes and white matter integrity in this population and explore brain structure under different treatment modalities.

METHODS

This cross-sectional study includes 24 patients with severe CKD (eGFR < 30) aged 8-30 years (median = 18.5, range = 9.1-30.5) on different therapy modalities (pre-dialysis, n = 7; dialysis, n = 7; transplanted, n = 10) and 21 healthy controls matched for age, sex, and parental educational level. Neuroimaging targeted brain volume using volumetric analysis on T1 scans and white matter integrity with tract-based spatial statistics and voxel-wise regression on diffusion tensor imaging (DTI) data.

RESULTS

CKD patients had lower white matter integrity in a widespread cluster of primarily distal white matter tracts compared to healthy controls. Furthermore, CKD patients had smaller volume of the nucleus accumbens relative to healthy controls, while no evidence was found for abnormal volumes of gray and white matter or other subcortical structures. Longer time since successful transplantation was related to lower white matter integrity. Exploratory analyses comparing treatment subgroups suggest lower white matter integrity and smaller volume of the nucleus accumbens in dialysis and transplanted patients relative to healthy controls.

CONCLUSIONS

Young CKD patients seem at risk for widespread disruption of white matter integrity and to some extent smaller subcortical volume (i.e., nucleus accumbens). Especially patients on dialysis therapy and patients who received a kidney transplant may be at risk for disruption of white matter integrity and smaller volume of the nucleus accumbens.

Functional Magnetic Resonance Imaging Findings in Children and Adolescents With Chronic Kidney Disease: Preliminary Findings

This cross-sectional study provides preliminary findings from one of the first functional brain imaging studies in children with chronic kidney disease (CKD). The sample included 21 children with CKD (ages, 14.4 ± 3.0 y) and 11 healthy controls (ages, 14.5 ± 3.4 y). Using functional magnetic resonance imaging during a visual-spatial working memory task, findings showed that the CKD group and healthy controls invoked similar brain regions for encoding and retrieval phases of the task, but significant group differences were noted in the activation patterns for both components of the task. For the encoding phase, the CKD group showed lower activation in the posterior cingulate, anterior cingulate, precuneus, and middle occipital gyrus than the control group, but more activation in the superior temporal gyrus, middle frontal gyrus, middle temporal gyrus, and the insula. For the retrieval phase, the CKD group showed underactivation for brain systems involving the posterior cingulate, medial frontal gyrus, occipital lobe, and middle temporal gyrus, and greater activation than the healthy controls in the postcentral gyrus. Few group differences were noted with respect to disease severity. These preliminary findings support evidence showing a neurologic basis to the cognitive difficulties evident in pediatric CKD, and lay the foundation for future studies to explore the neural underpinnings for neurocognitive (dys)function in this population.

Decreased Neural Connectivity in the Default Mode Network Among Youth and Young Adults With Chronic Kidney Disease

An increasing amount of literature has indicated that chronic kidney disease (CKD) is associated with cognitive deficits that increase with worsening disease severity. Although abnormalities in brain structure have been widely documented, few studies to date have examined the functioning of brain areas associated with the specific cognitive domains affected by CKD (namely, attention and executive functions). Furthermore, few studies have examined functional connectivity among CKD youth who are relatively early in the course of the disease. The present study used functional magnetic resonance imaging to examine the resting state connectivity in 67 youth with CKD (mean age, 17 y) and 58 age-matched healthy controls. Using seed-based multiple regression, decreased connectivity was observed within the anterior cingulate portion of the default mode network. In addition, decreased connectivity within the dorsolateral prefrontal cortex, paracingulate gyrus, and frontal pole were correlated significantly with disease severity. These data indicate that connectivity deficits in circuits implementing attentional processes may represent an early marker for cognitive decline in CKD.

Kidney damage causally affects the brain cortical structure: A Mendelian randomization study

BACKGROUND

Alterations in the brain cortical structures of patients with chronic kidney disease (CKD) have been reported; however, the cause has not been determined yet. Herein, we used Mendelian randomization (MR) to reveal the causal effect of kidney damage on brain cortical structure.

METHODS

Genome-wide association studies summary data of estimated glomerular filtration rate (eGFR) in 480,698 participants from the CKDGen Consortium were used to identify genetically predicted eGFR. Data from 567,460 individuals from the CKDGen Consortium were used to assess genetically determined CKD; 302,687 participants from the UK Biobank were used to evaluate genetically predicted albuminuria. Further, data from 51,665 patients from the ENIGMA Consortium were used to assess the relationship between genetic predisposition and reduced eGFR, CKD, and progressive albuminuria with alterations in cortical thickness (TH) or surficial area (SA) of the brain. Magnetic resonance imaging was used to measure the SA and TH globally and in 34 functional regions. Inverse-variance weighted was used as the primary estimate whereas MR Pleiotropy RESidual Sum and Outlier, MR-Egger and weighted median were used to detect heterogeneity and pleiotropy.

FINDINGS

At the global level, albuminuria decreased TH (β = -0.07 mm, 95% CI: -0.12 mm to -0.02 mm, P = 0.004); at the functional level, albuminuria reduced TH of pars opercularis gyrus without global weighted (β = -0.11 mm, 95% CI: -0.16 mm to -0.07 mm, P = 3.74×10^-6). No pleiotropy was detected.

INTERPRETATION

Kidney damage causally influences the cortex structure which suggests the existence of a kidney-brain axis.

FUNDING

This study was supported by the Science and Technology Planning Project of Guangdong Province (Grant No. 2020A1515111119 and 2017B020227007), the National Key Research and Development Program of China (Grant No. 2018YFA0902803), the National Natural Science Foundation of China (Grant No. 81825016, 81961128027, 81772719, 81772728), the Key Areas Research and Development Program of Guangdong (Grant No. 2018B010109006), Guangdong Special Support Program (2017TX04R246), Grant KLB09001 from the Key Laboratory of Malignant Tumor Gene Regulation and Target Therapy of Guangdong Higher Education Institutes, and Grants from the Guangdong Science and Technology Department (2020B1212060018).

Neuropathy - Exponent of Accelerated Involution in Uremia: The Role of Carbamylation

Premature loss of functional integrity of the nervous system in chronic renal failure (CRF) as a consequence of persistent biological activities of the general uremic milieu is almost identical to its structural and functional involution during the process of physiological ageing, but disproportionate and independent of chronological age. In the hyperuremic status of CRF (urea - carbamide), forced carbamylation, as a non-enzymatic post-translational modification (NEPTM) of proteins and amino acids, by changing their biological properties and decreasing proteolysis capacity, represents pathogenetic potential of intensified molecular ageing and accelerated, pathological involution. Physiological predisposition and the exposure of neuropathy before complications of other organs and organ systems in CRF, due to the simultaneous and mutually pathogenetically related uremic lesion and the tissue and vascular segment of the nervous system, direct interest towards proteomic analytical techniques of quantification of carbamylated products as biomarkers of uremic neurotoxicity. Hypothetically, identical to the already established applications of other NEPTM products in practice, they have the potential of clinical methodology in the evaluation of uremic neuropathy and its contribution to the general prediction, but also to the change of the conventional CRF classification. In addition, the identification and therapeutic control of the substrate of accelerated involution, responsible for the amplification of not only neurological but also general degenerative processes in CRF, is attractive in the context of the well-known attitude towards aging.

Cognitive Dysfunction and Gait Abnormalities in CKD

BACKGROUND AND OBJECTIVES

Cognitive impairment is a major cause of morbidity in CKD. We hypothesized that gait abnormalities share a common pathogenesis with cognitive dysfunction in CKD, and therefore would be associated with impaired cognitive function in older adults with CKD, and focused on a recently defined gait phenotype linked with CKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Gait assessments and neuropsychological testing were performed in 312 nondisabled, community-dwelling older adults (aged ≥65 years). A subset (n=115) underwent magnetic resonance imaging. The primary cognitive outcome was the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) total scale score. Associations with cognitive function were tested using multivariable linear regression and nearest-neighbor matching. The risk of developing mild cognitive impairment syndrome was assessed using Cox proportional hazards models.

RESULTS

Lower eGFR was associated with lower RBANS score only among participants with the gait phenotype (P for interaction =0.04). Compared with participants with neither CKD nor the gait phenotype, adjusted RBANS scores were 5.4 points (95% confidence interval, 1.8 to 9.1) lower among participants with both, who demonstrated poorer immediate memory, visuospatial ability, delayed memory, and executive function. In a matched analysis limited to participants with CKD, the gait phenotype was similarly associated with lower RBANS scores (-6.9; 95% confidence interval, -12.2 to -1.5). Neuroimaging identified a pattern of gray matter atrophy common to both CKD and the gait phenotype involving brain regions linked with cognition. The gait phenotype was associated with higher risk of mild cognitive impairment (hazard ratio, 3.91; 95% confidence interval, 1.46 to 10.44) independent of eGFR.

CONCLUSIONS

The gait phenotype was associated with poorer function in a number of cognitive domains among older adults with CKD, and was associated with incident mild cognitive impairment independent of eGFR. CKD and the gait phenotype were associated with a shared pattern of gray matter atrophy.

Structural and Functional Brain Changes in Hemodialysis Patients with End-Stage Renal Disease: DTI Analysis Results and ALFF Analysis Results

Introduction

The current study aimed to depict intrinsic structural changes and the spontaneous brain activity patterns in voxel level in patients with end-stage renal disease (ESRD) undergoing hemodialysis (HD) by using diffusion-tensor imaging and resting-state functional magnetic resonance (MR) imaging with an amplitude of low-frequency fluctuations (ALFF) algorithm and their clinical relevance.

Materials and Methods

In the study, the diffusion-tensor imaging and resting-state functional MR imaging were performed in forty-two hemodialysis patients with ESRD and 42 healthy control subjects. Neuropsychological and laboratory tests were performed in all subjects. ALFF, fraction anisotropy (FA), and mean diffusivity (MD) values were compared between the two groups. Correlations between ALFF, FA or MD values, and clinical markers were analyzed.

Results

We found that ESRD patients exhibited significantly lower ALFF values in multiple areas, including medial frontal gyrus, limbic lobe, superior frontal gyrus, bilateral lingual gyri, occipital lobe, parahippocampal gyrus, precuneus, while increased ALFF values in medial frontal gyrus than healthy controls. FA values were decreased in medial frontal gyrus, parietal lobe, and left precuneus regions in the ESRD group compared with controls. Importantly, FA for the frontal and parietal lobes was negatively associated with the dialysis duration of ESRD patients, ALFF z-scores for the medial prefrontal cortex (MPFC) were positively correlated with the dialysis duration of ESRD patients and Serum calcium of ESRD patients negatively correlated with FA values in the frontal and parietal lobes (p<0.05).

Conclusion

Our study revealed that both impaired brain structure and function in ESRD patients with routine hemodialysis distributed mainly in the parietal, temporal, and frontal lobes. ESRD patients have cognitive impairment and declined memory ability. Serum calcium and dialysis duration might be associated with the impairment of brain structure and function in patients with ESRD.

Early pediatric chronic kidney disease is associated with brain volumetric gray matter abnormalities

BACKGROUND

The impact of pediatric chronic kidney disease (pCKD) on the brain remains poorly defined. The objective of this study was to compare brain morphometry between children with early-stage pCKD and typically developing peers using structural magnetic resonance imaging (MRI).

METHODS

The sample age range was 6-16 years. A total of 18 children with a diagnosis of pCKD (CKD stages 1-3) due to congenital anomalies of the kidney and urinary tract and 24 typically developing peers were included. Volumetric data from MRI and neurocognitive testing were compared using linear models including pCKD status, age, maternal education level, and socioeconomic status.

RESULTS

Cerebellar gray matter volume was significantly smaller in pCKD, t₍₃₈₎ = -2.71, p = 0.01. In contrast, cerebral gray matter volume was increased in pCKD, t₍₃₈₎ = 2.08, p = 0.04. Reduced cerebellum gray matter volume was associated with disease severity, operationalized as estimated glomerular filtration rate (eGFR), t₍₁₄₎ = 2.21, p = 0.04 and predicted lower verbal fluency scores in the pCKD sample. Enlarged cerebral gray matter in the pCKD sample predicted lower scores on mathematics assessment.

CONCLUSIONS

This study provides preliminary evidence for a morphometric underpinning to the cognitive deficits observed in pCKD.

IMPACT

The impact of pediatric chronic kidney disease (CKD) on the brain remains poorly defined, with no data linking brain morphometry and observed cognitive deficits noted in this population. We explored the relationship between brain morphometry (using structural magnetic resonance imaging), cognition, and markers of CKD. Cerebellar and cerebral gray matter volumes are different in early CKD. Volumetric decreases in cerebellar gray matter are predicted by lower eGFR, suggesting a link between disease and brain morphometry. Reduced cerebellar gray matter predicted lower verbal fluency for those with pCKD. Enlarged cerebral gray matter in the pCKD sample predicted lower mathematics performance.

Intradialytic hypotension and relationship with cognitive function and brain morphometry

Background

The haemodynamic stress brought about by dialysis could justify the loss of structural and functional integrity of the central nervous system (CNS). The main objective of this study was to analyse the relationship between intradialytic hypotension (IDH) and cognitive function and brain morphometry.

Methods

The cross-sectional KIDBRAIN study (Cohort Study of Morphological Changes of the Brain by MRI in Chronic Kidney Disease Patients) included 68 prevalent patients with no history of neurological disorders (cerebrovascular disease and cognitive impairment) undergoing haemodialysis (HD). We analysed 18 non-consecutive dialysis sessions (first three of each month over a 6-month period) and various definitions of IDH were recorded. Global cognitive function (GCF) was assessed using the Mini-Mental State Examination (MMSE) and parameters of structural integrity of the CNS were obtained using volume morphometry magnetic resonance imaging analysis [grey matter (GM), white matter (WM) and hippocampus).

Results

A greater number of sessions with IDH were associated with less volume of WM (r = −0.359,P = 0.003) and hippocampus (r = −0.395, P = 0.001) independent of cardiovascular risk factors according to multivariable linear regression models (β = −0.198, P = 0.046 for WM; β = −0.253, P = 0.017 for hippocampus). The GCF by the MMSE was 27.3 ± 7.3.1 and was associated with WM volume (β = 0.403, P = 0.001) independent of GM and hippocampus volume. Symptomatic IDH was associated with GCF (r = −0.420, P < 0.001) in adjusted analysis (β = −0.339, P = 0.008).

Conclusions

Even when asymptomatic, IDH is associated with a lower WM and hippocampus volume and reduced GCF in patients undergoing HD, thus suggesting greater vulnerability of the brain to the haemodynamic stress that may be generated by a dialysis session.

The brain in pediatric chronic kidney disease-the intersection of cognition, neuroimaging, and clinical biomarkers

Brain growth and development occur at peak rates in early childhood through adolescence, and for some children, this must happen in conjunction with chronic kidney disease (CKD), associated medical conditions, and their treatment(s). This review provides an overview of key findings to date on the topic of the brain in pediatric CKD. Here, we specifically address the topics of neuroimaging and cognition in pediatric CKD with consideration to biomarkers of disease progression that may impact cognition. Current cognitive data suggest that most children with mild to moderate CKD do not exhibit significant cognitive impairments, but, rather, the presence of somewhat lower intellectual abilities and subtle deficits in selected executive functions. Although promising, modern neuroimaging data remain inconclusive in linking cognitive findings to neuroimaging correlates in the pediatric CKD population. Certainly, it is important to note that even subtle cognitive concerns can present barriers to learning, social functioning, and overall quality of life if not appropriately recognized or addressed. Further longitudinal research utilizing concurrent and targeted cognitive and neuroimaging evaluations is warranted to better understand the impact of CKD progression on brain development and associated neurocognitive outcomes.

Kidney Function and Cognitive Decline in Older Adults: Examining the Role of Neurodegeneration

BACKGROUND/OBJECTIVES

Cognitive decline associated with impaired kidney function might involve neurodegeneration. Our objectives were to evaluate the longitudinal association between kidney function and cognitive decline in older adults and to assess the involvement of cortical beta-amyloid and hippocampal atrophy (features of Alzheimer's disease (AD)) in this association.

DESIGN

Secondary analysis of the randomized controlled Multidomain Alzheimer Preventive Trial (MAPT).

SETTINGS

Thirteen memory centers (France and Monaco, 2008-2016).

PARTICIPANTS

A total of 1,334 community-dwellers >70 years old without dementia at baseline.

MEASUREMENTS

We estimated glomerular filtration rate (eGFR) from serum creatinine using CKD-Epi equation. Cognition was assessed at baseline, 6, 12, 24, 36, 48, and 60 months using a composite Z-score designed for MAPT. The Clinical Dementia Rating (CDR) score was used to assess cognition and functional independence. We examined the association between eGFR and (1) evolution of the composite cognitive Z-score using mixed-effect models and (2) progression on CDR using Cox models and mixed-effect models. Adjustments were made for age, sex, education, ApoE genotype, cardiovascular risk factors and disease, hippocampal volume (measured with magnetic resonance), and cortical beta-amyloid (measured with positron emission tomography).

RESULTS

Median (IQR) eGFR was 73(60-84) mL/min/1.73 m² . Two hundred sixty-nine participants experienced progression on CDR score during follow-up. eGFR<60 was significantly associated with progression on CDR score (adjusted hazard ratio (aHR) = 1.35, 95% CI 1.01-1.80) and with both the cognitive and functional independence components of CDR, but not with the evolution of the composite cognitive Z-score (adjusted β-coefficient -0.004, 95% CI -0.014; 0.006). Associations were not modified after further adjustment for beta-amyloid (subsample: n = 252) and hippocampal volume (subsample: n = 270).

CONCLUSIONS

We did not find a mild to moderate renal insufficiency to be associated with brain imaging features of AD, and our results do not support the involvement of AD mechanisms in the incidence of cognitive impairment and functional decline associated with chronic kidney disease.

Increased history of ischemic stroke and decreased neurocognitive performance in children with chronic kidney disease

BACKGROUND

This study aimed to determine stroke incidence and assess the association between stroke and neurocognitive functioning in children with chronic kidney disease (CKD).

METHODS

Data was derived from the Chronic Kidney Disease in Children (CKiD) cohort study. Stroke incidence was calculated after confirming self-reports of stroke occurrence by chart review. Each participant with stroke was matched with three stroke-free participants and performance on selected neurocognitive measures was compared. Wilcoxon rank-sum tests were used to compare neurocognitive test scores. Effect size (ES) was estimated using a modified version of Cohen's U₃ metric that measures the excess percentage of the stroke group worse than the median of the control group.

RESULTS

Of 891 subjects, five (0.56%) had a confirmed stroke prior to study entry. Median time at risk was 15.7 years [interquartile range, 12.5-18.4]. Estimated incidence rate of history of stroke was 36.8 per 100,000 children per year (95% confidence interval 15.3, 88.5). Controls and subjects with stroke were similar in age, CKD duration, race, and maternal education. ES for many of the neurocognitive comparisons was moderate to large. Subjects in the CKID cohort with a history of stroke had lower scores on spatial span reverse, spatial span forward, and design fluency, and worse parent ratings on BRIEF Metacognition Index compared to a matched sample of children with CKD without stroke.

CONCLUSIONS

Children with CKD have an increased incidence of prior ischemic stroke compared to the general pediatric population. A stroke history was associated with poorer performance on neurocognitive measures. Graphical abstract.

Patterns and characteristics of cognitive functioning in older patients approaching end stage kidney disease, the COPE-study

BACKGROUND

The prevalence of impaired cognitive functioning in older patients with end stage kidney disease (ESKD) is high. We aim to describe patterns of memory, executive function or psychomotor speed and to identify nephrologic, geriatric and neuroradiologic characteristics associated with cognitive impairment in older patients approaching ESKD who have not yet started with renal replacement therapy (RRT).

METHODS

The COPE-study (Cognitive Decline in Older Patients with ESRD) is a prospective cohort study including 157 participants aged 65 years and older approaching ESKD (eGFR ≤20 ml/min/1.73 m²) prior to starting with RRT. In addition to routinely collected clinical parameters related to ESKD, such as vascular disease burden and parameters of metabolic disturbance, patients received a full geriatric assessment, including extensive neuropsychological testing. In a subgroup of patients (n = 93) a brain MRI was performed.

RESULTS

The median age was 75.3 years. Compared to the normative data of neuropsychological testing participants memory performance was in the 24th percentile, executive function in the 18th percentile and psychomotor speed in the 20th percentile. Independent associated characteristics of impairment in memory, executive and psychomotor speed were high age, low educational level and low functional status (all p-values < 0.003). A history of vascular disease (p = 0.007) and more white matter hyperintensities on brain MRI (p = 0.013) were associated with a lower psychomotor speed.

CONCLUSION

Older patients approaching ESKD have a high prevalence of impaired memory, executive function and psychomotor speed. The patterns of cognitive impairment and brain changes on MRI are suggestive of vascular cognitive impairment. These findings could be of potentially added value in the decision-making process concerning patients with ESKD.

Risk Behaviors in Teens with Chronic Kidney Disease: A Study from the Midwest Pediatric Nephrology Consortium

Introduction

There is a paucity of information about risk behaviors in adolescents with chronic kidney disease (CKD). We designed this study to assess the prevalence of risk behaviors among teens with CKD in the United States and to investigate any associations between risk behavior and patient or disease characteristics.

Methods

After informed consent, adolescents with CKD completed an anonymous, confidential, electronic web-based questionnaire to measure risk behaviors within five domains: sex, teen driving, alcohol and tobacco consumption, illicit drug use, and depression-related risk behavior. The reference group was composed of age-, gender-, and race-matched US high school students.

Results

When compared with controls, teens with CKD showed significantly lower prevalence of risk behaviors, except for similar use of alcohol or illicit substances during sex (22.5% vs. 20.8%, p=0.71), feeling depressed for ≥2 weeks (24.3% vs. 29.1%, p=0.07), and suicide attempt resulting in injury needing medical attention (36.4% vs. 32.5%, p=0.78). Furthermore, the CKD group had low risk perception of cigarettes (28%), alcohol (34%), marijuana (50%), and illicit prescription drug (28%). Use of two or more substances was significantly associated with depression and suicidal attempts (p < 0.05) among teens with CKD.

Conclusions

Teens with CKD showed significantly lower prevalence of risk behaviors than controls. Certain patient characteristics were associated with increased risk behaviors among the CKD group. These data are somewhat reassuring, but children with CKD still need routine assessment of and counselling about risk behaviors.

A Low Ankle-Brachial Index and High Brachial-Ankle Pulse Wave Velocity Are Associated with Poor Cognitive Function in Patients Undergoing Hemodialysis

Patients with end-stage renal disease (ESRD) have an increased risk of both impaired cognitive function and peripheral artery disease (PAD) than the general population. The association between PAD and dementia is recognized, but there are limited studies in patients with ESRD. The aim of this study was to evaluate the relationship between ankle-brachial index (ABI) and brachial-ankle pulse wave velocity (baPWV) and cognitive impairment in patients receiving hemodialysis (HD). We enrolled 136 prevalent HD patients (mean age 59.3 ± 10.5 years, 55.9% male). Cognitive performance was measured using the Montreal Cognitive Assessment (MoCA) and Cognitive Abilities Screening Instrument (CASI) by trained psychiatrists. Associations between the cognitive function and ABI and baPWV were assessed using multiple linear regression analysis. Compared with HD patients with ABI ≥ 0.9, patients with ABI < 0.9 had lower MoCA score (p = 0.027) and lower CASI score but did not achieve significant level (p = 0.056). In the multivariate stepwise linear regression analysis, ABI (per 0.1) was independently positively associated with the MoCA score (β coefficient = 0.62, p = 0.011) and the CASI score (β coefficient = 1.43, p = 0.026). There is a negative association between baPWV (per 100 cm/s) and CASI (β coefficient = −0.70, p = 0.009). In conclusion, a low ABI or high baPWV was associated with a lower cognitive function in HD patients.

Neurocognitive and functional outcomes at 5 years of age after renal transplant in early childhood

BACKGROUND

Clinicians often use information about developmental outcomes in decision-making around offering complex, life-saving interventions in children such as dialysis and renal transplant. This information in children with end-stage renal disease (ESRD) is limited, particularly when ESRD onset is in infancy or early childhood.

METHODS

Using data from an ongoing prospective, longitudinal, inception cohort study of children with renal transplant before 5 years of age, we evaluated (1) the risk of adverse neurocognitive and functional outcomes at 5 years of age and (2) predictors of developmental outcomes.

RESULTS

We found evidence of neurocognitive sequelae of ESRD in very young children; however, developmental outcomes appear remarkably better when compared with findings of two or three decades ago. Less time on dialysis predicted higher developmental scores, and hemodialysis was associated with poorer developmental outcomes.

CONCLUSIONS

Our data suggest that renal replacement therapies in young children are associated with acceptable developmental outcome. Programs to identify those with developmental delays and provide early intervention may allow achievement of the child's full potential.

Brain abnormalities in children and adolescents with chronic kidney disease

BACKGROUND

Chronic kidney disease (CKD) is a risk factor for vascular disease and stroke. The spectrum of brain injury and microstructural white matter abnormalities in children with CKD is largely unknown.

METHODS

Cross sectional study at two North American pediatric hospitals. A cohort of 49 children, 29 with CKD, including renal transplant (mean age 14.4 ± 2.9 years; range 9-18), and 20 healthy controls (mean age 13.7 ± 3.1 years; range 9-18) had their conventional brain magnetic resonance images (MRIs) reviewed by one neuroradiologist to determine the prevalence of brain injury. Fractional anisotropy (FA) maps calculated from diffusion tensor imaging (DTI) were generated to compare white matter microstructure in CKD compared to controls, using tract-based spatial statistics (TBSS).

RESULTS

Focal and multifocal white matter injury was seen on brain MRI in 6 children with CKD (21%). Relative to controls, CKD subjects showed reduced white matter fractional anisotropy and increased mean diffusivity and radial diffusivity in the anterior limb of the internal capsule, suggestive of abnormal myelination.

CONCLUSION

Cerebral white matter abnormalities, including white matter injury, are under-recognized in pediatric CKD patients. Brain imaging studies through progression of CKD are needed to determine the timing of white matter injury and any potentially modifiable risk factors.

The Impact of Uremic Toxins on Cerebrovascular and Cognitive Disorders

Individuals at all stages of chronic kidney disease (CKD) have a higher risk of developing cognitive disorders and dementia. Stroke is also highly prevalent in this population and is associated with a higher risk of neurological deterioration, in-hospital mortality, and poor functional outcomes. Evidence from in vitro studies and in vivo animal experiments suggests that accumulation of uremic toxins may contribute to the pathogenesis of stroke and amplify vascular damage, leading to cognitive disorders and dementia. This review summarizes current evidence on the mechanisms by which uremic toxins may favour the occurrence of cerebrovascular diseases and neurological complications in CKD.

Regional Cerebral Blood Flow in Children and Young Adults with Chronic Kidney Disease

Purpose To investigate the pathophysiologic effects of chronic kidney disease (CKD) on brain function in children with CKD by correlating cerebral blood flow (CBF) with clinical and behavioral indexes. Materials and Methods In this prospective study, 73 pediatric patients with CKD (mean age, 15.80 years ± 3.63; range, 9-25 years) and 57 control subjects (mean age, 15.65 years ± 3.76; range, 9-25 years) were recruited. CBF measurements were acquired with an MRI arterial spin labeling scheme. Neurocognitive measurements were performed with traditional and computerized neurocognitive batteries. Clinical data were also collected. Group-level global and regional CBF differences between patients with CKD and control subjects were assessed. Regression analyses were conducted to evaluate the associations among regional CBF, clinical variables, and cognitive performance. Results Patients with CKD showed higher global CBF compared with control subjects that was attributable to reduced hematocrit level (mean, 60.2 mL/100 g/min ± 9.0 vs 56.5 mL/100 g/min ± 8.0, respectively). White matter CBF showed correlation with blood pressure (r = 0.244, P = .039), a finding suggestive of altered cerebrovascular autoregulation. Regional CBF differences between patients and control subjects included regions in the "default mode" network. In patients with CKD, positive extrema in the precuneus showed a strong correlation with executive function (ρ = 0.608, P = .001). Conclusion Systemic effects of estimated glomerular filtration rate, hematocrit level, and blood pressure on CBF and alterations in regional CBF may reflect impaired brain function underlying neurocognitive symptoms in CKD. These findings further characterize the nature of alterations in brain physiologic features in children, adolescents, and young adults with CKD.

Effect of blood T1 estimation strategy on arterial spin labeled cerebral blood flow quantification in children and young adults with kidney disease

PURPOSE

To compare blood T1 estimation approaches used for quantifying cerebral blood flow (CBF) with arterial spin labeled (ASL) perfusion MRI in a developmental cohort of chronic kidney disease (CKD) patients with anemia and a control group.

METHODS

61 patients with CKD and 47 age-matched control subjects were studied. Blood T1 approaches included: (1) a fixed value, (2) estimation based on measured hematocrit (Hct), and (3) estimation based on Age+Sex using a published formula. Resulting T1 and CBF values were compared along with group, age and sex effects.

RESULTS

Highly significant group differences in CBF using fixed blood T1 were reduced when Hct-corrected blood T1 was used, and were eliminated entirely when using the Age+Sex estimated approach. In the control cohort, fixed T1 method showed the strongest correlations of CBF with age and sex. Hct-corrected T1 preserved a significant correlation between CBF and age and sex, while Age+Sex estimated T1 produced a poor fit of CBF with age and sex.

CONCLUSIONS

Blood T1 estimation method can confound the interpretation of CBF changes measured using ASL MRI in patients with CKD. Blood T1 should ideally be corrected for hematocrit effects in clinical populations with anemia.

Association of Kidney Function Biomarkers with Brain MRI Findings: The BRINK Study

BACKGROUND

Chronic kidney disease (CKD) studies have reported variable prevalence of brain pathologies, in part due to low inclusion of participants with moderate to severe CKD.

OBJECTIVE

To measure the association between kidney function biomarkers and brain MRI findings in CKD.

METHODS

In the BRINK (BRain IN Kidney Disease) study, MRI was used to measure gray matter volumes, cerebrovascular pathologies (white matter hyperintensity (WMH), infarctions, microhemorrhages), and microstructural changes using diffusion tensor imaging (DTI). We performed regression analyses with estimated glomerular filtration rate (eGFR) and urine albumin to creatinine ratio (UACR) as primary predictors, and joint models that included both predictors, adjusted for vascular risk factors.

RESULTS

We obtained 240 baseline MRI scans (150 CKD with eGFR <45 in ml/min/1.73 m2; 16 mild CKD: eGFR 45-59; 74 controls: eGFR≥60). Lower eGFR was associated with greater WMH burden, increased odds of cortical infarctions, and worsening diffusion changes throughout the brain. In eGFR models adjusted for UACR, only cortical infarction associations persisted. However, after adjusting for eGFR, higher UACR provided additional information related to temporal lobe atrophy, increased WMH, and whole brain microstructural changes as measured by increased DTI mean diffusivity.

CONCLUSIONS

Biomarkers of kidney disease (eGFR and UACR) were associated with MRI brain changes, even after accounting for vascular risk factors. UACR adds unique additional information to eGFR regarding brain structural and diffusion biomarkers. There was a greater impact of kidney function biomarkers on cerebrovascular pathologies and microstructural brain changes, suggesting that cerebrovascular etiology may be the primary driver of cognitive impairment in CKD.

Brain Magnetic Resonance Imaging Findings in Children and Young Adults With CKD

BACKGROUND

The neuroanatomic basis for cognitive impairment in chronic kidney disease (CKD) is incompletely characterized. We performed advanced quantitative structural magnetic resonance imaging (MRI) to determine whether CKD affects brain structure and whether poorer neurocognitive performance in CKD is associated with structural brain differences.

STUDY DESIGN

Cross-sectional.

SETTING & PARTICIPANTS

85 individuals with CKD stages 2 to 5 and 63 healthy controls, aged 8 to 25 years PREDICTORS: CKD versus control, estimated glomerular filtration rate (eGFR), and kidney transplant status were analyzed as predictors of MRI findings. MRI volumes in 19 prespecified regions of gray matter (GM), white matter (WM), and cerebrospinal fluid were analyzed as predictors of neurocognitive performance (median z scores) in 7 prespecified domains.

OUTCOMES

19 prespecified brain regions of interest (ROIs) in 7 prespecified domains. Neurocognitive performance in 7 prespecified domains.

MEASUREMENTS

ROI volumes were compared in CKD versus controls using unadjusted t tests and analysis of covariance (ANCOVA). Associations of ROI volumes with eGFR and kidney transplant status in participants with CKD were analyzed using ANCOVA and linear regression. Associations of neurocognitive performance and ROI volumes were analyzed by linear regression.

RESULTS

Participants with CKD had lower whole-brain, cortical, and left parietal GM volumes than controls in unadjusted analyses, but no differences were found in adjusted analysis. In participants with CKD, lower eGFR was associated with higher WM volume in whole-brain (P=0.05) and frontal (P=0.04) ROIs, but differences were not significant after multiple comparisons correction. Kidney transplant recipients had lower GM volumes in whole-brain (P=0.01; Q=0.06), frontal (P=0.02; Q=0.08), and left and right parietal (P=0.01; Q=0.06; and P=0.03; Q=0.1) ROIs and higher whole-brain WM volume (P=0.04; Q=0.1). Neurocognitive performance in the CKD group was not associated with ROI volumes.

LIMITATIONS

Unable to assess changes in brain structure and kidney function over time; analysis limited to prespecified ROIs and neurocognitive domains.

CONCLUSIONS

CKD in children and young adults may be associated with lower GM and higher WM volumes in some ROIs. Differences were relatively subtle in the CKD group as a whole, but were more prominent in recipients of a kidney transplant. However, neurocognitive performance was not explained by differences in brain ROI volumes, suggesting a functional rather than structural basis for neurocognitive impairment in CKD.

Reduced estimated glomerular filtration rate is associated with depressive symptoms in elder Chinese: A population-based cross-sectional study

Depression has been associated with chronic kidney disease (CKD). However, few studies have examined whether such association exist in average older individuals with mild to moderate reduced kidney function. This study investigated the association between reduced estimated glomerular filtration rate (eGFR) and depressive symptoms in Chinese older population. Data was obtained from the Rugao Longevity and Ageing Study conducted in Jiangsu, China. Cockcroft-Gault (CG) equation was used to calculate eGFR. Depressive symptoms were defined by using Chinese version of 15-item Geriatric Depression Scale (GDS-15). The prevalence of depressive symptoms was 9.9% among 1749 elderly participants aged 70-84 years. Many elderly had a mild to moderate reduced renal function (84.3%, 57.1% in stage2 CKD and 27.2% in stage3 CKD, respectively). The overall GDS-15 score showed an upward trend with decreasing of eGFR (p < 0.05). Furthermore, a moderate decline of eGFR (in stage3 CKD) was significantly associated with increased risk of depressive symptoms even after adjusting for confounders (OR = 1.71, 95%CI 1.05-2.77, P = 0.03). Elder had no depressive symptoms if their eGFR was normal or mildly reduced. Our results suggest that a moderate decrease of eGFR (stage3 CKD) was independently associated with depressive symptoms in general Chinese elderly.

Cognitive impairment and hippocampal atrophy in chronic kidney disease

BACKGROUND

Cognition impairment is well known in patients with chronic kidney disease (CKD). The relationship between brain structure and cognitive performance in CKD patients is still under investigation. The study aimed to quantitatively assess the relationship between brain structure and cognitive performance in patients with CKD.

METHODS

We recruited 39 patients with CKD and 39 age- and sex-matched control participants from a tertiary medical center. All participants underwent 3-T MRI scan neuropsychological assessments, and renal function tests. FreeSurfer software was used for imaging processing and analysis, including measurement of cortical thickness and gray matter (GM) and white matter volumes.

RESULTS

Compared with control subjects (73.1±7.5 years old), patients with CKD (76.4±8.4 years old) had significantly lower scores on the Mini-Mental State Examination, and forward digit span test (P<.01). Patients with CKD had smaller cerebral GM volume, hippocampus, and decreased cortical thickness (P<.01) relative to the control group. Estimated glomerular filtration rate (eGFR) was correlated with cognitive performance, cortical thickness, GM volume, and hippocampal volume (P<.001). Linear regression analysis revealed that eGFR and GM volume were independently negatively associated with cognitive performance (P<.001), while eGFR and age were negatively associated with cortical thinning and GM volume after controlling for confounding factors.

CONCLUSIONS

This study demonstrated that impaired kidney function is associated not only with poor cognitive performance, but also with small cerebral GM volume and reduced cortical thickness.

Cognitive remediation in pediatric chronic kidney disease and end-stage kidney disease: rationale, candidate interventions, and applicability

The purpose of this paper is to address the potential use of cognitive remediation interventions for children and adolescents with chronic kidney disease (CKD) and end-stage kidney disease (ESKD). The prevalence and risk for neurocognitive dysfunction in children with this condition remains high, but, to date, interventions targeting these challenges have not been attempted either individually or as part of a larger treatment program. This is the next logical step in addressing the neurocognitive dysfunction that can be present in pediatric CKD/ESKD, with the field needing to determine the efficacy of cognitive remediation approaches for this population. To our knowledge, this paper is the first to raise this possibility by identifying candidate treatments addressing the neurocognitive challenges observed in children and adolescents with CKD/ESKD. Initially, we present the rationale for the importance of addressing the cognitive difficulties in this population, including an overview of the literature documenting the neurocognitive deficits associated with pediatric-onset CKD/ESKD. This is followed by a review of five candidate cognitive remediation programs that may be applicable to patients with this condition, and associated factors that could affect such treatment. The paper concludes with suggestions for both clinical and research initiatives that could be implemented to examine cognitive remediation as potential components of a larger treatment program for children and adolescents with CKD/ESKD.

Attention and memory impairments in pediatric patients with cystic fibrosis and inflammatory bowel disease in comparison to healthy controls

The main aim of the study was to analyze and compare attention and memory performance in pediatric patients with cystic fibrosis (CF), inflammatory bowel disease (IBD) and in healthy controls. 28 patients with CF, 30 patients with IBD and 30 healthy subjects took part in the study (all in age range of 7–17). All subjects were in intellectual norm. To analyze the functioning of attention, the d2 Test of Attention by Brickenkamp (d2 test) was applied. Memory performance was assessed using the Benton Visual Retention Test (BVRT) and the Trial of 10 words. The CF and IBD groups committed significantly more errors in the d2 test than the healthy controls. The CF group also had significantly higher fluctuation rates and received significantly lower scores in overall concentration performance than the control group. Patients with CF made more mistakes and had fewer correct memory projections in BVRT than the healthy controls. Patients with IBD committed significantly more errors in BVRT than the control group. Patients with CF and IBD also got significantly lower scores in the Trial of 10 words than the control group. Pediatric patients with CF and IBD performed more poorly than the healthy controls on attention and memory tests. More distinct cognitive impairments were observed in the CF group. Further research is needed to find the underlying mechanisms and clinical and/or functional significance of observed cognitive deficits.

Associations of Early Kidney Disease With Brain Magnetic Resonance Imaging and Cognitive Function in African Americans With Type 2 Diabetes Mellitus

BACKGROUND

Relationships between early kidney disease, neurocognitive function, and brain anatomy are poorly defined in African Americans with type 2 diabetes mellitus (T2DM).

STUDY DESIGN

Cross-sectional associations were assessed between cerebral anatomy and cognitive performance with estimated glomerular filtration rate (eGFR) and urine albumin-creatinine ratio (UACR) in African Americans with T2DM.

SETTING & PARTICIPANTS

African Americans with cognitive testing and cerebral magnetic resonance imaging (MRI) in the African American-Diabetes Heart Study Memory in Diabetes (AA-DHS MIND; n=512; 480 with MRI) and Action to Control Cardiovascular Risk in Diabetes (ACCORD) MIND (n=484; 104 with MRI) studies.

PREDICTORS

eGFR (CKD-EPI creatinine equation), spot UACR.

MEASUREMENTS

MRI-based cerebral white matter volume (WMV), gray matter volume (GMV), and white matter lesion volume; cognitive performance (Mini-Mental State Examination, Digit Symbol Coding, Stroop Test, and Rey Auditory Verbal Learning Test). Multivariable models adjusted for age, sex, body mass index, scanner, intracranial volume, education, diabetes duration, hemoglobin A_1c concentration, low-density lipoprotein cholesterol concentration, smoking, hypertension, and cardiovascular disease were used to test for associations between kidney phenotypes and the brain in each study; a meta-analysis was performed.

RESULTS

Mean participant age was 60.1±7.9 (SD) years; diabetes duration, 12.1±7.7 years; hemoglobin A_1c concentration, 8.3%±1.7%; eGFR, 88.7±21.6mL/min/1.73m²; and UACR, 119.2±336.4mg/g. In the fully adjusted meta-analysis, higher GMV associated with lower UACR (P<0.05), with a trend toward association with higher eGFR. Higher white matter lesion volume was associated with higher UACR (P<0.05) and lower eGFR (P<0.001). WMV was not associated with either kidney parameter. Higher UACR was associated with lower Digit Symbol Coding performance (P<0.001) and a trend toward association with higher Stroop interference; eGFR was not associated with cognitive tests.

LIMITATIONS

Cross-sectional; single UACR measurement.

CONCLUSIONS

In African Americans with T2DM, mildly high UACR and mildly low eGFR were associated with smaller GMV and increased white matter lesion volume. UACR was associated with poorer processing speed and working memory.

Effect of Kidney Dysfunction on Cerebral Cortical Thinning in Elderly Population

Chronic kidney disease has been linked to cognitive impairment and morphological brain change. However, less is known about the impact of kidney functions on cerebral cortical thickness. This study investigated the relationship between kidney functions and global or lobar cerebral cortical thickness (CTh) in 259 non-demented elderly persons. Forty-three participants (16.7%) had kidney dysfunction, which was defined as either a glomerular filtration rate (GFR) of <60 ml/min/1.73 m² or presence of proteinuria. Kidney dysfunction was associated with lower global (β = −0.05, 95% CI = −0.08 to −0.01) as well as frontal, parietal, temporal, occipital, and insular lobar CTh. In the stratified analysis, the associations were more pronounced in women, APOEε4 non-carriers, and participants with a lower cognitive score. Besides, kidney dysfunction significantly increased the risk of cortical thinning, defined as being the lowest CTh tertile, in the insular lobe (adjusted odds ratio = 2.74, 95% CI = 1.31−5.74). Our results suggested that kidney dysfunction should be closely monitored and managed in elderly population to prevent neurodegeneration.

The systemic nature of CKD

The accurate definition and staging of chronic kidney disease (CKD) is one of the major achievements of modern nephrology. Intensive research is now being undertaken to unravel the risk factors and pathophysiologic underpinnings of this disease. In particular, the relationships between the kidney and other organs have been comprehensively investigated in experimental and clinical studies in the last two decades. Owing to technological and analytical limitations, these links have been studied with a reductionist approach focusing on two organs at a time, such as the heart and the kidney or the bone and the kidney. Here, we discuss studies that highlight the complex and systemic nature of CKD. Energy balance, innate immunity and neuroendocrine signalling are highly integrated biological phenomena. The diseased kidney disrupts such integration and generates a high-risk phenotype with a clinical profile encompassing inflammation, protein-energy wasting, altered function of the autonomic and central nervous systems and cardiopulmonary, vascular and bone diseases. A systems biology approach to CKD using omics techniques will hopefully enable in-depth study of the pathophysiology of this systemic disease, and has the potential to unravel critical pathways that can be targeted for CKD prevention and therapy.

Related Factors and Predictors of Cognitive Dysfunction in Chronic Kidney Disease on Maintenance Hemodialysis in Nigeria

Background:

Previous studies suggest a high frequency of cognitive impairment (CI) in persons with chronic kidney disease (CKD); however, factors associated with CI and predictors of CI in persons with CKD remain largely unclear. The aim of this study was to determine the factors associated with CI and predictors of CI in CKD patients on maintenance hemodialysis.

Materials and Methods:

The first stage of the study included recruitment of 100 apparently healthy participants aimed at determining the reference values. The second stage of the study included eighty CKD patients on maintenance hemodialysis. The iron psychology (FEPSY) was used to assess the memory, psychomotor speed, concentration, and attention using simple auditory reaction time (ART) and visual reaction time (VRT) tasks, recognition memory tests (RMT), finger tapping task (FTT), and binary choice task (BCT).

Results:

Using normative values generated in this study, 41 (51.3%) and 43 (53.8%) CKD patients had abnormal scores on ART dominant (D) and nondominant (ND) sides, respectively. Forty (50%) and 42 (52.5%) patients had abnormal scores on VRT D and ND sides, respectively. Twenty-one (26.3%) and 68 (85%) had abnormal scores on BCT and computer-assisted visual scanning task, respectively. Sixty-four (80%) and 65 (81.3%) had abnormal scores on RMT (words) and RMT, respectively. Fifty-two (65%) and 48 (60%) patients had abnormal scores on D and ND sides of (FTT), respectively. Factors associated with psychomotor speed impairment were duration of CKD from diagnosis (P = 0.0001 and 0.043 in D and ND ART, respectively), duration on dialysis (P = 0.0001 across board in D and ND ART as well as in D and ND VRT, respectively), and plasma urea (PU) and plasma creatinine (PCr) (P < 0.05). Factors found to be associated with memory impairment included age (P = 0.045 and 0.025 on words and figures RMT, respectively), PU (P = 0.002 and 0.005 on words and figures RMT, respectively), and PCr (P = 0.012 and 0.040 on words and figures RMT, respectively). Duration on dialysis (P = 0.032) and PCr (P = 0.001) were associated with attention and concentration. Only psychomotor speed was independently predicted by duration of CKD.

Conclusion:

Factors associated with psychomotor speed impairment were duration of CKD, duration on dialysis, and PU and PCr while age, PU, and PCr were associated with memory. Duration on dialysis and PCr were associated with attention and concentration. Only psychomotor speed was independently predicted by duration of CKD.

Brain-kidney cross-talk: Definition and emerging evidence

Cross-talk is broadly defined as endogenous homeostatic signaling between vital organs such as the heart, kidneys and brain. Kidney-brain cross-talk remains an area with excitingly few publications despite its purported clinical relevance in the management of currently undertreated conditions such as resistant hypertension. Therefore, this review aims to establish an organ-specific definition for kidney-brain cross-talk and review the available and forthcoming literature on this topic.

An Evidence-Based Approach to Conducting Systematic Reviews on CKD

With the growing need to integrate best evidence to inform clinical care, systematic reviews have continued to flourish. Although this type of review is integral to the synthesis of evidence-based information, systematic reviews are often conducted omitting well-established processes that ensure the validity and replicability of the study; elements of which are integral based on standards developed by the Cochrane Collaboration and the National Academy of Medicine. This review article will share best practices associated with conducting systematic reviews on the topic of CKD using an 8-step process and an evidence-based approach to retrieving and abstracting data. Optimal methods for conducting systematic review searching will be described, including development of appropriate search strategies and utilization of varied resources including databases, grey literature, primary journals, and handsearching. Processes and tools to improve research teams' coordination and efficiency, including integration of systematic review protocols and sophisticated software to streamline data management, will be investigated. In addition to recommended strategies for surveying and synthesizing CKD literature, techniques for maneuvering the complex field of Nephrology will also be explored.

Cognitive Changes in Chronic Kidney Disease and After Transplantation

Cognitive impairment is very common in chronic kidney disease (CKD) and is strongly associated with increased mortality. This review article will discuss the pathophysiology of cognitive impairment in CKD, as well as the effect of dialysis and transplantation on cognitive function. In CKD, uremic toxins, hyperparathyroidism and Klotho deficiency lead to chronic inflammation, endothelial dysfunction and vascular calcifications. This results in an increased burden of cerebrovascular disease in CKD patients, who consistently have more white matter hyperintensities, microbleeds, microinfarctions and cerebral atrophy on magnetic resonance imaging scans. Hemodialysis, although beneficial in terms of uremic toxin clearance, also contributes to cognitive decline by causing rapid fluid and osmotic shifts. Decreasing the dialysate temperature and increasing total dialysis time limits these shifts and helps maintain cognitive function in hemodialysis patients. For many patients, kidney transplantation is the preferred treatment modality, because it reverses the underlying mechanisms causing cognitive impairment in CKD. These positive effects have to be balanced against the possible neurotoxicity of infections and immunosuppressive medications, especially glucocorticosteroids and calcineurin inhibitors. A limited number of studies have addressed the overall effect of transplantation on cognitive function. These have mostly found an improvement after transplantation, but have a limited applicability to daily practice because they have only included relatively young patients.

Lifestyle and Self-Management by Those Who Live It: Patients Engaging Patients in a Chronic Disease Model

BACKGROUND

Patients pursuing organ transplantation have complex medical needs, undergo comprehensive evaluation for possible listing, and require extensive education. However, transplant patients and their supports frequently report the need for more lifestyle and self-management strategies for living with organ transplantation.

OBJECTIVES

First, to explore feasibility of a successful, patient-run transplant lifestyle educational group (Transplant Living Community), designed to complement medical care and integrated into the clinical setting; and second, to report the major themes of patients' and supports' qualitative and quantitative feedback regarding the group.

METHODS

Informal programmatic review and patient satisfaction surveys.

RESULTS

A total of 1862 patient satisfaction surveys were disseminated and 823 were returned (response rate, 44.2%). Patients and their supports reported positive feedback regarding the group, including appreciation that the volunteer was a transplant recipient and gratitude for the lifestyle information. Five areas were associated with the success of Transplant Living Community: 1) a "champion" dedicated to the program and its successful integration into a multidisciplinary team; 2) a health care environment receptive to integration of a patient-led group with ongoing community development; 3) a high level of visibility to physicians and staff, patients, and supports; 4) a clearly presented and manageable lifestyle plan ("Play Your ACES"(a) [Attitude, Compliance, Exercise, and Support]), and 5) a strong volunteer structure with thoughtful training with the ultimate objective of volunteers taking ownership of the program.

CONCLUSION

It is feasible to integrate a sustainable patient-led lifestyle and self-management educational group into a busy tertiary care clinic for patients with complex chronic illnesses.

Gray matter volume and white matter lesions in chronic kidney disease: exploring the association with depressive symptoms

OBJECTIVE

Chronic kidney disease (CKD) is associated with structural brain damage and with a high prevalence of depression. We therefore investigated structural brain alterations in both gray and white matter in CKD patients, focusing on depression-related (frontal-subcortical) regions.

METHOD

This cross-sectional MRI study in 24 CKD patients and 24 age- and sex-matched controls first tested whether CKD was associated with regionally lower gray matter (GM) volumes and more severe white matter lesions (WMLs). In exploratory subanalyses, we examined whether differences were more pronounced in CKD patients with depressive symptoms.

RESULTS

CKD patients showed lower global GM volume (P=.04) and more severe WMLs (P=.04) compared to controls. In addition, we found substantial clusters of lower GM in the bilateral orbitofrontal-cortex for CKD patients, which were however nonsignificant after proper multiple-comparison correction. In exploratory analyses for depressed CKD patients, reduced GM clusters were mainly detected within the frontal lobe. WML severity was unrelated to depression.

CONCLUSION

CKD was characterized by differences in brain structure. Although subthreshold, lower GM volumes were observed in depression-related brain areas and were more pronounced for depressed patients. There is a need for replication in larger and longitudinal studies to investigate whether WMLs and regional GM reductions may render CKD patients more susceptible for depression.