Neuropsychological patterns in uremia

Better Preservation of Cognitive Faculty in Continuous Ambulatory Peritoneal Dialysis

We employed the so-called event-correlated potential (ECP) P300, a neurophysiological test which explores the circuits of attention and memory in the brain and is altered in subjects with a dismetabolic or degenerative encephalopathy, in order to evaluate the cognitive faculty in two groups of uremic patients [18 on continuous ambulatory peritoneal dialysis (CAPD), 15 on hemodialysis (HD)] comparable with respect to age and time on dialysis. The values of latency (msec) of P300 resulted in CAPD patients 356±26 in CZ (central zero electrodes) and 357.5±25 in PZ (parietal zero electrodes), not significantly different from the values in normal controls (341±14.5 in CZ and 340± 15.6 in PZ) and in HD patients postdialysis (354±24.4 in CZ and 354±25.6 in PZ). On the contrary, the predialytic values of HD patients (384±25.6 CZ and 385±25.5 in PZ) were significantly different from the postdialytic values and from the values of CAPD patients and controls (p<0.01). These results support the conclusion that HD Is able to restore a normal cognitive faculty only transiently in the postdialytic phase, while CAPD maintains this important function steadily close to the normal range, thus being clearly better than HD.

Cognitive Impairment in CKD: Pathophysiology, Management, and Prevention

Patients with chronic kidney disease (CKD) are at substantially higher risk for developing cognitive impairment compared with the general population, and both lower glomerular filtration rate and the presence of albuminuria are associated with the development of cognitive impairment and poorer cognitive function. Given the excess of vascular disease seen in individuals with CKD, cerebrovascular disease is likely the predominant pathology underlying these associations, though impaired clearance of uremic metabolites, depression, sleep disturbance, anemia, and polypharmacy may also contribute. Modification of vascular disease risk factors may be helpful in limiting decline, though definite data are lacking. Specific to CKD, targeting a low blood pressure and reduction in albuminuria with angiotensin-converting enzyme inhibitors or angiotensin receptor blockers may slow cognitive decline, albeit modestly. Initiation of dialysis can improve severe impairment associated with uremia but does not appear to affect more subtle chronic cognitive impairment. In contrast, kidney transplantation appears to lead to improved cognitive function in many transplant recipients, suggesting that dialysis methods do not provide the same cognitive benefits as having a functioning kidney. Management of patients with both CKD and cognitive impairment should include a comprehensive plan including more frequent follow-up visits; involvement of family in shared decision making; measures to improve compliance, such as written instruction and pill counts; and a focus on advance directives in conjunction with an emphasis on understanding an individual patient's life goals. Further research is needed on novel therapies, including innovative dialysis methods, that aim to limit the development of cognitive impairment, slow decline in those with prevalent impairment, and improve cognitive function.

Quantifying cognitive dysfunction across the spectrum of end-stage kidney disease: A systematic review and meta-analysis

Cognitive dysfunction is reportedly highly prevalent among chronic kidney disease (CKD) patients. A variety of screening tools and neuropsychiatric batteries are used to quantify the magnitude and nature of this dysfunction. Our objective is to summarize the neurocognitive testing used, and determine what degree cognitive dysfunction is reported in CKD patients. All study designs published in English that contained participants who were either pre-dialysis patients, haemodialysis (HD) or peritoneal dialysis (PD) patients or renal transplant recipients were considered. Reported comparative non-CKD control data was also collected. All study designs were included. The search period encompassed articles from 1980 to May 2018. This review is registered with PROSPERO (CRD42018096568). Of the 1711 articles screened, 148 articles were relevant and used in the meta-analysis. Commonly used assessments were The Mini-Mental State Examination (MMSE), The Modified Mini-Mental State Examination, the Trails Making Tests (TMT) forms A and B and components of the Wechsler Adult Intelligence Scale: Digit Span and Digit Symbol. Means for all assessments were adjusted using a random effects model to account for the differences in variance. Adjusted mean MMSE scores were significantly lower for both pre-dialysis (26.08, n = 17 073) and HD (26.31, n = 3314) patients when compared to non-CKD controls (28.21, n = 5226). PD (58.01 s, n = 859) and HD (56.04 s, n = 2344) patients also took significantly longer to complete the Trails Making Task A than non-CKD controls (37.62 s, n = 4809). Patients with CKD, especially pre-dialysis and those requiring dialysis, are likely to exhibit impairments in cognition that can be identified with specific screening neuropsychological assessments.

Cognitive Testing in Patients with CKD: The Problem of Missing Cases

BACKGROUND AND OBJECTIVES

Cognitive testing is only valid in individuals with sufficient visual and motor skills and motivation to participate. Patients on dialysis usually suffer from limitations, such as impaired vision, motor difficulties, and depression. Hence, it is doubtful that the true value of cognitive functioning can be measured without bias. Consequently, many patients are excluded from cognitive testing. We focused on reasons for exclusion and analyzed characteristics of nontestable patients.

DESIGN, SETTING, PARTICIPANTS & MEASUREMENTS

Within the Choice of Renal Replacement Therapy Project (baseline survey: May 2014 to May 2015), n=767 patients on peritoneal dialysis (n=240) or hemodialysis (n=527) were tested with the Trail Making Test-B and the German d2-Revision Test and completed the Kidney Disease Quality of Life Short Form cognition subscale. We divided the sample into patients with missing cognitive testing data and patients with full cognitive testing data, analyzed reasons for nonfeasibility, and compared subsamples with regard to psychosocial and physical metrics. The exclusion categories were linked to patient characteristics potentially associated with missing data (age, comorbidity, depression, and education level) by calculation of λ-coefficient.

RESULTS

The subsamples consisted of n=366 (48%) patients with missing data (peritoneal dialysis =62, hemodialysis =304) and n=401 patients with full cognitive testing data (peritoneal dialysis =178, hemodialysis =223). Patients were excluded due to visual impairment (49%), lack of motivation (31%), and motor impairment (13%). The remaining 8% did not follow instructions, suffered from medical incidents, or had language difficulties. Compared with patients with full cognitive testing data, they were more likely to have depression; be treated with hemodialysis; be older, nonworking, or more comorbid; and experience poorer shared decision making. Reasons for exclusion were not related to levels of age, comorbidity score, depression score, or education level.

CONCLUSIONS

We excluded almost one half of eligible patients from cognitive testing due to visual, motivational, or motor difficulties. Our findings are consistent with exclusion categories reported from the literature. We should be aware that, because of disease-related limitations, conclusions about cognitive functioning in the CKD population may be biased. In the future, nonvisual and nonverbal cognitive testing can be a valuable resource.

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.

Is there differences in cognitive and motor functioning between hemodialysis and peritoneal dialysis patients?

OBJECTIVE

Change in cognitive function is one of the well-known consequences of the end-stage renal disease (ESRD). The aim of this study was to determine the effect of hemodialysis (HD) and continuous ambulatory peritoneal dialysis (CAPD) on cognitive and motor functions.

METHODS

In this cross-sectional study, cognitive and motor functions were investigated in a selected population of 42 patients with ESRD (22 patients on chronic HD and 20 patients on CAPD, aged 50.31 ± 11.07 years). Assessment of cognitive and motor functions was performed by Symbol Digit Modalities Test (SDMT) and Complex Reactiometer Drenovac (CRD-series), a battery of computer-generated psychological tests to measure simple visual discrimination of signal location, short-term memory, simple convergent visual orientation, and convergent thinking.

RESULTS

The statistically significant difference in cognitive-motor functions between HD and CAPD patients was not found in any of the time-related parameters in all CRD-series tests or SDMT score. Higher serum levels of albumin, creatinine, and calcium were correlated with better cognitive-motor performance among all patients regardless of dialysis modality. The significant correlation between ultrafiltration rate per HD and short-term memory actualization test score (CRD-324 MT) among HD patients was found (r = 0.434, p = 0.025).

CONCLUSION

This study has demonstrated that well-nourished and medically stable HD and CAPD patients without clinical signs of dementia or cognitive impairment and without significant difference in age and level of education performed all tests of cognitive-motor abilities without statistically significant difference.

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.

Patients' level of knowledge measured five days after kidney transplantation

BACKGROUND

Kidney recipients' knowledge is important in terms of coping with short-term problems posed by transplantation and the long-term outcome. Little attention has been given to the development of instruments for measuring patient's knowledge in this field.

AIM

The purpose of this study was to describe the development of a knowledge questionnaire for kidney recipients and to explore possible factors related to the knowledge level.

METHODS

The sample consisted of 159 kidney recipients at a Norwegian transplant center, answering the questionnaire five d post-transplantation.

RESULTS

The questionnaire was generated on the basis of literature review and clinical experience - and was pilot tested. Mean score of the questionnaire was 11, of 19 obtainable points. Longer duration of kidney disease was significantly correlated with an increased knowledge level, whereas the longer the time on dialysis prior to transplantation and post-operative complications were found to have significantly negative impact on total knowledge score.

CONCLUSIONS

The positive impact of disease duration may suggest that insight gained over time makes patients better prepared for the transplantation itself and for life post-transplant. However, the negative impact of dialysis duration could be attributed to impaired cognitive function imposed by chronic dialysis treatment. Further research is needed regarding the questionnaire's responsiveness to educational interventions.

Cognitive Status in Hemodialysis as a Function of Fluid Adherence

Previous work has shown that dialysis improves cognitive functioning in hemodialysis patients, perhaps due to improvements in anemia among these patients. Such improvements in cognitive performance may lead to better levels of self-care and adherence with treatment. This study examined the relationship between fluid adherence and cognitive functioning in patients receiving hemodialysis. One hundred forty-seven patients were assessed with a brief screening instrument, the Cognistat, to determine their current level of functioning during the first hour of hemodialysis. Fluid nonadherence was operationalized as interdialytic weight gain above 1 kg/day. Rates of impairment on the Cognistat subscale ranged from 2.7% (orientation) to 54% (memory) in this sample. Roughly 68% of the sample was nonadherent during the course of treatment. Results found no differences in mean levels of cognitive performance between those who were adherent and those who were not and only modest relationships of measures of anemia to certain aspects of cognitive performance. For the hemodialysis patient to benefit from self-care education, the patient must be able to understand, remember, reason, and use cognitive processes to modify behavior. These results suggest that more in-depth assessment of cognitive performance may be needed. In addition, this assessment may need to be conducted on a day when treatment is not received.

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.

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.

Cognitive and emotional effects of renal transplantation

BACKGROUND

Recent studies have shown a high prevalence of depression and cognitive changes in patients with end-stage renal disease (ERSD) and renal transplant recipients. There are few data available on the cognitive and emotional changes in patients undergoing renal transplantation in India.

AIM

To evaluate the changes in cognitive profile and depression in renal transplant recipients.

METHODS

Thirty consecutive patients undergoing renal transplantation were evaluated 1 month before and 3 months after successful renal transplant with Beck Depression Inventory (BDI), Weschler Adult Performance Intelligence Scale (WAPIS), Luria Nebraska Neuropsychological battery (LNNB) and Life satisfaction scale.

RESULTS

Our study revealed an 86.7% prevalence of depression in ESRD patients as compared to 56.7% in post renal transplant patients. Analysis of neurocognitive functions on LNNB did not reveal any significant impairment. Furthermore, analysis of the Life satisfaction scale revealed most of the patients scored high satisfaction levels despite the stress of their disease. Results on WAPIS brought out significant improvement in intelligence quotient (IQ) after renal transplantation.

CONCLUSION

Successful renal transplant is associated with improvement in depression, IQ and life satisfaction.

Chronic kidney disease and cognitive impairment in menopausal women

BACKGROUND

Although end-stage renal disease has been associated with cognitive impairment, the relation between lesser degrees of chronic kidney disease (CKD) and cognitive impairment is less well understood.

METHODS

Data for 1,015 women enrolled at 10 of the 20 Heart Estrogen/Progestin Replacement Study clinical sites were analyzed. All participants were younger than 80 years and had established coronary artery disease at study entry. Participants underwent 6 standard tests of cognitive function evaluating various domains. Unadjusted, residual age- and race-adjusted, and multivariable-adjusted linear and logistic regression models were used. Glomerular filtration rate (GFR) was estimated using the Modification of Diet in Renal Disease regression equation. In addition to analyses across the spectrum of GFRs, CKD was categorized as mild (estimated GFR [eGFR], 45 to 60 mL/min/1.73 m2), moderate (eGFR, 30 to 44 mL/min/1.73 m2), and severe (eGFR, <30 mL/min/1.73 m2) according to a modification of recently established classification guidelines.

RESULTS

Mean eGFR was 57 +/- 14 mL/min/1.73 m2. In multivariable analyses, eGFR was associated significantly with impairment in global cognition, executive function, language, and memory (approximately 15% to 25% increase in risk for dysfunction/10-mL/min/1.73 m2 decrement in eGFR). Associations among eGFR and cognitive function were independent of residual effects of age and race (2 key determinants of GFR) and the contributions of education, lifestyle factors, stroke, diabetes, and other laboratory variables.

CONCLUSION

CKD is associated with cognitive impairment in menopausal women with coronary artery disease.

Cognitive function in dialysis patients

There are few detailed studies of cognitive function in dialysis patients. However, appreciating the prevalence and risk factors for cognitive impairment is important because cognitive impairment may decrease an individual's quality of life, increase resource utilization, and result in suboptimal medical care because of difficulty following caregiver recommendations. Cognitive impairment also is likely to become more of a problem as the dialysis population ages. In this review, we argue that cerebrovascular disease is an important cause of cognitive impairment in dialysis patients and discuss risk factors specific for vascular disease, as well as other factors that may influence cognitive function. We describe the structural brain abnormalities frequently seen in dialysis patients and the specific neurocognitive changes noted in prior studies. We explore potential measures to reduce cognitive impairment in this population. We conclude that additional research is needed in this area.

GSA: behavioral, histological, electrophysiological and neurochemical effects

Renal insufficient patients suffer from a variety of complications as direct and indirect consequence of accumulation of retention solutes. Guanidinosuccinic acid (GSA) is an important probable uremic toxin, increased in plasma, urine, cerebrospinal fluid and brain of patients with uremia and supposed to play a role in the pathogenesis of some neurological symptoms. GSA, an NMDA-receptor agonist and GABA-receptor antagonist, is suggested to act as an excitotoxin and shown to be convulsive. The effect of hippocampal (i.h.) GSA injection on behavior and hippocampal volume in mice is presented here. In addition, hippocampal cGMP concentration after systemic injection of GSA was measured. The effect of co-application of NMDA-receptor antagonist CGP37849 with GSA was tested, in vivo, after hippocampal GSA injection and, in vitro, on GSA evoked currents in spinal cord neurons. A significant dose-dependent effect of i.h. injection of GSA on cognitive performance, activity and social exploratory behavior was observed. There was a protective effect of CGP37849 on GSA induced behavioral alterations. Volume of hippocampal cornu ammonis region decreased significantly and dose-dependently after GSA injection. Systemic GSA injection increased cGMP concentration in hippocampal formation. It can be concluded that GSA is an important neurotoxin. As GSA is increased in patients with uremia, it probably contributes to their neurological symptoms. Knowledge of neurotoxic effects and mechanisms of action of GSA and other uremic retention solutes could help in the development of more efficient treatment of uremic patients. Animal models like the 'GSA mouse model' are useful tools for research in this context.

Cognitive Impairment in Chronic Kidney Disease

OBJECTIVES

To assess the prevalence of cognitive impairment in persons with chronic kidney disease (CKD) and its relation to the severity of CKD.

DESIGN

Cross-sectional study.

SETTING

University-affiliated ambulatory nephrology and dialysis practices.

PARTICIPANTS

Eighty subjects with CKD Stages III and IV not requiring dialysis (CKD) and 80 subjects with CKD Stage V on hemodialysis (end-stage renal disease (ESRD)) with a mean age+/-standard deviation of 62.5+/-14.3.

MEASUREMENTS

Three standardized cognitive tests, the Modified Mini-Mental State Examination (3MS), Trailmaking Test B (Trails B), and California Verbal Learning Trial (CVLT). Glomerular filtration rate was estimated in subjects with CKD using the six-variable Modification of Diet in Renal Disease equation.

RESULTS

There was a graded relation between cognitive function and severity of CKD. Mean scores on the 3MS, Trails B, and CVLT immediate and delayed recall were significantly worse for subjects with ESRD than for subjects with CKD or published norms (P<.001 for all comparisons). Scores on the Trails B (P<.001) and CVLT immediate (P=.01) and delayed (P<.001) recall were significantly worse for subjects with CKD not requiring dialysis than for published norms. In addition, the fraction of subjects with impairment on the 3MS and Trails B increased with decreasing kidney function.

CONCLUSION

Cognitive impairment is associated with the severity of kidney disease. Further studies are needed to determine the reasons for cognitive impairment in subjects with CKD and ESRD.

Temporal effects of dialysis on cognitive functioning in patients with ESRD

BACKGROUND

Although dialysis has been shown to improve cognitive deficits resulting from uremia, little is known about potential temporal variations in cognitive measures between hemodialysis treatments.

METHODS

We studied dialysis patients for possible fluctuations in attention and memory by using repeatable neuropsychological measures. Twenty patients undergoing hemodialysis on a thrice-weekly dialysis schedule were assessed at intervals of 1, 24, and 67 hours after the last weekly hemodialysis session. For purposes of comparison, we also studied 10 patients on continuous ambulatory peritoneal dialysis (CAPD) therapy at similar intervals.

RESULTS

CAPD patients showed overall stable performance on measures of attention and memory. However, hemodialysis patients showed significant changes (P < 0.05) in auditory memory for both immediate and delayed recall, with the greatest impairment occurring 67 hours postdialysis. Hemodialysis patients also showed a significant change (P < 0.05) in attention between the second and third test periods, ie, 24 to 67 hours postdialysis, with the greatest impairment seen at the 67-hour assessment time. No relationship was found between performance on measures of cognition and levels of postdialysis fatigue in hemodialysis patients.

CONCLUSION

CAPD patients showed cognitive stability, whereas hemodialysis patients showed temporal fluctuations in cognitive performance.

Behavioural deficits during the acute phase of mild renal failure in mice

Partially nephrectomized (NX) and sham-operated mice were biochemically and behaviourally compared, 10 days, 1 month and 1 year post-surgery. Plasma urea and creatinine concentrations were mildly increased in all NX groups, but creatinine clearance was significantly decreased, 10 days post-surgery only. NX mice showed lower body weights and reduced growth. Wire suspension and rotarod indicated unaffected motor functions, but NX mice did show reduced ambulation and swimming velocity, 10 days post-surgery. Hidden-platform water maze indicated a spatial learning impairment in NX mice, 10 days post-surgery, which could not be entirely reduced to motor incapacity. The acute behavioural deficits in these mildly uremic mice may relate to analogous symptoms in uraemic encephalopathy, a poorly understood brain syndrome occurring in uraemic patients.

Erythropoietin therapy in chronic uremia: the impact of normalization of hematocrit

The target hematocrit to be achieved when treating anemia in hemodialysis patients with erythropoietin is controversial. Current evidence-based recommendations suggest a target hematocrit range of 33% to 36%. Small studies suggest that normalization of hematocrit with erythropoietin may benefit hemodialysis patients in terms of brain function, physical performance, quality of life, and prevention of progressive left ventricular dilatation. However a recent study of the effects of erythropoietin-induced normalization of hematocrit in hemodialysis patients with symptomatic heart disease has shown an increase in both mortality and the rate of vascular access thrombosis. Currently, normalization of hematocrit in patients with symptomatic heart disease is not recommended, nor is it possible to conclude that possible benefits of normalization of hematocrit will outweigh risks in hemodialysis patients without symptomatic heart disease.

Neurocognitive function in chronic hemodialysis patients

We administered a comprehensive neuropsychological test battery, including measures of intelligence, immediate and delayed memory, attention and mental processing speed, language abilities, complex problem solving, motor skills, and depression, to 16 well-dialyzed (Kt/Vurea = 1.46 +/- 0.24) patients with end-stage renal disease (ESRD) and 12 age- and education-matched medical controls. We observed no clear neuropsychological deficits in these ESRD patients who had low average intelligence and limited educational achievement, and hypothesize that previously observed apparent deficits resulted either from very low dialysis delivery or comparison with poorly-matched historical controls. There were significant deficits in language ability and intelligence in ESRD patients with higher than median scores on the Beck Depression Inventory compared with less-depressed ESRD patients. However, this effect of depression did not result in differences between dialysis and non-ESRD patient groups.

N-methyl-D-aspartate receptor activation by guanidinosuccinate but not by methylguanidine: behavioural and electrophysiological evidence

Levels of methylguanidine (MG) and guanidinosuccinate (GSA) are known to be highly increased in uraemic patients. In the present work, the effects of these uraemic guanidino compounds on the excitatory amino acid system were investigated in vivo and in vitro. It was found that convulsions induced by intracerebroventricular GSA injection in mice were antagonized by N-methyl-D-aspartate (NMDA) receptor blockade, whereas those induced by MG were not significantly altered. Application of GSA (between 25 and 10,000 microM) to mouse spinal cord neurones in primary dissociated cell cultures, evoked depolarizing, inward whole-cell currents in a dose-dependent fashion and with reversal potential at 0 mV; MG did not produce such effects. GSA-induced whole-cell currents were caused by NMDA receptor activation since NMDA receptor antagonists (2-amino-5-phosphonovalerate, Mg2+ and ketamine) blocked GSA-evoked whole-cell currents completely and reversibly, whereas co-application of a non-NMDA receptor antagonist (6-cyano-7-nitroquinoxaline-2,3-dione) did not affect GSA-induced current. Evoked field potentials in CA1 region of rat hippocampal slices were completely abolished by GSA, and this effect was antagonized by NMDA receptor blockade. All data were consistent with selective agonist action of GSA upon the NMDA-type glutamate receptor. In view of the results presented here, it should be examined whether NMDA receptors contribute to the neurological complications of renal failure through GSA-induced inappropriate or excessive activation of NMDA receptors.

Differential diagnosis of steroid-dependent nephrotic syndrome with psychosis: Practical and ethical issues

The present case illustrates practical and ethical issues that can be encountered by clinical psychologists providing consultation services in medical settings. The neuropsychological consultation service was asked to evaluate a 22-year-old male with psychosis, steroid-dependent nephrotic syndrome, and a family history of schizophrenia. MRI revealedmarked cortical atrophy. Clinical findings were consistent with (1) steroid inducedapparent atrophy, which has been shown to be reversible with withdrawal of steroids; (2) uremia secondary to steroid withdrawal; (3) cortical atrophy, found in some schizophrenics; or (4) an atypical, diffuse degenerative disorder. Clinical interview and psychological testing revealed significant thought disorder, prominent delusions, somatic hallucinations, and mood disturbance. Deterioration in social and academic functioning was also present. Except for impaired attention and concentration, neuropsychological evaluation showed no clear evidence of brain-based dysfunction. Further, neuropsychological results effectively ruled out a degenerative process and were not consistent with a steroid effects profile. A conclusive differential diagnosis of steroid induced psychosis versus severe psychopathology would require withdrawal from steroids and antipsychotics. In addition to the practical and ethical issues of withholding antipsychotics, steroid withdrawal would require either dialysis or renal transplant surgery. Decision making regarding dialysis dependency and the possibility of postsurgical psychosis secondary to true psychopathology were salient issues to both the patient and the treatment team.

Pathogenesis of cognitive complaints in patients on hemodialysis

Memory-concentration complaints are a common symptom among end-stage renal disease patients receiving hemodialysis. However, assuming an organic basis for these complaints might lead to unnecessary and expensive testing. To further explore the etiology of cognitive complaints, this study examined the contribution of demographic, neuropsychological, medical, affective, and personality variables to memory-concentration complaints in 426 hemodialysis patients. Following stepwise multiple regression to identify the best predictor variables within each domain, hierarchical multiple-regression analysis determined the significant predictors of memory-concentration complaints. Education, digit symbol score, and hemoglobin jointly accounted for approximately 7% of the variance. Cognitive (psychological) symptoms of depression explained an additional 9% of variance. Somatic symptoms of depression did not significantly contribute, whereas state anxiety did. Finally, personality variables collectively accounted for another 9% of variance. Overall, the model accounted for 28% of explained variance in memory-concentration complaints. These findings demonstrate that affect and personality factors are more predictive of memory-concentration complaints in hemodialysis patients than are neuropsychological or medical factors. The clinical implication is that the initial response to memory-concentration complaints in these patients should be evaluations of psychological condition.

Effects of rHuEPO on Q-EEG and event-related potentials in chronic renal failure

Quantitative electroencephalography is a powerful tool to evaluate brain function, and preliminary data have shown its usefulness in the evaluation of patients with chronic renal failure (CRF). In this study, baseline values of different quantitative EEG variables, as well as data from the P300 component of the visual event-related potential, in 43 patients with chronic renal failure, were compared with those of a group of healthy subjects and with the results obtained after 3, 6, 9 and 12 months of treatment of these patients with rHuEPO. Baseline total power was much lower in patients with CRF than in healthy subjects, and the distribution of power among the frequency bands was also abnormal. rHuEPO promptly normalized total power and progressively improved power distribution, although full normality was not achieved. Mean dominant frequencies in brain areas were abnormal in patients with CRF, and progressive improvement was seen along the study. The latency of P300, which was increased before treatment, decreased in all subjects, but normal values were not reached. The same applies to the hypomanic and psychopathic scores of psychological tests. Altogether, brain dysfunction of CRF seems to substantially improve by treatment of the anemia with rHuEPO.

A comparison of evaluative indices of quality of life and cognitive function in hemodialysis patients

In the setting of end-stage renal disease, the reproducibility and responsiveness of three health-related quality-of-life instruments were evaluated. The Time Trade Off instrument (TTO) is a generic instrument used to evaluate the utility of a health state. The Hemodialysis Quality-of-Life questionnaire (HQL) is a disease-specific instrument. A series of function-specific tests evaluated neurocognitive function. The TTO and HQL instruments are patient centric in that patient values define the health status while the neurocognitive function tests reflect the values of healthcare professionals. Forty-seven chronic hemodialysis patients participated. Those with adequate dialysis, defined as a Kt/V (a measure of small solute removal during hemodialysis) above 1.0 were maintained at the level for two administrations of the three instruments separated by six to eight weeks. The test-retest intraclass correlation coefficient exceeded 0.90 for all five domains of the HQL questionnaire and exceeded 0.70 for nine neurocognitive function tests. Patients with inadequate dialysis (Kt/V less than 0.8) had Kt/V increased to above 1.0. The TTO was not responsive. For the HQL questionnaire, an item was considered responsive if a 1-point improvement, on a 7-point Likert type scale, occurred significantly more often among those with an improvement in hemodialysis treatment compared to those without improvement. Only one item had such a change and therefore the HQL cannot be considered responsive.(ABSTRACT TRUNCATED AT 250 WORDS)

rHuEPO treatment improves brain and cognitive function of anemic dialysis patients

Twenty-four patients with chronic renal failure, stabilized on hemodialysis, were treated with recombinant human erythropoietin. Before treatment, all patients were anemic (mean Hct = 23.7%). Hematocrits reached normal levels (36.5%) after three months of treatment. Brain event-related potentials and neuropsychological tests were used to assess changes in brain and cognitive functions associated with the correction of anemia. Assessments were done prior to and after three and twelve months of rHuEPO treatment. The P3 component of the event-related potential increased in amplitude significantly with treatment, while its latency was unaffected. Of the four neuropsychological tests administered, scores on two improved significantly with treatment, and the other two approached significance. Taken together, these findings suggest that the correction of anemia to hematocrits near normal in uremic patients by rHuEPO treatment improves brain and cognitive function by raising levels of sustained attention, thus increasing speed and efficiency of scanning and perceptual-motor functions and enhancing learning and memory. These findings also suggest that anemia, either directly or indirectly, may impair brain function.

Cognitive function, mood and P3 latency: effects of the amelioration of anemia in dialysis patients

Attention difficulties and psychomotor slowing associated with depressed mood affect the ability of individuals to perform on most neuropsychological tests. It has been suggested that latency of the P3 (P300) component of the event-related EEG potential is an index of neurocognitive status which is not affected by mood. Dialysis patients, who experience diminished dysphoric mood with the reversal of anemia when treated with recombinant human erythropoietin (rHuEPO), were tested for neurocognitive performance, mood and latency of P3. Prior to rHuEPO treatment mood was dysphoric, and neurocognitive testing showed mild deficits, but P3 latency was normal. After treatment, mood improved and neurocognitive test performance was normal. P3 amplitude increased over frontal areas, while P3 latency remained unchanged. Thus, in the case of dysphoric mood, P3 latency may provide a more accurate index of cognitive capacity (as opposed to level of functioning) than neurocognitive test measures.

Recombinant human erythropoietin treatment may improve quality of life and cognitive function in chronic hemodialysis patients

Medical, psychological, and social adaptation (quality of life) as well as cognitive function were studied in 15 chronic stable hemodialysis patients before the onset of treatment with recombinant human erythropoietin (r-HuEPO), 1 month after stabilization of normal hematocrit levels, and 10 to 15 months after treatment onset. After r-HuEPO treatment, subjects had significantly higher hematocrits, markedly improved energy levels, and marginally improved global health. r-HuEPO treatment was also associated with progressively decreased levels of subject mood disturbance and dialysis-related stresses. Subjects had no increased participation in paid employment and only minimally increased participation in social and leisure activities at posttreatment data points. There was no significant improvement in cognitive function after treatment. r-HuEPO treatment appears to be associated with higher energy levels, significant psychological benefits, and minimal improvements in social adaptation. The effects on cognitive function merit further study.

Relationship of dialysis modality and other factors to cognitive function in chronic dialysis patients

To determine if dialysis modality may be an independent factor in the level of cognitive function in chronic dialysis patients, cognitive function was studied in 17 pairs of continuous ambulatory peritoneal dialysis (CAPD) and center hemodialysis (CHD) subjects matched for sex, age, diabetic status, and interval since dialysis onset. Data on current metabolic, medical, psychological, and vocational function status were obtained. Neuropsychological (NP) measures included the Number Cancellation Protocol (NCP), Trailmaking test forms A and B (TMT A, TMT B), Symbol Digit Modalities (SDM), and the Rey Auditory Verbal Learning Test (RAVLT). The CAPD subject group had consistently more efficient cognitive function than the CHD subject group. Regardless of modality, the groups of subjects under age 51 and those who were vocationally active had significantly better NP performance. No cognitive function differences were found in groups categorized by sex or duration of dialysis. Creatinine levels were more highly correlated with NP scores than were BUN levels, with higher creatinine levels associated with better cognitive function. Serum calcium, CO2, total protein, albumin, and SGOT levels also were correlated with NP scores. CAPD may be more effective than HD in reversing uremic encephalopathy by mechanisms mostly unrelated to serum creatinine and BUN levels. Longitudinal studies will be needed to determine if dialysis modality is an independent factor in the degree of reversal of uremic encephalopathy.

Electrophysiological indices of CNS function in hemodialysis and CAPD

Fourteen Center hemodialysis (CHD) patients, 13 continuous ambulatory peritoneal dialysis (CAPD) patients, and 10 normals matched by group for age and sex were compared using a battery of evoked (EP) and event-related (ERP) brain potential measures to determine the effects on central nervous system (CNS) functioning of these two dialysis modes. While some differences were observed in early brainstem EP waves, the majority of differences occurred in the later waves associated with higher levels of cognitive processing. With tasks involving easy discriminations, CHD patients had longer latencies, indicative of less efficient cognitive processing, than CAPD patients who resembled controls. With difficult tasks, both CHD and CAPD groups showed abnormally-delayed later components. Similar results were obtained for the amplitude of the middle latency N1-P2 component, that is, reduced amplitudes for the CHD group with respect to both CAPD and control groups under low task demand, while both dialysis groups had reduced amplitudes under high task demand. These results suggest that CAPD patients are more similar to normals than CHD patients in ERP indices of attention and the efficiency of cognitive processing.