Neurocognitive function in chronic hemodialysis patients

Iron deficiency and cognitive functioning in kidney transplant recipients: findings of the TransplantLines biobank and cohort study

BACKGROUND

Neurocognitive impairment is common in kidney transplant recipients (KTRs). Adequate brain functioning requires energy and neurotransmitter activity, for which iron is essential. We aimed to investigate iron deficiency (ID) as a potentially modifiable risk factor for cognitive impairment in KTRs.

METHODS

We analyzed stable KTRs participating in the TransplantLines Biobank and Cohort study. Participants underwent neuropsychological tests for memory, mental speed, and attention and executive functioning. ID was defined as ferritin <100 µg/mL or 100-299 µg/mL with transferrin saturation (TSAT) ≤20%. Associations between iron status and norm scores of neurocognitive outcomes, corrected for age, sex and education, were assessed using multivariable linear regression analyses adjusted for potential confounders including hemoglobin.

RESULTS

We included 166 KTRs [median (IQR) age 57 (45-65) years, 59% male, estimated glomerular filtration rate 51±18 mL/min/1.73 m2]. Time since transplantation was 5.8 (1.0-12.0) years. Prevalence of ID was 65%. ID was independently associated with lower scores for mental speed (std.β = -0.19, P = .02) and attention and executive functioning (std.β = -0.19, P = .02), and tended to be associated with worse memory (std.β = -0.16, P = .07). Lower plasma ferritin levels were associated with worse memory (std.β = 0.23, P = .007), mental speed (std.β = 0.34, P < .001), and attention and executive functioning (std.β = 0.30, P = .001). Lower TSAT was associated with worse memory (std.β = 0.19, P = .04) and mental speed (std.β = 0.27, P = .003), and tended to be associated with worse attention and executive functioning (std.β = 0.16, P = .08).

CONCLUSIONS

Iron-deficient KTRs performed worse on neurocognitive tasks measuring memory, mental speed, and attention and executive functioning. These findings set the stage for prospective studies addressing whether ID correction restores cognitive function after kidney transplantation.

Dialysis adequacy and hemoglobin levels predict cerebral atrophy in maintenance-hemodialysis patients

The pathogenesis of cerebral atrophy (CA) is not clear. Previous studies show a high incidence of preterm CA in hemodialysis patients. This study aims to investigate the factors influencing CA and to derive a CA prediction nomogram in maintenance-hemodialysis patients. First, brain volumes of hemodialysis patients (≤55 years) were compared against age- and sex-matched healthy controls, and differences were revealed in bilateral insular cisterns width, maximum cerebral sulci width, Evans index, ventricular-brain ratio, frontal atrophy index, and temporal lobe ratio. Then, the patients were divided equally into "no or mild" or "severe" CA groups. Potential factors influencing CA were screened. Kt/V (urea removal index) and hemoglobin levels negatively correlated with CA degree, and were used to establish a nomogram within randomly assigned training and validation patient groups. The areas under the receiver operating characteristic curves (AUROC) for training and validation groups were 0.703 and 0.744, respectively. When potassium and calcium were added to the nomogram, the AUROC for training/validation group increased to 0.748/0.806. The nomogram had optimal AUROC for training (0.759) and validation (0.804) groups when albumin was also included. Hemodialysis patients showed reduced anterior brain volumes and the nomogram established herein may have predictive value for developing CA.

Uremic encephalopathy

Uremic encephalopathy encompasses a wide range of central nervous system abnormalities associated with poor kidney function occurring with either progressive chronic kidney disease or acute kidney injury. The syndrome is likely caused by retention of uremic solutes, alterations in hormonal metabolism, changes in electrolyte and acid-base homeostasis, as well as changes in vascular reactivity, blood-brain barrier transport, and inflammation. There are no defining clinical, laboratory, or imaging findings, and the diagnosis is often made retrospectively when symptoms improve after dialysis or transplantation. The diagnosis is also made difficult because of the many confounding and overlapping conditions seen in patients with chronic kidney disease and acute kidney injury. Thus, institution of kidney replacement therapy should be considered as a trial to improve symptoms in the right clinical context. Neurological symptoms that do not improve after improvement in clearance should prompt a search for other explanations. Further knowledge linking possible uremic retention solutes with neurological symptoms is needed to better understand this syndrome as well as to develop more tailored treatments that aim to improve cognitive function.

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 potential barrier to adherence? Memory for future intentions is impaired in hemodialysis patients

INTRODUCTION

End-stage renal disease (ESRD) has been associated with a range of cognitive deficits, including impaired retrospective memory and attention. Prospective memory (PM) is memory for future intentions, such as remembering to take medication on time. Prospective memory has not been examined in any ESRD patients; yet, the implications upon diet and medication management could potentially have detrimental effects on patient welfare. This is the first study to examine PM in ESRD patients being treated with hemodialysis (HD).

METHODS

Hemodialysis patients (n = 18) were compared with age-matched and education-matched controls (n = 18) on a boardgame task that emulates a typical week of activities (i.e., grocery shopping, meetings with friends), requiring the participant to remember a series of upcoming tasks. Other measures were also examined, including general cognitive decline, measures of independent living, IQ, and mood.

FINDINGS

Patients recalled significantly fewer upcoming events than the control group, suggesting an impairment of PM. No significant relationship was found between PM performance and any other measures, suggesting the difference between groups is likely due to the effects of ESRD, HD treatment, or some associated comorbidity.

DISCUSSION

This is the first study to demonstrate a PM deficit in patients undergoing HD treatment. This finding contributes to the current knowledge of the cognitive profile of patients undergoing HD while also highlighting the implications that a PM deficit may have on patient quality of life. The finding may go some way to explaining variances in patients' ability to monitor and adhere to medication and dietary regimes and, ultimately, to live independently. The study also highlights the necessity of viewing treatment for ESRD as a holistic process to maximize patient well-being.

Increased Serum Level of IGF-1 Correlates With Better Cognitive Status in End-Stage Renal Disease Patients Undergoing Hemodialysis

Prevalence of cognitive function decline in end stage renal disease (ESRD) patients undergoing hemodialysis is higher than in the general population. We analyzed risk factors for cognitive function decline in those patients. This study included 93 ESRD patients undergoing hemodialysis two or three times a week in three centers for hemodialysis in Montenegro. The cognitive status of patients was assessed using the mini mental score examination (MMSE) test. All 93 patients have been divided into three groups according to the results of MMSE. Patients in the first group had severe cognitive impairment and MMSE score below 17 (26.88%), patients in the second group with MMSE score 18-23 had moderate cognitive impairment (40.86%) and third group of patients have MMSE >24 and no cognitive impairment (32.26%). There were no significant differences between groups for gender, smoking habits and level of parathyroid hormone. Level of schooling was significantly different between groups of patients (P < 0.001). Laboratory markers observed in this study with significant differences between groups were: IGF 1, IGFBP 3, erythrocytes and hemoglobin (P < 0.001, P = 0.004, P < 0.001, P = 0.002, respectively). IGF 1 proved to be of great importance for evaluating cognitive status in our study. This marker was statistically different between groups (P < 0.001) and Tukey post hoc analysis showed significant differences between all three groups (first and second group P = 0.045, second and third group P = 0.015, first and third group P < 0.001). Our data suggest that IGF 1 can be considered as novel biomarker for assessment of cognitive functioning in CKD patients, which can be of huge clinical importance.

Analysis of Risk Factors for Development of Cognitive Disorders in Maintenance Hemodialysis Patients – Pilot Study

Prevalence of cognitive disorders is high in maintenance hemodialysis patients. Montreal cognitive assessment (MoCA) is used for detecting and evaluation of cognitive disorder degree in this patient population. In examined patient population, only 5 (12.5%) of them had normal cognitive function (MoCA ≥26). Mild cognitive impairment (MoCA 18-26) was found in 65.9% (29) patients, while moderate cognitive disorder (MoCA 10-17) was detected in 6 (21.6%) patients. Major cognitive disorder wasn’t detected in examined population. Statistically significant correlation was not established between laboratory parameters and overall MoCA score. Statistically significant correlation, however, was established between MoCA item that evaluates space and time orientation and intermediate secondary hyperparathyroidism and space and time orientation and severe secondary hyperparathyroidism. Hemodynamic instability during hemodialysis and silent ischemia of the brain are increasing risk of appearance of cognitive disorders in maintenance hemodialysis patients.

Oropharyngeal swallowing in chronic renal failure

OBJECTIVE

To characterize the oropharyngeal swallowing profile of patients with chronic renal failure.

METHODS

A cross-sectional clinical study involving 20 adults diagnosed with chronic renal failure in hospital stay was conducted. The evaluation of swallowing was performed by videofluoroscopy, and characterization of findings was based on effectiveness and safety parameters. Functional Oral Intake Scale (FOIS) was also applied.

RESULTS

On videofluoroscopy, 16 patients presented changes in oral and pharyngeal patterns, three individuals presented impairment at the pharyngeal phase, and only one individual presented changes only at the oral phase of swallowing. Furthermore, videofluoroscopy showed penetration and tracheal aspiration in 30% of the sample. Before the videofluoroscopy, four individuals (20%) were at level 5 of FOIS scale, whereas 16 individuals (80%) were at level 7. After adjustments of the oral diet consistency because of safety and swallowing effectiveness, FOIS classification was six individuals at level 1, seven at level 4, four at level 5, and three at level 6.

CONCLUSION

The characterization of oropharyngeal swallowing profile in chronic renal patients showed abnormalities at oral and pharyngeal phase, including penetration and tracheal aspiration, which requires oral intake changes.

Analysis of Risk Factors for Development of Cognitive Disorders in Maintenance Hemodialysis Patients - Pilot Study

Prevalence of cognitive disorders is high in maintenance hemodialysis patients. Montreal cognitive assessment (MoCA) is used for detecting and evaluation of cognitive disorder degree in this patient population. In examined patient population, only 5 (12.5%) of them had normal cognitive function (MoCA ≥26). Mild cognitive impairment (MoCA 18-26) was found in 65.9% (29) patients, while moderate cognitive disorder (MoCA 10-17) was detected in 6 (21.6%) patients. Major cognitive disorder wasn’t detected in examined population. Statistically signifi cant correlation was not established between laboratory parameters and overall MoCA score. Statistically signifi cant correlation, however, was established between MoCA item that evaluates space and time orientation and intermediate secondary hyperparathyroidism and space and time orientation and severe secondary hyperparathyroidism. Hemodynamic instability during hemodialysis and silent ischemia of the brain are increasing risk of appearance of cognitive disorders in maintenance hemodialysis patients.

Cognition in People With End-Stage Kidney Disease Treated With Hemodialysis: A Systematic Review and Meta-analysis

BACKGROUND

Cognitive impairment is associated with poorer quality of life, risk for hospitalization, and mortality. Cognitive impairment is common in people with end-stage kidney disease treated with hemodialysis, yet the severity and specific cognitive deficits are uncertain.

STUDY DESIGN

Systematic review and meta-analysis.

SETTING & POPULATION

Adults receiving hemodialysis compared with the general population, people with non-dialysis-dependent chronic kidney disease (NDD-CKD), people receiving peritoneal dialysis, or people with nondialyzed chronic kidney failure.

SELECTION CRITERIA FOR STUDIES

Randomized controlled trials, cohort or cross-sectional studies without language restriction.

INDEX TESTS

Validated neuropsychological tests of cognition.

OUTCOMES

Cognitive test scores, aggregated by cognitive domain: orientation and attention, perception, memory, language, construction and motor performance, concept formation and reasoning, and executive functions.

RESULTS

42 studies of 3,522 participants. Studies were of high or uncertain risk of bias, assessed by the Newcastle-Ottawa Scale. People treated with hemodialysis had worse cognition than the general population, particularly in attention (n=22; standardized mean difference [SMD], -0.93; 95% CI, -1.18 to -0.68). Hemodialysis patients performed better than nondialyzed patients with chronic kidney failure in attention (n=6; SMD, 0.70; 95% CI, 0.45 to 0.96) and memory (n=6; SMD, 0.36; 95% CI, 0.08 to 0.63), but had poorer memory than the general population (n=16; SMD, -0.41; 95% CI, -0.91 to 0.09) and people with NDD-CKD (n=5; SMD, -0.40; 95% CI, -0.60 to -0.21). There were insufficient data to show other differences among people receiving hemodialysis and those receiving peritoneal dialysis or with NDD-CKD.

LIMITATIONS

Potentially biased studies, not wholly adjusted for education. High heterogeneity, mainly due to the large variety of tests used to assess cognition.

CONCLUSIONS

People treated with hemodialysis have impaired cognitive function compared to the general population, particularly in the domains of orientation and attention and executive function. Cognitive deficits in specific domains should be further explored in this population and should be considered when approaching education and chronic disease management.

Scale development study: The Fluid Control in Hemodialysis Patients

AIM

The aim of this study was to develop a valid and reliable measurement instrument to identify knowledge, behaviors, and attitudes of hemodialysis (HD) patients about fluid control as these patients are inadequate in ensuring and sustaining fluid control.

METHODS

The sample of this methodological study consisted of 276 HD patients who are being treated in two public and two private hemodialysis centers. The validity of the scale was assessed through content validity, construct validity, and similar scale validity, and its reliability through item analysis, internal consistency coefficient and test-retest. For the content validity of the scale, expert views were assessed, and opinions of a Turkish language specialist were obtained.

RESULTS

According to the exploratory factor analysis, the scale had 24 items and three subdimensions, namely, knowledge, behavior, and attitude. The total variance explained was found to be 51.15%. Cronbach's alpha reliability coefficient of the Fluid Control in Hemodialysis Patients Scale (FCHPS) turned out to be 0.88 and Cronbach's alpha for its subdimensions were 0.92, 0.80, and 0.67, respectively. The correlation value between test and retest was 0.94 (P < 0.001). A moderate significant correlation (r = 0.58, P < 0.001) was found between the scale scores and the scores of the Dialysis Diet and Fluid Restrictions Non-adherence Questionnaire.

CONCLUSION

The FCHPS that was developed has good validity and reliability. This scale can be used to measure knowledge, behavior, and attitude of hemodialysis patients about fluid restriction.

Effectiveness of microbubble removal in an airtrap with a free surface interface

An end stage renal disease patient will undergo haemodialysis (HD) three or four times a week for four to five hours per session. Because of the chronic nature of the treatment, any minor imperfection in the extracorporeal system may become significant over time. Clinical studies have raised concerns relating to small microbubbles entering HD patients. These bubbles lead to further pathophysiological complications with the size of the bubble being a major factor. Microbubbles of different sizes can be generated throughout the extra-corporeal HD circuit. It is important to understand the possibility of these bubbles passing through the air trap or successfully being removed which indicates the performance of the air trap, the only mechanics of removing air bubbles. Chronic exposure to various sizes of microbubbles was analysed in detail for haemodialysis patients. However, smaller microbubbles are shown to be able to pass our modelled air trap. While studies have reported the presence of bubbles before and after the air trap, because these bubbles are only counted and not tracked, the performance of the air trap for removing different bubble sizes is not understood. Here, the performance of the air trap in filtering bubbles and the possibility of different bubble sizes passing through the air trap with the presence of the free surface interface have been evaluated. The modelled air trap is shown to be ineffective for filtering small micro bubbles.

Pulsatility Produced by the Hemodialysis Roller Pump as Measured by Doppler Ultrasound

Microbubbles have previously been detected in the hemodialysis extracorporeal circuit and can enter the blood vessel leading to potential complications. A potential source of these microbubbles is highly pulsatile flow resulting in cavitation. This study quantified the pulsatility produced by the roller pump throughout the extracorporeal circuit. A Sonosite S-series ultrasound probe (FUJIFILM Sonosite Inc., Tokyo, Japan) was used on a single patient during normal hemodialysis treatment. The Doppler waveform showed highly pulsatile flow throughout the circuit with the greatest pulse occurring after the pump itself. The velocity pulse after the pump ranged from 57.6 ± 1.74 cm/s to -72 ± 4.13 cm/s. Flow reversal occurred when contact between the forward roller and tubing ended. The amplitude of the pulse was reduced from 129.6 cm/s to 16.25 cm/s and 6.87 cm/s following the dialyzer and venous air trap. This resulted in almost nonpulsatile, continuous flow returning to the patient through the venous needle. These results indicate that the roller pump may be a source of microbubble formation from cavitation due to the highly pulsatile blood flow. The venous air trap was identified as the most effective mechanism in reducing the pulsatility. The inclusion of multiple rollers is also recommended to offer an effective solution in dampening the pulse produced by the pump.

Aberrant functional connectome in neurologically asymptomatic patients with end-stage renal disease

Purpose

This study aimed to investigate the topological organization of intrinsic functional brain networks in patients with end-stage renal disease (ESRD).

Materials and Methods

Resting-state functional MRI data were collected from 22 patients with ESRD (16 men, 18–61 years) and 29age- and gender-matched healthy controls (HCs, 19 men, 32–61 years). Whole-brain functional networks were obtained by calculating the interregional correlation of low-frequency fluctuations in spontaneous brain activity among 1,024 parcels that cover the entire cerebrum. Weighted graph-based models were then employed to topologically characterize these networks at different global, modular and nodal levels.

Results

Compared to HCs, the patients exhibited significant disruption in parallel information processing over the whole networks (P< 0.05). The disruption was present in all the functional modules (default mode, executive control, sensorimotor and visual networks) although decreased functional connectivity was observed only within the default mode network. Regional analysis showed that the disease disproportionately weakened nodal efficiency of the default mode components and tended to preferentially affect central or hub-like regions. Intriguingly, the network abnormalities correlated with biochemical hemoglobin and serum calcium levels in the patients. Finally, the functional changes were substantively unchanged after correcting for gray matter atrophy in the patients.

Conclusion

Our findings provide evidence for the disconnection nature of ESRD’s brain and therefore have important implications for understanding the neuropathologic substrate of the disease from disrupted network organization perspective.

Patient-reported cognitive functioning and daily functioning in chronic dialysis patients

Subjective cognitive impairment negatively affects daily functioning, health-related quality of life, and health care consumption, and is predictive of future cognitive decline in many patient populations. However, no subjective measures of multidimensional cognitive functioning have been evaluated for dialysis patients. Our purposes were to examine (1) the association between patient-reported (subjective) cognitive functioning and objective cognitive functioning and (2) the relationships between subjective and objective cognitive functioning and everyday functioning of dialysis patients. We used baseline data from an ongoing longitudinal observational study of trajectories in dialysis patients' multidimensional quality of life. One hundred thirty-five patients completed a telephone-based neuropsychological battery (Brief Test of Adult Cognition by Telephone, a measure of objective cognitive functioning), a measure of subjective cognitive functioning (Patient's Assessment of Own Functioning Inventory), and measures of everyday functioning (Activities of Daily Living [ADL] and Instrumental Activities of Daily Living [IADL] scales). After controlling for age and education, there was a modest correlation (r = 0.33, P > 0.001) between subjective and objective cognitive functioning. Multivariate logistic regression models showed subjective, but not objective, cognitive functioning was a significant predictor of both ADLs and IADLs. The findings suggest the potential clinical value of subjective measures of cognitive functioning, not to replace objective measures or diagnostic tests, but rather to optimize the meaningfulness of clinical assessment and management.

Predominant gray matter volume loss in patients with end-stage renal disease: a voxel-based morphometry study

To investigate the pattern of brain volume changes in patients with end-stage renal disease (ESRD) using voxel-based morphometry (VBM) and correlation with clinical and neuropsychological (NP) tests. Fifty seven ESRD patients with no anatomical abnormalities in conventional magnetic resonance imaging [24 patients with abnormal NP scores, 16 male, 39 ± 12 years; 33 patients with normal NP scores, 23 male, 35 ± 9.7 years] and 22 age- and gender-matched healthy controls (14 male, 36 ± 10.1 years) were recruited in this study. Results from VBM analysis were analyzed with ANOVA test among 3 groups (controls, minimal nephro-encephalopathy group, non-nephro-encephalopathy group). Multiple linear regression analysis was used to investigate the effect of serum urea and creatinine, and dialysis duration on the brain volumes in ESRD patients. Correlation analysis was performed to investigate the association between NP scores with the brain volumes in ESRD patients. Compared with healthy controls, ESRD patients showed diffusely decreased gray matter volume that further decreased in the presence of encephalopathy. Multiple linear regression results showed that serum urea was negatively associated with changes in gray matter volume in many regions, while dialysis duration was negatively associated with some white matter volume changes (All P < 0.05, AlphaSim correction). NP scores correlated with some decreased gray matter volume in ESRD patients (All P < 0.05, AlphaSim correction). No correlation was found between white matter volume and any NP test scores in ESRD patients. This study found predominantly decreased gray matter volume in ESRD patients, which was associated with neurocognitive dysfunction. Serum urea level may be a risk factor for decreased gray matter in ESRD patients.

The prevalence, severity, and association with HbA1c and fibrinogen of cognitive impairment in chronic kidney disease

Cognitive impairment is a frequent finding in patients with chronic kidney disease (CKD). We examined cognitive performance in a prospective study of 119 patients with CKD stages 3-5 (including dialysis) and 54 control patients of the same age without CKD but with similar vascular risk profiles. Analysis included a comprehensive test battery evaluating memory, information processing speed, executive function, language, and visuoconstructive function, in addition to depression and anxiety. Thirty percent of patients with CKD had cognitive deficits (one or more s.d. below control patient performance). Cognitive deficits (T-value related to published norm values) were mild but significantly decreased to 48.8 in patients with stage 3-5 CKD not requiring hemodialysis and 47.2 in patients with stage 5D disease requiring hemodialysis, compared with 51.5 in control patients. Linear regressions among patients with CKD (forced entry strategy) showed that age (β=-0.50 per s.d.), HbA1c (β=-0.18 per s.d.), and fibrinogen (β=-0.18 per s.d.) predicted cognitive performance. Interestingly, HbA1c discriminated cognition in all age groups, while fibrinogen differentiated cognition particularly in patients over 70 years of age. Thus, our cross-sectional study suggests the severity of cognitive impairment in CKD is mild. As such, longitudinal studies are required to further characterize the role of cognitive deficits in CKD.

Altered pattern of spontaneous brain activity in the patients with end-stage renal disease: a resting-state functional MRI study with regional homogeneity analysis

PURPOSE

To investigate the pattern of spontaneous neural activity in patients with end-stage renal disease (ESRD) with and without neurocognitive dysfunction using resting-state functional magnetic resonance imaging (rs-fMRI) with a regional homogeneity (ReHo) algorithm.

MATERIALS AND METHODS

rs-fMRI data were acquired in 36 ESRD patients (minimal nephro-encephalopathy [MNE], n = 19, 13 male, 37±12.07 years; non-nephro-encephalopathy [non-NE], n = 17, 11 male, 38±12.13 years) and 20 healthy controls (13 male, 7 female, 36±10.27 years). Neuropsychological (number connection test type A [NCT-A], digit symbol test [DST]) and laboratory tests were performed in all patients. The Kendall's coefficient of concordance (KCC) was used to measure the regional homogeneity for each subject. The regional homogeneity maps were compared using ANOVA tests among MNE, non-NE, and healthy control groups and post hoc t -tests between each pair in a voxel-wise way. A multiple regression analysis was performed to evaluate the relationships between ReHo index and NCT-A, DST scores, serum creatinine and urea levels, disease and dialysis duration.

RESULTS

Compared with healthy controls, both MNE and non-NE patients showed decreased ReHo in the multiple areas of bilateral frontal, parietal and temporal lobes. Compared with the non-NE, MNE patients showed decreased ReHo in the right inferior parietal lobe (IPL), medial frontal cortex (MFC) and left precuneus (PCu). The NCT-A scores and serum urea levels of ESRD patients negatively correlated with ReHo values in the frontal and parietal lobes, while DST scores positively correlated with ReHo values in the bilateral PCC/precuneus, MFC and inferior parietal lobe (IPL) (all P<0.05, AlphaSim corrected). No significant correlations were found between any regional ReHo values and disease duration, dialysis duration and serum creatinine values in ESRD patients (all P>0.05, AlphaSim corrected).

CONCLUSION

Diffused decreased ReHo values were found in both MNE and non-NE patients. The progressively decreased ReHo in the default mode network (DMN), frontal and parietal lobes might be trait-related in MNE. The ReHo analysis may be potentially valuable for elucidating neurocognitive abnormalities of ESRD patients and detecting the development from non-NE to MNE.

Attention and information processing in end stage renal disease and effect of hemodialysis: a bedside study

The neurobehavioral syndrome of uremia in chronic kidney disease affects the functioning of the central nervous system. Cognitive impairment is one of the most important manifestations of this dysfunction. The process of hemodialysis is known to bring about conflicting changes in the cognitive status of patients. In the present study an assessment of cognitive status of patients with end stage renal disease was done in comparison to controls before and after a session of hemodialysis using simple bedside paper-pencil tests. Thirty patients of end stage renal disease on maintenance dialysis for at least one month with MMSE score >24 were assessed one hour before and one hour after hemodialysis using Digit Symbol Substitution Test, One Letter and Three Letter Cancellations tasks. Their results were compared to age and sex matched healthy controls. The patients with end stage renal disease had significantly lower performance in cognitive tests in comparison to controls. The performance improved 1 hour after hemodialysis in comparison to pre-dialysis values. However, the values after dialysis were significantly lower than in controls, thereby indicating that though the cognitive functions improved after hemodialysis, they did not reach the control levels. There was also a significant change in the biochemical parameters after dialysis. We conclude that patients with end stage renal disease suffered from cognitive impairment which improved on hemodialysis due to removal of metabolic waste products.

Evaluation of the cognitive functions in patients with chronic renal failure before and after renal transplantation

Chronic renal failure (CRF) and dialysis treatment affect central nervous system and studies have shown that neurocognitive dysfunctions are caused by CRF and dialysis treatment. The aim of this study was to evaluate the changes in cognitive functions of CRF patients after renal transplantation. Neurocognitive functions of 40 renal transplantation patients aged 18-65 years were determined before, 6 and 12 months after transplantation between 2008 and 2010 using neuropsychological tests. Rey Auditory-Verbal Learning Test (RVLT), Rey Complex Figure Test (RCFT), ADAS-cog Test, Stroop Test (ST), Digit Span Test (DST), and Trail Making Test (TMT) were applied. The test results were statistically compared taking into consideration the patients' levels of education, age, gender, donor type, duration of dialysis, dialysis type, and duration of CRF. Neuropsychological test results statistically significantly increased in all the patients after renal transplantation (p < 0.05). The female patients' RVLT test results were statistically higher than the test results of the male patients (p < 0.05). DST, RCFT, RVLT, and (Verbal Fluency Test) VFT results were statistically higher in the patients who were 33 years old or younger (p < 0.05). The patients with high school and college education had statistically significantly higher results in all the tests when compared with the patients that were elementary school graduates (p < 0.05). DST forward task, ST, and RVLT results of the patients, who had received dialysis treatment for 1 year or less, were found to be statistically higher than the results of the patients who had received dialysis for more than 1 year (p < 0.05). The results of RCFT, RVLT, DST backward task, and VFT were statistically higher in the peritoneal dialysis patients than in the hemodialysis patients (p < 0.05). The donor type and the duration of CRF had no significant effects on the results (p > 0.05). The results of this study showed significant improvement in attention, memory, executive functions, pace of data processing and language functions in CRF patients after renal transplantation, as proven with neuropsychological tests.

A high blood level in the venous chamber and a wet-stored dialyzer help to reduce exposure for microemboli during hemodialysis

During hemodialysis (HD), microemboli develop in the blood circuit of the apparatus. These microemboli can pass through the venous chamber and enter into the patient's circulation. The aim of this study was to investigate whether it is possible to reduce the risk for exposure of microemboli by altering of the treatment mode. Twenty patients on chronic HD were randomized to a prospective cross-over study of three modes of HD: (a) a dry-stored dialyzer (F8HPS, Fresenius, steam sterilized) with a low blood level in the venous chamber (DL), (b) the same dialyzer as above, but with a high level in the venous chamber (DH), and (c) a wet-stored dialyzer (Rexeed, Asahi Kasei Medical, gamma sterilized) with a high blood level (WH). Microemboli measurements were obtained in a continuous fashion during 180 minutes of HD for all settings. A greater number of microemboli were detected during dialysis with the setting DL vs. WH (odds ratio [OR] 4.07, 95% confidence interval [CI] 4.03-4.11, P<0.0001) and DH vs. WH (OR 1.18, 95% CI 1.17-1.19, P<0.0001) and less for DH vs. DL (OR 0.290, 95% CI 0.288-0.293, P<0.0001). These data indicate that emboli exposure was least when using WH, greater with DH, and most with DL. This study shows that using a high blood level in the venous chamber and wet-stored dialyzers may reduce the number of microemboli.

Psychological Characteristics of Patients Treated by Chronic Maintenance Hemodialysis

Studies related to psychological aspects of dialysis patients show that depression and anxiety are the most common characteristics.

The aim of our study was to analyze the personality profile in patients on chronic maintenance dialysis and to evaluate more specifically the level of depression. The total number of patients was 68 (30 females and 38 males), with mean age 62.3 and 56.5 for females and males respectively. Mean duration of dialysis was 6.73 years for females and 6.68 years for men (the period varied from 0.5 to 18 years).

For the evaluation of psychological characteristics, we used two psychometric instruments: Minnesota Multiphase Personality Inventory (MMPI- 201) and Beck Depression Inventory. The obtained results confirmed the presence of depression in patients treated with hemodialysis. The level of depression is variable (minimal is present in 21.43%; mild in 35.71%; moderate in 17.85% and severe in 14.28% of patients). The depression is significantly positively correlated with age (p<0.05) as well as with educational level, and negatively with the duration of dialysis.

Specific characteristics of personality obtained with MMPI are hypersensitivity, depressive mood, and withdrawal from friends and relatives. More specific emotional traits are the accentuated anxiety, low level of hostility, but very high passive aggression which destroys their social communications. Some response measures for depression such as relaxation training, psychological support, music therapy, or peripheral biofeedback are recommended.

Neurocognitive effects in welders exposed to aluminium

Objectives:

Various authors who studied the effects of aluminium (Al) exposure on the neurocognitive system in the last 30 years have reached different and often contradictory conclusions. The aim of this study is to help clarify the effects that the metal causes on cognitive ability in a group of naval welders exposed to Al.

Methods:

The study was performed on a sample of 86 male Al welders in a shipyard in Messina. The average value of environmental Al, recorded in the workplace, was 19.5 mg/m3. The blood levels of Al, zinc, manganese, lead and chromium were monitored in all the subjects. The reagents used for the neuropsychic study were the Wechsler Memory Scale (WMS), the Colour Word Test or Stroop Test and the Test of Attention Matrixes. The results were compared with those obtained in a similar control group not exposed to Al and with an Al-b value of 6.93 g/l.

Results:

For all the mental reagents used, the reply is obtained in the sample of exposed subjects showed decreased cognitive response with regard to attention and memory performance. The comparison between the individual tests showed greater sensitivity of performance studied using the WMS and the Stroop Test compared with the Test of Attention Matrixes. The alterations encountered in the cognitive functions studied increased proportionally to time of exposure and quantity of metal absorbed.

Conclusion:

The study confirmed that occupational exposure to Al causes alteration in cognitive responses that are more evident in complex functions.

Are there neurological consequences of recurrent intradialytic hypotension?

Structural abnormalities of the brain are common in hemodialysis (HD) patients, as are a wide range of severe functional deficiencies of cerebral function. Both depression and increasing dependency are highly prevalent in HD patients and worsen severely within the first 12 months of dialysis initiation. HD, as it is commonly practiced, is associated with significant recurrent episodes of circulatory stress. This results in acute injury to the heart, skin, kidney and gut, and drives longer term end-organ chronic injury. This article aims to explore the hypothesis that the cerebral microcirculation is also sensitive to dialysis-based circulatory stress (and other multiorgan consequences of recurrent dialysis-induced ischemia), and that this may drive specific patterns of brain injury with resultant psychiatric and functional consequences.

Kidney transplantation improves cognitive and psychomotor functions in adult hemodialysis patients

BACKGROUND

Kidney failure is believed to have a negative impact on cognitive function, and cognitive impairment is common among maintenance hemodialysis (HD) patients. Previous studies have shown a beneficial effect of kidney transplantation in certain cognitive tests but not across all cognitive domains assessed. But, most of these studies performed a cross-sectional analysis, suffered from lack of standardization of adequate dialysis dose, hemoglobin level, and insufficient sensitivity of neuropsychological tests. The aim of this study was to evaluate the effect of successful kidney transplantation on cognitive and psychomotor function in adequately dialyzed HD patients without severe anemia, using sensitive neuropsychological tests.

METHODS

Twenty-one medically stable patients (aged 45.1 ± 7.9 years) on maintenance HD (7.6 ± 4.2 years) were investigated before and 20.5 ± 8.5 months after successful kidney transplantation using Complex Reactiometer Drenovac, a battery of computer-generated psychological tests which measure a simple visual discrimination of signal location, short-term memory, simple convergent visual orientation and convergent thinking.

RESULTS

Our findings indicated significantly better cognitive and psychomotor performance after transplantation on tests that assess processing speed, attention, short time memory, convergent thinking and executive functioning. Also, significant negative correlation between follow-up time after transplantation and cognitive and psychomotor performance in minimum time of solving test of convergent thinking was found.

CONCLUSION

We conclude that cognitive and psychomotor functions are superior after successful kidney transplantation compared with HD, and that early beneficial effects of transplantation are not transient and cognitive and psychomotor performance might be even improved in time following successful transplantation.

Prospective Changes in Health-Related Quality of Life and Emotional Outcomes in Kidney Transplantation over 6 Years

Little is known on long-term outcomes in kidney transplantation. This study evaluated changes and predictors of generic and transplantation-specific health-related quality of life (HQoL) over six years in N = 102 kidney transplant survivors using the Short-form Health Survey-36 and the Transplant Effects questionnaire. Mixed models analysis was used to determine long-term outcomes. Emotional HQoL improved over time: Mental Component score, Mental Health, Energy (Ps = .000). Physical HQoL deteriorated: Physical Component Score (P = .001), Pain (P = .002). LRD transplant recipients had greater decline in physical functioning (P = .003) and PCS (P = .000) compared to cadaver recipients. Worry about the transplant (P = .036) and feelings of responsibility (P = .008) increased significantly over time. Worry about the transplant and perceived ability to work predicted 12.7% and 31.1% in variance in MCS and PCS, respectively. Efforts should be made to maintain HQoL and emotional outcomes with ongoing monitoring and support programs throughout the course of posttransplant care.

Cardiovascular disease and cognitive function in maintenance hemodialysis patients

BACKGROUND

Cardiovascular disease (CVD) and cognitive impairment are common in dialysis patients. Given the proposed role of microvascular disease on cognitive function, particularly cognitive domains that incorporate executive functions, we hypothesized that prevalent systemic CVD would be associated with worse cognitive performance in hemodialysis patients.

DESIGN

Cross-sectional cohort.

SETTING & PARTICIPANTS

200 maintenance hemodialysis patients without prior stroke from 5 Boston-area hemodialysis units.

PREDICTOR

CVD, defined as history of coronary disease or peripheral vascular disease.

OUTCOME

Performance on a detailed neurocognitive battery. Primary analyses quantified cognitive performance using principal components analysis to reduce cognitive tests to a processing speed/executive function domain and a memory domain. Multivariable linear regression models adjusted for age, sex, education, race, and other clinical and demographic characteristics.

RESULTS

Mean age of participants was 62 ± 18 (standard deviation) years and 75 (38%) had CVD. Individuals with CVD were older and more likely to be men, have diabetes, and be current or former smokers. In adjusted models, individuals with CVD performed 0.50 standard deviation worse (P < 0.001) on tests assessing processing speed/executive function, whereas there was no difference in performance on tests of memory. Similar results were seen assessing individual tests, with performance on the Block Design, Digit Symbol Coding, and Trail Making Tests A and B significantly associated with CVD in age-, sex-, education-, and race-adjusted analyses and approaching significance in fully adjusted models.

LIMITATIONS

CVD ascertainment dependent on patient recall and dialysis unit documentation. No brain imaging.

CONCLUSIONS

The presence of CVD is associated with worse cognitive performance on tests of processing speed and executive functioning in hemodialysis patients and identifies a high-risk population for greater difficulty with complex tasks.

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.

Neurocognitive profile of an adult sample with chronic kidney disease

Chronic kidney disease (CKD) is a common and debilitating illness that impacts neurocognitive function. However, the majority of previous studies varied in methodologic design and rigor, thus minimizing definitive conclusions. The present study was designed to determine the impact of CKD on neurocognitive function through specific examination of CKD factors and therapeutic interventions. We evaluated 120 CKD outpatients and 41 healthy donors (controls) in terms of neurocognitive function, anxiety, and depressive symptomatology, and somnolence. Information regarding medical and treatment history was recorded. Twenty-three percent of CKD patients presented with cognitive impairment. Stage 5 patients had lower scores (p < .05) compared with controls and patients in stage 3 and 4 on measures of global cognitive function. No differences in global cognitive function were found between stage 3 and 4 patients and controls. A greater proportion of patients undergoing hemodialysis relative to those treated with peritoneal dialysis showed impairment on measures of memory functions. Results suggest that stage 5 CKD patients may present with impaired cognitive functions. Anemia appeared to be a key variable that may explain the memory impairment in this sample. Future longitudinal investigations of CKD are warranted to determine the trajectory of cognitive impairment.

[Cognitive impairment and chronic kidney disease: which links?]

Ageing of the population leads to an increase of cognitive disorders and chronic renal failure incidence. Compared to the general population, prevalence of cognitive impairment is more important in renal failure patients, especially in dialyzed patients. No direct link has been established between renal failure and cognitive impairment. The care of older and older patients and the high frequency of vascular risk factors, in particular hypertension and diabetes, partially explain the prevalence of vascular dementia and Alzheimer disease in this population. Other factors as the anemia, phosphocalcic metabolism disorders facilitate the cognitive impairment. The present work reviews the links existing between chronic renal failure and cognitive impairment.

Cognitive function and dialysis adequacy: no clear relationship

BACKGROUND/AIMS

Cognitive impairment is common in hemodialysis patients and may be impacted by multiple patient and treatment characteristics. The impact of dialysis dose on cognitive function remains uncertain, particularly in the current era of increased dialysis dose and flux.

METHODS

We explored the cross-sectional relationship between dialysis adequacy and cognitive function in a cohort of maintenance hemodialysis patients. Adequacy was defined as the average of the 3 most proximate single pool Kt/V assessments. A detailed neurocognitive battery was administered during the 1st hour of dialysis. Multivariable linear regression models were adjusted for age, sex, education, race and other clinical and demographic characteristics.

RESULTS

Among 273 patients who underwent cognitive testing, the mean (SD) age was 63 (17) years and the median dialysis duration was 13 months, 47% were woman, 22% were African American, and 48% had diabetes. The mean (SD) Kt/V was 1.51 (0.24). In univariate, parsimonious and multivariable models, there were no significant relationships between decreased cognitive function and lower Kt/V.

CONCLUSION

In contrast to several older studies, there is no association between lower Kt/V and worse cognitive performance in the current era of increased dialysis dose. Future studies should address the longitudinal relationship between adequacy of dialysis and cognitive function to confirm these findings.

Merging health literacy with computer technology: self-managing diet and fluid intake among adult hemodialysis patients

OBJECTIVE

The Dietary Intake Monitoring Application (DIMA) is an electronic dietary self-monitor developed for use on a personal digital assistant (PDA). This paper describes how computer, information, numerical, and visual literacy were considered in development of DIMA.

METHODS

An iterative, participatory design approach was used. Forty individuals receiving hemodialysis at an urban inner-city facility, primarily middle-aged and African American, were recruited.

RESULTS

Computer literacy was considered by assessing abilities to complete traditional/nontraditional PDA tasks. Information literacy was enhanced by including a Universal-Product-Code (UPC) scanner, picture icons for food with no UPC code, voice recorder, and culturally sensitive food icons. Numerical literacy was enhanced by designing DIMA to compute real-time totals that allowed individuals to see their consumption relative to their dietary prescription. Visual literacy was considered by designing the graphical interface to convey intake data over a 24-h period that could be accurately interpreted by patients. Pictorial icons for feedback graphs used objects understood by patients.

PRACTICE IMPLICATIONS

Preliminary data indicate the application is extremely helpful for individuals as they self-monitor their intake. If desired, DIMA could also be used for dietary counseling.

Microemboli, developed during haemodialysis, pass the lung barrier and may cause ischaemic lesions in organs such as the brain

BACKGROUND

Chronic haemodialysis (HD) may relieve some medical problems of terminal uraemia, but the life expectancy of patients is still significantly shortened, and there is a greatly increased morbidity. This includes pulmonary morbidity and chronic central nervous system (CNS) abnormalities. Previous studies have shown that a considerable amount of air microbubbles emanate within the blood lines of the dialysis device and pass the air detector without sounding an alarm. The aim of this study was to investigate whether microemboli can pass to the patient and whether they could be detected in the carotid artery.

METHODS

A total of 54 patients on chronic HD (16 with central dialysis catheter) were investigated with an ultrasound detector (Hatteland, Røyken, Norway) for the presence of microemboli at the arteriovenous (AV) fistula/graft and at the common carotid artery before and during HD. Measurements were taken for 2 and 5 min, respectively. Non-parametric paired statistics were used (Wilcoxon).

RESULTS

The median number (range) and mean +/- SD of microembolic signals detected at the AV access site before commencing dialysis and during HD were 0 (0-3) and 0.2+/- 0.5 versus 4 (0-85) and 13.5 +/- 20 (P = 0.000); at the carotid artery, 1 (0-14) and 1.7 +/- 2.9 versus 2 (0-36) and 3.5 +/- 5.8 (P = 0.008).

CONCLUSIONS

The infused and returning fluid from HD devices contains air microbubbles that enter the patient without triggering any alarms. These small emboli pass the lung and may cause ischaemic lesions in organs supported by the arterial circuit, such as the brain.

Cognitive performance before and after kidney transplantation: a prospective controlled study of adequately dialyzed patients with end-stage renal disease

Patients with end-stage renal disease (ESRD) who receive dialysis have been shown to have impaired neuropsychological performance. It remains unclear, however, whether cognitive deficits associated with ESRD and/or dialysis are reversible after successful kidney transplantation. Thus, the main purpose of this study was to longitudinally compare the cognitive performance of adequately dialyzed patients with ESRD before and shortly after kidney transplantation. Twenty-two dialyzed patients with ESRD who subsequently received a kidney transplant, 20 dialyzed patients who were medically qualified and awaiting kidney transplant but did not receive it, and 30 matched controls were the participants for this study. Overall, our results demonstrate that a successful kidney transplant is associated with improved neuropsychological performance in patients with ESRD. Specifically, a significant improvement was seen on measures of psychomotor speed, visual planning, retrieval of learnt material, and abstract thinking. Additionally, the degree of cognitive improvement following kidney transplant was significantly associated with some pre-, intra-, and postoperative factors (e.g., age, duration of chronic kidney disease, postoperative graft function). The results of this study also show that the cognitive performance of adequately dialyzed patients without a kidney transplant, although often below that of matched controls, remains relatively stable over time.

Effect of Hemodialysis on Cognitive Function in ESRD Patients

BACKGROUND

Uremia is associated with impairment of different cognitive functions. However the pathogenesis of this cognitive dysfunction is unknown.

OBJECTIVE

In this study, long-latency event related potentials (ERPs) were used to assess changes in cortical function due to hemodialysis treatment.

METHODS

In this cross-sectional study, we measured event related potentials in 15 end stage renal disease (ESRD) patients maintained on hemodialysis, two hours before and two hours after they underwent hemodialysis and compared their data with a strictly age and sex matched healthy control group. The P3 was elicited by using standard auditory "odd-ball" paradigm and the data obtained was statistically analyzed (Wilcoxon signed ranks, Mann Whitney).

RESULTS

Before hemodialysis, the patients' P3 latency (347.73 +/- 39.47 ms) was significantly increased as compared with that of healthy control group (308.4 +/- 13.73 ms) (p = 0.001). After hemodialysis, P3 latency of the patients showed a significant decrease (347.73 +/- 39.47 ms to 325.20 +/- 37.15 ms, p = 0.001). P3 latency after dialysis was not significantly different from controls. No significant correlation was noted between various biochemical parameters (hemoglobin, blood urea, creatinine, uric acid and calcium) and P3 latency or amplitude.

CONCLUSIONS

Removal of uremic toxins by hemodialysis leads to an improvement in cognitive processing.

Effects of hemodialysis on profound memory deficits in renal insufficiency due to multiple myeloma: a case study

Multiple myeloma, a rare cancer for individuals less than 65 years of age, and its pathophysiological effects have a profound impact on neurocognitive function. Specific transient deficits in patients with renal failure secondary to multiple myeloma have been noted to improve with hemodialysis. We present a complex case of an individual with multiple myeloma, renal insufficiency, treated seizure disorder, and schizophrenia, paranoid type, who experienced functional improvements in memory and visuospatial function with short- and long-term administration of hemodialysis. Within weeks of treatment, memory impairments resolved. With continued hemodialysis, some areas of neurocognitive function were in the superior range, indicating an overall improvement of more than three standard deviations. Implications and recommendations for clinicians treating individuals with similar challenges are offered.

Cognitive impairment in the aging dialysis and chronic kidney disease populations: an occult burden

The high burden of cognitive impairment in hemodialysis and chronic kidney disease (CKD) patients has only recently become recognized. Up to 70% of hemodialysis patients aged 55 years and older have moderate to severe chronic cognitive impairment, yet it is largely undiagnosed. Recent studies describe the strong graded relation between estimated glomerular filtration rate and cognitive function in CKD patients. The process of conventional hemodialysis may induce recurrent episodes of acute cerebral ischemia, which, in turn, may contribute to acute decline in cognitive function during dialysis. Thus, the worst time to communicate with dialysis patients may be during the hemodialysis session. Both symptomatic and occult, subclinical ischemic cerebrovascular disease appears to play a large role in a proposed model of accelerated vascular cognitive impairment in these populations. Severe cognitive impairment or dementia among hemodialysis patients is associated with an approximately 2-fold increased risk of both mortality and dialysis withdrawal. Predialysis cognitive screening and adding dementia to the list of comorbidities on Form 2728 would provide critical information regarding the benefit versus risks of receiving dialysis. It could also improve quality of care and outcomes by raising clinicians' awareness of the potential effects of cognitive impairment on medication, fluid, and dietary compliance and the ability to make advance directive decisions among dialysis patients. Although much remains to be learned regarding the pathophysiology of cognitive impairment in kidney disease, the public health implications of this substantial burden are immediate.

Acute variation in cognitive function in hemodialysis patients: a cohort study with repeated measures

BACKGROUND

Although cognitive function in hemodialysis patients is believed to be best 24 hours after the dialysis session, the extent of variation during the dialysis cycle is unknown.

STUDY DESIGN

Cohort study with repeated measures.

SETTING & PARTICIPANTS

Hemodialysis centers; patients aged 55 years or older.

PREDICTOR

Time of assessment related to the dialysis session. Time 1 (T1) occurred approximately 1 hour before the dialysis session; T2, 1 hour into the session; T3, 1 hour after; and T4, the next day.

OUTCOMES

Measures of cognitive function using a 45-minute cognitive battery. An average composite score was calculated to measure global cognitive function, equal to the average of subjects' standardized scores on all tests given at each test time. Times were classified as best and worst according to composite scores.

MEASUREMENTS

Testing was conducted on average over 2 dialysis sessions to avoid test fatigue. The cognitive battery included tests of verbal fluency, immediate and delayed verbal and visual memory, and executive function, administered at 4 times.

RESULTS

In the 28 subjects who completed testing at 3 or 4 testing times, mean age was 66.7 +/- 9.5 years and mean dialysis vintage was 44.7 +/- 33.3 months. Using a general linear model for correlated data, the composite score was significantly lower (poorer) during dialysis (T2) than shortly before the session (T1) or on the next day (T4; P < 0.001 for both).

LIMITATIONS

Relatively small sample size, testing delays, results may not be generalizable.

CONCLUSION

Global cognitive function varies significantly during the dialysis cycle, being worst during dialysis and best shortly before the session or on the day after. Clinician visits may be most effective at these times.

Subcortical cognitive impairment in dialysis patients

Given the high burden of atherosclerotic cardiovascular disease in dialysis patients, we hypothesized that cognitive testing would reveal subtle abnormalities in subcortical brain function, a measure frequently associated with cerebrovascular disease. Detailed neurocognitive testing was performed in 25 hemodialysis patients. All patients had Mini-Mental State Examination (MMSE) scores >24 and had no history of cerebrovascular disease. Where appropriate, scores were normalized for age, gender, and education. One-sample t tests were used to compare differences in cognitive function between dialysis patients and normative data. The mean age was 57 years, and the mean MMSE was 27.5. Fourteen subjects (56%) were females, and 15 white (60%). Results of the North American Adult Reading Test, a measure of verbal intelligence, were comparable with the general population. Similarly, measures of cortical function, namely retention and recognition scores from the Word List Learning subtest of the Wechsler Memory Scale-III, were preserved when compared with normative data where reference = 10. Significant deficits were seen on tests assessing subcortical function: scores (mean+/-standard deviation) for block design, and symbol coding subtests of the Wechsler Adult Intelligence Scale-III were 7.0+/-1.7 and 7.7+/-3.1, respectively (p<0.001 for both comparisons with normative data). Similarly, adjusted scores on the trails A and B tests were 40.5+/-8.3 and 41.8+/-11.3, respectively (p<0.001 for both comparisons with normative data where reference= 50). These results suggest that, despite relatively normal MMSE scores, mild cognitive impairment may be prevalent in hemodialysis patients. The pattern of cognitive dysfunction is primarily subcortical in nature.

Moderate Chronic Kidney Disease and Cognitive Function in Adults 20 to 59 Years of Age: Third National Health and Nutrition Examination Survey (NHANES III)

Previous studies among elderly suggest an association between chronic kidney disease (CKD) and cognitive impairment. The purpose of this study was to determine whether moderate CKD is associated with cognitive performance among young, healthy, ethnically diverse adults. Three computerized cognitive function tests of visual-motor reaction time (Simple Reaction Time), visual attention (Symbol Digit Substitution), and learning/concentration (Serial Digit Learning) were administered to a random sample of participants, aged 20 to 59 yr, who completed initial interviews and medical examination in the Third National Health and Nutrition Examination Survey (NHANES III). Participants for this study (n = 4849) completed at least one cognitive function test. GFR was estimated using the Modification of Diet in Renal Disease (MDRD) equation. Moderate CKD was defined as estimated GFR (eGFR) 30 to 59 ml/min per 1.73 m(2). Unadjusted, residual-adjusted, and multivariate-adjusted logistic regression models were used. The cohort was 49.0% male and 11.6% black, and median (interquartile range) age was 36 yr (27 to 45) and eGFR was 107.9 ml/min per 1.73 m(2) (95.0 to 125.4). There were 31 (0.8%) prevalent cases of moderate CKD. Models were adjusted for residual effects of age, gender, race, diabetes, and other known potential confounders. In multivariate models, moderate CKD was not significantly associated with reaction time but was significantly associated with poorer learning/concentration (odds ratio 2.41; 95% confidence interval 1.30 to 5.63) and impairment in visual attention (odds ratio 2.74; 95% confidence interval 1.01 to 7.40). In summary, among those in a large nationally representative sample of healthy, ethnically diverse 20- to 59-yr-old adults, moderate CKD, reflected by eGFR 30 to 59 ml/min per 1.73 m(2), was significantly associated with poorer performance in visual attention and learning/concentration.

Differential impact of age on verbal memory and executive functioning in chronic kidney disease

We compared aspects of verbal memory and executive functioning in 51 community-dwelling persons with chronic kidney disease (CKD) and 55 healthy controls matched on age and education. Depressive symptoms were assessed with the Centre for Epidemiological Studies-Depression Scale (CES-D), and illness variables included glomerular filtration rate (GFR) and hemoglobin. Findings indicate that persons with CKD exhibited poorer performance on measures of memory (CVLT-II) and executive functioning (DKEFS Trailmaking Test B and Color-Word Interference Tests) in comparison with healthy controls. Furthermore, performance decrements were magnified in older CKD participants on measures of verbal memory and inhibition. Nearly half of CKD participants aged 61 and older exhibited significant impairments in verbal memory and inhibition in comparison to matched controls. Cognitive performance in CKD was not associated with measures of illness severity. The differences observed were not accounted for by depressive symptoms, which were only weakly associated with cognitive performance, and negatively associated with age. Findings highlight the need for further exploration of the etiologies and functional consequences of the neuropsychological presentation of CKD.