Cognitive profile of chronic kidney disease and hemodialysis patients without dementia

Synergistic susceptibility to environmental lead toxicity in chronic kidney disease

PURPOSE OF REVIEW

While high levels of lead exposure, as occurs accidentally or occupationally, can cause toxicity across multiple organ systems, the hazard of commonly encountered levels of lead in the environment remains unresolved. Challenges to researching the health effects of lead include its complex interplay with renal function, rendering analyses at risk of unaccounted confounding, and the likely small effect size of environmental levels of exposure. While children are known to be disproportionately susceptible to lead toxicity, resulting in appropriately more stringent regulatory surveillance for those under 5 years old, emerging evidence suggests that those with chronic kidney disease (CKD) similarly are at a greater risk. This review summarizes the role of environmental lead toxicity as a potential cause and consequence of CKD.

RECENT FINDINGS

Whether environmental lead exposure causes CKD remains debatable, with little recent research advancing the conflicting, mostly cross-sectional, analyses from years ago. However, an emerging body of evidence suggests that CKD increases the susceptibility to lead toxicity. Higher circulating lead levels and lower urinary excretion result in greater lead accumulation in CKD, with simultaneous greater risk of clinically meaningful disease. Recent studies suggest that levels of lead found commonly in the United States drinking water supply, and currently permissible by the Environmental Protection Agency, associate with hematologic toxicity in those with advanced CKD. Whether environmental lead contamination may have additional negative health impact among this at-risk population, including cardiovascular and neurocognitive disease, warrants further study.

SUMMARY

The underlying pathophysiology of kidney disease synergizes the susceptibility to environmental lead toxicity for those with CKD. Low levels of exposure, as found commonly in the United States water supply, may have adverse health impact in CKD. Further research will be needed to determine if more stringent environmental regulations are warranted to protect the health of all.

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).

Efficacy of erythropoietin as a neuroprotective agent in CKD-associated cognitive dysfunction: A literature systematic review

Patients with chronic kidney disease (CKD) often experience mild cognitive impairment and other neurocognitive disorders. Studies have shown that erythropoietin (EPO) and its receptor have neuroprotective effects in cell and animal models of nervous system disorders. Recombinant human EPO (rHuEPO), commonly used to treat anemia in CKD patients, could be a neuroprotective agent. In this systematic review, we aimed to assess the published studies investigating the cognitive benefits of rHuEPO treatment in individuals with reduced kidney function. We comprehensively searched Pubmed, Cochrane Library, Scopus, and Web of Science databases from 1990 to 2023. After selection, 24 studies were analyzed, considering study design, sample size, participant characteristics, intervention, and main findings. The collective results of these studies in CKD patients indicated that rHuEPO enhances brain function, improves performance on neuropsychological tests, and positively affects electroencephalography measurements. These findings suggest that rHuEPO could be a promising neuroprotective agent for managing CKD-related cognitive impairment.

Emotional Intelligence in Hemodialysis Patients: The Impact of an Intradialytic Exercise Training Program

The current study aimed to investigate whether there is a relationship between emotional intelligence (EI), functional capacity, fatigue, cognitive function, and quality of life (QoL) in HD patients and to assess the effect of a 9-month intradialytic exercise training program on EI levels. Seventy-eight dialysis patients (50 M/28 F, 60.6 ± 17.2 years) participated in the cross-sectional study. Afterward, a subgroup of 18 patients (15 M/3 F, 56.7 ± 12.3 years) completed a 9-month supervised intradialytic exercise training program (three times weekly). EI was assessed by the Schutte Self Report Emotional Intelligence Test (SSEIT) and the Wong and Law Emotional Intelligence Scale (WLEIS). Functional capacity was assessed by a battery of tests. Sleep quality, depression levels, and daily sleepiness were assessed via validated questionnaires. All assessments were carried out before and after the intervention. A significant positive correlation was found between the WLEIS scores and the physical component summary of the QoL questionnaire. In contrast, the WLEIS scores were negatively associated with general and physical fatigue. The SSEIT scores were positively associated with cognitive function. After nine months of exercise training, only the group with low WLEIS scores improved their EI score significantly compared to the baseline values (98.7 ± 7.0 vs. 73.0 ± 4.0, p = 0.020), while no changes were observed in the medium or high EI groups. In conclusion, patients with higher levels of EI showed increased quality of life and lower levels of fatigue. Patients with low levels of EI are more likely to benefit from an exercise training program compared to their medium- and high-level counterparts.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Relationship between Lower Extremity Peripheral Arterial Disease and Mild Cognitive Impairment in Hemodialysis Patients

Background: The link between arterial stiffness and mild cognitive impairment (MCI) in patients on hemodialysis (HD) has been receiving increased attention. The purpose of this study was to investigate the relationship between cognitive function and ankle brachial index (ABI) and toe brachial index (TBI) values in patients on hemodialysis. Of the 100 participants (mean age: 67.9 years; average history of hemodialysis: 7.3 years). Of these, 46.0% had MCI. The MoCA-J scores were significantly higher in the ABI ≥ 1.06 group. However, the MoCA-J scores divided into the two groups according to the TBI cutoff value were not significantly different. In a multiple regression model with the MoCA-J scores as the objective variable, the ABI was a significantly associated factor. This study indicates that a low ABI might be associated with MCI.

Can residual kidney function affect quality of life and cognitive function in hemodialysis patients?

BACKGROUND

Residual kidney function (RKF) may provide many benefits to patients on permanent renal replacement therapy that are reflected in better control of biochemical parameters. In hemodialysis patients, quality of life (QOL) and cognitive function are often impaired. This study aimed to assess the predictors of RKF and its impact on QOL and cognitive function in chronic hemodialysis patients.

PATIENTS AND METHODS

The study involved seventy-eight patients suffering from end-stage renal disease on regular hemodialysis. The patients were divided into two groups according to the presence or absence of RKF (24-hour urine volume ≥ 100 ml). Beside basic laboratory investigations, all patients were subjected to Kidney Disease Quality of Life-Short Form (KDQOL-SF) version 1.3 for assessing the quality of life and Montreal cognitive assessment (MoCA) score for assessing cognitive function.

RESULTS

There was a significantly higher score for KDQOL domains and MoCA score in patients with RKF compared to patients without RKF. There was a significant positive correlation between RKF and both of MoCA score and the physical composite score (PCS) of QOL. Moreover, there were statistically significant positive correlations between the MoCA score and both PCS and mental composite score (MCS). On multivariate analysis, hemodialysis duration was the only predictor for RKF; whereas age was a significant predictor for PCS; and MoCA score could be significantly predicted by the measured RKF and patients' age.

CONCLUSION

HD patients with maintained RKF had better QOL and cognitive function. The duration of HD and the age of the patients were found to be related to RKF and PCS in this study. RKF was associated with the cognitive performance of hemodialysis patients.

Changes of Brain Functional Connectivity in End-Stage Renal Disease Patients Receiving Peritoneal Dialysis Without Cognitive Decline

Background: Functional connectivity detected by resting-state functional MRI (R-fMRI) helps to discover the subtle changes in brain activities. Patients with end-stage renal disease (ESRD) on hemodialysis (HD) have impaired brain networks. However, the functional changes of brain networks in patients with ESRD undergoing peritoneal dialysis (PD) have not been fully delineated, especially among those with preserved cognitive function. Therefore, it is worth knowing about the brain functional connectivity in patients with PD by using R-fMRI.

Methods: This case-control study prospectively enrolled 19 patients with ESRD receiving PD and 24 age- and sex- matched controls. All participants without a history of cognitive decline received mini-mental status examination (MMSE) and brain 3-T R-fMRI. Comprehensive R-fMRI analyses included graph analysis for connectivity and seed-based correlation networks. Independent t-tests were used for comparing the graph parameters and connectivity networks between patients with PD and controls.

Results: All subjects were cognitively intact (MMSE > 24). Whole-brain connectivity by graph analysis revealed significant differences between the two groups with decreased global efficiency (E_glob, p < 0.05), increased betweenness centrality (BC) (p < 0.01), and increased characteristic path length (L, p < 0.01) in patients with PD. The functional connections of the default-mode network (DMN), sensorimotor network (SMN), salience network (SN), and hippocampal network (HN) were impaired in patients with PD. Meanwhile, in DMN and SN, elevated connectivity was observed in certain brain regions of patients with PD.

Conclusion: Patients with ESRD receiving PD had specific disruptions in functional connectivity. In graph analysis, E_glob, BC, and L showed significant connectivity changes compared to the controls. DMN and SN had the most prominent alterations among the observed networks, with both decreased and increased connectivity regions. Our study confirmed that significant changes in cerebral connections existed in cognitively intact patients with PD.

Health-care use and cost for multimorbid persons with dementia in the National Health and Aging Trends Study

BACKGROUND

Most persons with dementia have multiple chronic conditions; however, it is unclear whether co-existing chronic conditions contribute to health-care use and cost.

METHODS

Persons with dementia and ≥2 chronic conditions using the National Health and Aging Trends Study and Medicare claims data, 2011 to 2014.

RESULTS

Chronic kidney disease and ischemic heart disease were significantly associated with increased adjusted risk ratios of annual hospitalizations, hospitalization costs, and direct medical costs. Depression, hypertension, and stroke or transient ischemic attack were associated with direct medical and societal costs, while atrial fibrillation was associated with increased hospital and direct medical costs. No chronic condition was associated with informal care costs.

CONCLUSIONS

Among older adults with dementia, proactive and ambulatory care that includes informal caregivers along with primary and specialty providers, may offer promise to decrease use and costs for chronic kidney disease, ischemic heart disease, atrial fibrillation, depression, and hypertension.

Cognitive Dysfunction in Patients with Chronic Kidney Disease

Cognitive impairment is a common entity in patients with chronic kidney disease (CKD), which plays an important role in increasing the morbidity in these patients. This study was performed to evaluate cognitive dysfunction and its severity in different stages of CKD and identify the correlation with factors affecting this dysfunction. A cross-sectional design study was conducted on 100 patients with CKD Stage III to V-D fulfilling the eligibility criteria. Cognitive status was assessed using the mini-mental state examination (MMSE) and Montreal cognitive assessment (MoCA) tests. The patients were divided into four groups according to their estimated glomerular filtration rate (eGFR); Group A with eGFR ranging between 30 and 59 mL/min/1.73 m², Group B with eGFR between 15 and 29 mL/min/1.73 m², Group C with eGFR <15 mL/min/1.73 m² not on hemodialysis (HD), and Group D with eGFR <15 mL/min/1.73 m² and on HD for the past six months. Factors affecting MMSE and MoCA scores were assessed using univariate and multivariate linear regression analysis. Mean MMSE score was 28.72 ± 1.37 in Group A, 26.00 ± 3.67 in Group B, 20.76 ± 4.84 in Group C, and 17.28 ± 3.32 in Group D, which showed a statistically significant difference. The mean MoCA score also showed a statistically significant decline from Group A to Group D with values being 26.36 ± 1.91, 24.56 ± 1.94, 22.08 ± 2.12 and 20.12 ± 1.81, respectively (P < 0.05). The MMSE and MoCA scores were found to have a statistically significant positive correlation with hemoglobin; serum corrected calcium and eGFR (P < 0.01) and statistically significant negative correlation with blood urea, serum creatinine, serum uric acid, serum phosphate, serum potassium and stage of CKD (P < 0.01). By raising the clinician's awareness about cognitive dysfunction in CKD patients and its potential effects on medication, fluid and, dietary compliance improved quality of care is expected. Early intervention will improve the patient's quality of life.

A Study of Executive Function in Patients with Chronic Kidney Disease before and after a Single Session of Hemodialysis

Background  Executive functions (EFs) are critical to daily life and sensitive to our physiological functioning and emotional states. The number of people living with chronic kidney disease (CKD) on hemodialysis (HD) globally is increasing steadily. We aimed to determine the impact of a single session of HD on EFs in patients with CKD receiving maintenance HD (MHD). Methods  This was a quasi-experimental study conducted at the department of psychiatry and dialysis unit of a tertiary hospital. Patients undergoing MHD underwent screening to rule out delirium, using the Confusion Assessment Method prior to EF testing. The tests of EF used were the Trail-Making Test-Part B (TMT-B) and Frontal Assessment Battery (FAB), both of which were administered before and after a session of HD. Statistical tests used were Wilcoxon matched pairs signed ranks test, paired t -test, single sample t -test, and correlation analyses. Results  The mean time taken on TMT-B before HD was 195.36 seconds and after HD, 171.1 seconds; difference is significant ( p = 0.0001). The mean FAB score was 13.19 before HD and 14.83 after HD; the difference is significant ( p < 0.0001). Significant differences were observed on similarities (p = 0.003), lexical fluency (p = 0.02), and go-no go ( p = 0.003) subtests of FAB. Mean TMT-B scores before and after HD differed significantly from that of a reference study (reference TMT-B 150.69 seconds), p = 0.0002 and 0.04, respectively. Conclusion  We conclude that patients with CKD on MHD, in general, have worse executive cognitive functioning compared with healthy populations. A session of HD results in significant improvement in these functions.

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.

The assessment of cognitive function in older adult patients with chronic kidney disease: an integrative review

INTRODUCTION

Chronic kidney disease (CKD) is a common chronic condition in older adults that is associated with cognitive decline. However, the exact prevalence of cognitive impairment in older adults with CKD is unclear likely due to the variety of methods utilized to assess cognitive function. The purpose of this integrative review is to determine how cognitive function is most frequently assessed in older adult patients with CKD.

METHODS

Five electronic databases were searched to explore relevant literature related to cognitive function assessment in older adult patients with CKD. Inclusion and exclusion criteria were created to focus the search to the assessment of cognitive function with standardized cognitive tests in older adults with CKD, not on renal replacement therapy.

RESULTS

Through the search methods, 36 articles were found that fulfilled the purpose of the review. There were 36 different types of cognitive tests utilized in the included articles, with each study utilizing between one and 12 tests. The most commonly utilized cognitive test was the Mini Mental State Exam (MMSE), followed by tests of digit symbol substitution and verbal fluency. The most commonly assessed aspect of cognitive function was global cognition.

DISCUSSION

The assessment of cognitive function in older adults with CKD with standardized tests is completed in various ways. Unfortunately, the common methods of assessment of cognitive function may not be fully examining the domains of impairment commonly found in older adults with CKD. Further research is needed to identify the ideal cognitive test to best assess older adults with CKD for cognitive impairment.

Does Chronic Kidney Disease-Induced Cognitive Impairment Affect Driving Safety?

PURPOSE OF REVIEW

One of the principal mechanisms by which illness can affect driving safety is by impairing cognition. Nevertheless, despite the substantial evidence demonstrating cognitive impairment in chronic kidney disease (CKD), little is known about the effects of CKD on driving safety.

OBJECTIVE

Investigate the current national medical guidelines and research literature with respect to CKD and driving safety.

SOURCES OF INFORMATION

Medline, CINAHL, PEDro, Scopus as of August 2017. The most up to date national driving guidelines and available information provided by the provincial and territorial ministries of transportation across Canada.

FINDINGS

Fives studies of driving fitness in patients with CKD have been published with minimal data available for patients at early stages of the disease. Amongst these studies, only two come from an era when modern end stage renal disease therapies were routinely provided. The first study demonstrated that 40% of 186 surveyed patients on hemodialysis felt uncomfortable driving and that 1/3 of patients were involved in motor vehicle collisions (MVC) since starting dialysis. Of the patients who felt comfortable driving, more than 75% were found to be at increased driving risk. The second study reported that 15% of patients on hemodialysis were involved in MVCs over a three year span and that the "Am I A Safe Driver" assessment tool by the American Medical Association may not capture all patients at high driving risk. Despite these alarming numbers, national guidelines place few driving restrictions on this patient population and only 3 of 11 available provincial or territorial driving forms include kidney disease as a category that physicians should consider when assessing medical fitness to drive.

LIMITATIONS

Our review is limited by the lack of randomized control studies evaluating the effects of CKD on driving safety.

IMPLICATIONS

Our review demonstrates that driving safety in this patient population remains poorly understood. The limited evidence that does exist, however, suggests that these patients are at substantial risk for unsafe driving. Future research is necessary to determine the impact of CKD-associated cognitive impairment on driving risk, and to parse out the contributions of CKD and its various treatments to driving impairment.

Consequences of CKD on Functioning

Chronic kidney disease (CKD) is highly prevalent in the United States and throughout the world,(1) with approximately 13% of adults affected.(2) In addition, according to recent estimates, almost half of patients with CKD stages 3 to 5 are 70 years of age and older.(2) In the United States, the number of prevalent end-stage renal disease cases continues to increase in patients older than age 65. In light of the demographic characteristics of patients with CKD and ESRD, there has been considerable focus on associations between CKD and cardiovascular outcomes.(3) Until recently, less attention had been paid to other consequences of CKD in general and among older individuals with CKD in particular, but there is now solid evidence linking CKD with impairments of physical function, cognitive function, and emotional function and quality of life. This review summarizes available literature on these topics, focusing specifically on physical functioning and frailty, cognitive function, emotional health, including depression and anxiety, and health-related quality of life.

The effect of the interdialytic interval on cognitive function in patients on haemodialysis

BACKGROUND

Cognitive deficits are common among individuals on haemodialysis (HD). The degree of dysfunction may shift over the course of the interdialytic interval.

OBJECTIVES

To use ecological momentary assessment (EMA) to examine the relationship between the length of the interdialytic interval and reports of cognitive dysfunction.

DESIGN

A quantitative study whereby each patient's cognitive functioning was measured during both short and long interdialytic intervals.

PARTICIPANTS

Adults maintained on HD (Female n = 15, Male n = 11; M_Age  = 42.7 ± 15.8 years) were drawn from a standalone HD unit within a large university medical centre.

MEASUREMENTS

Tests of baseline neurocognitive functioning were undertaken (Mini-Mental Status Examination, Digit Span, California Verbal Learning Test, Benton Visual Retention Test, Trail-Making Test) and smartphone-based electronic diary reports of cognitive impairment were made around six times each day for one week.

RESULTS

Cognitive function and aptitude in this sample, although low, did not reflect clinically-significant impairment, with a mean Mini-Mental Status Exam score of 25.7 ± 3.0. Diary reports of cognitive impairment were also minimal, with an overall mean rating of .22 out of 5. Contrary to expectations, cognitive impairment was significantly greater on the one-day interdialytic days than on Day 2 of the two-day interdialytic interval (β = .094, p = .017).

CONCLUSIONS

Although cognitive impairment appears to be mild in stable, young patients with end stage renal disease, volumetric disruptions caused by HD may exacerbate such dysfunction.

Cognitive Impairment and Dementia in Older Adults With Chronic Kidney Disease: A Review

Individuals with chronic kidney disease (CKD), especially older adults, are at more risk of experiencing cognitive impairment, possibly leading to mild cognitive impairment and/or dementia. Studies report associations between CKD and cognitive impairment; although unclear, there seems to be a graded association between stage of CKD and affected cognitive domains, with executive function being affected earlier in the process than episodic memory and global ability. In CKD, dysexecutive mild cognitive impairment and vascular dementia are also more prominent than other subtypes. Explanations are directed toward traditional and nontraditional vascular factors, which may also explain or mediate the association between CKD and type of cognitive impairment. Future research is urged to focus on the longitudinal association between specific domains of cognitive function, including executive function and memory and CKD; to develop screening tools fit for every CKD stage in elderly individuals, and lastly, to use imaging methods that may help clarify the underlying mechanisms connecting the kidney and the brain.

Long-term risk of dementia following acute kidney injury: A population-based study

OBJECTIVE

Adverse neurological effects may be common following acute kidney injury (AKI). The purpose of our study was to investigate the long-term risk of dementia following AKI and temporary dialysis during hospitalization.

MATERIALS AND METHODS

The study was based on data from the National Health Insurance Research Database of Taiwan. Patients 18-year-old and older who were withdrawn from temporary dialysis because of AKI and survived for at least 90 days following discharge were included in our acute-dialysis-recovery group. Patients without AKI and dialysis were the control group. A Cox proportional-hazards regression model was applied to determine the risk of dementia.

RESULTS

Of 2905 acute-dialysis patients, 689 (23.7%) survived for at least 90 days following recovery from acute dialysis. The Cox proportional-hazards regression model showed that the acute-dialysis-recovery group had an increased long-term risk of dementia (hazard ratio [HR], 2.01; P = 0.01) compared with the control group. The conditional effects plot showed that the risk of dementia was amplified in patients who were older than 58 years. The development of dementia following recovery from acute dialysis was associated with an increase in all-cause mortality (HR, 2.38; P < 0.001).

CONCLUSIONS

Patients with acute dialysis have a greater risk for the subsequent development of dementia after recovery than patients without AKI and dialysis, and patients who develop dementia after recovery from temporary dialysis are at increased risk for mortality.

Mid-life proteinuria and late-life cognitive function and dementia in elderly men: the Honolulu-Asia Aging Study

BACKGROUND

Impaired renal function has been linked to cognitive impairment. We assessed mid-life proteinuria and late-life cognitive function in elderly Asian men.

METHODS

The Honolulu Heart Program is a prospective study that began in 1965 with 8006 Japanese-American men aged 45 to 68 years. Mid-life proteinuria was detected by urine dipstick in 1971 to 1974. The Honolulu-Asia Aging Study began 20 years later, with cognitive assessment by the Cognitive Abilities Screening Instrument (CASI) in 3734 men. Standard criteria were used to classify 8-year incident dementia and subtypes.

RESULTS

The age-adjusted incidence of dementia increased significantly from 13.8, to 22.8, to 39.7 per 1000 person years follow-up, among those with no, trace, and positive mid-life proteinuria (P=0.004). Using linear regression adjusting for age, education, APOEε4, stroke, hypertension, systolic blood pressure, diabetes, fasting blood glucose, physical activity, and baseline CASI, those with positive proteinuria had significantly higher annual change in CASI over 8 years follow-up (-1.24, P=0.02) (reference=no proteinuria). Multivariate Cox regression found that positive proteinuria had a significant association with incident all-cause dementia (RR=2.66; 95%CI, 1.09-6.53; P=0.03), but no significant associations with incident Alzheimer disease or vascular dementia.

CONCLUSION

Mid-life proteinuria was an independent predictor for late-life incident all-cause dementia and cognitive decline over 8 years.

Vitamin D Status Is an Independent Risk Factor for Global Cognitive Impairment in Peritoneal Dialysis Patients

Objective

Vitamin D (VD) deficiency is an independent risk factor for cognitive impairment (CI) in the general population, but VD status in peritoneal dialysis (PD) patients has not been investigated. In this study, we aimed to investigate the relationship between serum VD levels and global and specific cognitive functions in PD patients.

Design and Setting

Cross-sectional study, simultaneously conducted at two PD centers.

Patients

Clinically stable patients (n = 273) undergoing PD for at least 3 months were enrolled over a period of one year.

Main outcome Measures

Demographic and comorbidity data were recorded, and routine biochemical parameters and serum 25-hydroxyvitamin D (25(OH) D) levels of overnight fasted patients were determined. Global cognitive function was assessed by the Modified Mini-Mental State Examination (3MS) score; executive function, by the trail making tests (Trails A and B); and immediate memory, delayed memory, and language ability by the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) sub-tests.

Results

In the univariate analysis, serum 25(OH) D levels significantly correlated with 3MS scores (r = -0.139; P = 0.02), and Trail A (r = -0.188; P = 0.002) and B (r = -0.154; P = 0.01) completion times. In the multivariate analysis, 25(OH) D was found to be independently associated with global CI, but not with executive dysfunction. Serum 25(OH) D could not predict scores of immediate/delayed memory and language ability.

Conclusions

VD deficiency is highly prevalent in PD patients and is an independent risk factor for global CI in this patient cohort.

Abnormal degree centrality in neurologically asymptomatic patients with end-stage renal disease: A resting-state fMRI study

OBJECTIVE

End-stage renal disease (ESRD), characterized by multi-organ dysfunction, has been shown to co-occur with abnormal brain function. Previous resting-state fMRI studies suggested that regional brain spontaneous activity and functional connectivity within the default mode network are abnormal in ESRD patients. The current study aimed to depict intrinsic dysconnectivity pattern of whole-brain functional networks in voxel level in neurologically asymptomatic patients with ESRD.

METHODS

fMRI datasets were acquired from 22 ESRD patients (without clinical neurological disease) and 29 healthy control (HC) subjects. We investigated the degree centrality for a given element in a network to reveal the changes of functional connectivity throughout the huge human functional network. In the brain regions showing a difference between the HC and ESRD groups, we further conducted receptive operation characteristic (ROC) analyses to confirm the accuracy, sensitivity and specificity of our results.

RESULTS

ESRD patients showed decreased functional connectivity in the left inferior parietal and left precuneus within the brain network; both regions are important components of the default-mode network (DMN). In contrast, patients showed increased connectivity in depression-related regions including bilateral inferior frontal gyrus and right superior temporal gyrus. These regions showed an acceptable accuracy (0.68-0.75), sensitivity (0.64-0.70) and high specificity (0.82-0.96) in distinguishing between the two groups.

CONCLUSIONS

Our findings reveal abnormal intrinsic dysconnectivity pattern of whole-brain functional networks in ESRD patients.

SIGNIFICANCE

Our results could lead to a better understanding of the intrinsic dysconnectivity patterns of default-mode network-related regions in ESRD patients from the whole brain network perspective.

Low eGFR is associated with dysexecutive and amnestic mild cognitive impairment

BACKGROUND

Few studies have explored the association between renal function and major subtypes of mild cognitive impairment (MCI).

METHODS

The sample was from the Einstein Aging Study. The estimated glomerular filtration rate (eGFR, calculated in mL/min/1.73m2 units) was classified into low (<45), moderate (45-59) and high (≥60). Separate binary logistic regression models were run to determine if eGFR is associated withamnestic MCI (aMCI) and dysexecutive MCI (dMCI).

RESULTS

Out of 622 eligible participants 65 (10.5%) had low eGFR, 43 (7.1%) had aMCI, and 46 (7.6) had dMCI. Low eGFR was independently associated with dMCI and aMCI in fully adjusted models.

CONCLUSION

At cross-section low eGFR is associated with a higher risk of both dMCI and aMCI. eGFR may contribute to the development of these cognitive states directly. Alternatively, low eGFR may be a marker for risk factors that influence both the kidney and the brain, such as coronary microvascular disease.

Increased cerebral water content in hemodialysis patients

Little information is available on the impact of hemodialysis on cerebral water homeostasis and its distribution in chronic kidney disease. We used a neuropsychological test battery, structural magnetic resonance imaging (MRI) and a novel technique for quantitative measurement of localized water content using 3T MRI to investigate ten hemodialysis patients (HD) on a dialysis-free day and after hemodialysis (2.4±2.2 hours), and a matched healthy control group with the same time interval. Neuropsychological testing revealed mainly attentional and executive cognitive dysfunction in HD. Voxel-based-morphometry showed only marginal alterations in the right inferior medial temporal lobe white matter in HD compared to controls. Marked increases in global brain water content were found in the white matter, specifically in parietal areas, in HD patients compared to controls. Although the global water content in the gray matter did not differ between the two groups, regional increases of brain water content in particular in parieto-temporal gray matter areas were observed in HD patients. No relevant brain hydration changes were revealed before and after hemodialysis. Whereas longer duration of dialysis vintage was associated with increased water content in parieto-temporal-occipital regions, lower intradialytic weight changes were negatively correlated with brain water content in these areas in HD patients. Worse cognitive performance on an attention task correlated with increased hydration in frontal white matter. In conclusion, long-term HD is associated with altered brain tissue water homeostasis mainly in parietal white matter regions, whereas the attentional domain in the cognitive dysfunction profile in HD could be linked to increased frontal white matter water content.

Cerebral blood flow in patients with peritoneal dialysis by an easy Z-score imaging system for brain perfusion single-photon emission tomography

Cognitive impairment has long been recognized as a complication of chronic kidney disease. However, there is little information available regarding regional cerebral blood flow (rCBF) in patients with peritoneal dialysis (PD). Therefore, we evaluated rCBF using brain single photon emission computed tomography (SPECT). We conducted a cross-sectional study in our hospital. Eighteen consecutive PD patients who could visit the hospital by themselves without any history of stroke were examined by Technetium-99 m-labeled ethylcrysteinate dimer brain SPECT. An easy Z-score imaging system (eZIS) was used to compare rCBF in PD patients with those in age-matched healthy controls. We also evaluated cognitive dysfunction with the mini-mental state examination (MMSE) questionnaire. Only one patient showed an MMSE score of 18 points, and the remaining 14 patients were considered as normal (MMSE ≥ 27), and three patients were considered to have mild cognitive impairment (24 ≤ MMSE ≤ 26). In all patients, rCBF in the posterior cingulated gyri, precunei, and parietal cortices was significantly decreased. The ratio of the reduction of rCBF in each region relative to that of rCBF across the whole brain correlated positively with the PD duration (r = 0.559; P < 0.05). The serum β2-microglobulin level was significantly higher in patients who had a higher ratio of rCBF reduction compared with those with lower ratios. In conclusion, all PD patients in the present study had decreased rCBF irrespective of MMSE scores.

Association between renal function and cognitive ability domains in the Einstein aging study: a cross-sectional analysis

BACKGROUND

The relationships between renal function and specific domains of cognitive function have rarely been explored in representative, community-based samples of older adults. We assessed the association between renal and cognitive function based on an extensive battery of neurocognitive tests.

METHODS

In a sample of Einstein Aging Study participants (n = 649, age = 70+ years) we calculated estimated glomerular filtration rate (eGFR) using the Chronic Kidney Disease Epidemiology Collaboration formula. We predefined three groups based on eGFR units of mL/min/1.73 m(2) as low (<45), medium (45-59), and high (≥60). Thirteen neurocognitive tests were subjected to principle component analysis revealing three components: a global component, an episodic memory component, and a frontal-executive component. We first examined the relationship of eGFR group to cognitive performance in each domain and then examined subtests for the domains which proved to be statistically significant.

RESULTS

The sample (mean = 79.2, 61% = female) was distributed among eGFR categories as follows: low (n = 67), medium (n = 151), and high (n = 431). The frontal-executive domain was significantly associated with poor cognitive performance in the low eGFR group (p <.001). When we examined the neuropsychological test components for frontal-executive domain, performance was lower on two of four contributing tests (Trail Making Test Part B and the Digit Symbol Substitution test). Other domains of cognitive function were not associated with eGFR.

CONCLUSIONS

Low eGFR is associated with reduced performance on executive function. Individuals with poor renal function should be assessed for cognitive impairment. Potential mechanisms are discussed.

The Montreal Cognitive Assessment (MoCA) - a sensitive screening instrument for detecting cognitive impairment in chronic hemodialysis patients

BACKGROUND

Chronic kidney disease (CKD) patients undergoing hemodialysis (HD) therapy have an increased risk of developing cognitive impairment and dementia, which are known relevant factors in disease prognosis and therapeutic success, but still lack adequate screening in clinical routine. We evaluated the Montreal Cognitive Assessment (MoCA) for suitability in assessing cognitive performance in HD patients in comparison to the commonly used Mini-Mental State Examination (MMSE) and a detailed neuropsychological test battery, used as gold standard.

METHODS

43 HD patients and 42 healthy controls with an average age of 58 years, were assessed with the MoCA, the MMSE and a detailed neuropsychological test battery, covering the domains of memory, attention, language, visuospatial and executive functions. Composite scores were created for comparison of cognitive domains and test results were analyzed using Spearman's correlation and linear regression. Cognitive dysfunction was defined using z-score values and predictive values were calculated. Sensitivity and specificity of the MoCA were determined using receiver operating characteristic (ROC) analysis.

RESULTS

HD patients performed worse in all cognitive domains, especially in memory recall and executive functions. The MoCA correlated well with the detailed test battery and identified patients with cognitive impairment with a sensitivity of 76.7% and specificity of 78.6% for a cut-off value of ≤24 out of 30 points. In the detailed assessment executive functions accounted significantly for performance in the MoCA. The MMSE only discriminated weakly between groups.

CONCLUSIONS

The MoCA represents a suitable cognitive screening tool for hemodialysis patients, demonstrating good sensitivity and specificity levels, and covering executive functions, which appear to play an important role in cognitive performance of HD patients.

The extent of informed decision-making about starting dialysis: does patients' age matter?

BACKGROUND

A growing number of elderly patients with end-stage renal disease start dialysis. We examined elderly (≥65 years) patients' views about their decision-making experience after starting dialysis in comparison with patients aged 50-64 years, and patients ≤49 years.

METHODS

Ninety-nine patients from 15 outpatient dialysis centers in North Carolina, USA completed a semi-structured interview asking them about the context of decision-making and their decision-making experience, and a 10-item investigator-developed Informed Decision-Making (IDM) questionnaire with binary response options (yes/no).

RESULTS

While IDM scores were low for all three groups (<5 out of 10), they were significantly lower for the older group compared to the other two younger groups (p = 0.02). A significantly lower percentage of the older group said that the doctor explained underlying conditions that led to kidney failure (p = 0.04), the impact of dialysis on daily life (p = 0.04), and the life-long need for dialysis (p < 0.01), and that the doctor tried to make sure the patient understood the information (p = 0.01). Also a significantly higher percentage of elderly patients felt the decision was made by the doctor rather than on their own or with their family, or collaboratively with the doctor (p = 0.04).

CONCLUSIONS

Informed decision-making is significantly poorer in patients aged 65 years or older than in younger patients. Clinicians should communicate clearly about the benefits and burdens of dialysis to older adults and provide an opportunity for them to understand the significant trade-offs that dialysis may require.

Cerebro-renal interactions: impact of uremic toxins on cognitive function

Cognitive impairment (CI) associated with chronic kidney disease (CKD) has received attention as an important problem in recent years. Causes of CI with CKD are multifactorial, and include cerebrovascular disease, renal anemia, secondary hyperparathyroidism, dialysis disequilibrium, and uremic toxins (UTs). Among these causes, little is known about the role of UTs. We therefore selected 21 uremic compounds, and summarized reports of cerebro-renal interactions associated with UTs. Among the compounds, uric acid, indoxyl sulfate, p-cresyl sulfate, interleukin 1-β, interleukin 6, TNF-α, and PTH were most likely to affect the cerebro-renal interaction dysfunction; however, sufficient data have not been obtained for other UTs. Notably, most of the data were not obtained under uremic conditions; therefore, the impact and mechanism of each UT on cognition and central nervous system in uremic state remains unknown. At present, impacts and mechanisms of UT effects on cognition are poorly understood. Clarifying the mechanisms and establishing novel therapeutic strategies for cerebro-renal interaction dysfunction is expected to be subject of future research.

Bronchial asthma is associated with increased risk of chronic kidney disease

Background

Bronchial asthma influences some chronic diseases such as coronary heart disease, diabetes mellitus, and hypertension, but the impact of asthma on vital diseases such as chronic kidney disease is not yet verified. This study aims to clarify the association between bronchial asthma and the risk of developing chronic kidney disease.

Methods

The National Health Research Institute provided a database of one million random subjects for the study. A random sample of 141 064 patients aged ≥18 years without a history of kidney disease was obtained from the database. Among them, there were 35 086 with bronchial asthma and 105 258 without asthma matched for sex and age for a ration of 1:3. After adjusting for confounding risk factors, a Cox proportional hazards model was used to compare the risk of developing chronic kidney disease during a three-year follow-up period.

Results

Of the subjects with asthma, 2 196 (6.26%) developed chronic kidney disease compared to 4 120 (3.91%) of the control subjects. Cox proportional hazards regression analysis revealed that subjects with asthma were more likely to develop chronic kidney disease (hazard ratio [HR]: 1.56; 95% CI: 1.48-1.64; p < 0.001). After adjusting for sex, age, monthly income, urbanization level, geographic region, diabetes mellitus, hypertension, hyperlipidemia, and steroid use, the HR for asthma patients was 1.40 (95% CI: 1.33-1.48; p = 0.040). There was decreased HRs in steroid use (HR: 0.56; 95% CI: 0.62-0.61; p < 0.001) in the development of chronic kidney disease. Expectorants, bronchodilators, anti-muscarinic agents, airway smooth muscle relaxants, and leukotriene receptor antagonists may also be beneficial in attenuating the risk of chronic kidney disease.

Conclusions

Patients with bronchial asthma may have increased risk of developing chronic kidney disease. The use of steroids or non-steroidal drugs in the treatment of asthma may attenuate this risk.

Clinical predictors of individual cognitive fluctuations in patients undergoing hemodialysis

BACKGROUND

Cognitive impairment in hemodialysis (HD) patients is frequent and mediated by several factors. It is unclear which patients are more susceptible to cognitive variations around the dialysis cycle and which clinical factors may play a mediator role. We aimed to answer these issues by investigating intraindividual changes within the dialysis cycle.

STUDY DESIGN

Cross-sectional observational study with repeated measures.

SETTING & PARTICIPANTS

47 HD patients and 40 controls without kidney disease, both without history of neurologic disease.

PREDICTORS

Dialysis vintage, disease duration, vascular risk factors, comorbidity index score, intradialytic weight change, frequency of hypotensive episodes, and biochemical levels (hemoglobin, leukocytes, urea, creatinine, sodium, and potassium). Covariates included demographics (age, education, and sex).

OUTCOMES & MEASUREMENTS

Significant individual deterioration in attention and executive functions (phasic and intrinsic alertness, Stroop test, and Trail Making Test) after dialysis, as measured by a regression-based reliable change method. Regression models were used to identify clinical predictors of individual cognitive decline after dialysis.

RESULTS

After dialysis, patients primarily showed prolonged reaction times and psychomotor slowing. However, individual-based analyses revealed that fluctuations in attention and executive functions were present in only a minority of patients. Significant individual fluctuations on particular attention and executive tasks were associated moderately with intradialytic hypotensive episodes, as well as with psychoactive medication, and were predicted weakly by blood leukocyte count, sodium level, dialysis vintage, and volume.

LIMITATIONS

Small sample size; patient group younger and healthier than the overall HD population, limiting generalizability.

CONCLUSIONS

Only a minority of patients exhibit significant individual cognitive fluctuations, predominantly showing deterioration after dialysis in attention and executive functions. Susceptibility to such fluctuations was predicted in part by both HD-dependent and -independent factors.

Regional homogeneity changes in hemodialysis patients with end stage renal disease: in vivo resting-state functional MRI study

OBJECTIVE

To prospectively investigate and detect early cerebral regional homogeneity (ReHo) changes in neurologically asymptomatic patients with end stage renal disease (ESRD) using in vivo resting-state functional MR imaging (Rs-fMRI).

METHODS

We enrolled 20 patients (15 men, 5 women; meanage, 37.1 years; range, 19-49 years) with ESRD and 20 healthy controls (15 men, 5 women; mean age, 38.3 years; range, 28-49 years). The mean duration of hemodialysis for the patient group was 10.7±6.4 monthes. There was no significant sex or age difference between the ESRD and control groups. Rs-fMRI was performed using a gradient-echo echo-planar imaging sequence. ReHo was calculated using software (DPARSF). Voxel-based analysis of the ReHo maps between ESRD and control groups was performed with a two-samples t test. Statistical maps were set at P value less than 0.05 and were corrected for multiple comparisons. The Mini-Mental State Examination (MMSE) was administered to all participants at imaging.

RESULTS

ReHo values were increased in the bilateral superior temporal gyrus and left medial frontal gyrus in the ERSD group compared with controls, but a significantly decreased ReHo value was found in the right middle temporal gyrus. There was no significant correlation between ReHo values and the duration of hemodialysis in the ESRD group. Both the patients and control subjects had normal MMSE scores (≥28).

CONCLUSIONS

Our finding revealed that abnormal brain activity was distributed mainly in the memory and cognition related cotices in patients with ESRD. The abnormal spontaneous neuronal activity in those areas provide information on the neural mechanisms underlying cognitive impairment in patients with ESRD, and demonstrate that Rs-fMRI with ReHo analysis is a useful non-invasive imaging tool for the detection of early cerebral ReHo changes in hemodialysis patients with ESRD.

Patient perspectives on informed decision-making surrounding dialysis initiation

BACKGROUND

Careful patient-clinician shared decision-making about dialysis initiation has been promoted, but few studies have addressed patient perspectives on the extent of information provided and how decisions to start dialysis are made.

METHODS

Ninety-nine maintenance dialysis patients recruited from 15 outpatient dialysis centers in North Carolina completed semistructured interviews on information provision and communication about the initiation of dialysis. These data were examined with content analysis. In addition, informed decision-making (IDM) scores were created by summing patient responses (yes/no) to 10 questions about the decision-making.

RESULTS

The mean IDM score was 4.4 (of 10; SD = 2.0); 67% scored 5 or lower. Age at the time of decision-making (r = -0.27, P = 0.006), years of education (r = 0.24, P = 0.02) and presence of a warning about progressing to end-stage kidney disease (t = 2.9, P = 0.005) were significantly associated with IDM scores. Nearly 70% said that the risks and burdens of dialysis were not mentioned at all, and only one patient recalled that the doctor offered the option of not starting dialysis. While a majority (67%) said that they felt they had no choice about starting dialysis (because the alternative would be death) or about dialysis modality, only 21.2% said that they had felt rushed to make a decision. About one-third of the patients perceived that the decision to start dialysis and modality was already made by the doctor.

CONCLUSIONS

A majority of patients felt unprepared and ill-informed about the initiation of dialysis. Improving the extent of IDM about dialysis may optimize patient preparation prior to starting treatment and their perceptions about the decision-making process.

Increased presence of cognitive impairment in hemodialysis patients in the absence of neurological events

BACKGROUND/AIMS

Cognitive impairment (CI) is highly prevalent among hemodialysis (HD) patients and is associated with increased morbidity and mortality. The aim was to compare cognitive function in HD patients with no history of stroke or dementia and well-matched controls. Studies are required to determine the impact of HD and chronic kidney disease-specific risks on CI.

METHODS

76 outpatients (50 receiving outpatient HD and 26 with normal kidney function matched for age and comorbidity) underwent a cross-sectional observational study. HD patients were well dialyzed and had optimal hemoglobin levels. A battery of eight neuropsychological tests was used. Outcomes included assessment scores of neurocognitive testing and prevalence and subtype of CI.

RESULTS

Compared to controls, HD subjects had significantly lower composite scores for each tested cognitive domain. In each domain except memory, the percentage of subjects with impairment was significantly higher in HD subjects than controls. Differences between the groups were independent of vascular and dementia risk factors. 82% of HD subjects met criteria for CI versus 50% of controls. Non-amnestic subtype of CI was more prevalent in both groups.

CONCLUSION

Well-dialyzed HD patients with optimized hemoglobin levels and with no history of stroke or dementia performed significantly worse on multiple measures of cognition compared to controls. A higher prevalence of non-memory impairment may suggest an underlying vascular versus neurodegenerative mechanism. HD and chronic kidney disease-specific risk factors may contribute to early CI not readily detected by routine screening methods.

Is chronic kidney disease in older people a new geriatric giant?

The global population is aging, and the number of people above the age of 85 years is growing faster than any other age group. There is an age-related decline in kidney function; however, not all individuals will develop chronic kidney disease (CKD) with advancing age. Those who are genetically predisposed and exposed to lifetime cardiovascular risk factors are likely to develop systemic atherosclerosis and CKD as a part of its manifestation. CKD promotes poor health through its association with inflammation and oxidative stress. Malnutrition, weight loss and sarcopenia are common in CKD patients, leading to poor outcomes, such as physical and cognitive dysfunction, manifesting as major geriatric syndromes. Frailty is likely to be one of the underlying processes that leads to the clinical manifestations of geriatric syndromes in patients with CKD. Therefore, functional outcomes, such as cognition and physical functioning, might be more relevant outcomes to older patients with CKD. Interventions should be developed and assessed in terms of maintaining quality rather than quantity of life before disability develops.

Continuous cognitive improvement 1 year following successful kidney transplant

Successful kidney transplantation was recently shown to lead to improvement in the cognitive performance of patients on chronic dialysis. To examine whether the early cognitive benefits of transplantation continue to develop over time, along with the patients' ongoing recovery, we addressed these questions in a prospective controlled study of 27 dialyzed patients who subsequently received a kidney transplant, 18 dialyzed patients awaiting kidney transplant, and 30 matched controls without kidney disease. Overall, successful kidney transplant contributed to a statistically significant improvement in performance on tests of motor/psychomotor speed, visual planning, memory, and abstract reasoning tested 1 year later. We also studied whether the cognitive performance of patients maintained on dialysis is stable or declines over time and found that it actually declined over this time even in adequately dialyzed patients. Measures of memory functions were particularly affected. This study indicates that the early beneficial effects of transplantation are not transient and were still evident 1 year following transplantation.