Prevalence and Risk of Severe Cognitive Impairment in Advanced Chronic Kidney Disease

Kidney-brain axis in the pathogenesis of cognitive impairment

The kidney-brain axis is a bidirectional communication network connecting the kidneys and the brain, potentially affected by inflammation, uremic toxin, vascular injury, neuronal degeneration, and so on, leading to a range of diseases. Numerous studies emphasize the disruptions of the kidney-brain axis may contribute to the high morbidity of neurological disorders, such as cognitive impairment (CI) in the natural course of chronic kidney disease (CKD). Although the pathophysiology of the kidney-brain axis has not been fully elucidated, epidemiological data indicate that patients at all stages of CKD have a higher risk of developing CI compared with the general population. In contrast to other reviews, we mentioned some commonly used medicines in CKD that may play a pivotal role in the pathogenesis of CI. Revealing the pathophysiology interactions between kidney damage and brain function can reduce the potential risk of future CI. This review will deeply explore the characteristics, indicators, and potential pathophysiological mechanisms of CKD-related CI. It will provide a theoretical basis for identifying CI that progresses during CKD and ultimately prevents and treats CKD-related CI.

Curcumin Supplementation and Vascular and Cognitive Function in Chronic Kidney Disease: A Randomized Controlled Trial

Chronic kidney disease (CKD) increases the risk of cardiovascular disease and cognitive impairment. Curcumin is a polyphenol that improves vascular and cognitive function in older adults; however, its effects on vascular and cognitive function in patients with CKD are unknown. We hypothesized that curcumin supplementation would improve vascular and cognitive function in patients with CKD. Eighty-eight adults diagnosed with stage 3b or 4 CKD (aged 66 ± 8 years, 75% male) participated in a 12-month, randomized, double-blind, placebo-controlled study to test the effects of curcumin (Longvida®, 2000 mg/day) on vascular and cognitive function. Our primary outcome was brachial artery flow-mediated dilation (FMD). Our secondary outcomes were nitroglycerin-mediated dilation, carotid-femoral pulse wave velocity (cfPWV), and cognitive function assessed via the NIH Toolbox Cognition Battery. At baseline, the mean estimated glomerular filtration rate was 34.7 ± 10.8, and the median albumin/creatinine ratio was 81.9 (9.7, 417.3). A total of 44% of participants had diabetes. Compared with placebo, 12 months of curcumin did not improve FMD (median change from baseline was -0.7 (-2.1, 1.1) and -0.1 (-1.5, 1.5) for curcumin and placebo, respectively, with p = 0.69). Similarly, there were no changes in nitroglycerin-mediated dilation, cfPWV, or cognitive outcomes. These results do not support chronic curcumin supplementation to improve vascular and cognitive function in patients with CKD.

Prevalence of cognitive impairment and its predictors among chronic kidney disease patients: A systematic review and meta-analysis

BACKGROUND

Cognitive impairment (CI) is common among patients with chronic kidney disease (CKD), and is associated with a poor prognosis. We assessed the prevalence and associated factors of CI in patients with CKD.

METHODS

A systematic review and meta-analysis were conducted by searching PubMed, Embase, and the Web of Science through December 1, 2023. Random effects models were performed with subgroup analyses to further explore the heterogeneity.

RESULTS

50 studies involving 25,289 CKD patients were included. The overall prevalence of CI was 40% (95% confidence interval 33-46). The pooled prevalence of CI was relatively higher in CKD patients from Africa (58%), Asia (44%) and America (37%). Attention and executive dysfunction appeared to be the most common manifestations. The prevalence of CI was higher among patients with hemodialysis (53%) and peritoneal dialysis (39%) than those without dialysis (32%) and post-kidney transplanted (26%). In addition, advanced age, the presence of diabetes and hypertension might increase the risk of CI in CKD patients.

CONCLUSIONS

People with CKD have a high prevalence of CI, especially in patients with hemodialysis. An early and comprehensive screening for CI in CKD patients is needed to improve clinical outcomes.

TRIAL REGISTRATION

Registration number: PROSPERO (CRD42023412864).

Alzheimer's disease cerebrospinal fluid biomarkers and kidney function in normal and cognitively impaired older adults

INTRODUCTION

Recent Alzheimer's disease (AD) clinical trials have used cerebrospinal fluid (CSF) biomarker levels for screening and enrollment. Preliminary evidence suggests that AD risk is related to impaired renal function. The impact of kidney function on commonly used AD biomarkers remains unknown.

METHODS

Participants in studies conducted at the Goizueta Alzheimer's Disease Research Center (N = 973) had measurements of serum creatinine and CSF AD biomarkers. General linear models and individual data were used to assess the relationships between biomarkers and eGFR.

RESULTS

Lower estimated glomerular filtration rate (eGFR) was associated with lower amyloid beta (Aβ)42/tau ratio (p < 0.0001) and Aβ42 (p = 0.002) and higher tau (p < 0.0001) and p-tau (p = 0.0002). The impact of eGFR on AD biomarker levels was more robust in individuals with cognitive impairment (all p-values were < 0.005).

DISCUSSION

The association between eGFR and CSF AD biomarkers has a significant impact that varies by cognitive status. Future studies exploring this impact on the pathogenesis of AD and related biomarkers are needed.

Highlights

There is a significant association between Alzheimer's disease (AD) cerebrospinal fluid (CSF) biomarkers and both estimated glomerular filtration rate (eGFR) and mild cognitive impairment (MCI).Kidney function influences CSF biomarker levels in individuals with normal cognitive function and those with MCI.The impact of kidney function on AD biomarker levels is more pronounced in individuals with cognitive impairment.The variation in CSF tau levels is independent of cardiovascular factors and is likely directly related to kidney function.Tau may have a possible role in both kidney and cognitive function.

Comparison of the effects of peritoneal dialysis and hemodialysis on spontaneous brain activity in CKD patients: an rs-fMRI study

OBJECTIVE

To compare the effects of peritoneal dialysis and hemodialysis on spontaneous brain activity in patients with end-stage renal disease.

METHODS

A total of 52 dialysis patients with end-stage renal disease, including 25 patients with chronic kidney disease undergoing hemodialysis (HD-CKD) and 27 patients with chronic kidney disease undergoing peritoneal dialysis (PD-CKD), and 49 healthy controls (normal control) were included. All participants underwent neuropsychological testing (Mini-Mental State Examination and Montreal cognitive assessment) and resting-state functional magnetic resonance imaging. Fractional amplitude of low frequency fluctuations and Regional Homogeneity algorithms were employed to evaluate spontaneous brain activity. Statistical analysis was performed to discern differences between the groups.

RESULTS

When compared with the normal control group, the PD-CKD group exhibited significant alterations in fractional amplitude of low frequency fluctuations in various cerebellum regions and other brain areas, while the HD-CKD group showed decreased fractional amplitude of low frequency fluctuations in the bilateral pericalcarine cortex. The Regional Homogeneity values in the PD-CKD group were notably different than those in the normal control group, particularly in regions such as the bilateral caudate nucleus and the right putamen.

CONCLUSION

Both peritoneal dialysis and hemodialysis modalities impact brain activity, but manifest differently in end-stage renal disease patients. Understanding these differences is crucial for optimizing patient care.

Chronic Kidney Disease Induces Cognitive Impairment in the Early Stage

OBJECTIVE

Previous research indicates a link between cognitive impairment and chronic kidney disease (CKD), but the underlying factors are not fully understood. This study aimed to investigate the progression of CKD-induced cognitive impairment and the involvement of cognition-related proteins by developing early- and late-stage CKD models in Sprague-Dawley rats.

METHODS

The Morris water maze test and the step-down passive avoidance task were performed to evaluate the cognitive abilities of the rats at 24 weeks after surgery. Histopathologic examinations were conducted to examine renal and hippocampal damage. Real-time PCR, Western blotting analysis, and immunohistochemical staining were carried out to determine the hippocampal expression of brain-derived neurotrophic factor (BDNF), choline acetyltransferase (ChAT), and synaptophysin (SYP).

RESULTS

Compared with the control rats, the rats with early-stage CKD exhibited mild renal damage, while those with late-stage CKD showed significantly increased serum creatinine levels as well as apparent renal and brain damage. The rats with early-stage CKD also demonstrated significantly impaired learning abilities and memory compared with the control rats, with further deterioration observed in the rats with late-stage CKD. Additionally, we observed a significant downregulation of cognition-related proteins in the hippocampus of rats with early-stage CKD, which was further exacerbated with declining renal function as well as worsening brain and renal damage in rats with late-stage CKD.

CONCLUSION

These results suggest the importance of early screening to identify CKD-induced cognitive dysfunction promptly. In addition, the downregulation of cognition-related proteins may play a role in the progression of cognitive dysfunction.

CKD Associates with Cognitive Decline in Middle-Aged and Older Adults with Long-Standing Type 1 Diabetes

Key Points

We found that development of both albuminuria and reduced eGFR was associated with clinically significant cognitive decline, particularly in the psychomotor and mental efficiency domain. There was also a significant interaction between worsened albuminuria and eGFR, the combination of which augmented cognitive deficits. A more comprehensive longitudinal phenotype of albuminuria showed that regressed albuminuria did not associate with worsened cognitive decline, as opposed to persistent albuminuria.

Background

Individuals with CKD or type 1 diabetes (T1D) are at risk for cognitive decline, but it is unclear whether these associations are with albuminuria, eGFR, or both.

Methods

We examined the longitudinal relationships between CKD and change in cognition in 1051 participants with T1D in the Diabetes Control and Complications Trial and its follow-up, the Epidemiology of Diabetes Interventions and Complications study. Albumin excretion rate and eGFR were measured every 1–2 years. Three cognitive domains were assessed repeatedly over a 32-year period: immediate memory, delayed memory, and psychomotor and mental efficiency. Associations between cognitive function and CKD were assessed: (1 ) longitudinally and (2 ) in models using eGFR and albuminuria measurements over the first 15–20 years with subsequent change in cognitive function over the ensuing 14 years (when decline in cognition was greatest).

Results

In fully adjusted longitudinal analyses, the magnitude of decline in the psychomotor and mental efficiency domain score was associated with eGFR <60 ml/min per 1.73 m2 (β −0.449; 95% confidence interval [CI], −0.640 to −0.259) and sustained albumin excretion rate 30 to <300 mg/24 hours (β −0.148; 95% CI, −0.270 to −0.026). This was equivalent to a decrease associated with approximately 11 and 4 years of aging, respectively. In analyses focused on changes in cognition between study years 18 and 32, eGFR <60 ml/min per 1.73 m2 was associated with reduced psychomotor and mental efficiency (β −0.915; 95% CI, −1.613 to −0.217).

Conclusions

In T1D, development of CKD was associated with a subsequent reduction on cognitive tasks requiring psychomotor and mental efficiency. These data highlight the need for increased recognition of risk factors for neurologic sequelae in patients with T1D, as well as preventive and treatment strategies to ameliorate cognitive decline.

Frailty and Age-Associated Assessments Associated with Chronic Kidney Disease and Transplantation Outcomes

Background. Frailty is often defined as a decrease in physiological reserve and has been shown to be correlated with adverse health outcomes and mortality in the general population. This condition is highly prevalent in the chronic kidney disease (CKD) patient population as well as in kidney transplant (KT) recipients. Other age-associated changes include sarcopenia, nutrition, cognition, and depression. In assessing the contributions of these components to patient outcomes and their prevalence in the CKD and KT patient population, it can be determined how such variables may be associated with frailty and the extent to which they may impact the adverse outcomes an individual may experience. Objectives. We sought to perform a systematic literature review to review published data on frailty and associated age-associated syndromes in CKD and KT patients. Results. Over 80 references pertinent to frailty, sarcopenia, nutrition, cognition, or depression in patients with CKD or KT were identified. Systematic review was performed to evaluate the data supporting the use of the following approaches: Fried Frailty, Short Physical Performance Battery, Frailty Index, Sarcopenia Index, CT scan quantification of muscle mass, health-related quality of life, and assessment tools for nutrition, cognition, and depression. Conclusion. This report represents a comprehensive review of previously published research articles on this topic. The intersectionality between all these components in contributing to the patient’s clinical status suggests a need for a multifaceted approach to developing comprehensive care and treatment for the CKD and KT population to improve outcomes before and after transplantation.

Astrocytic aryl hydrocarbon receptor mediates chronic kidney disease-associated mental disorders involving GLT1 hypofunction and neuronal activity enhancement in the mouse brain

Chronic kidney disease (CKD)-associated mental disorders have been attributed to the excessive accumulation of hemodialysis-resistant indoxyl-3-sulfate (I3S) in the brain. I3S not only induces oxidative stress but is also a potent endogenous agonist of the aryl hydrocarbon receptor (AhR). Here, we investigated the role of AhR in CKD-induced brain disorders using a 5/6 nephrectomy-induced CKD mouse model, which showed increased I3S concentration in both blood and brain, anxiety and impaired novelty recognition, and AhR activation in the anterior cortex. GFAP⁺ reactive astrocytes were increased accompanied with the reduction of glutamate transporter 1 (GLT1) on perineuronal astrocytic processes (PAPs) in the anterior cingulate cortex (ACC) in CKD mice, and these alterations were attenuated in both neural lineage-specific and astrocyte-specific Ahr conditional knockout mice (nAhrCKO and aAhrCKO). By using chronic I3S treatment in primary astrocytes and glia-neuron (GN) mix cultures to mimic the CKD brain microenvironment, we also found significant reduction of GLT1 expression and activity in an AhR-dependent manner. Chronic I3S treatment induced AhR-dependent pro-oxidant Nox1 and AhR-independent anti-oxidant HO-1 expressions. Notably, AhR mediates chronic I3S-induced neuronal activity enhancement and synaptotoxicity in GN mix, not neuron-enriched cortical culture. In CKD mice, neuronal activity enhancement was observed in ACC and hippocampal CA1, and these responses were abrogated by both nAhrCKO and aAhrCKO. Finally, intranasal AhR antagonist CH-223191 administration significantly ameliorated the GLT1/PAPs reduction, increase in c-Fos⁺ neurons, and memory impairment in the CKD mice. Thus, astrocytic AhR plays a crucial role in the CKD-induced disturbance of neuron-astrocyte interaction and mental disorders.

The Association of Kidney Function with Plasma Amyloid-β Levels and Brain Amyloid Deposition

BACKGROUND

Reduced kidney function is related to brain atrophy and higher risk of dementia. It is not known whether kidney impairment is associated with higher levels of circulating amyloid-β and brain amyloid-β deposition, which could contribute to elevated risk of dementia.

OBJECTIVE

To investigate whether kidney impairment is associated with higher levels of circulating amyloid-β and brain amyloid-β deposition.

METHODS

This cross-sectional study was performed within the community-based Atherosclerosis Risk in Communities (ARIC) Study cohort. We used estimated glomerular filtration rate (eGFR) based on serum creatinine and cystatin C levels and urine albumin-to-creatinine ratio (ACR) to assess kidney function. Amyloid positivity was defined as a standardized uptake value ratios > 1.2 measured with florbetapir positron emission tomography (PET) (n = 340). Plasma amyloid-β1 - 40 and amyloid-β1 - 42 were measured using a fluorimetric bead-based immunoassay (n = 2,569).

RESULTS

Independent of demographic and cardiovascular risk factors, a doubling of ACR was associated with 1.10 (95% CI: 1.01,1.20) higher odds of brain amyloid positivity, but not eGFR (odds ratio per 15 ml/min/1.73 m2 lower eGFR: 1.08; 95% CI: 0.95,1.23). A doubling of ACR was associated with a higher level of plasma amyloid-β1 - 40 (standardized difference: 0.12; 95% CI: 0.09,0.14) and higher plasma amyloid-β1 - 42 (0.08; 95% CI: 0.05,0.10). Lower eGFR was associated with higher plasma amyloid-β1 - 40 (0.36; 95% CI: 0.33,0.39) and higher amyloid-β1 - 42 (0.32; 95% CI: 0.29,0.35).

CONCLUSION

Low clearance of amyloid-β and elevated brain amyloid positivity may link impaired kidney function with elevated risk of dementia. kidney function should be considered in interpreting amyloid biomarker results in clinical and research setting.

Insights into Cognitive Brain Health in Chronic Kidney Disease

Cognitive impairment and Chronic Kidney Disease (CKD) are common in older adults. With advances in medicine, the average lifespan is expected to increase, further increasing the prevalence of both conditions. The mechanisms underlying cognitive impairment in CKD are unclear. While mild-moderately low estimated glomerular filtration rate (eGFR) may not be associated with cognitive impairment, severely decreased eGFR and albuminuria do. Patients on dialysis have a high prevalence of cognitive impairment. Cognitive function improves after kidney transplantation. However, some residual cognitive deficits persist after transplantation, indicating that restoring the kidney function alone may not be enough to restore cognitive function, and other etiological factors may play a role. Albuminuria, another marker of CKD is also associated with cognitive impairment. However, albuminuria is often undiagnosed. Improving early identification and management of patients with albuminuria may be a good population-based dementia prevention strategy. Other factors associated with cognitive impairment in CKD include anemia and other metabolic derangements commonly observed in CKD. In this article, we reviewed the prevalence of cognitive impairment in CKD, the potential mechanisms underlying cognitive impairment in CKD, andthecurrent evidence on the association between cognitive impairment and eGFR and albuminuria.

Mild to moderate decrease in eGFR and cognitive decline in older adults

BACKGROUND

Whether mild to moderately low estimated glomerular filtration rate (eGFR) is associated with cognitive decline in older adults is not clear. We evaluated changes in cognition in relation to baseline eGFR in older adults participating in the Alzheimer's Disease Neuroimaging Initiative (ADNI).

METHODS

This is a longitudinal secondary analysis of an established observational cohort. We used data from the ADNI, an National Institutes of Health-funded, multicenter longitudinal observational study that includes participants with and without cognitive impairment who were administered a comprehensive battery of neuropsychological tests every 6 months. We related the Chronic Kidney Disease Epidemiology Collaboration eGFR with previously validated cognition composite scores for memory (ADNI-Mem) and executive function (ADNI-EF) in multivariable linear regression analysis adjusted for age, sex, race and level of education.

RESULTS

A total of 1127 ADNI participants (mean age 74 ± 7 years, 57% men, 97% Caucasian, mean follow-up 6 ± 2.6 years) were included in the analysis. The mean baseline eGFR was 76 ± 19 mL/min/1.73 m2, with 6% with eGFR <45, 22% with eGFR 45-<60, 51% with eGFR 60-90 and 21% with eGFR >90 mL/min/1.73 m2 at baseline. Both ADNI-Mem and ADNI-EF scores declined over time. In the multivariable linear regression model, older age (β = -0.117, P = 0.01), female sex (β = 0.312, P < 0.001) and lower education (β = 0.079, P < 0.001) were associated with a decline in ADNI-Mem scores, whereas baseline eGFR (each 10 mL/min/1.73 m2 change) was not {β = -0.03 [confidence interval (CI) -0.06-0.001], P = 0.11}. Similarly, older age (β = -0.278, P < 0.001) and lower education (β = 0.099, P < 0.001) were associated with a decline in ADNI-EF scores, whereas baseline eGFR was not [β = 0.004 (95% CI -0.04-0.04), P = 0.84].

CONCLUSIONS

In this cohort from the ADNI study, there was no association between baseline eGFR and cognitive decline in older adults with mild to moderately low eGFR.

Peter WL, Reule SA, Murray AM. Cognitive impairment, perceived medication adherence, and high-risk medication use in patients with reduced kidney function: A cross-sectional analysis

Background and Aims

Reduced estimated glomerular filtration rate (eGFR < 60 ml/min/1.73 m2) is a risk factor for cognitive impairment (CI) and medication nonadherence. However, the association between CI and medication adherence in adults with reduced eGFR has not been adequately examined. Our pragmatic objectives were to assess the cross-sectional relationship between CI and self-reported medication adherence, medication number, and use of potentially high-risk medications among adults with reduced eGFR.

Methods

An observational cohort study of the epidemiology of CI in community-dwelling adults aged 45 years or older with reduced eGFR.

Results

Our analytic cohort consisted of 420 participants (202 with CI; mean age: 69.7 years) with reduced eGFR, at least one prescription medication, and nonmissing medication adherence data. Participants with CI had four times greater unadjusted odds of reporting good medication adherence than participants without CI (self-report of missing medications <4 days/month; odds ratio [OR]: 4.04, 95% confidence interval [CI]:​​​​​ 1.62-10.10). This difference persisted following adjustment for demographic factors and comorbidities (OR: 5.50, 95% CI: 1.86-16.28). Participants with CI were no more likely than participants without CI to report forgetfulness as a reason for missing medication doses. Participants with CI were, on average, taking more total (mean: 13.3 vs. 11.5, median: 12 vs. 11) and more high-risk (mean: 5.0 vs. 4.2, median: 5 vs. 4) medications than those without CI; these differences were attenuated and no longer significant following adjustment for demographics and comorbidities.

Conclusion

Given the well-documented association between CI and medication nonadherence, better self-reported medication adherence among those with CI may represent perceptions of adherence rather than actual adherence. Participants with CI were, on average, taking more total and more high-risk medications than those without CI, suggesting a possible increased risk for adverse drug events. Our results highlight the potential risks of relying on self-reported medication adherence in reduced eGFR patients with CI.

Associations of amyloid and neurodegeneration plasma biomarkers with comorbidities

INTRODUCTION

Blood-based biomarkers of amyloid pathology and neurodegeneration are entering clinical use. It is critical to understand what factors affect the levels of these markers.

METHODS

Plasma markers (Aβ42, Aβ40, NfL, T-tau, Aβ42/40 ratio) were measured on the Quanterix Simoa HD-1 analyzer for 996 Mayo Clinic Study of Aging (MCSA) participants, aged 51 to 95 years. All other data were collected during in-person MCSA visits or abstracted from the medical record.

RESULTS

Among cognitively unimpaired (CU) participants, all plasma markers correlated with age. Linear regression models revealed multiple relationships. For example, higher Charlson Comorbidity Index and chronic kidney disease were associated with higher levels of all biomarkers. Some relationships differed between mild cognitive impairment and dementia participants.

DISCUSSION

Multiple variables affect plasma biomarkers of amyloid pathology and neurodegeneration among CU in the general population. Incorporating this information is critical for accurate interpretation of the biomarker levels and for the development of reference ranges.

Emotional and cognitive changes in chronic kidney disease

Chronic kidney disease (CKD) leads to cognitive impairment and emotional changes. However, the precise mechanism underlying the crosstalk between the kidneys and the nervous system is not fully understood. Inflammation and cerebrovascular disease can influence the development of depression in CKD. CKD is one of the strongest risk factors for cognitive impairment. Moreover, cognitive impairment occurs in CKD as patients experience the dysregulation of several brain functional domains due to damage caused to multiple cortical regions and to subcortical modulatory neurons. The differences in structural brain changes between CKD and non-CKD dementia may be attributable to the different mechanisms that occur in CKD. The kidney and brain have similar anatomical vascular systems, which may be susceptible to traditional risk factors. Vascular factors are assumed to be involved in the development of cognitive impairment in patients with CKD. Vascular injury induces white matter lesions, silent infarction, and microbleeds. Uremic toxins may also be directly related to cognitive impairment in CKD. Many uremic toxins, such as indoxyl sulfate, are likely to have an impact on the central nervous system. Further studies are required to identify therapeutic targets to prevent changes in the brain in patients with CKD.

CKD Biomarkers, Cognitive Impairment, and Incident Dementia in an Older Healthy Cohort

Background

CKD is a risk factor for cognitive impairment (CI), but reports of individual associations of eGFR and albuminuria with CI and incident dementia in healthier, older, longitudinal populations are lacking. Our goal was to estimate these associations in a large cohort of older healthy persons.

Methods

In a longitudinal cohort study of older persons without prior cardiovascular disease, we estimated the associations between baseline eGFR (in ml/min per 1.73 m2) and albuminuria, measured as urine albumin-creatinine ratio (UACR; in mg/mmol) and cognitive test scores, declines in cognitive test scores, and incident dementia using adjusted linear and linear mixed models. Cox proportional hazards regression models assessed the association between baseline kidney function and incident CI no dementia (CIND) or dementia at a median of 4.7 years.

Results

At baseline, among 18,131 participants, median age was 74 years, eGFR was 74 (IQR, 63-84) ml/min per 1.73 m2, UACR was 0.8 (IQR, 0.5-1.5) mg/mmol (7.1 [4.4-13.3] mg/g), and 56% were female. Baseline eGFR was not associated with performance on any cognitive tests in cross-sectional analysis, nor was incident CIND or dementia over a median follow-up of 4.7 years. However, baseline UACR ≥3 mg/mmol (≥26.6 mg/g) was significantly associated with lower baseline scores and larger declines on the Modified Mini-Mental State Exam, verbal memory and processing speed tests, and with incident CIND (hazard ratio [HR], 1.19; 95% CI, 1.07 to 1.33) and dementia (HR, 1.32; 95% CI, 1.06 to 1.66).

Conclusion

Mild albuminuria was associated with worse baseline cognitive function, cognitive decline, and increased risk for incident CIND and dementia. Screening global cognitive tests for older persons with UACR ≥3 mg/mmol could identify those at elevated risk of cognitive decline and dementia.

Risk and incidence of cognitive impairment in patients with chronic kidney disease and diabetes: the results from a longitudinal study in a community cohort of patients and an age and gender-matched control cohort in North Wales, UK

OBJECTIVES

The aim of the current investigation is to estimate the incidence and risk for neurocognitive disorders (NCD) in a chronic kidney disease (CKD) cohort with diabetes, compared with an age and sex-matched control cohort.

DESIGN

Longitudinal follow-up.

SETTING

District general hospital North Wales, UK.

PARTICIPANTS

Ninety-two patients with CKD and an age and gender-matched sample of 143 controls at baseline and at approximately 36 months.

INTERVENTIONS

Cognitive function was assessed in the patients with CKD (mean age 75.8±9.1; 49 men: 43 women) and the control cohort (mean age 74.4±6.2; 71 men: 72) at baseline and at approximately 36 months. An NCD diagnosis was based on patient, informant, case note review, neuropsychological assessment and application of Diagnostic and Statistical Manual of Mental disorders V.5 (DSM-5) for an NCD and Petersen's criteria for mild cognitive impairment.

RESULTS

Follow-up neuropsychological assessment and application of DSM-5 criteria of the cognitively normal patients and controls revealed, 25/92 (27%) of the CDK and 20/143 (13.9%) in the control cohort developed an NCD. The CKD cohort had a twofold increased risk for the development of an NCD compared with the controls, adjusted for age and sex. The incidence rate for an NCD in the CKD cohort was 10.5 and 5.1 in the controls, respectively. No association was observed with the stage of CKD and cognitive function.

CONCLUSIONS

This longitudinal investigation found that patients with CKD have a twofold increased risk for the development of an NCD. The current investigation highlighted the need to recognise that NCD in patients with CKD is a common comorbidity and that they are at a much higher risk for the development of a significant neurodegenerative disorders. In view of these risks, neuropsychological screening and assessment should be incorporated into normal CKD clinical practice and management.

Disentangling the Relationship Between Chronic Kidney Disease and Cognitive Disorders

Chronic kidney disease (CKD) is a rapidly rising global health burden that affects nearly 40% of older adults. Epidemiologic data suggest that individuals at all stages of chronic kidney disease (CKD) have a higher risk of developing cognitive disorders and dementia, and thus represent a vulnerable population. It is currently unknown to what extent this risk may be attributable to a clustering of traditional risk factors such as hypertension and diabetes mellitus leading to a high prevalence of both symptomatic and subclinical ischaemic cerebrovascular lesions, or whether other potential mechanisms, including direct neuronal injury by uraemic toxins or dialysis-specific factors could also be involved. These knowledge gaps may lead to suboptimal prevention and treatment strategies being implemented in this group. In this review, we explore the mechanisms of susceptibility and risk in the relationship between CKD and cognitive disorders.

Chronic kidney disease, physical activity, and cognitive function in older adults- results from the National Health and Nutrition Examination Survey (2011-2014)

BACKGROUND

Cognitive impairment is common among persons with chronic kidney disease (CKD) due in part to reduced kidney function. Given that physical activity (PA) is known to mitigate cognitive decline, we examined whether associations between CKD stage and global/domain-specific cognitive function differs by PA.

METHODS

We leveraged 3,223 participants (aged≥60years) enrolled in National Health and Nutrition Examination Survey (NHANES,2011-2014), with at least one measure of objective cognitive function (immediate recall [CERAD-WL], delayed recall [CERAD-DR], verbal fluency [AF], executive function/processing speed [DSST], global [average of 4 tests]) or self-perceived memory decline [SCD]. We quantified the association between CKD stage (no CKD: eGFR≥60 mL/min/1.73m2 and albuminuria(ACR)<30 mg/g; stage G1-G3: eGFR≥60mL/min/1.73m2 and ACR≥30mg/g or eGFR 30-59mL/min/1.73m2; stage G4-G5: eGFR<30mL/min/1.73m2) and cognitive function using linear regression (objective measures) and logistic regression (SCD), accounting for sampling weights for nationally-representative estimates. We tested whether associations differed by physical activity (Global Physical Activity Questionnaire, high PA≥600MET*min/week vs. low PA<600MET*min/week) using a Wald test.

RESULTS

Among NHANES participants, 34.9% had CKD stageG1-G3, 2.6% had stageG4-G5, and 50.7% had low PA. CKD stageG4-G5 was associated with lower global cognitive function (difference = -0.38SD, 95%CI:-0.62,-0.15). This association differed by PA (pinteraction = 0.01). Specifically, among participants with low PA, those with CKD stageG4-G5 had lower global cognitive function (difference = -0.57SD, 95%CI: -0.82,-0.31) compared to those without CKD. Among those with high PA, no difference was found (difference = 0.10SD, 95%CI:-0.29,0.49). Similarly, CKD stage was only associated with immediate recall, verbal fluency, executive function, and processing speed among those with low PA; no associations were observed for delayed recall or self-perceived memory decline.

CONCLUSIONS

CKD is associated with lower objective cognitive function among those with low, but not high PA. Clinicians should consider screening older patients with CKD who have low PA for cognitive impairment and encourage them to meet PA guidelines.

Prevalence of mild cognitive impairment in automated peritoneal dialysis patients

BACKGROUND

Cognitive deterioration decreases quality of life, self-care and adherence to treatment, increasing mortality risk. There is scarce information of cognitive impairment in peritoneal dialysis, and data are controversial.

OBJECTIVE

To determine the frequency and associated factors of cognitive impairment in patients on automated peritoneal dialysis (APD).

METHODS

Cross-sectional study; 71 patients on APD underwent clinical, biochemical and cognitive function evaluation by means of the Mini Mental State Examination (MMSE) and the Montreal Cognitive Assessment (MoCA). Cognitive function was also evaluated in healthy controls.

RESULTS

Mean age was 42 ± 16 years, 79% were men and dialysis vintage was 17 (7-32) months. In APD patients, cognitive impairment was present in 7% (mild deterioration) and 68% according to the MMSE and MoCA, respectively, and in 4% and 37% in the healthy controls. Patients with cognitive impairment (according to MoCA) were older, with lower educational degree, had more frequently diabetes, and higher serum glucose, as well as lower serum creatinine, phosphorus and sodium concentrations than patients with normal cognitive function. In multiple linear regression analysis, predictors for the MoCA score (R2 0.63, p = 0.002) were schooling [B = 0.54 (0.20 to 0.89), p = 0.003], age [B=-0.11 (-0.21 to -0.01), p = 0.04], serum sodium [B = 0.58 (0.05 to 1.11), p = 0.03] and creatinine concentrations [B = 3.9 (0.03 to 0.83), p = 0.03].

CONCLUSION

In this sample of APD patients with mean age in the early 40 s, the prevalence of cognitive impairment by MoCA test was 65%, and it was associated to older age, lower educational level and lower serum concentrations of sodium and creatinine.

Cognitive Impairment and Associated Factors Among Chronic Kidney Disease Patients: A Comparative Cross-Sectional Study

BACKGROUND

Cognitive impairment is one of the public health problems affecting 50 million people in the world. Chronic kidney disease (CKD) patients are at high risk to develop cognitive impairment which leads to poor quality of life, difficulty in adhering to medications, increased risk of mortality, and health resource utilization. However, there is no study done on the prevalence of cognitive impairment and associated factors among chronic kidney disease patients in Ethiopia.

OBJECTIVE

This study aimed to assess the prevalence of cognitive impairment and associated factors among chronic kidney disease patients at the University of Gondar Comprehensive Specialized and Felege Hiwot Referral Hospitals in 2020, Northwest Ethiopia, 2020.

METHODS

An institution-based comparative cross-sectional study was conducted at the University of Gondar Comprehensive Specialized and Felege Hiwot Referral Hospitals in 2020. A systematic random sampling technique was used to select the study participants. Data were collected using standard tools. Data were checked for its completeness and entered into Epi data version 3.0 then exported into STATA 14. Multi-variable logistic regression analysis was employed to identify associated factors of cognitive impairment among CKD patients, and variables having a p-value of ≤0.05 were declared as significant.

RESULTS

In this study, 116 CKD patients and 116 age, sex, and educational level matched controls were included with a response rate of 100%. The prevalence of cognitive impairment was 49.1% [95% CI (40%, 58.3%)] among CKD patients and 28.4% [95% CI (20.9%, 37.5%)] among controls. Independent predictors of cognitive impairment among CKD patients were estimated glomerular filtration (eGFR) <60mL/min/m2 [AOR=3.9, 95% CI (1.1-14.74)], proteinuria [AOR=6.0, 95% CI (1.83-20.3)], age greater than 65 years [AOR=4.0, 95% CI (1.12-14.64)], and educational level of grade 8 and less [AOR= 4.7, 95% CI (1.22 -18.47)].

CONCLUSION

The prevalence of cognitive impairment among CKD patients was higher than healthy controls. Cognitive impairment was higher among CKD patients with eGFR <60mL/min/m2, proteinuria, educational level of grade 8 and less, and age greater than 65 years. Therefore, there is a need to have a regular evaluation and follow-up of CKD patients for cognitive impairment.

The renal microcirculation in chronic kidney disease: novel diagnostic methods and therapeutic perspectives

Chronic kidney disease (CKD) affects 8–16% of the population worldwide and is characterized by fibrotic processes. Understanding the cellular and molecular mechanisms underpinning renal fibrosis is critical to the development of new therapeutics. Microvascular injury is considered an important contributor to renal progressive diseases. Vascular endothelium plays a significant role in responding to physical and chemical signals by generating factors that help maintain normal vascular tone, inhibit leukocyte adhesion and platelet aggregation, and suppress smooth muscle cell proliferation. Loss of the rich capillary network results in endothelial dysfunction, hypoxia, and inflammatory and oxidative effects and further leads to the imbalance of pro- and antiangiogenic factors, endothelial cell apoptosis and endothelial-mesenchymal transition. New techniques, including both invasive and noninvasive techniques, offer multiple methods to observe and monitor renal microcirculation and guide targeted therapeutic strategies. A better understanding of the role of endothelium in CKD will help in the development of effective interventions for renal microcirculation improvement. This review focuses on the role of microvascular injury in CKD, the methods to detect microvessels and the novel treatments to ameliorate renal fibrosis.

Psychological Flexibility and Depression in Advanced CKD and Dialysis

Rationale & Objective

Depression is prevalent and highly associated with mortality among patients with chronic kidney disease (CKD). Psychological flexibility can be captured as acceptance in psychology, and its improvement by behavioral therapy is associated with reduced depression in some clinical settings. However, no study has been reported on patients with CKD. This study aimed to examine the association between psychological flexibility and depression in patients with CKD.

Study Design

Cohort study.

Setting & Participants

This multicenter study of 5 hospitals in Japan included patients with nondialysis stage 3-5 CKD or stage 5D CKD receiving hemodialysis or peritoneal dialysis.

Predictor

Psychological flexibility measured using the 7-item Acceptance and Action Questionnaire (AAQ-II).

Outcomes

The prevalence and incidence of depression after 1 year, which was defined by a score ≥ 16 points on the Center for Epidemiologic Studies Depression (CES-D) questionnaire.

Analytical Approach

Gamma regression was used in the examination of correlates of the psychological flexibility value. Modified Poisson regression models were fit for the prevalence and incidence of depression.

Results

The cross-sectional and longitudinal analyses included 433 and 191 patients, respectively. Lower (ie, worse) psychological flexibility levels were associated with hemodialysis and peritoneal dialysis. Higher (ie, better) psychological flexibility levels were associated with lower prevalence of depression (per 5-point increase; adjusted prevalence ratio, 0.75; 95% CI, 0.70-0.80) and lower incidence of depression (per 5-point increase; adjusted risk ratio, 0.72; 95% CI, 0.61-0.85).

Limitations

Depression was assessed using the CES-D questionnaire. Cultural differences may exist in the interpretation of AAQ-II scores.

Conclusions

Better psychological flexibility was associated with lower prevalence and incidence of depression in patients with CKD. Further studies are warranted to determine the possible prevention and treatment of depression by the development of behavioral interventions to improve psychological flexibility.

Mild-moderate CKD is not associated with cognitive impairment in older adults in the Alzheimer's Disease Neuroimaging Initiative cohort

BACKGROUND

Chronic kidney disease (CKD) is associated with cognitive impairment and dementia. We examined whether this relationship hold true in older adults, who have a higher prevalence of both CKD and dementia.

DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS

We conducted a cross-sectional secondary analysis of an established observational cohort. We analyzed data from the Alzheimer's Disease Neuroimaging Initiative (ADNI), an NIH funded, multicenter longitudinal observational study, which includes participants with normal and impaired cognition and assesses cognition with a comprehensive battery of neuropsychological tests. We included a non-probability sample of all ADNI participants with serum creatinine measurements at baseline (N = 1181). Using multivariable linear regression analysis, we related the CKD Epidemiology Collaboration equation eGFR with validated composite scores for memory (ADNI-mem) and executive function (ADNI-EF).

RESULTS

For the 1181 ADNI participants, the mean age was 73.7 ± 7.1 years. Mean estimated glomerular filtration rate (eGFR) was 76.4 ± 19.7; 6% had eGFR<45, 22% had eGFR of 45 to <60, 51% had eGFR of 60-90 and 21% had eGFR>90 ml/min/1.73 m2. The mean ADNI-Mem score was 0.241 ± 0.874 and mean ADNI-EF score was 0.160 ± 1.026. In separate multivariable linear regression models, adjusted for age, sex, race education and BMI, there was no association between each 10 ml/ min/1.73 m2 higher eGFR and ADNI-Mem (β -0.02, 95% CI -0.04, 0.02, p = 0.56) or ADNI-EF (β 0.01, 95% CI -0.03, 0.05, p = 0.69) scores.

CONCLUSION

We did not observe an association between eGFR and cognition in the older ADNI participants.

Microvascular disease in chronic kidney disease: the base of the iceberg in cardiovascular comorbidity

Chronic kidney disease (CKD) is a relentlessly progressive disease with a very high mortality mainly due to cardiovascular complications. Endothelial dysfunction is well documented in CKD and permanent loss of endothelial homeostasis leads to progressive organ damage. Most of the vast endothelial surface area is part of the microcirculation, but most research in CKD-related cardiovascular disease (CVD) has been devoted to macrovascular complications. We have reviewed all publications evaluating structure and function of the microcirculation in humans with CKD and animals with experimental CKD. Microvascular rarefaction, defined as a loss of perfused microvessels resulting in a significant decrease in microvascular density, is a quintessential finding in these studies. The median microvascular density was reduced by 29% in skeletal muscle and 24% in the heart in animal models of CKD and by 32% in human biopsy, autopsy and imaging studies. CKD induces rarefaction due to the loss of coherent vessel systems distal to the level of smaller arterioles, generating a typical heterogeneous pattern with avascular patches, resulting in a dysfunctional endothelium with diminished perfusion, shunting and tissue hypoxia. Endothelial cell apoptosis, hypertension, multiple metabolic, endocrine and immune disturbances of the uremic milieu and specifically, a dysregulated angiogenesis, all contribute to the multifactorial pathogenesis. By setting the stage for the development of tissue fibrosis and end organ failure, microvascular rarefaction is a principal pathogenic factor in the development of severe organ dysfunction in CKD patients, especially CVD, cerebrovascular dysfunction, muscular atrophy, cachexia, and progression of kidney disease. Treatment strategies for microvascular disease are urgently needed.

Uremic Toxic Blood-Brain Barrier Disruption Mediated by AhR Activation Leads to Cognitive Impairment during Experimental Renal Dysfunction

BACKGROUND

Uremic toxicity may play a role in the elevated risk of developing cognitive impairment found among patients with CKD. Some uremic toxins, like indoxyl sulfate, are agonists of the transcription factor aryl hydrocarbon receptor (AhR), which is widely expressed in the central nervous system and which we previously identified as the receptor of indoxyl sulfate in endothelial cells.

METHODS

To characterize involvement of uremic toxins in cerebral and neurobehavioral abnormalities in three rat models of CKD, we induced CKD in rats by an adenine-rich diet or by 5/6 nephrectomy; we also used AhR^-/- knockout mice overloaded with indoxyl sulfate in drinking water. We assessed neurologic deficits by neurobehavioral tests and blood-brain barrier disruption by SPECT/CT imaging after injection of ^99mTc-DTPA, an imaging marker of blood-brain barrier permeability.

RESULTS

In CKD rats, we found cognitive impairment in the novel object recognition test, the object location task, and social memory tests and an increase of blood-brain barrier permeability associated with renal dysfunction. We found a significant correlation between ^99mTc-DTPA content in brain and both the discrimination index in the novel object recognition test and indoxyl sulfate concentrations in serum. When we added indoxyl sulfate to the drinking water of rats fed an adenine-rich diet, we found an increase in indoxyl sulfate concentrations in serum associated with a stronger impairment in cognition and a higher permeability of the blood-brain barrier. In addition, non-CKD AhR^-/- knockout mice were protected against indoxyl sulfate-induced blood-brain barrier disruption and cognitive impairment.

CONCLUSIONS

AhR activation by indoxyl sulfate, a uremic toxin, leads to blood-brain barrier disruption associated with cognitive impairment in animal models of CKD.

Mechanisms of cognitive dysfunction in CKD

Cognitive impairment is an increasingly recognized major cause of chronic disability and is commonly found in patients with chronic kidney disease (CKD). Knowledge of the relationship between kidney dysfunction and impaired cognition may improve our understanding of other forms of cognitive dysfunction. Patients with CKD are at an increased risk (compared with the general population) of both dementia and its prodrome, mild cognitive impairment (MCI), which are characterized by deficits in executive functions, memory and attention. Brain imaging in patients with CKD has revealed damage to white matter in the prefrontal cortex and, in animal models, in the subcortical monoaminergic and cholinergic systems, accompanied by widespread macrovascular and microvascular damage. Unfortunately, current interventions that target cardiovascular risk factors (such as anti-hypertensive drugs, anti-platelet agents and statins) seem to have little or no effect on CKD-associated MCI, suggesting that the accumulation of uraemic neurotoxins may be more important than disturbed haemodynamic factors or lipid metabolism in MCI pathogenesis. Experimental models show that the brain monoaminergic system is susceptible to uraemic neurotoxins and that this system is responsible for the altered sleep pattern commonly observed in patients with CKD. Neural progenitor cells and the glymphatic system, which are important in Alzheimer disease pathogenesis, may also be involved in CKD-associated MCI. More detailed study of CKD-associated MCI is needed to fully understand its clinical relevance, underlying pathophysiology, possible means of early diagnosis and prevention, and whether there may be novel approaches and potential therapies with wider application to this and other forms of cognitive decline.

Everyday Discrimination and Kidney Function Among Older Adults: Evidence From the Health and Retirement Study

BACKGROUND

With advancing age, there is an increase in the time of and number of experiences with psychosocial stressors that may lead to the initiation and/or progression of chronic kidney disease (CKD). Our study tests whether one type of experience, everyday discrimination, predicts kidney function among middle and older adults.

METHODS

The data were from 10 973 respondents (ages 52-100) in the 2006/2008 Health and Retirement Study, an ongoing biennial nationally representative survey of older adults in the United States. Estimated glomerular filtration rate (eGFR) derives from the Chronic Kidney Disease Epidemiology Collaboration equation. Our indicator of everyday discrimination is drawn from self-reports from respondents. Ordinary Least Squared regression (OLS) models with robust standard errors are applied to test hypotheses regarding the link between everyday discrimination and kidney function.

RESULTS

Everyday discrimination was associated with poorer kidney function among respondents in our study. Respondents with higher everyday discrimination scores had lower eGFR after adjusting for demographic characteristics (B = -1.35, p < .05), and while attenuated, remained significant (B = -0.79, p < .05) after further adjustments for clinical, health behavior, and socioeconomic covariates.

CONCLUSIONS

Our study suggests everyday discrimination is independently associated with lower eGFR. These findings highlight the importance of psychosocial factors in predicting insufficiency in kidney function among middle-aged and older adults.

The gut microbiota-inflammation-brain axis in end-stage renal disease: perspectives from default mode network

The gut-brain axis in end-stage renal disease (ESRD) is attracting more and more attention. However, the mechanism of gut-brain axis based cognitive disorders in ESRD patients remains unclear. The purpose of this study was to investigate the linkages between the gut microbiota, inflammatory cytokines, brain default mode network (DMN) and cognitive function in ESRD patients. Methods: This prospective study enrolled 28 ESRD patients (13 males and 15 females, mean age of 44 ± 14 years) and 19 healthy controls (HCs) (12 males and 7 females, mean age of 44 ± 10 years). All subjects underwent stool microbiota analysis, blood inflammatory cytokines examination, brain MRI scans and cognitive assessments. Resting state functional MRI (rs-fMRI) data were used to construct DMN and graph theory was applied to characterize network topological properties. Two samples t-test was applied for the comparisons between ESRD and HCs. Correlation analysis and mediation analysis were conducted among factors with significant group differences. Results: ESRD patients displayed gut microbiota alterations, increased systemic inflammation and worse cognitive performance compared to HCs (all p < 0.05). Graph analysis revealed disrupted DMN topological organization, aberrant nodal centralities and functional connectivities (FCs) in ESRD patients relative to HCs (all p < 0.05, FDR corrected). Significant correlations were found between gut microbiota, inflammatory cytokines, DMN network measures and cognitive assessments. Mediation analysis found that gut microbiota alteration impaired DMN connectivity by increasing systemic inflammation. Conclusion: The present study first revealed gut microbiota alterations, systemic inflammation, DMN dissociation and cognitive dysfunction in ESRD patients simultaneously and further illuminated their inner relationship.

Metabolic Biomarkers of Aging and Aging-related Diseases in Chinese Middle-Aged and Elderly Men

BACKGROUND

Aging is an acknowledged risk factor for most chronic diseases and functional impairments. The practicability of potential biomarkers of aging remains unsure. Moreover, biomarkers related to certain geriatric diseases, such as carotid atherosclerosis and multiple co-morbidities are less understood. The purpose of this study was to investigate the definite relationship between metabolic biomarkers and aging-related diseases.

METHODS

Eighty-five male adults aged fifty years or older from the general population were enrolled. Plasma metabolic biomarkers, including fourteen amino acids and thirty-six acylcarnitines, were measured by liquid chromatography mass spectrometry. Bivariate correlation analysis was employed to estimate the correlations between variables and age, and also to evaluate the relationship between metabolic biomarkers and aging-related diseases. Receiver operating characteristic (ROC) curve was conducted to judge the diagnostic efficiency of potential metabolic biomarkers for co-morbidities.

RESULTS

Certain metabolic biomarkers were strongly positively correlated with age, such as tetradecenoylcarnitine (C14:1), microalbumin-urine creatinine ratio (UACR), dodecenoylcarnitine (C12:1) and citrulline (p < 0.001). Carotid atherosclerosis and co-morbidities were positively correlated with aging (p < 0.001). After adjustment for age, hydroxytetradecanoylcarnitine (C14OH) remained positively correlated with carotid plague area. Besides, citrulline had diagnostic power for co-morbidities.

CONCLUSIONS

Citrulline may be a promising metabolic biomarker in the middle-aged and elderly men. Larger-scale and long-term studies are needed to confirm our findings.