Mild cognitive impairment and kidney disease: clinical aspects

Animal models to study cognitive impairment of chronic kidney disease

Mild cognitive impairment (MCI) is common in people with chronic kidney disease (CKD), and its prevalence increases with progressive loss of kidney function. MCI is characterized by a decline in cognitive performance greater than expected for an individual age and education level but with minimal impairment of instrumental activities of daily living. Deterioration can affect one or several cognitive domains (attention, memory, executive functions, language, and perceptual motor or social cognition). Given the increasing prevalence of kidney disease, more and more people with CKD will also develop MCI causing an enormous disease burden for these individuals, their relatives, and society. However, the underlying pathomechanisms are poorly understood, and current therapies mostly aim at supporting patients in their daily lives. This illustrates the urgent need to elucidate the pathogenesis and potential therapeutic targets and test novel therapies in appropriate preclinical models. Here, we will outline the necessary criteria for experimental modeling of cognitive disorders in CKD. We discuss the use of mice, rats, and zebrafish as model systems and present valuable techniques through which kidney function and cognitive impairment can be assessed in this setting. Our objective is to enable researchers to overcome hurdles and accelerate preclinical research aimed at improving the therapy of people with CKD and MCI.

A nomogram to predict cognitive function impairment in patients with chronic kidney disease: A national cross-sectional survey

Background

Cognitive function impairment (CFI) is common in patients with chronic kidney disease (CKD) and significantly impacts treatment adherence and quality of life. This study aims to create a simplified nomogram for early CFI risk detection.

Methods

Data were obtained from the National Health and Nutrition Examination Survey cycles spanning from 1999 to 2002 and again from 2011 to 2014. Stepwise logistic regression was used to select variables and construct a CFI risk prediction model. Furthermore, C-statistic and Brier Score (BS) assessed model performance. Additionally, Kaplan-Meier survival curves were utilised to assess risk group-death prognosis relationships.

Results

Of the 545 participants in the CKD model development cohort, a total of 146 (26.8 %) had CFI. The final model included the variables of age, race, education, annual family income, body mass index, estimated glomerular filtration rate, serum albumin and uric acid. The model had a C-statistic of 0.808 (95 % confidence interval (CI): 0.769-0.847) and a BS of 0.149. Furthermore, the 5-fold cross-validation internal C-statistic was 0.764 (interquartile range: 0.763-0.807) and BS was 0.154. Upon external validation, the model's C-statistic decreased to 0.752 (95 % CI: 0.654-0.850) and its BS increased to 0.182. The Kaplan-Meier survival curves demonstrated that intermediate-to-high-risk participants had shorter overall survival time than low-risk participants (log-rank test: p = 0.00042).

Conclusions

This study established an effective nomogram for predicting CFI in patients with CKD, which can be used for the early detection of CFI and guide the treatment of patients with CKD.

Higher remnant cholesterol is associated with an increased risk of amnestic mild cognitive impairment: a community-based cross-sectional study

Background and aims

Amnestic mild cognitive impairment (aMCI) is the most common subtype of MCI, which carries a significantly high risk of transitioning to Alzheimer's disease. Recently, increasing attention has been given to remnant cholesterol (RC), a non-traditional and previously overlooked risk factor. The aim of this study was to explore the association between plasma RC levels and aMCI.

Methods

Data were obtained from Brain Health Cognitive Management Team in Wuhan (https://hbtcm.66nao.com/admin/). A total of 1,007 community-dwelling elders were recruited for this project. Based on ten tools including general demographic data, cognitive screening and some exclusion scales, these participants were divided into the aMCI (n = 401) and normal cognitive groups (n = 606). Physical examinations were conducted on all participants, with clinical indicators such as blood pressure, blood sugar, and blood lipids collected.

Results

The aMCI group had significantly higher RC levels compared to the normal cognitive group (0.64 ± 0.431 vs. 0.52 ± 0.447 mmol/L, p < 0.05). Binary logistics regression revealed that occupation (P<0.001, OR = 0.533, 95%CI: 0.423-0.673) and RC (p = 0.014, OR = 1.477, 95% CI:1.081-2.018) were associated factors for aMCI. Partial correlation analysis, after controlling for occupation, showed a significant negative correlation between RC levels and MoCA scores (r = 0.059, p = 0.046), as well as Naming scores (r = 0.070, p = 0.026). ROC curve analysis demonstrated that RC levels had an independent predictive efficacy in predicting aMCI (AUC = 0.580, 95%CI: 0.544 ~ 0.615, P < 0.001).

Conclusion

Higher RC levels were identified as an independent indicator for aMCI, particularly in the naming cognitive domain among older individuals. Further longitudinal studies are necessary to validate the predictive efficacy of RC.

Abnormal grey matter structural changes in patients with end-stage kidney disease and mild cognitive impairment: correlations with clinical features

End-stage kidney disease and mild cognitive impairment (ESKD-MCI) affect the quality of life and long-term treatment outcomes of patients affected by these diseases. Clarifying the morphological changes from brain injuries in ESKD-MCI and their relationship with clinical features is helpful for the early identification and intervention of MCI before it progresses to irreversible dementia. This study gathered data from 23 patients with ESKD-MCI, 24 patients with ESKD and non-cognitive impairment (NCI), and 27 health controls (HCs). Structural magnetic resonance studies, cognitive assessments, and general clinical data were collected from all participants. Voxel-based morphometry analysis was performed to compare grey matter (GM) volume differences between the groups. The patients' GM maps and clinical features were subjected to univariate regression to check for possible correlations. Patients with ESKD-MCI displayed significantly more impairments in multiple cognitive domains, including global cognition, visuospatial and executive function, and memory, compared to patients with ESKD-NCI. Using a more liberal threshold (P < 0.001, uncorrected), we found that compared to patients with ESKD-NCI, patients with ESKD-MCI exhibited clusters of regions with lower GM volumes, including the right hippocampus (HIP), parahippocampal gyrus (PHG), Rolandic operculum, and supramarginal gyrus. The volumes of the right HIP and PHG were negatively correlated with serum calcium levels. ESKD-MCI was associated with a subtle volume reduction of GM in several brain areas known to be involved in memory, language, and auditory information processing. We speculate that these slight morphometric impairments may be associated with disturbed calcium metabolism.

Cognitive disorders in patients with chronic kidney disease: Approaches to prevention and treatment

BACKGROUND

Cognitive impairment is common in patients with chronic kidney disease (CKD), and early intervention may prevent the progression of this condition.

METHODS

Here, we review interventions for the complications of CKD (anemia, secondary hyperparathyroidism, metabolic acidosis, harmful effects of dialysis, the accumulation of uremic toxins) and for prevention of vascular events, interventions that may potentially be protective against cognitive impairment. Furthermore, we discuss nonpharmacological and pharmacological methods to prevent cognitive impairment and/or minimize the latter's impact on CKD patients' daily lives.

RESULTS

A particular attention on kidney function assessment is suggested during work-up for cognitive impairment. Different approaches are promising to reduce cognitive burden in patients with CKD but the availabe dedicated data are scarce.

CONCLUSIONS

There is a need for studies assessing the effect of interventions on the cognitive function of patients with CKD.

Methodological challenges and biases in the field of cognitive function among patients with chronic kidney disease

Chronic kidney disease (CKD) affects approximately 850 million people globally and is associated with an increased risk of cognitive impairment. The prevalence of cognitive impairment among CKD patients ranges from 30 to 60%, and the link between CKD and cognitive impairment is partially understood. Methodological challenges and biases in studying cognitive function in CKD patients need to be addressed to improve diagnosis, treatment, and management of cognitive impairment in this population. Here, we review the methodological challenges and study design issues, including observational studies' limitations, internal validity, and different types of bias that can impact the validity of research findings. Understanding the unique challenges and biases associated with studying cognitive function in CKD patients can help to identify potential sources of error and improve the quality of future research, leading to more accurate diagnoses and better treatment plans for CKD patients.

Longitudinal effects of a common UMOD variant on kidney function, blood pressure, cognitive and physical function in older women and men

Genetic variants in UMOD associate with kidney function and hypertension. These phenotypes are also linked to sex-related differences and impairment in cognitive and physical function in older age. Here we evaluate longitudinal associations between a common UMOD rs4293393-A>G variant and changes in estimated glomerular filtration rate (eGFR), blood pressure (BP), cognitive and physical function parameters in older participants in the BASE-II after long-term follow-up as part of the GendAge study. Overall, 1010 older participants (mean age 75.7 ± 3.7 years, 51.6% women) were analyzed after follow-up (mean 7.4 years) both in cross-sectional analysis and in longitudinal analysis as compared to baseline. In cross-sectional analysis, heterozygous G-allele carriers exhibited significantly higher eGFR values (AA, 71.3 ml/min/1.73 m2, 95% CI, 70.3-72.3 vs. AG, 73.5 ml/min/1.73 m2, 95% CI, 72.1-74.9, P = 0.033). Male heterozygous G-allele carriers had lower odds of eGFR < 60 mL/min/1.73 m2 (OR 0.51, 95% CI, 0.28-0.95, P = 0.032) and in Timed Up and Go-Test ≥ 10 s (OR 0.50, 95% CI, 0.29-0.85, P = 0.011) whereas women were less likely to have hypertension (OR 0.58, CI, 0.37-0.91, P = 0.018). UMOD genotypes were not significantly associated with longitudinal changes in any investigated phenotype. Thus, while the impact of UMOD rs4293393 on kidney function is maintained in aging individuals, this variant has overall no impact on longitudinal changes in BP, kidney, cognitive or functional phenotypes. However, our results suggest a possible sex-specific modifying effect of UMOD on eGFR and physical function in men and hypertension prevalence in women.

Effect of a common UMOD variant on kidney function, blood pressure, cognitive and physical function in a community-based cohort of older adults

In genome-wide association studies, genetic variants in the UMOD gene associate with kidney function, blood pressure (BP), and hypertension. Elevated BP is linked to kidney function and impaired cognitive as well as physical performance in later life. We investigated the association between UMOD rs4293393-A > G and kidney function, BP, cognitive and physical function in the Berlin Aging Study II (BASE-II). Data of 1556 older BASE-II participants (mean age 68.2 ± 3.7 years) were analyzed. BP was determined by standardized automated measurements, estimated glomerular filtration rate (eGFR) by CKD Epidemiology Collaboration creatinine equation. Cognitive function was assessed by Mini-Mental State Examination and Digit Symbol Substitution Test, while physical function by Handgrip Strength and Timed Up and Go-Test. Association analyses were performed by covariance and logistic regression models adjusting for sex. G-allele carriers at UMOD rs4293393 exhibited significantly higher eGFR values compared to non-carriers (AA, 76.4 ml/min/1.73 m², CI: 75.7-77.2 vs. AG, 78.4 ml/min/1.73 m², CI: 77.3-79.5 vs. GG, 78.5 ml/min/1.73 m², CI: 75.4-81.7; P = 0.010), and a lower risk of eGFR < 60 mL/min/1.73 m² (AG, OR: 0.63, CI: 0.41-0.97, P = 0.033). However, UMOD rs4293393 genotypes were not associated with BP, diagnosis of hypertension or cognitive and physical function parameters. Our data corroborate previous findings on the association of UMOD rs4293393-G with better kidney function in older adults. However, no association between UMOD and BP or physical and cognitive parameters in these community-dwelling older adults was detected.

The impact of chronic pre-dialysis hyponatremia on clinical outcomes in maintenance hemodialysis patients

OBJECTIVE

Chronic pre-dialysis hyponatremia is not rare in maintenance hemodialysis (MHD) patients. However, the association between chronic pre-dialysis hyponatremia and mortality is uncertain due to multiple potential confounders such as hyperglycemia, fluid overload, and malnutrition. This study aimed to more comprehensively evaluate the association between chronic pre-dialysis hyponatremia and clinical outcomes in MHD patients.

METHODS

We analyzed the data of 194 MHD patients with regular real-time measurements of pre-dialysis serum sodium from July 2015 to March 2021. Hyponatremia was defined as SNa ≤ 135 mmol/L and normonatremia as SNa > 135 mmol/L and < 145 mmol/L. We evaluated the association of baseline pre-dialysis serum sodium (SNa) and time-averaged SNa (TASNa) levels with all-cause mortality or new major adverse cardiovascular events (MACE) in MHD patients. Furthermore, the SNa levels were glucose, serum albumin, and fluid overload adjusted. The associations between SNa levels and all-cause mortality or new MACE were analyzed using time-varying Cox regression models.

RESULTS

Among the total of 194 patients, 24 patients died and 45 new MACE occurred during a mean 35.2-month follow-up period. The baseline pre-dialysis SNa level was 137.1 ± 2.8 mmol/L (127-144 mmol/L). Kaplan-Meier survival analysis showed that there were no significant differences in all-cause mortality or new MACE between hyponatremia and normonatremia groups according to baseline pre-dialysis SNa or glucose-corrected SNa (gcSNa). The mean values of both TASNa and time-averaged glucose-corrected SNa (TAgcSNa) were 136.9 ± 2.4 mmol/L and 138.3 ± 2.0 mmol/L, respectively. Kaplan-Meier survival analysis showed that patients with pre-dialysis hyponatremia had higher all-cause mortality or new MACE compared with normonatremia patients whether grouped on TASNa or TAgcSNa. Cox models showed an increased risk of all-cause mortality and new MACE in MHD patients with pre-dialysis hyponatremia based on TASNa or TAgcSNa. Even after full adjustment including time-dependent age and dialysis vintage, gender, diabetes, time-averaged weight gain (TAWG), and serum albumin, patients with pre-dialysis hyponatremia based on TASNa (HR 2.89; 95% CI 1.18-7.04; model 3) or TAgcSNa (HR 5.03; 95% CI 1.87-13.57; model 3) had approximately twofold or fourfold greater risk of all-cause mortality, respectively, compared with those with normonatremia. The risk of new MACE was also significantly elevated in patients with pre-dialysis hyponatremia based on TASNa (HR 3.86; 95% CI 2.13-7.01; model 1) or TAgcSNa (HR 2.43; 95% CI 1.14-5.15; model 1). After adjustment for time-dependent age and dialysis vintage, gender, diabetes, TAWG, and serum albumin, patients with pre-dialysis hyponatremia based on TASNa (HR 2.33; 95% CI 1.16-4.68; model 3) had a higher risk of new MACE compared with those with normonatremia.

CONCLUSIONS

Pre-dialysis time-averaged hyponatremia is independently associated with increased risks of all-cause mortality or new MACE in MHD patients. The baseline SNa level is not a predictor of clinical outcomes due to its variation over time. Hyperglycemia, fluid overload, and malnutrition do not have a significant impact on the risk association between chronic hyponatremia and all-cause mortality or new MACE in MHD patients.

Phosphate in the Context of Cognitive Impairment and Other Neurological Disorders Occurrence in Chronic Kidney Disease

The nervous system and the kidneys are linked under physiological states to maintain normal body homeostasis. In chronic kidney disease (CKD), damaged kidneys can impair the central nervous system, including cerebrovascular disease and cognitive impairment (CI). Recently, kidney disease has been proposed as a new modifiable risk factor for dementia. It is reported that uremic toxins may have direct neurotoxic (astrocyte activation and neuronal death) and/or indirect action through vascular effects (cerebral endothelial dysfunction, calcification, and inflammation). This review summarizes the evidence from research investigating the pathophysiological effects of phosphate toxicity in the nervous system, raising the question of whether the control of hyperphosphatemia in CKD would lower patients’ risk of developing cognitive impairment and dementia.

Prevalence of mild cognitive impairment and its association with handgrip strength in patients on hemodialysis

Dementia is associated with a high risk of death and hospitalization among patients on hemodialysis (HD). We retrospectively evaluated the prevalence of mild cognitive impairment (MCI) in 421 patients on maintenance HD across nine facilities and investigated whether decreased handgrip strength was associated with decreased cognitive function. The Montreal Cognitive Assessment-Japan (MoCA-J) score and handgrip strength were measured. The mean age was 69.8 ± 11.2 years, and the median dialysis vintage 74.5 (IQR 30–150) months. The median MoCA-J score was 25 (IQR 21–27), and MCI was confirmed in 245 (58.2%) patients. Both the MoCA-J score and MoCA-J executive score were associated with age, history of cerebrovascular disease (CVA), and handgrip strength after adjustments. We found, among patients on HD aged under 70 years with a history of CVA, a handgrip strength < 90% (25.2 kg in males and 16.2 kg in females) correlated with significantly lower MoCA-J scores. A high prevalence of MCI and decreased handgrip strength were observed in patients on HD. Handgrip strength may be useful for the easy detection of MCI. A decrease in handgrip strength would allow for the early detection of MCI, especially among patients on HD aged under 70 years with a history of CVA.

Analysis of the clinical efficacy of continuous slow and low-efficiency dialysis in the treatment of end-stage renal disease complicated with refractory heart failure and refractory hypertension

To study the Sustained Low Efficiency Dialysis (SLED) in the treatment of end-stage renal disease with refractory heart failure and the clinical curative effect of refractory hypertension. choose department of Nephrology, third People's Hospital of Gansu Province of 54 cases of end-stage renal disease with refractory heart failure. The patients with intractable hypertension were randomly divided into control group and observation group, with 27 cases in each group. The control group was treated with Intermittent HemoDialysis (IHD), the observation group was treated with SLED for 2 weeks. The levels of Scr, mean arterial pressure (MAP), BUN, heart rate (HR), CRP, IL-1β, TNF-α, TP, Alb and Hb in the observation group were better than those in the control group, and Closer to normal. The continuous low-efficiency and slow approach is better than the intermittent approach for hemodialysis in the treatment of end-stage renal disease complicated by refractory heart failure and refractory hypertension, which has a better treatment and prognostic effect, and can be promoted in clinical treatment.

Risk Factors and Clinical Outcomes of Cognitive Impairment in Diabetic Patients Undergoing Peritoneal Dialysis

INTRODUCTION

Cognitive impairment (CI) is common in patients with CKD or diabetes mellitus (DM). However, the relevance between DM and CI in diabetic patients undergoing peritoneal dialysis (PD) has not been clearly established. This study aimed to explore the role of DM in CI, the association of glycemic control with CI, and clinical outcomes of CI in diabetic PD patients.

METHODS

Continuous ambulatory PD (CAPD) patients followed up in our PD center between 2014 and 2016 were enrolled. The participants were followed until an endpoint was reached or December 2017. Demographic data and clinical characteristics were collected, and laboratory parameters were measured. The Montreal Cognitive Assessment (MoCA) was used to evaluate global cognitive function, and a score of <26 was considered to indicate CI. A propensity score matching according to age, gender, and mean arterial pressure was conducted between the DM and non-DM groups.

RESULTS

A total of 913 CAPD patients were enrolled, of whom 186 (20.4%) had diabetes. After appropriate matching, 175 patients in the DM group and 270 patients in the non-DM group were included. Patients with diabetes had a higher prevalence of CI and lower scores for visuospatial/executive function, naming, language, delayed recall, and orientation. Higher HbA1c (odds ratio [OR], 1.547; 95% confidence interval [95% CI], 1.013-2.362) and cardiovascular disease (CVD; OR, 2.926; 95% CI, 1.139-7.516) significantly correlated with a risk of CI in diabetic patients. During a median of 26.0 (interquartile range 13.5-35.6) months of follow-up, diabetic patients with CI demonstrated a significantly lower survival rate than those without CI, and CI was an independent risk factor for mortality after adjustment (hazard ratio, 7.224; 95% CI, 1.694-30.806). However, they did not show worse technique survival or higher peritonitis rate than patients without CI.

CONCLUSIONS

HbA1c and CVD are independent risk factors for CI in diabetic patients undergoing CAPD, and CI is independently associated with a higher risk of mortality.

A history of uraemic toxicity and of the European Uraemic Toxin Work Group (EUTox)

The uraemic syndrome is a complex clinical picture developing in the advanced stages of chronic kidney disease, resulting in a myriad of complications and a high early mortality. This picture is to a significant extent defined by retention of metabolites and peptides that with a preserved kidney function are excreted or degraded by the kidneys. In as far as those solutes have a negative biological/biochemical impact, they are called uraemic toxins. Here, we describe the historical evolution of the scientific knowledge about uraemic toxins and the role played in this process by the European Uraemic Toxin Work Group (EUTox) during the last two decades. The earliest knowledge about a uraemic toxin goes back to the early 17th century when the existence of what would later be named as urea was recognized. It took about two further centuries to better define the role of urea and its link to kidney failure, and one more century to identify the relevance of post-translational modifications caused by urea such as carbamoylation. The knowledge progressively extended, especially from 1980 on, by the identification of more and more toxins and their adverse biological/biochemical impact. Progress of knowledge was paralleled and impacted by evolution of dialysis strategies. The last two decades, when insights grew exponentially, coincide with the foundation and activity of EUTox. In the final section, we summarize the role and accomplishments of EUTox and the part it is likely to play in future action, which should be organized around focus points like biomarker and potential target identification, intestinal generation, toxicity mechanisms and their correction, kidney and extracorporeal removal, patient-oriented outcomes and toxin characteristics in acute kidney injury and transplantation.

Robotic technology quantifies novel perceptual-motor impairments in patients with chronic kidney disease

BACKGROUND

Neurocognitive impairment is commonly reported in patients with chronic kidney disease (CKD). The precise nature of this impairment is unclear, due to the lack of objective and quantitative assessment tools used. The feasibility of using robotic technology to precisely quantify neurocognitive impairment in patients with CKD is unknown.

METHODS

Patients with stage 4 and 5 CKD with no previous history of stroke or neurodegenerative disease were eligible for study enrollment. Feasibility was defined as successful study enrollment, high data capture rates (> 90%), and assessment tolerability. Our assessment included a traditional assessment: The Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), and a robot-based assessment: Kinarm.

RESULTS

Our enrollment rate was 1.6 patients/month. All patients completed the RBANS portion of the assessment, with a 97.8% (range 92-100%) completion rate on Kinarm. Missing data on Kinarm were mainly due to time constraints. Data from 49 CKD patients were analyzed. Kinarm defined more individuals as impaired, compared to RBANS, particularly in the domains of perceptual-motor function (17-49% impairment), complex attention (22-49% impairment), and executive function (29-37.5% impairment). Demographic features (sex and education) predicted performance on some, but not all neurocognitive tasks.

CONCLUSIONS

It is feasible to quantify neurocognitive impairments in patients with CKD using robotic technology. Kinarm characterized more patients with CKD as impaired, and importantly identified novel perceptual-motor impairments in these patients, when compared to traditional assessments.

Review of the structural and functional brain changes associated with chronic kidney disease

Chronic kidney disease (CKD) leads to profound metabolic and hemodynamic changes, which damage other organs, such as heart and brain. The brain abnormalities and cognitive deficit progress with the severity of the CKD and are mostly expressed among hemodialysis patients. They have great socio-economic impact. In this review, we present the current knowledge of involved mechanisms.

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.

Regulation of urinary calcium excretion by vasopressin

Background

The antidiuretic hormone (ADH) or arginine vasopressin (AVP) regulates the body's water balance. Recently, modifications in AVP levels have been related to osteoporosis during ageing and microgravity/bed rest. Therefore the present study was devised to assess whether the absence of AVP, as in patients with central diabetes insipidus (CDI), modulates renal calcium excretion.

Methods

We retrospectively analysed data from 12 patients with CDI with measured 24-h urinary excretion levels of calcium. Data were available at the moment of the diagnosis when patients were drug-free and after therapy with dDAVP, an analog of AVP. Hypercalciuria was defined as 24-h urinary Ca²⁺ >275 mg/day in males and >250 mg/day in females and a urinary calcium (Ca):creatinine (Cr) ratio >0.20 mg/mg.

Results

Untreated CDI patients had a daily urinary Ca²⁺ excretion of 383 ± 47 mg/day and a urinary Ca:Cr ratio of 0.26 ± 0.38 mg/mg. The urine osmolarity significantly increased after the administration of dDAVP by 210% and the urinary flow decreased by 72%. Furthermore, the estimated glomerular filtration rate (eGFR) increased by 7%, which did not reach statistical significance. dDAVP treatment did not significantly modify the urinary Ca²⁺ concentration; however, the daily calcium excretion and the urinary Ca:Cr ratio were significantly decreased (160 ± 27 mg/day and 0.11 ± 0.02 mg/mg, respectively).

Conclusions

Patients with CDI show hypercalciuria even though urine is more diluted than normal controls, and dDAVP reverses this effect. These data support the intriguing relationship between AVP and osteoporosis in ageing and microgravity/bed rest.

Cerebrovascular Disease and Cognition in Chronic Kidney Disease Patients

Chronic kidney disease (CKD) affects both brain structure and function. Patients with CKD have a higher risk of both ischemic and hemorrhagic strokes. Age, prior disease history, hypertension, diabetes, atrial fibrillation, smoking, diet, obesity, and sedimentary lifestyle are most common risk factors. Renal-specific pathophysiologic derangements, such as oxidative stress, chronic inflammation, endothelial dysfunction, vascular calcification, anemia, gut dysbiosis, and uremic toxins are important mediators. Dialysis initiation constitutes the highest stroke risk period. CKD significantly worsens stroke outcomes. It is essential to understand the risks and benefits of established stroke therapeutics in patients with CKD, especially in those on dialysis. Subclinical cerebrovascular disease, such as of silent brain infarction, white matter lesions, cerebral microbleeds, and cerebral atrophy are more prevalent with declining renal function. This may lead to functional brain damage manifesting as cognitive impairment. Cognitive dysfunction has been linked to poor compliance with medications, and is associated with greater morbidity and mortality. Thus, understanding the interaction between renal impairment and brain is important in to minimize the risk of neurologic injury in patients with CKD. This article reviews the link between chronic kidney disease and brain abnormalities associated with CKD in detail.

Association between chronic kidney disease and incident diagnosis of dementia in England: a cohort study in Clinical Practice Research Datalink

OBJECTIVES

To investigate the association between chronic kidney disease (CKD) and dementia diagnosis in a real-world primary care setting in England.

DESIGN

Matched cohort study.

SETTINGS

English primary care in the Clinical Practice Research Datalink.

PARTICIPANTS

People aged ≥18 years with predialysis CKD (stages 3-5, defined as two measurements of estimated glomerular filtration rate <60 mL/min/1.73 m² for 3 months) from 2004 to 2014, and people without known CKD who were matched on age, sex, general practice and calendar time in a 1:1 ratio.

PRIMARY AND SECONDARY OUTCOME MEASURES

First-ever diagnosis of dementia recorded by GPs. We also examined all-cause death as a secondary outcome to discuss potential competing risk of mortality in the association between CKD and dementia diagnosis.

RESULTS

In a matched cohort of 242 349 pairs with and without CKD (mean age 75.4±9.7 years, 39.3% male), the crude incidence rate of dementia diagnosis was 11.4/1000 and 9.4/1000 person-years, respectively. There was an association between CKD status and incident dementia diagnosis in the first 6 months of the follow-up (adjusted rate ratio (aRR) 1.58, 95% CI 1.44 to 1.74), which attenuated after 6 months (aRR 1.12, 95% CI 1.08 to 1.16). Among patients with CKD, there was no evidence of association between CKD stage and incident dementia diagnosis; compared with stage 3a, aRR (95% CI) was 1.04 (0.91 to 1.18) for stage 3b and 0.94 (0.74 to 1.20) for stages 4 or 5 in the first 6 months, and 0.97 (0.92 to 1.01) and 0.89 (0.80 to 0.98) thereafter. We found a strong association between worsening CKD stage and all-cause mortality.

CONCLUSION

We identified a co-occurrence of detection of CKD and dementia in real-world clinical practice and a strong competing risk of mortality in the association between CKD stage and dementia, while a weak association between CKD status and dementia was suggested in the long term.

Association between Sleep Duration and Incident Chronic Kidney Disease: A Population-Based Cohort Analysis of the NAGALA Study

BACKGROUND

The duration of sleep might be a risk factor for chronic kidney disease (CKD). We investigated the relationship between sleep duration and incident CKD.

METHODS

In this retrospective cohort study of 7,752 men and 6,722 women, we divided the subjects into 4 groups according to sleep duration, i.e., those whose reported regular sleep duration was <6 h (the "<6 h group"), those whose sleep duration was >6 but <7 h (the "6 to <7 h group"), those with a sleep duration of 7 to <8 h (the "7 to <8 h group"), and those with ≥8 h sleep (the "≥8 h group"). CKD was defined as the presence of proteinuria and/or an estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m2. The HR of the 4 groups for incident CKD were calculated with a Cox proportional hazards model, with the 7 to <8 h group set as the reference.

RESULTS

Incident CKD was detected in 1,513 (19.5%) men and 688 (10.2%) women over the median follow-up period of 7.0 (3.3-11.9) years in the men and 6.7 (3.1-10.8) years in the women. There was no association between sleep duration and incident CKD in the women. In the men, the HR of incident CKD was 0.54 (95% CI 0.45-0.64, p < 0.001) in the <6 h group, 0.73 (95% CI 0.66-0.82, p < 0.001) in the 6 to <7 h group, and 0.93 (95% CI 0.78-1.11, p = 0.433) in the ≥8 h group.

CONCLUSION

The risk of incident CKD is lowest in those who sleep <6 h. We revealed that the risk of incident CKD is lowest in those who sleep <6 h among apparently healthy men.

Combining Serum Cystatin C and Urinary N-Acetyl-Beta-D-Glucosaminidase Improves the Precision for Acute Kidney Injury Diagnosis after Resection of Intracranial Space-Occupying Lesions

BACKGROUND

Postoperative acute kidney injury (AKI) is frequent and associated with adverse outcomes. Unfortunately, the early diagnosis of AKI remains a challenge. Combining functional and tubular damage biomarkers may provide better precision for AKI detection. However, the diagnostic accuracy of this combination for AKI after neurosurgery is unclear. Serum cystatin C (sCysC) and urinary albumin/creatinine ratio (uACR) are considered functional biomarkers, while urinary N-acetyl-β-D-glucosaminidase (uNAG) represents tubular damage. We aimed to assess the performances of these clinical available biomarkers and their combinations for AKI prediction after resection of intracranial space-occupying lesions.

METHODS

A prospective study was conducted, enrolling adults undergoing resection of intracranial space-occupying lesions and admitted to the neurosurgical intensive care unit. The discriminative abilities of postoperative sCysC, uNAG, uACR, and their combinations in predicting AKI were compared using the area under the receiver operating characteristic curve (AUC-ROC), continuous net reclassification index (cNRI), and incremental discrimination improvement (IDI).

RESULTS

Of 605 enrolled patients, AKI occurred in 67 patients. The cutoff values of sCysC, uNAG, and uACR to predict postoperative AKI were 0.72 mg/L, 19.98 U/g creatinine, and 44.21 mg/g creatinine, respectively. For predicting AKI, the composite of sCysC and uNAG (AUC-ROC = 0.785) outperformed either individual biomarkers or the other two panels (uNAG plus uACR or sCysC plus uACR). Adding this panel to the predictive model improved the AUC-ROC to 0.808. Moreover, this combination significantly improved risk reclassification over the clinical model alone, with cNRI (0.633) and IDI (0.076). Superior performance of this panel was further confirmed with bootstrap internal validation.

CONCLUSIONS

Combination of functional and tubular damage biomarkers improves the predictive accuracy for AKI after resection of intracranial space-occupying lesions.

Kidney function changes and their relation with the progression of cerebral small vessel disease and cognitive decline

AIMS

We aimed to study whether worsening in markers of kidney function parallels the progression in cerebral small vessel disease (cSVD) and cognitive decline.

METHODS

Data from the ISSYS (Investigating Silent Strokes in Hypertensives Study), a longitudinal population-based study in hypertensives aged 50-70 and dementia and stroke-free at baseline. At both visits, patients underwent a brain MRI, a cognitive diagnosis (normal aging or mild cognitive impairment, [MCI]) and urine and blood sampling collection. We assessed the incidence of infarcts and cerebral microbleeds, and the progression of white matter hyperintensities at periventricular (PVH) and deep areas. We determined changes in albumin-creatinine ratio and estimated glomerular filtration rate (eGFR). These changes were dichotomized into microalbuminuria at follow-up -either in subjects with or without baseline microalbuminuria- and significant decline in eGFR -lowest quintile of eGFR change (-10.57 mL/min/1.73m²)-.

RESULTS

360 patients were followed-up for 4 years. 80 (23%) patients presented microalbuminuria at follow-up and 68 (20.1%) experienced a significant eGFR decline. Considering cSVD change, we found a relationship between microalbuminuria at follow-up and progression in PVH (β = 0.31, P-value = .01). Regarding cognitive decline, presence of microalbuminuria at follow-up related to a steeper decrease in memory function (β = -0.36, P-value<.01). Moreover, patients with significant decline in eGFR were at higher risk of incident MCI (OR = 3.54, P-value = .02). These associations were independent of progression of cSVD.

CONCLUSION

The worsening in markers of kidney function paralleled the decrease in cognition and the progression of cSVD, and this may be explained by common shared underlying risk factors.

Serum xanthophyll carotenoids are associated with estimated glomerular filtration rate in an aged cohort

Progressive renal decline is associated with increasing oxidative stress. However, the majority of studies have investigated endogenous antioxidants in predominantly advanced stages of kidney disease. Many traditional risk factors associated with renal dysfunction have been linked with cognitive decline as the kidneys and brain share comparable anatomic and haemodynamic characteristics that leave them susceptible to common pathogenic mechanisms. The objective of this study was to examine serum dietary antioxidants and their association with renal function characterised by estimated glomerular filtration rate (eGFR) in a cross-sectional analysis of 570 participants. High performance liquid chromatography quantified serum levels of retinol, α-tocopherol, γ-tocopherol and six carotenoids (α-carotene, β-carotene, β-cryptoxanthin, lutein, lycopene and zeaxanthin) in participants. Multiple regression analyses were used to evaluate associations while adjusting for potential confounders. A sensitivity analysis was performed in cognitively-intact participants only. Serum levels of the xanthophyll carotenoid lutein were positively associated with eGFR in analyses adjusted for age (years), gender, smoking, APOE4 status and Alzheimer’s disease. Retinol was inversely associated with eGFR, although was no longer significant in the smaller sensitivity analysis. Our findings identify significant associations between the xanthophyll carotenoids and eGFR. Further investigations are required to confirm these findings.

Sleep Disorders and Cognitive Impairment in Peritoneal Dialysis: A Multicenter Prospective Cohort Study

BACKGROUND

Patients with chronic kidney disease experience a high burden of sleep disorders, and there are associations between sleep disorders and cognitive impairment.

OBJECTIVES

Based on our previous cross-sectional survey on cognitive impairment in peritoneal dialysis, we further explored the relationship between sleep disorders and cognitive impairment, and predictors for declining cognitive function.

METHOD

We conducted a multicenter prospective cohort study enrolling 458 clinically stable patients on peritoneal dialysis who were then followed up for 2 years.Demographic data, comorbidities, depression, and biochemistry data were collected at baseline. Sleep disorders including insomnia, restless legs syndrome, sleep apnea syndrome, excessive daytime sleepiness, possible narcolepsy, sleep walking and nightmares, and possible rapid eye movement behavior disorders were assessed using a panel of specific sleep questionnaires at baseline and in a second survey. Global cognitive function was measured at baseline and in a second survey, using the Modified Mini-Mental State Examination. Specific cognitive domains were evaluated using Trail-Making Test Forms A and B for executive function, and subtests of the Battery for the Assessment of Neuropsychological Status were used to asses immediate and delayed memory, visuospatial skills, and language ability.

RESULTS

Sleep disorders were common among peritoneal dialysis patients. The prevalence of cognitive impairment evaluated by the Modified Mini-Mental State Examination (3MS) increased from 19.8 to 23.9%. Possible narcolepsy was associated with decreased Modified Mini-Mental State Examination scores at baseline. During follow-up, sleepwalking and nightmares were associated with higher risks of declined delayed memory in the longitudinal study.

CONCLUSIONS

Possible narcolepsy was associated with general cognitive dysfunction, and sleep walking and nightmares were risk factors for impaired delayed memory.