Meta-analysis of cognitive functioning in patients following kidney transplantation

The Clock Drawing Task reveals executive dysfunction in the dialysis population - an underrecognized and underestimated problem

AIM OF THE STUDY

The study aimed to assess the prevalence of executive function impairment among patients with chronic kidney disease (CKD) undergoing dialysis, with no subjective cognitive problems and with normal global cognition on the Mini-Mental State Examination (MMSE). We also investigated the relationship between cardiovascular risk factors and cognitive test results.

RATIONALE FOR THE STUDY

Patients with CKD, including those undergoing renal replacement therapy, are at a higher risk of developing cognitive impairment (CI) than the general population. Recent research has shown CI to be a growing problem among CKD patients worldwide. Yet, it remains underdiagnosed, even though it may significantly influence the lives of patients.

MATERIALS AND METHODS

In this cross-sectional, prospective study, 58 dialysis patients with no cognitive decline on the MMSE screening were assessed for executive function impairment using the Executive Clock-Drawing Task (CLOX). Moreover, past medical history, demographic data, and laboratory test results were collected.

RESULTS

The mean patient age was 59.47 ± 14.98 years, and the mean duration of dialysis was 45.93 ± 48.49 months. The prevalence of executive function impairment amounted to 8.6%. Moreover, remarkably similar pattern of clock drawing was observed, with numbers written outside the clock face in the CLOX1 test.

CONCLUSIONS

Executive dysfunctions in dialysis patients may manifest itself before the onset of global cognitive impairment. There appear to be a deficit in the spatial domain as well. Better education may play a protective role.

Exploring the Cognitive Profiles of Haemodialysis Patients using Objective and Subjective Indicators: A Cross-sectional Observational Study

BACKGROUND

Cognitive impairment is common in haemodialysis patients and associated with adverse health outcomes. Previous work focused primarily on neuropsychological tests, the gold standard measure of cognition. However, these tests reflect performance under optimal conditions rather than performance in everyday life. This study aims to assess both objective and subjective cognition in haemodialysis patients.

METHODS

Adult haemodialysis patients completed measures of objective cognitive impairment (Montreal Cognitive Assessment), subjective cognitive complaints, mood and fatigue symptoms, and provided sociodemographic information. Clinical data such as comorbidity were extracted from patients' medical record.

RESULTS

A total of 268 haemodialysis patients (mean age = 59.87 years; 42.5% female) participated. Only 25.0% of the sample had normal cognition, while the rest had either objective cognitive impairments or clinically significant cognitive complaints, or both (both objective impairments and subjective complaints: 26.1%; objective impairments without complaint: 38.4%; significant complaints without objective impairments: 10.4%). Lower education was associated with the presence of objective cognitive impairments, whereas depression was associated with the presence of clinically significant cognitive complaints. Patients who exhibited both objective cognitive impairments and significant cognitive complaints were more likely to have diabetes and higher dialysis dose (Kt/V). Patients with objective cognitive impairments but no significant complaints were significantly older.

CONCLUSIONS

The cognitive burden of haemodialysis patients can be manifested as objective impairments and/or subjective complaints. When combined the two indicators may better represent the overall cognitive well-being in this population. There is a need to screen for cognitive difficulties and develop cognitive rehabilitative strategies in dialysis settings.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

TRIAL REGISTRATION

Registration number: PROSPERO (CRD42023412864).

A new approach for cognitive impairment pattern in chronic kidney disease

BACKGROUND

Chronic kidney disease (CKD) is associated with an elevated risk of neurocognitive disorders (NCDs). It remains unclear whether CKD-related NCDs have a specific cognitive pattern or are earlier-onset phenotypes of the main NCDs (vascular NCDs and Alzheimer's disease).

METHODS

We used the Mini Mental State Examination score (MMSE) to assess cognitive patterns in 3003 CKD patients (stage 3-4) followed up over 5 years in the Chronic Kidney Disease-Renal Epidemiology and Information Network (CKD-REIN) cohort. After normalizing MMSE scores to a 0-to-100 scale, the associations between the baseline estimated glomerular filtration rate (eGFR, using the Chronic Kidney Disease Epidemiology Collaboration creatinine formula) and changes in each MMSE domain score were assessed in linear mixed models.

RESULTS

Patients (age: 67 ± 13 years old; males: 65%, mean eGFR: 33± 12 mL/min/1.73 m2) had a good baseline cognitive functions: the mean MMSE score was 26.9/30 ± 2.9. After adjustment for age, sex, educational level, depression (past or present), cardiovascular risk factors and cerebrovascular disease, a lower baseline eGFR (per 10 mL/min/1.73 m2) was associated with a 0.53-point decrement [P < .001; 95% confidence interval (CI) (-0.98, -0.08)] for orientation, a 1.04-point decrement [P = .03; 95% CI (-1.96, -0.13)] for attention and calculation, a 0.78-point decrement [P = .003; 95% CI (-1.30, -0.27)] for language, and a 0.94-point decrement [P = .02; 95% CI (-1.75, -0.13)] for praxis. Baseline eGFR was not, however, associated with significant changes over time in MMSE domain scores.

CONCLUSION

A lower eGFR in CKD patients was associated with early impairments in certain cognitive domains: praxis, language and attention domains before an obvious cognitive decline. Early detection of NCD in CKD patients must be performed before clinically cognitive decline using preferably tests assessing executive, attentional functions and language, rather than memory tests. This early cognitive screening could lead to a better management of cognitive impairment and their consequences on CKD management.

[Formula: see text] The multifaceted role of neuropsychology in pediatric solid organ transplant: preliminary guidelines and strategies for clinical practice

The incidence of pediatric solid organ transplantation (SOT) has increased in recent decades due to medical and surgical advances as well as improvements in organ procurement. Survival rates for pediatric kidney, liver, and heart transplantation are above 85% but patients continue to experience complex healthcare needs over their lifetime. Long-term developmental and neuropsychological sequelae are becoming increasingly recognized in this population, although preliminary work is limited and deserves further attention. Neuropsychological weaknesses are often present prior to transplantation and may be related to underlying congenital conditions as well as downstream impact of the indicating organ dysfunction on the central nervous system. Neuropsychological difficulties pose risk for functional complications, including disruption to adaptive skill development, social-emotional functioning, quality of life, and transition to adulthood. The impact of cognitive dysfunction on health management activities (e.g., medication adherence, medical decision-making) is also an important consideration given these patients' lifelong medical needs. The primary aim of this paper is to provide preliminary guidelines and clinical strategies for assessment of neuropsychological outcomes across SOT populations for pediatric neuropsychologists and the multidisciplinary medical team, including detailing unique and shared etiologies and risk factors for impairment across organ types, and functional implications. Recommendations for clinical neuropsychological monitoring as well as multidisciplinary collaboration within pediatric SOT teams are also provided.

Cognitive Impairment and Brain Atrophy in Patients with Chronic Kidney Disease

In Japan, the aging of the population is rapidly accelerating, with an increase in patients with chronic kidney disease (CKD) and those undergoing dialysis. As a result, the number of individuals with cognitive impairment (CI) is rising, and addressing this issue has become an urgent problem. A notable feature of dementia in CKD patients is the high frequency of vascular dementia, making its prevention through the management of classical risk factors such as hypertension, diabetes mellitus, dyslipidemia, smoking, etc., associated with atherosclerosis and arteriosclerosis. Other effective measures, including the use of renin-angiotensin system inhibitors, addressing anemia, exercise therapy, and lifestyle improvements, have been reported. The incidence and progression of CI may also be influenced by the type of kidney replacement therapy, with reports suggesting that long-duration dialysis, low-temperature hemodialysis, peritoneal dialysis, and kidney transplantation can have a preferable effect on the preservation of cognitive function. In conclusion, patients with CKD are at a higher risk of developing CI, with brain atrophy being a contributing factor. Despite the identification of various preventive measures, the evidence substantiating their efficacy remains limited across all studies. Future expectations lie in large-scale randomized controlled trials.

Subjective cognitive complaints in end-stage renal disease: a systematic review and meta-analysis

Cognitive impairment is common in patients with end-stage renal disease (ESRD) and is associated with compromised quality of life and functional capacity, as well as worse clinical outcomes. Most previous research and reviews in this area were focused on objective cognitive impairment, whereas patients' subjective cognitive complaints (SCCs) have been less well-understood. This systematic review aimed to provide a broad overview of what is known about SCCs in adult ESRD patients. Electronic databases were searched from inception to January 2022, which identified 221 relevant studies. SCCs appear to be highly prevalent in dialysis patients and less so in those who received kidney transplantation. A random-effects meta-analysis also shows that haemodialysis patients reported significantly more SCCs than peritoneal dialysis patients (standardised mean difference -0.20, 95% confidence interval -0.38 to -0.03). Synthesis of longitudinal studies suggests that SCCs remain stable on maintenance dialysis treatment but may reduce upon receipt of kidney transplant. Furthermore, SCCs in ESRD patients have been consistently associated with hospitalisation, depression, anxiety, fatigue, and poorer quality of life. There is limited data supporting a strong relation between objective and subjective cognition but preliminary evidence suggests that this association may be domain-specific. Methodological limitations and future research directions are discussed.

Prevalence and trajectories of subjective cognitive complaints and implications for patient outcomes: A prospective study of haemodialysis patients

OBJECTIVES

Cognitive impairment is common in haemodialysis patients and is associated with increased hospitalization and mortality. However, subjective cognitive complaints (SCCs), the self-experienced difficulties in everyday cognitive activities, remain poorly understood. This study examined the prevalence and course of SCCs in haemodialysis patients and its longitudinal associations with sociodemographic, clinical and patient-reported variables.

DESIGN

Observational prospective study with baseline and 12-month follow-up assessment.

METHODS

Based on a validated cut-off point on the Kidney Disease Quality of Life Cognitive Function subscale, haemodialysis patients (N = 159; 40.3% female, mean age 53.62) were classified into cognitive complaint trajectories: (1) resilient (60.4%; no/low SCCs throughout); (2) persistent (8.8%; stable high SCCs); (3) deterioration (17.6%; from no/low to high SCCs); and (4) recovery (13.2%; from high to no/low SCCs). Sociodemographic/clinical characteristics, self-efficacy, self-management skills, adherence, mood and biochemical assays were measured at both assessments and compared among trajectories using mixed ANOVAs.

RESULTS

Interaction effects indicated significant improvements in the recovery group in clinical outcomes (i.e., decreased phosphorus and calcium-phosphorus product), self-efficacy and mood over time. Group effects indicated significantly poorer self-efficacy, self-management skills and adherence in the persistent group than other trajectories across both assessments. None of the sociodemographic/clinical characteristics was associated with SCC trajectories.

CONCLUSIONS

The extent of SCCs vary over time across haemodialysis patients. Routine screening of SCCs in dialysis settings may help identifying patients at risk of poor self-management and worse prognosis. Strategies that compensate for cognitive lapses may mitigate the perceived cognitive burden of this population.

Cognitive Impairment and Anxiety Are Prevalent in Kidney Transplant Recipients

INTRODUCTION

Cognitive impairment (CI) is common in end-stage kidney disease (ESKD), including kidney transplant recipients. Patients with cognitive problems may find it difficult to comply with medical recommendations after kidney transplantation (KT), which can be the cause of many complications, poorer prognosis, and increased hospitalization rates after transplantation. Additionally, some patients after KT may experience depression and anxiety, which are prevalent comorbidities in patients with ESKD.

METHODS

In this single-center, cross-sectional study, we included 56 consecutive adult patients after KT. Cognitive function was assessed using the Addenbrooke Cognitive Test III (ACE III). In addition, all patients were screened for depression and anxiety using the Hospital Anxiety and Depression Scale (HADS). The impact of immunosuppressive therapy and other disease-related variables on cognitive function was also assessed.

RESULTS

A total of 56 KT patients, with a mean age of 50.3 ± 11.7 years, transplanted ≤35 months ago were included in the study. The prevalence of CI was 30%. Compared with cognitively unimpaired patients, patients with CI scored significantly lower in all cognitive domains. Furthermore, better cognitive functioning after KT was significantly associated with more years of schooling. We found no significant correlation between CI and age at assessment, duration of dialysis before KT, creatinine levels, creatinine clearance, uric acid levels, hemoglobin levels, comorbid cardiovascular diseases, and immunosuppressive therapy. In addition, the prevalence of depression and anxiety in screening tests was 12.5% and 27%, respectively, and patients receiving higher daily dose of prednisone had higher HADS scores on both the depression and anxiety subscales (not statistically significant).

DISCUSSION

Cognitive disorders are a relevant issue in kidney transplant recipients. There might be many factors, both before and after KT, that have a negative impact on cognition. Therefore, further research is needed to increase knowledge about the course and profile of cognitive function after KT.

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.

Cognitive Outcome After Islet Transplantation

Severe or repeated hypoglycemia events may favor memory complaints in type 1 diabetes (T1D). Pancreatic islet transplantation (IT) is an alternative option to exogenous insulin therapy in case of labile T1D, implying a maintenance immunosuppression regimen based on sirolimus or mycophenolate, associated with tacrolimus, that may also have neurological toxicity. The objective of this study was to compare a cognitive rating scale Mini-Mental State Examination (MMSE) between T1D patients with or without IT and to identify parameters influencing MMSE.

Methods

This retrospective cross-sectional study compared MMSE and cognitive function tests between islet-transplanted T1D patients and nontransplanted T1D controls who were transplant candidates. Patients were excluded if they refused.

Results

Forty-three T1D patients were included: 9 T1D patients before IT and 34 islet-transplanted patients (14 treated with mycophenolate and 20 treated with sirolimus). Neither MMSE score (P = 0.70) nor higher cognitive function differed between islet versus non-islet-transplanted patients, whatever the type of immunosuppression. In the whole population (N = 43), MMSE score was negatively correlated to glycated hemoglobin (r = -0.30; P = 0.048) and the time spent in hypoglycemia on the continuous glucose monitoring (r = -0.32; P = 0.041). MMSE score was not correlated to fasting C-peptide level, time spent in hyperglycemia, average blood glucose, time under immunosuppression, duration of diabetes, or beta-score (success score of IT).

Conclusions

This first study evaluating cognitive disorders in islet-transplanted T1D patients argues for the importance of glucose balance on cognitive function rather than of immunosuppressive treatment, with a favorable effect of glucose balance improvement on MMSE score after IT.

Secondary Hyperparathyroidism and Cognitive Decline

Purpose of Review

Secondary hyperparathyroidism (SHPT) likely contributes to the high prevalence of cognitive decline found among individuals with end-stage kidney disease (ESKD). Our objective is to critically evaluate the recent literature regarding the association between SHPT and cognitive decline and identify potential mechanisms.

Recent Findings

Nine studies assessing the relationship between SHPT and cognition have been published in the last two decades, each showing that elevated parathyroid hormone (PTH) levels were associated with cognitive decline. One also found structural changes within the brain related to SHPT. Additionally, two found that SHPT treatment decreases the risk of cognitive decline in ESKD patients.

Summary

SHPT is associated with cognitive impairment. However, the severity of SHPT associated with these changes and the specific cognitive domains affected remain unclear. Future studies are needed to focus on specific cognitive domains, the trajectory of cognitive decline, and optimal treatment strategies including the impact of kidney transplant and tertiary hyperparathyroidism.

Effect of Intravenous Ferric Carboxymaltose on Exercise Capacity After Kidney Transplantation (EFFECT-KTx): rationale and study protocol for a double-blind, randomised, placebo-controlled trial

INTRODUCTION

Iron deficiency (ID) is common and has been associated with an excess mortality risk in kidney transplant recipients (KTRs). In patients with chronic heart failure and ID, intravenous iron improves exercise capacity and quality of life. Whether these beneficial effects also occur in KTRs is unknown. The main objective of this trial is to address whether intravenous iron improves exercise tolerance in iron-deficient KTRs.

METHODS AND ANALYSIS

The Effect of Ferric Carboxymaltose on Exercise Capacity after Kidney Transplantation study is a multicentre, double-blind, randomised, placebo-controlled clinical trial that will include 158 iron-deficient KTRs. ID is defined as plasma ferritin <100 µg/L or plasma ferritin 100-299 µg/L with transferrin saturation <20%. Patients are randomised to receive 10 mL of ferric carboxymaltose (50 mg Fe³⁺/mL, intravenously) or placebo (0.9% sodium chloride solution) every 6 weeks, four dosages in total. The primary endpoint is change in exercise capacity, as quantified by the 6 min walk test, between the first study visit and the end of follow-up, 24 weeks later. Secondary endpoints include changes in haemoglobin levels and iron status, quality of life, systolic and diastolic heart function, skeletal muscle strength, bone and mineral parameters, neurocognitive function and safety endpoints. Tertiary (explorative) outcomes are changes in gut microbiota and lymphocyte proliferation and function.

ETHICS AND DISSEMINATION

The protocol of this study has been approved by the medical ethical committee of the University Medical Centre Groningen (METc 2018/482;) and is being conducted in accordance with the principles of the Declaration of Helsinki, the Standard Protocol Items: Recommendations for Interventional Trials checklist and the Good Clinical Practice guidelines provided by the International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use. Study results will be disseminated through publications in peer-reviewed journals and conference presentations.

TRIAL REGISTRATION NUMBER

NCT03769441.

The role of subjective cognitive complaints in self-management among haemodialysis patients: a cross-sectional study

Background

Subjective cognitive complaints refer to self-experienced difficulties with everyday cognitive tasks. Although there has been a fair amount of research on cognitive impairments and cognitive complaints in end-stage renal disease, the practical implications of these complaints remain unclear. The current study aims to examine the associations of cognitive complaints with sociodemographic and clinical variables, mood, as well as key patient-reported outcomes, i.e., self-efficacy, self-management skills, and treatment adherence.

Methods

A total of 305 haemodialysis patients (mean age = 53.97 years, 42.6% female) completed the Kidney Disease Quality of Life Cognitive Function subscale, a brief measure of cognitive complaints. The recommended cut-off point of 60 was used to identify probable cognitive impairment. Measures of self-efficacy, self-management skills (i.e., symptom coping, health monitoring, health service navigation), treatment adherence, and mood symptoms were also administered. Between-group comparisons and correlational analyses were performed to examine associations of cognitive complaints with sociodemographic, clinical, and health behaviour variables. Mediation analyses were also conducted to investigate the mediating role of self-efficacy on the relationship between cognitive complaints and treatment adherence.

Results

Nearly a quarter (23.0%) of haemodialysis patients reported cognitive complaints indicative of clinical impairments. Risk of probable impairments was higher for patients with hypertension, diabetes, those diagnosed with end-stage renal disease at an older age, and those with shorter time on dialysis. Subjective cognitive complaints (both rates of probable impairments as per cut-off and continuous scores) were significantly associated with lower disease and treatment self-efficacy, poorer self-management skills, lower treatment adherence, as well as higher symptoms of distress. Mediation analysis indicated that treatment self-efficacy mediated the relationship between cognitive complaints and treatment adherence.

Conclusions

The current study demonstrated the clinical characteristics of haemodialysis patients who report cognitive complaints indicative of probable cognitive impairments and showed the associations of these complaints with self-management outcomes. Future studies should adopt more comprehensive measures of cognitive complaints and longitudinal designs to confirm the current findings.

Neurocognitive Function Changes Following Kidney Transplant: A Prospective Study

Rationale & Objective

Patients with advanced kidney disease are at risk for cognitive impairment, which may persist after kidney transplantation. We sought to understand changes in neurocognitive function domains utilizing comprehensive cognitive assessments.

Study Design

Prospective cohort study.

Setting & Population

Single-center study of patients undergoing kidney transplantation.

Exposure

Kidney transplantation.

Outcomes

Changes in neurocognitive function as measured by the Repeatable Battery for Assessment of Neuropsychological Status (RBANS) and the Trail Making Test Parts A and B (TRAIL A and B) before transplantation (baseline) and compared to 3 months and 12 months posttransplant.

Analytical Approach

Wilcoxon signed-rank and linear mixed effect models were utilized to assess changes in neurocognitive scores at 3 months and 12 months compared to baseline.

Results

Thirty-two patients were included with a mean age of 45 years, 47% female, 85% White, and 62% with at least some college education. Hypertension and diabetes were etiologies of kidney disease in 31% and 25% of patients, respectively. Baseline RBANS and TRAIL A and B scores averaged 84.7 ± 14, 40.4 ± 9.9, and 41 ± 11.5, respectively. Although there were posttransplant improvements in immediate and delayed memory at 3 months, these were not sustained at 12 months. There were no significant differences from baseline at 3 months and 12 months in RBANS index scores for language, visuospatial/constructional abilities, and attention. Compared to baseline, TRAIL A scores were not significantly different at 3 months but were significantly improved at 12 months, whereas TRAIL B scores improved significantly at both 3 months and 12 months.

Limitations

Single-center design and small sample size.

Conclusions

Utilizing comprehensive cognitive assessments, we found improvements in attention and executive function in the first posttransplant year as measured by TRAIL A and B. However, there was no significant change in global cognition as measured by RBANS. These findings identify cognitive domains for potential intervention in the posttransplant population.

Patient Perspectives on the Use of Frailty, Cognitive Function, and Age in Kidney Transplant Evaluation

BACKGROUND

The allocation of scarce deceased donor kidneys is a complex process. Transplant providers are increasingly relying on constructs such as frailty and cognitive function to guide kidney transplant (KT) candidate selection. Patient views of the ethical issues surrounding the use of such constructs are unclear. We sought to assess KT candidates' attitudes and beliefs about the use of frailty and cognitive function to guide waitlist selection.

METHODS

KT candidates were randomly recruited from an ongoing single-center cohort study of frailty and cognitive function. Semi-structured interviews were conducted, and thematic analysis was performed. Inductively derived themes were mapped onto bioethics principles.

RESULTS

Twenty interviews were conducted (65% contact rate, 100% participation rate) (60% male; 70% White). With respect to the use of frailty and cognitive function in waitlisting decisions, four themes emerged in which participants: (1) valued maximizing a scarce resource (utility); (2) prioritized equal access to all patients (equity); (3) appreciated a proportional approach to the use of equity and utility (precautionary utility); and (4) sought to weigh utility- and equity-based concerns regarding social support. While some participants believed frailty and cognitive function were useful constructs to maximize utility, others believed their use would jeopardize equity. Patients were uncomfortable with using single factors such as frailty or cognitive impairment to deny someone access to transplantation; participants instead encouraged using the constructs to identify opportunities for intervention to improve frailty and cognitive function prior to KT.

CONCLUSIONS

KT candidates' values mirrored the current allocation strategy, seeking to balance equity and utility in a just manner, albeit with conflicting viewpoints on the appropriate use of frailty and cognitive impairment in waitlisting decisions.

Cognitive impairment and kidney transplantation- underestimated, underrecognized but clinically relevant problem

BACKGROUND

Chronic kidney disease (CKD) affects the crosstalk between organs in the body and vast majority of studies were devoted to the interactions between the kidneys and the cardiovascular system. As of today, there is more evidence of the kidney and the central nervous system connections.

SUMMARY

Indeed, CKD and in particular dialysis therapy is linked to the increased prevalence of neurological complications, such as cerebrovascular disorders, movement disorders, cognitive impairment, and depression. Both traditional cardiovascular risk factors (such as diabetes, hypertension, and lipid disorders), non-traditional risk factors (such as uremic toxins, anemia, secondary hyperparathyroidism) may predispose CKD patients to neurological disorders. Likewise, cognitive problems occur more commonly in kidney transplant recipients, regardless of age, than in the general population, but the prevalence is still understudied. Cognitive impairment is associated with a higher risk of hospitalization, mortality, decreased quality of life or health care costs in kidney transplant recipients. Here, we review (i) the potential clinical impact of kidney transplantation on cerebrovascular and neurological complications, (ii) evaluation of patients with cognitive impairment for kidney transplantation (iii) the potential impact cognitive impairment on waitlisted and transplanted patients on patient care, and (iv) unmet medical needs.

KEY MESSAGES

• Cognitive impairment in kidney transplant recipients is underestimated, underrecognized but clinically relevant problem. • The screening for cognitive declines after kidney transplantation is not yet a routine practice. • Several prospective and cross-sectional studies reported improvement across some of the assessed cognitive domains after transplantation.

Hemodialyzed Individuals' Left Spatial Attentional Bias Is Normalized Following Successful Kidney Transplantation

BACKGROUND

Healthy people have a leftward spatial attentional bias, called pseudoneglect. Individuals with end-stage renal disease (ESRD) who are receiving hemodialysis often demonstrate an increase in their leftward spatial attentional bias. Whereas a successful kidney transplant often improves the cognitive functions of individuals who previously received hemodialysis, the effect of a kidney transplant on this abnormal allocation of spatial attention has not been investigated.

OBJECTIVE

To investigate the effects of kidney transplant on individuals who were being treated with dialysis and had an increase in their left spatial attentional bias.

METHOD

The performance of 20 hemodialyzed individuals with ESRD on the line bisection test was compared to that of 17 demographically matched individuals with ESRD, who had received a kidney transplant, and 23 demographically matched healthy controls (HC).

RESULTS

All of the participants exhibited a left spatial bias on the line bisection task. When compared with the HC, the hemodialyzed individuals demonstrated a significantly greater left spatial bias. There was, however, no difference in spatial bias between the HC and the individuals who had received a kidney transplant.

CONCLUSION

A successful kidney transplant can improve patients' abnormal leftward allocation of spatial attention. However, future studies are needed to better understand the mechanisms of this spatial attentional bias in hemodialyzed individuals and the normalization of bias following transplantation.

Long-term cognitive impairments in kidney transplant recipients: impact on participation and quality of life

BACKGROUND

Cognitive impairment is often present shortly after transplantation in kidney transplant recipients (KTR). To date, it is unknown whether these impairments persist in thelong term, to what extent they are associated with disease-related variables and whether they affect societal participation and quality of life (QoL) of KTR.

METHOD

This study was part of the TransplantLines Biobank & Cohort Study in the University Medical Center Groningen. A total of 131 KTR, with a mean age of 53.6 years (SD = 13.5) transplanted ≥1 year ago (M = 11.2 years, range 1-41.7 years), were included and compared with 306 healthy controls (HC). KTR and HC were well matched; there were no significant differences regarding age, sex and education. All participants were assessed with neuropsychological tests measuring memory, mental speed, attention and executive functioning, and with questionnaires examining societal participation and QoL.

RESULTS

Compared with HC, KTR performed significantly worse on memory, mental speed and measures of executive functioning (all P-values <0.05). Moreover, 16% of KTR met the criteria for mild cognitive impairment (MCI), compared with 2.6% of the HC. MCI in KTR was not significantly correlated with age- and disease-related variables. Poorer cognitive functioning was significantly related to lower levels of societal participation and to lower QoL (all P-values <0.01).

CONCLUSIONS

This study shows long-term cognitive impairments in KTR, which are not related to disease-related variables. Neuropsychological assessment is important to timely signal these impairments, given their serious negative impact on societal participation and QoL.

ssessment of Tacrolimus Neurotoxicity Measured by Retinal OCT

BACKGROUND

Neurotoxicity secondary to anticalcineurinics is a prevalent side effect in transplant recipients. Optical coherence tomography (OCT) scans the central nervous system by direct access to the retina. OCT assesses central nervous system involvement by measuring the thickness of the retinal layers, especially the ganglion cell layer (GCL). The retinal scan divides the scanned area into affected and unaffected segments, which can be quantified for each eye. The aim of this study was to determine retinal GCL thickness by means of OCT, analyzing the proportion of affected segments in individuals exposed to tacrolimus compared with a control group.

MATERIALS AND METHODS

We evaluated 20 renal transplant recipients exposed to tacrolimus for ≥6 months. The number of affected segments in the GCL of the retina was quantified by OCT. The control group was drawn from the general population attending routine ophthalmologic checkups.

RESULTS

Patients exposed to tacrolimus had a pathologic examination in 50% of cases compared with 20% in the control group (P < .044). Furthermore, among patients with an exposure time to tacrolimus >5 years, the examination was pathologic in 80% (P < .005). Linear regression analysis showed the presence of GCL segments with decreased thickness to be associated with the duration of exposure to tacrolimus (P = .036) and the time in dialysis before kidney transplant (P = .030).

CONCLUSION

Although this is a preliminary study, OCT scanning could serve to detect the neurotoxic effect of tacrolimus on the retinal GCL and central nervous system in renal transplant recipients.

Pretransplant Comprehensive Geriatric Assessment in Older Patients with Advanced Chronic Kidney Disease

BACKGROUND

In older patients with advanced chronic kidney disease (CKD), the decision of kidney transplantation (KT) is a challenge for nephrologists. The use of comprehensive geriatric assessment (CGA) is increasingly gaining interest into the process of decision-making about treatment modality choice for CKD. The aim of this study was to assess the prevalence of geriatric impairment and frailty in older dialysis and nondialysis patients with advanced CKD using a pretransplant CGA model and to identify geriatric impairments influencing the geriatricians' recommendations for KT.

METHODS

An observational study was conducted with retrospective data from July 2017 to January 2020. Patients aged ≥65 years with advanced CKD, treated or not with dialysis, and referred by the nephrologist were included in the study. The CGA assessed comorbidity burden, cognition, mood, nutritional status, (instrumental) activities of daily living, physical function, frailty, and polypharmacy. Geriatric impairments influencing the geriatricians' recommendations for KT were identified using univariate and multivariate logistic regressions.

RESULTS

156 patients were included (74.2 ± 3.5 years and 62.2% on dialysis). Geriatric conditions were highly prevalent in both dialysis and nondialysis groups. The rate of geriatric impairments was higher in dialysis patients regarding comorbidity burden, symptoms of depression, physical function, autonomy, and frailty. Geriatrician's recommendations for KT were as follows: favorable (79.5%) versus not favorable or multidisciplinary discussion needed with nephrologists (20.5%). Dependence for Instrumental Activities of Daily Living (IADL) (odds ratio [OR] = 3.01 and 95% confidence interval [CI] = 1.30-7.31), physical functions (OR = 2.91 and 95% CI = 1.08-7.87), and frailty (OR = 2.66 and 95% CI = 1.07-6.65) were found to be independent geriatric impairments influencing geriatrician's recommendations for KT.

CONCLUSIONS

Understanding the burden of geriatric impairment provides an opportunity to direct KT decision-making and to guide interventions to prevent functional decline and preserve quality of life.

A cross-sectional study exploring cognitive impairment in kidney failure

BACKGROUND

Little is known of the prevalence or associated factors of cognitive impairment in people with kidney failure. Assessment of cognition is necessary to inform comprehension of healthcare information, aptitude for dialysis modality and informed decision making.

OBJECTIVES

This study sought to determine the prevalence and factors associated with cognitive impairment in people with kidney failure.

DESIGN

Prospective cross-sectional.

PARTICIPANTS

Participants (n = 222) with chronic kidney disease grade 5 (CKD G5) including those not treated with dialysis, those undertaking dialysis independently or in a facility (CKD 5D), and those with a kidney transplant (CKD 5T).

MEASUREMENTS

Data were collected using the Montreal Cognitive Assessment tool, the Hospital Anxiety and Depression Scale (only the depression subscale), and a demographic questionnaire. Type of kidney disease and comorbidities were extracted from participants' hospital records.

RESULTS

Participants were 61 ± 13.63 years old; most were male (61.26%), and diabetes was the primary cause of kidney disease (34%). Prevalence of cognitive impairment was 34% although it was significantly higher for those in CKD G5 compared with other groups. A number of factors were found to be associated with cognitive impairment including, age, diabetes, hypertension, education, haemoglobin, albumin, parathyroid hormone, CKD G5, and length of time on treatment.

CONCLUSIONS

Cognitive impairment in kidney failure is common and it has significant implications for informed decision making and treatment choices. Routine assessment of cognitive function is an important part of clinical practice.

Association of renal impairment with cognitive dysfunction in the Northern Ireland Cohort for the Longitudinal Study of Ageing (NICOLA)

Introduction

Chronic kidney disease (CKD) is a recognized risk factor for cognitive impairment. Identification of those at greatest risk of cognitive impairment may facilitate earlier therapeutic intervention. This study evaluated associations between estimated glomerular filtration rate (eGFR) and cognitive function in the Northern Ireland Cohort for the Longitudinal Study of Ageing.

Methods

Data were available for 3412 participants ≥50 years of age living in non-institutionalized settings who attended a health assessment between February 2014 and March 2016. Measures of serum creatinine (SCr) and cystatin C (cys-C) were used for eGFR. Cognitive function was measured using the Montreal Cognitive Assessment (MoCA) and the Mini-Mental State Examination (MMSE).

Results

Following adjustment for potential confounders, a single unit decrease in eGFR was significantly associated with reduced cognitive function defined by an MMSE ≤24/30 {eGFR calculated using serum cys-C [eGFRcys]: β = −0.01 [95% confidence interval (CI) −0.001 to −0.01], P = 0.01} and MoCA <26/30 [β = −0.01 (95% CI −0.002 to −0.02), P = 0.02]. Similarly, CKD Stages 3–5 were also associated with a moderate increase in the odds of cognitive impairment (MMSE ≤24) following adjustment for confounders [eGFRcys: odds ratio 2.73 (95% CI 1.38–5.42), P = 0.004].

Conclusions

Decreased eGFRcys was associated with a significantly increased risk of cognitive impairment in a population-based cohort of older adults. However, there was no evidence of an association between cognitive impairment and the more commonly used eGFR calculated using SCr. eGFRcys may offer improved sensitivity over eGFRcr in the determination of renal function and associated risk of cognitive impairment.

Improved cognitive function after kidney transplantation compared to hemodialysis

End-stage renal disease is associated with chronic stress that in turn may result in endocrine changes, affect cognitive, and physical capacities and increase the risk for cardiovascular events. The objective of this study was to evaluate and characterize possible stress parameters and compare cognitive function in those patients. Physiological and biochemical stress parameters as well as cognitive function were assessed in 17 hemodialysis and 18 renal transplant patients and both groups were compared. Serum cortisol and interleukin-6 levels were elevated in both groups but showed no significant difference. Cholesterol and low-density lipoprotein levels were significantly higher in patients following renal transplantation. While heart rate variability was comparable in both groups, most cognitive tests showed better results in renal transplant patients. We showed that: (1) cognitive function may improve following renal transplantation; (2) standard biochemical stress parameters are not useful to discriminate stress in patients with chronic kidney disease; and (3) heart rate variability is unaltered in this setting.

Molecular Diversity of Clinically Stable Human Kidney Allografts

IMPORTANCE

Clinical decision and immunosuppression dosing in kidney transplantation rely on transplant biopsy tissue histology even though histology has low specificity, sensitivity, and reproducibility for rejection diagnosis. The inclusion of stable allografts in mechanistic and clinical studies is vital to provide a normal, noninjured comparative group for all interrogative studies on understanding allograft injury.

OBJECTIVE

To refine the definition of a stable allograft as one that is clinically, histologically, and molecularly quiescent using publicly available transcriptomics data.

DESIGN, SETTING, AND PARTICIPANTS

In this prognostic study, the National Center for Biotechnology Information Gene Expression Omnibus was used to search for microarray gene expression data from kidney transplant tissues, resulting in 38 studies from January 1, 2017, to December 31, 2018. The diagnostic annotations included 510 acute rejection (AR) samples, 1154 histologically stable (hSTA) samples, and 609 normal samples. Raw fluorescence intensity data were downloaded and preprocessed followed by data set merging and batch correction.

MAIN OUTCOMES AND MEASURES

The primary measure was area under the receiver operating characteristics curve from a set of feature selected genes and cell types for distinguishing AR from normal kidney tissue.

RESULTS

Within the 28 data sets, the feature selection procedure identified a set of 6 genes (KLF4, CENPJ, KLF2, PPP1R15A, FOSB, TNFAIP3) (area under the curve [AUC], 0.98) and 5 immune cell types (CD4+ T-cell central memory [Tcm], CD4+ T-cell effector memory [Tem], CD8+ Tem, natural killer [NK] cells, and Type 1 T helper [TH1] cells) (AUC, 0.92) that were combined into 1 composite Instability Score (InstaScore) (AUC, 0.99). The InstaScore was applied to the hSTA samples: 626 of 1154 (54%) were found to be immune quiescent and redefined as histologically and molecularly stable (hSTA/mSTA); 528 of 1154 (46%) were found to have molecular evidence of rejection (hSTA/mAR) and should not have been classified as stable allografts. The validation on an independent cohort of 6 months of protocol biopsy samples in December 2019 showed that hSTA/mAR samples had a significant change in graft function (r = 0.52, P < .001) and graft loss at 5-year follow-up (r = 0.17). A drop by 10 mL/min/1.73m2 in estimated glomerular filtration rate was estimated as a threshold in allograft transitioning from hSTA/mSTA to hSTA/mAR.

CONCLUSIONS AND RELEVANCE

The results of this prognostic study suggest that the InstaScore could provide an important adjunct for comprehensive and highly quantitative phenotyping of protocol kidney transplant biopsy samples and could be integrated into clinical care for accurate estimation of subsequent patient clinical outcomes.

Cognitive Function and Uremic Toxins after Kidney Transplantation: An Exploratory Study

BACKGROUND

Cognitive functions are altered in patients with CKD. However, it is suggested that cognitive functions improve after kidney transplantation, at least partially. A possible cause for this improvement could be the reduction of uremic retention solutes after transplantation. This study assessed the association between the changes in uremic toxin concentration with the changes in cognitive function in patients after kidney transplantation.

METHODS

Ten recipients of kidney transplants were compared with 18 controls (nine patients on hemodialysis, and nine patients with CKD stage 4 or 5 [eGFR <30 ml/min per 1.73 m²] who were not on dialysis). An extensive neuropsychological assessment, covering the five major cognitive domains (i.e., memory, attention and concentration, information processing speed, abstract reasoning, and executive function), was done before transplantation, at 1 week post-transplant, and 3 months after transplantation. Similarly, assessments of the 18 matched, control patients were performed longitudinally over a period of 3-5 months. Concentrations of 16 uremic retention solutes (indoxyl glucuronide, p-cresyl glucuronide, phenylglucuronide, 3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid, indoxyl sulfate, p-cresyl sulfate, hippuric acid, phenyl sulfate, kynurenine, tryptophan, kynurenic acid, tyrosine, indole-3-acetic acid, phenylalanine, trimethylamine N-oxide, and phenylacetylglutamine) were measured in serum samples collected at the time of the neuropsychological assessments.

RESULTS

A significant improvement in cognitive function was only found in the processing-speed domain, and this was observed in both patients who received a transplant and patients with CKD. No significant differences between patients who received a transplant and the control groups were seen in the other cognitive domains. As expected, the serum concentration of most uremic toxins decreased significantly within 1 week after kidney transplantation.

CONCLUSIONS

There was no significant improvement in cognitive function that could be specifically related to kidney transplantation in the first 3 months after the procedure. These data do not support the notion that uremic toxins exert an immediate effect on cognitive function.

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

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

Interventions to Preserve Cognitive Functioning Among Older Kidney Transplant Recipients

PURPOSE OF REVIEW

To summarize the research on effective interventions for preserving cognitive function and prevent cognitive decline in patients with end-stage kidney disease (ESKD) who are undergoing dialysis and/or kidney transplantation (KT).

RECENT FINDINGS

Among ESKD patients undergoing hemodialysis, exercise training has been administered through home-based and intradialytic interventions. Additionally, one pilot study identified intradialytic cognitive training, electronic brain games, as an intervention to preserve cognitive function among patients undergoing hemodialysis. Fewer studies have investigated interventions to preserver cognitive function among KT recipients. To date, the only randomized controlled trial in this population identified B-vitamin supplements as an intervention to preserve cognitive function. The evidence from these trials support a short-term benefit of cognitive and exercise training as well as B-vitamin supplementation among patients with ESKD. Future studies should: 1) replicate these findings, 2) identify interventions specific to KT candidates, and 3) investigate the synergistic impact of both cognitive and exercise training.

SUMMARY

Cognitive prehabilitation, with cognitive and/or exercise training, may be novel interventions for KT candidates that not only reduces delirium risk and long-term post-KT cognitive decline but also prevents dementia.

Cognitive Function in Kidney Transplantation

Purpose of the review

Cognitive impairment is common in kidney transplant recipients and affects quality of life, graft survival, morbidity, and mortality. In this review article we discuss the epidemiology, diagnosis, pathophysiology and future directions for cognitive impairment in kidney transplantation. We describe the potential role of pre-transplant cognition, immunosuppression and peri-transplant factors in post -transplant cognitive impairment.

Recent Findings

A majority of patients with kidney transplant have cognitive impairment. Cognitive impairment affects both pre-transplant evaluation and post-transplant outcomes. Failure to identify patients with cognitive impairment can withhold appropriate care and timely intervention.

Summary

Cognitive impairment is common in kidney transplant and affects outcomes. Studies addressing modifiable risk factors and possible interventions to slow cognitive decline in patients with kidney disease are needed.

An Approach to Neurological Disorders in a Kidney Transplant Recipient

Kidney transplantation is the preferred treatment modality in patients with ESKD. However, there are associated complications that arise from immunosuppressive medications, infections, and associated comorbidities. Neurologic disorders frequently develop in patients who have received a kidney transplant, which in turn increases the associated morbidity and mortality. This review discusses the common neurologic disorders after kidney transplantation, including infections, cognitive decline, drug-related conditions, malignancy, seizure, and other neurologic complications.

Prevalence, Types and Recognition of Cognitive Impairment in Dialysis Patients in South Eastern Sydney

BACKGROUND

In international studies, cognitive impairment is a common but underdetected issue in dialysis patients. Chronic Kidney Disease (CKD) shares risk factors with and is an independent risk factor for cognitive impairment. There is a lack of Australian data of cognitive impairment in this at-risk population. This has implications on service planning because cognitive impairment in CKD is associated with higher mortality, morbidity, and healthcare costs.

AIMS

This study examines the prevalence, types, and clinician recognition of cognitive impairment within an Australian dialysis population.

METHODS

A cross-sectional study of haemodialysis and peritoneal dialysis patients in South-East Sydney screened for cognitive impairment using the Montreal Cognitive Assessment (MoCA). Participant interviews, medical records, physician and carer questionnaires, were used to determine the types of cognitive impairment and rate of recognition.

RESULTS

106 participants were included (median age 66 years, median dialysis duration 2 years) and 58 (54.7%) were cognitively impaired on the MoCA, of whom old age psychiatrists subclassified 21 (36.2%) as having dementia, and 31 (53.4%) with 'Cognitive Impairment, No Dementia'. 36/58 (62.0%) of the cognitively impaired participants on the MoCA were suspected of having cognitive impairment by nephrologists but only 14/58 (24.1%) had this documented in medical records.

CONCLUSION

Although cognitive impairment is common in dialysis patients, there are low levels of detection by clinical teams. Cognitive screening of dialysis patients should be incorporated as part of wider assessment and determination of management goals such as individuals' capacity to self-care and provide informed consent to treatments. This article is protected by copyright. All rights reserved.

Cognitive Function, Access to Kidney Transplantation, and Waitlist Mortality Among Kidney Transplant Candidates With or Without Diabetes

RATIONALE & OBJECTIVE

Intact cognition is generally a prerequisite for navigating through and completing evaluation for kidney transplantation. Despite kidney transplantation being contraindicated for those with severe dementia, screening for more mild forms of cognitive impairment before referral is rare. Candidates may have unrecognized cognitive impairment, which may prolong evaluation, elevate mortality risk, and hinder access to kidney transplantation. We estimated the burden of cognitive impairment and its association with access to kidney transplantation and waitlist mortality.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

3,630 participants (January 2009 to June 2018) with cognitive function measured (by the Modified Mini-Mental State Examination [3MS]) at kidney transplantation evaluation at 1 of 2 transplantation centers.

PREDICTORS

Cognitive impairment (3MS score<80).

OUTCOMES

Listing, waitlist mortality, and kidney transplantation.

ANALYTICAL APPROACH

We estimated the adjusted chance of listing (Cox regression), risk for waitlist mortality (competing-risks regression), and kidney transplantation rate (Poisson regression) by cognitive impairment. Given potential differences in cause of cognitive impairment among those with and without diabetes, we tested whether these associations differed by diabetes status using a Wald test.

RESULTS

At evaluation, 6.4% of participants had cognitive impairment, which was independently associated with 25% lower chance of listing (adjusted HR, 0.75; 95% CI, 0.61-0.91); this association did not differ by diabetes status (Pinteraction=0.07). There was a nominal difference by diabetes status for the association between cognitive impairment and kidney transplantation rate (Pinteraction=0.05), while the association between cognitive impairment and waitlist mortality differed by diabetes status kidney transplantation rates (Pinteraction=0.02). Among candidates without diabetes, those with cognitive impairment were at 2.47 (95% CI, 1.31-4.66) times greater risk for waitlist mortality; cognitive impairment was not associated with this outcome among candidates with diabetes.

LIMITATIONS

Single measure of cognitive impairment.

CONCLUSIONS

Cognitive impairment is associated with a lower chance of being placed on the waitlist, and among patients without diabetes, with increased mortality on the waitlist. Future studies should investigate whether implementation of screening for cognitive impairment improves these outcomes.

Mechanisms of cognitive dysfunction in CKD

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

Cognitive Improvement After Kidney Transplantation Is Associated With Structural and Functional Changes on MRI

Supplemental Digital Content is available in the text.

Background.

Several studies have reported improved cognitive outcomes after kidney transplantation, but most studies either did not include controls or lacked extensive neuroimaging. In addition, there is uncertainty whether kidney donation is a safe procedure in terms of cognitive outcomes.

Methods.

We prospectively studied neurocognitive function in kidney transplant recipients. The primary outcome was change in neurocognitive function after 1 year compared with baseline, which was evaluated using the Amsterdam Neuropsychological Task battery and verbal fluency tests. Secondary outcomes included changes in depression and anxiety (measured by the Hospital Anxiety and Depression scale) and changes in fatigue (measured by the Checklist for Individual Strength). We included kidney donors to control for learning effects, socioeconomic status, and surgery. In addition, kidney transplant recipients were evaluated with MRI scans at baseline and at year 1. The MRI protocol included conventional MRI, automated volumetric measurement, diffusion tensor imaging, magnetic resonance spectroscopy, arterial spin labeling, and a resting state functional MRI.

Results.

Twenty-seven recipients and 24 donors were included. For both recipients and donors, neuropsychologic testing scores improved 1 year after transplantation (donation). Recipient improvement significantly exceeded donor improvement on tasks measuring attention and working memory. These improvements were associated with increases in white matter volume and N-acetylaspartate/creatine (a marker for neuronal integrity).

Conclusions.

Attention and working memory improve significantly 1 year after kidney transplantation. Learning effects do not account for these improvements because recipient improvement in these areas exceeds donor improvement and correlates with an improvement in white matter integrity after transplantation. Kidney donation appears to be a safe procedure in terms of cognitive outcomes.

Psychological and Psychopathological Aspects of Kidney Transplantation: A Systematic Review

Kidney transplantation is a serious event that involves profound psychological, relational and social changes both for the patient and his family context. Assessment of personality profile, awareness of disease, family and social support of the patient candidate for kidney transplantation are necessary because factors not adequately considered, can influence the success of the transplant and alter the psychological stability of the patient. The present study aims to provide a systematic review of the literature of the last twelve years (2006-2018), focusing in particular on patient's readiness level and illness management and on possible psychopathology. Sixty-two studies were examined. Based on the Downs and Black checklist, most studies (n = 32) were of high quality; 15 of which related to lifestyle, health education, and therapeutic adherence in post-renal transplantation, 17 studies concerned the possible existence of psychopathology and cognitive impairment of renal deceased transplanted subjects. The literature used has shown that the population of kidney transplant patients is exposed to a high risk of psychiatric disorders with repercussions on the quality of life and the risk of rejection. Therefore, an adequate pre-transplant psychosocial assessment is necessary, which allows a more in-depth knowledge of the candidate to plan coping strategies and possible post-transplant psychotherapy.

Exercise and cognitive function in patients with end-stage kidney disease

In this review we summarize the research pertaining to the role of exercise in preventing cognitive decline in patients with end-stage kidney disease (ESKD). Impairment in cognitive function, especially in executive function, is common in patients with ESKD, and may worsen with maintenance dialysis as a result of retention of uremic toxins, recurrent cerebral ischemia, and high burden of inactivity. Cognitive impairment may lead to long-term adverse consequences, including dementia and death. Home-based and intradialytic exercise training (ET) are among the nonpharmacologic interventions identified to preserve cognitive function in ESKD. Additionally, cognitive training (CT) is an effective approach recently identified in this population. While short-term benefits of ET and CT on cognitive function were consistently observed in patients undergoing dialysis, more studies are needed to replicate these findings in diverse populations including kidney transplant recipients with long-term follow-up to better understand the health and quality of life consequences of these promising interventions. ET as well as CT are feasible interventions that may preserve or even improve cognitive function for patients with ESKD. Whether these interventions translate to improvements in quality of life and long-term health outcomes, including dementia prevention and better survival, are yet to be determined.

Frailty and Changes in Cognitive Function after Kidney Transplantation

BACKGROUND

Restoration of kidney function after kidney transplant generally improves cognitive function. It is unclear whether frail recipients, with higher susceptibility to surgical stressors, achieve such post-transplant cognitive improvements or whether they experience subsequent cognitive decline as they age with a functioning graft.

METHODS

In this two-center cohort study, we assessed pretransplant frailty (Fried physical frailty phenotype) and cognitive function (Modified Mini-Mental State Examination) in adult kidney transplant recipients. To investigate potential short- and medium-term effects of frailty on post-transplant cognitive trajectories, we measured cognitive function up to 4 years post-transplant. Using an adjusted mixed effects model with a random slope (time) and intercept (person), we characterized post-transplant cognitive trajectories by pretransplant frailty, accounting for nonlinear trajectories.

RESULTS

Of 665 recipients (mean age 52.0 years) followed for a median of 1.5 years, 15.0% were frail. After adjustment, pretransplant cognitive scores were significantly lower among frail patients compared with nonfrail patients (89.0 versus 90.8 points). By 3 months post-transplant, cognitive performance improved for both frail (slope =0.22 points per week) and nonfrail (slope =0.14 points per week) recipients. Between 1 and 4 years post-transplant, improvements plateaued among nonfrail recipients (slope =0.005 points per week), whereas cognitive function declined among frail recipients (slope =-0.04 points per week). At 4 years post-transplant, cognitive scores were 5.8 points lower for frail recipients compared with nonfrail recipients.

CONCLUSIONS

On average, both frail and nonfrail recipients experience short-term cognitive improvement post-transplant. However, frailty is associated with medium-term cognitive decline post-transplant. Interventions to prevent cognitive decline among frail recipients should be identified.

Prevalence and Correlates of Cognitive Impairment in Kidney Transplant Patients Using the DemTect-Results of a KTx360 Substudy

Cognitive impairment in kidney transplantation (KTx) patients is associated with allograft survival and mortality. However, the prevalence of cognitive impairment after KTx is still understudied. Thus, we aimed to assess the prevalence of cognitive impairment in KTx patients and to identify sociodemographic, medical, donation-specific, and psychological variables associated with cognitive impairment. In this cross-sectional two-center study, 583 KTx patients participated in a structured post-transplant care program. The DemTect was used to assess cognition, and cognitive impairment was defined as a score of < 13. Mean age was 52.11 years, 59% were male, 27.4% had ≥12 years of school attendance, and 85.9% had hypertension. The prevalence of cognitive impairment was 15.6%. Cognitive impairment was significantly associated with higher age, male sex, lower educational level, subjective perception of cognitive decline, higher rates of hypertension, lower kidney functioning, and obesity (BMI > 30 kg/m²). Using logistic regression analysis, all variables except age remained significant. Our results suggest that cognitive impairment affects a significant number of patients after KTx. Transplant centers may consider screening for cognitive impairment using objective tests, especially in patients with a high-risk profile. Furthermore, studies with longitudinal designs are required in order to assess moderators and mediators for cognitive trajectories.