Prevalence and correlates of cognitive impairment in kidney transplant recipients

Changes in Cognitive Function After Kidney Transplantation: A Longitudinal Cohort Study

RATIONALE & OBJECTIVE

Kidney disease negatively affects cognition. We assessed the effect of kidney transplantation (KT) on different cognitive domains.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

We examined pre- versus post-KT cognition in patients waitlisted for KT at an academic center.

PREDICTORS

Transplant status. We measured cognitive function before KT (n=101), 3 months after KT (n=78), and 1 year after KT (n = 83).

OUTCOMES

Our primary outcome was change in cognitive function before versus after KT. We used standard neuropsychological tests to assess global cognition (Mini-Mental State Exam [MMSE]), episodic/declarative memory (Logical Memory), psychomotor speed/visuospatial function (Digit Symbol Substitution Test [DSST], Trail Making Test [TMT] A), working memory/attention (Digit Span), executive function (TMT B), and semantic memory/verbal fluency/language (Category Fluency).

ANALYTICAL APPROACH

Using linear mixed model analysis, we evaluated the changes in neuropsychological test scores adjusted for age, sex, race, education, and number of assessments.

RESULTS

Before KT, Logical Memory I and II, DSST, MMSE, Category Fluency (animal naming), and Digit Span backward scores were low compared with normative values from the National Alzheimer's Coordinating Center data. Logical Memory I and II scores improved after KT (pre- vs post-KT, estimated group difference [d]=3.3, P<0.001 for Logical Memory I; d=4.27, P<0.001 for Logical Memory II), such that post-KT scores were similar to normative values (post-KT vs normative values, d = -0.37, P=0.06 for Logical Memory I; d = -0.89, P=0.08 for Logical Memory II). Category Fluency (animal naming; d=2.4, P<0.001) and DSST (d=3.12, P=0.01) scores also improved with KT, but post-KT DSST scores remained lower than normative values (post-KT vs normative values, d = -5.17, P<0.001). MMSE, Digit Span, and TMT A and B scores did not change after KT.

LIMITATIONS

Single-center study.

CONCLUSIONS

Episodic and verbal declarative memory normalize after KT. Semantic memory, verbal fluency, language, psychomotor speed, and visuospatial function show partial improvement. Cognitive impairment in kidney disease is therefore at least partly reversible with KT.

PLAIN-LANGUAGE SUMMARY

Cognitive impairment in kidney disease affects self-esteem, vocational abilities, quality of life, health care costs, and mortality. It is not clear whether kidney transplantation (KT) improves cognition and whether the improvement is uniform across cognitive domains. The distinction between reversible and irreversible cognitive impairment has important implications in the clinical care of patients before and after KT. We assessed cognition before KT and 3 months and 12 months after KT and discovered that episodic and verbal declarative memory normalized with KT. Semantic memory, verbal fluency, language, psychomotor speed, and visuospatial function also improved with KT but did not reach normal levels. Cognitive impairment in kidney disease is therefore at least partly reversible.

Cognitive profile of kidney transplant patients and impact of deceased vs. living donor transplantation

BACKGROUND

It is important to learn more about the prevalence, severity and characteristics (i.e., which cognitive abilities are especially affected) of cognitive impairment in kidney transplant patients. Furthermore, the impact of living vs. deceased donor renal transplantation on cognitive outcome in this patient group needs further studies.

METHODS

Fifty-nine patients (43 men, age 55 ± 13 years) who received a deceased donor or living donor kidney transplant, completed a comprehensive neuropsychological test assessment. Neuropsychological tests explored the cognitive domains of verbal and visual memory, attention, and executive functions.

RESULTS

Fifteen percent  of the patients had mild, 25% moderate, and 15% severe cognitive impairment. The level of domain-specific cognitive deficit differed between verbal memory, attention, and executive functions (χ2(2) = 7.11, p = 0.029). On average, patients showed the highest deficit in executive functions, and the lowest deficit in verbal memory. Patients who received a kidney graft from a deceased donor were more likely to have a cognitive impairment than those who received a kidney graft from a living donor (OR = 3.03, 95% CI [0.99,9.32], Wald χ2(1) = 3.74, p = 0.053). This effect was independent of time on dialysis as well as of creatinine levels, or creatinine clearance.

CONCLUSIONS

Our results show that in kidney transplant patients with cognitive impairment, the cognitive domain of executive functions is the most affected one. This might be detrimental for quality of life. The fact that patients who received living donor kidneys seem to do better in terms of cognition than patients with deceased donor kidneys deserves more attention in future research.

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).

Age Is Just a Number for Older Kidney Transplant Patients

The rise in the mean age of the global population has led to an increase in older kidney transplant (KT) patients. This demographic shift, coupled with the ongoing organ shortage, requires a nuanced understanding of which older adults are most suitable for KT. Recognizing the increased heterogeneity among older adults and the limitations of solely relying on chronological age, there is a need to explore alternative aging metrics beyond chronological age. In this review, we discuss the impact of older age on access to KT and postoperative outcomes. Emphasizing the need for a comprehensive evaluation that extends beyond chronological age, we explore alternative aging metrics such as frailty, sarcopenia, and cognitive function, underscoring their potential role in enhancing the KT evaluation process. Most importantly, we aim to contribute to the ongoing discourse, fostering an optimized approach to KT for the rapidly growing population of older adults.

Increased serum methylmalonic acid levels were associated with the presence of cognitive dysfunction in older chronic kidney disease patients with albuminuria

BACKGROUND

This study aimed to evaluate the correlation between serum methylmalonic acid (MMA) levels and cognition function in patients with chronic kidney disease (CKD).

METHODS

In this cross-sectional study, we included 537 CKD individuals aged ≥ 60-year-old with albuminuria from the National Health and Nutrition Examination Survey (NHANES) 2011-2014. Four cognitive tests including the Digit Symbol Substitution Test (DSST), the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) Delayed Recall and Word Learning tests, and the Animal Fluency test (AF) were performed. Associations between MMA and cognition scores were assessed with linear regression models.

RESULTS

MMA level was negatively associated with residual renal function and nutrition status. After multivariate adjustment, elevated serum MMA levels were independently correlated with decline of cognition in CKD patients with albuminuria.

CONCLUSION

Our study showed that higher serum MMA levels were independently associated with the presence of cognition dysfunction in CKD patients. The exact pathogenesis of MMA and cognition needs further research.

Incidence and risk factors of venous thromboembolism in kidney transplantation patients: a prospective cohort study

To investigate the incidence and explore the risk factors of venous thromboembolism (VTE) within 6 months after kidney transplantation. Total of 331 kidney transplant recipients were assessed by venous ultrasonography for VTE at 14 days, 1 month, 3 months, and 6 months post-transplantation. Cox forward regression were used to identify the independent risk factors of VTE. This study registration number is ChiCTR1900020567 and the date of registration was 2019/01/08. The cumulative incidence of VTE was 2.72% (9/331) within 6 months after transplant. 77.8% (7/9) of VTEs occurred in the first 3 months post-transplantation. 88.9% (1/9) of VTEs were asymptomatic, 66.7% (6/9) of VTEs were mural thromboses and in the right lower extremity. Central vena catheterization (HR = 6.94) and severe pulmonary disease (including pneumonia) (HR = 57.35) were the risk factors for VTE in kidney transplantation recipients. KT patients are the high risk population of VTE. Future interventions should be strengthen for KT patients to receive a minimum of 3-month of precautionary measures for VTE, including infection prevention, and strengthening thromboprophylaxis on the CVC or transplanted side of lower extremity.

Protective effect of unsaturated fatty acids on cognitive impairment in CKD patients: Results from the National Health and Nutrition Examination Survey (2011-2014)

BACKGROUND

It is still unknown whether unsaturated fatty acids (UFA) have the same effect on preventing cognitive impairment in chronic kidney disease (CKD) patients as in healthy people.

OBJECTIVE

To investigate the protective effect of dietary UFA intake and proportion on cognitive impairment in patients with CKD.

METHODS

We extracted data from the National Health and Nutrition Examination Survey (NHANES, 2011-2014) on participants with a previous diagnosis of CKD and at least one complete cognitive assessment (Consortium to Establish a Registry for Alzheimer's Disease test, Animal Fluency Test and Digit Symbol Substitution Test). We used the lower quartile of the total scores of these three tests as the cut-off point, and divided the participants into two groups of normal cognitive performance and low cognitive performance to extract participants' intake of various UFA from the NHANES dietary module. The data were weighted using weighting parameters included in NHANES, and logistics regression and restricted cubic spline were used to analyze the protective effect of UFA intake on cognitive impairment in CKD participants.

RESULTS

We found that participants with low cognitive performance all had significantly lower intakes of total monounsaturated fatty acids, total polyunsaturated fatty acids, ω-3 UFA, ω-6 UFA and ω-9 UFA than participants with normal cognitive performance (p< 0.05), and the ω-6 UFA and ω-9 UFA had the most significant protective effects on cognitive impairment of participants. We also discovered that oleic and linoleic acids play important roles in protecting against cognitive impairment in CKD participants. The protective effect of oleic acid, but not linoleic acid, on cognitive impairment showed a nonlinear relationship. The changes in the proportion of monounsaturated fatty acids to polyunsaturated fatty acids, ω-6 UFA to ω-3 UFA, and oleic acid to linoleic acid did not affect the risk of cognitive impairment in CKD participants.

CONCLUSIONS

UFA can reduce the risk of cognitive impairment in CKD patients, especially oleic acid and linoleic acid have a more obvious protective effect on cognitive impairment in patients with CKD. Among them, the protective effect of linoleic acid on cognitive impairment was continuously enhanced with the increase of intake, indicating that linoleic acid may be the most important UFA to reduce cognitive impairment in CKD patients.

Screening of cognitive performance in kidney transplant recipients: a mini review

Why should we screen?

The prevalence of cognitive impairment in kidney transplant recipients (KTRs) is up to 58%. The 10-year graft loss and mortality rates are above 30% and 50%, respectively, and executive malfunctioning increases disadvantageous outcomes.

What causes cognitive impairment in KTRs?

Strong risk factors are older age and chronic kidney disease. However, causes are multifactorial and include cardiovascular, cerebrovascular, neurodegenerative, inflammatory, uremic, psychiatric, and lifestyle-related susceptibilities.

How should we screen?

KTR-specific validated instruments or strategies do not exist. The central element should be a multidomain cognitive screening test that is sensitive to mild cognitive impairment, corrects for age and education, and includes executive functions testing. Cognitive trajectories, effects on everyday life and psychiatric comorbidities should be assessed by integrating the perspectives of both patients and knowledgeable informants.

When should we screen?

Screening should not be postponed if there is suspicion of impaired cognition. Different time points after transplantation tend to have their own characteristics.

Who should conduct the screening?

Screening should not be limited to specialists. It can be carried out by any healthcare professional who has received a limited amount of training.

What are the benefits of screening?

Screening does not provide a diagnosis. However, suggestive results change care in multiple ways. Goals are: Initiation of professional dementia work-up, securing of adherence, anticipation of potential complications (delirium, falls, frailty, functional impairment, malnutrition, etc.), mitigation of behavioral disorders, adjustment of diagnostic and therapeutic "load", reduction of caregiver burden and meeting of changing needs. We summarize data on the prevalence, risk factors and sequelae of cognitive impairment in KTRs. We also discuss the requirements for appropriate screening strategies and provide guiding principles regarding appropriate and safe care.

The Association of Tacrolimus Formulation on Cerebral Blood Flow and Cognitive Function

Calcineurin inhibitors are inherent vasoconstrictors. Cerebral vasoconstriction can reduce cerebral blood flow (CBF), and negatively impact cerebrovascular response (CVR) to exercise, and cognitive function. The once-daily extended-release (LCP) tacrolimus has fewer side effects than the immediate-release (IR) tacrolimus. The role of calcineurin inhibitors on CBF and the impact of specific formulations of tacrolimus on CBF, CVR, and cognitive function are unknown. In this pilot study, we evaluated whether changing from IR tacrolimus to LCP tacrolimus modulates CBF, CVR, or cognitive function in kidney transplant (KT) recipients.

Methods

We randomized (2:1) 30 stable KT recipients on IR tacrolimus to intervention (switch to LCP tacrolimus) and control (continue IR tacrolimus) arms. We measured CBF, CVR, and cognitive function at baseline and at 12 wk. We used ANCOVA to evaluate changes in outcome variables, with baseline values and study arm as covariates. We used descriptive statistics with mean changes in outcome variables to compare the 2 groups.

Results

Participants were 51 ± 13 y old. There was no difference in plasma tacrolimus levels at baseline and at 12 wk in the 2 arms. The changes in CBF, resting middle cerebral artery velocity, CVR, and cognitive function were more favorable in the intervention arm than in the control group.

Conclusions

Changing IR tacrolimus to LCP tacrolimus may improve CBF, cerebrovascular dynamics, and cognitive function in KT recipients. Larger studies are needed to confirm these results.

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.

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.

Pre-transplant cognitive screening is a poor predictor of post-transplant cognitive status

INTRODUCTION

Transplant centers hesitate to transplant patients with cognitive impairment. It is unclear if pre-kidney transplant (KT) cognitive screening can predict post-KT cognitive function.

METHODS

We evaluated pre- to post-KT cognitive function with the Montreal Cognitive Assessment (MoCA) in a cohort of 108 patients. We used an adjusted logistic regression model to assess pre- to post-KT changes in cognitive status (continuous variable) and a linear mixed model to assess changes in MoCA scores (categorical variable) pre- to post- KT.

RESULTS

The average pre- and post-KT MoCA scores were 25.3 ± 3.0 and 26.4 ± 2.8, respectively. Final pre-KT score did not predict post-KT cognitive status (OR = 1.08; 95% CI: .92-1.26; P = .35). 32% of the patients with a final pre-KT score ≥26 had at least one post-KT score < 26. Conversely, 61% of the patients with a final pre-KT score < 26 had at least one post KT score ≥26. In the linear mixed model analysis, the final pre-KT score was associated with a small, clinically insignificant (β = .34; 95% CI: .19-.49; P < .001) effect on the post-KT score.

CONCLUSION

A low pre-KT MoCA score is not a strong independent predictor of post-KT cognitive function and should not preclude patients from receiving a KT.

The Patient Care Experience as Perceived by Hispanic Patients With Chronic Illness Undergoing Transplant: A Grounded Theory

Hispanics are one of the largest-growing minorities, yet little is understood of the patient experience from their perspective. Patient experience is the current federally mandated hospital quality indicator that is measured via the Hospital Consumer Assessment of Healthcare Providers and Systems (HCAHPS) survey. Minority representation in the HCAHPS survey development however was not robust. This study used a constructivist grounded theory method to explore how English- and Spanish-speaking Hispanic patients seeking kidney and liver transplant care at a safety-net hospital perceive and interpret the care experience. A grounded theory process model emerged finding comfort, communication, connection, and care to be interdependent factors crucial for a positive hospital admission. Furthermore, "cultural context" was found to influence perception of each of these concepts. This research provides key insights into how Hispanics may perceive their needs when seeking care. A Supplemental Digital Content video abstract is available at http://links.lww.com/ANS/A50 .

Prevalence of frailty and cognitive impairment in older transplant candidates - a preview to the Kidney Transplantation in Older People (KTOP): impact of frailty on outcomes study

BACKGROUND

Kidney transplantation in older people has increased, however older transplant recipients experience mixed outcomes that invariably impacts on their quality of life. The increased vulnerability of older end stage kidney disease patients to frailty and cognitive impairment, may partially explain the differences in outcomes observed. The Kidney Transplantation in Older People (KTOP): impact of frailty on clinical outcomes study is an active clinical study aiming to explore the experience of older people waiting for and undergoing transplantation. In this manuscript we present the study protocol, the study cohort, and the prevalence of frailty and cognitive impairment identified at recruitment.

METHODS

The KTOP study is a single centre, prospective, mixed methods, observational study. Recruitment began in October 2019. All patients aged 60 or above either active on the deceased donor waitlist or undergoing live donor transplantation were eligible for recruitment. Recruited participants completed a series of questionnaires assessing frailty, cognition, and quality of life, which are repeated at defined time points whilst on the waitlist and post-transplant. Clinical data was concurrently collected. Any participants identified as frail or vulnerable were also eligible for enrolment into the qualitative sub-study.

RESULTS

Two hundred eight participants have been recruited (age 60-78). Baseline Montreal Cognitive Assessments were available for 173 participants, with 63 (36.4%) participants identified as having scores below normal (score < 26). Edmonton Frail Scale assessments were available for 184 participants, with 29 participants (15.8%) identified as frail (score ≥ 8), and a further 37 participants (20.1%) identified as being vulnerable (score 6-7).

CONCLUSION

In the KTOP study cohort we have identified a prevalence of 36.4% of participants with MoCA scores suggestive of cognitive impairment, and a prevalence of frailty of 15.8% at recruitment. A further 20.1% were vulnerable. As formal testing for cognition and frailty is not routinely incorporated into the work up of older people across many units, the presence and significance of these conditions is likely not known. Ultimately the KTOP study will report on how these parameters evolve over time and following a transplant, and describe their impact on quality of life and clinical outcomes.

Insights into Cognitive Brain Health in Chronic Kidney Disease

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

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Neuropsychological Assessment of Cognitive Impairment in Kidney Transplantation (NAsKiT) and its related risk factors: a study protocol

BACKGROUND

Association of cognitive impairment with chronic kidney disease has been reported over the last decade. Individuals show better cognitive performance after kidney transplantation than individuals on dialysis but are more likely to be affected by cognitive impairment than age-matched comparison groups. Better knowledge of the prevalence as well as course and profile of cognitive impairment is important for the design of future studies assessing the clinical impact of cognitive impairment and developing management strategies. The goal of our study is to examine the extent of cognitive impairment before and after transplantation and to derive a distinct profile of cognitive function using standard neurocognitive tests. Furthermore, we aim to assess whether transplantation per se leads to an improvement in cognitive performance.

METHODS

We are conducting a prospective single-center cohort study involving 100 kidney transplant individuals. Individuals who are wait-listed to receive a kidney transplantation or have already received one will be included in this study. Individuals will undergo a battery of detailed neurocognitive tests at baseline (in part before surgery), and then 3 and 12 months afterwards. Furthermore, the enrolled patients will complete a validated German version of the Cognitive Failure Questionnaire for self-assessment (s-CFQ) as well as the Hospital Anxiety and Depression Scale -Deutsche (HADS-D), a self-report screening instrument with two scales that capture anxiety and depression. In addition, a hair sample will be taken at each measurement time point for the determination of hair cortisol levels as a parameter for the cumulative hypothalamic-pituitary-adrenocortical axis activity over the previous three months. The primary outcome measure will be (a) the effect of kidney transplantation on the cognitive performance up to 12 months after transplantation and (b) the course of cognitive performance following kidney transplantation over time.

DISCUSSION

The results of our study have potentially important implications for the prevention and treatment of cognitive impairment in kidney transplant individuals. By increasing our knowledge of the neurocognitive profile and assigning the corresponding deficits, it might be possible to create an individualized training program to positively impact cognitive deficits in kidney transplant patients.

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.

Age at Time of Kidney Transplantation as a Predictor for Mortality, Graft Loss and Self-Rated Health Status: Results From the Swiss Transplant Cohort Study

Introduction: The effect of age on health outcomes in kidney transplantation remains inconclusive. This study aimed to analyze the relationship between age at time of kidney transplantation with mortality, graft loss and self-rated health status in adult kidney transplant recipients.

Methods: This study used data from the Swiss Transplant Cohort Study and included prospective data of kidney transplant recipients between 2008 and 2017. Time-to-event analysis was performed using Cox’ regression analysis, and -in the case of graft loss- competing risk analysis. A random-intercept regression model was applied to analyse self-rated health status.

Results: We included 2,366 kidney transplant recipients. Age at transplantation linearly predicted mortality. It was also predictive for graft loss, though nonlinearly, showing that recipients aged between 35 and 55 years presented with the lowest risk of experiencing graft loss. No relationship of age with self-rated health status was detected.

Conclusion: Higher mortality in older recipients complies with data from the general population. The non-linear relationship between age and graft loss and the higher scored self-rated health status at all follow-up time-points compared to the pre-transplant status -regardless of age- highlight that age alone might not be an accurate measure for risk prediction and clinical decision making in kidney transplantation.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Cognitive impairment burden in older and younger adults across the kidney transplant care continuum

BACKGROUND

Younger kidney transplant (KT) candidates and recipients may have cognitive impairment due to chronic diseases and reliance on dialysis.

METHODS

To quantify cognitive impairment burden by age across the KT care continuum, we leveraged a two-center cohort study of 3854 KT candidates at evaluation, 1114 recipients at admission, and 405 recipients at 1-year post-KT with measured global cognitive performance (3MS) or executive function (Trail Making Test). We also estimated burden of severe cognitive impairment that affects functional dependence (activities of daily living [ADL] < 6 or instrumental activities of daily living [IADL] < 8).

RESULTS

Among KT candidates, global cognitive impairment (18-34 years: 11.1%; 35-49 years: 14.0%; 50-64 years: 19.5%; ≥65 years: 22.0%) and severe cognitive impairment burden (18-34 years: 1.1%; 35-49 years: 3.0%; 50-64 years: 6.2%; ≥65 years: 7.7%) increased linearly with age. Among KT recipients at admission, global cognitive impairment (18-34 years: 9.1%; 35-49 years: 6.1%; 50-64 years: 9.3%; ≥65 years: 15.7%) and severe cognitive impairment burden (18-34 years: 1.4%; 35-49 years: 1.4%; 50-64 years: 2.2%; ≥65 years: 4.6%) was lower. Despite lowest burden of cognitive impairment among KT recipients at 1-year post-KT across all ages (18-34 years: 1.7%; 35-49 years: 3.4%; 50-64 years: 4.3%; ≥65 years: 6.5%), many still exhibited severe cognitive impairment (18-34 years: .0%; 35-49 years: 1.9%; 50-64 years: 2.4%; ≥65 years: 3.5%).

CONCLUSION

Findings were consistent for executive function impairment. While cognitive impairment increases with age, younger KT candidates have a high burden comparable to community-dwelling older adults, with some potentially suffering from severe forms. Transplant centers should consider routinely screening patients during clinical care encounters regardless of age.

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Normalization of Cerebral Blood Flow, Neurochemicals, and White Matter Integrity after Kidney Transplantation

BACKGROUND

CKD is associated with abnormalities in cerebral blood flow, cerebral neurochemical concentrations, and white matter integrity. Each of these is associated with adverse clinical consequences in the non-CKD population, which may explain the high prevalence of dementia and stroke in ESKD. Because cognition improves after kidney transplantation, comparing these brain abnormalities before and after kidney transplantation may identify potential reversibility in ESKD-associated brain abnormalities.

METHODS

In this study of patients with ESKD and age-matched healthy controls, we used arterial spin labeling to assess the effects of kidney transplantation on cerebral blood flow and magnetic resonance spectroscopic imaging to measure cerebral neurochemical concentrations (N-acetylaspartate, choline, glutamate, glutamine, myo-inositol, and total creatine). We also assessed white matter integrity measured by fractional anisotropy (FA) and mean diffusivity (MD) with diffusion tensor imaging. We used a linear mixed model analysis to compare longitudinal, repeated brain magnetic resonance imaging measurements before, 3 months after, and 12 months after transplantation and compared these findings with those of healthy controls.

RESULTS

Study participants included 29 patients with ESKD and 19 controls; 22 patients completed post-transplant magnetic resonance imaging. Cerebral blood flow, which was higher in patients pretransplant compared with controls (P=0.003), decreased post-transplant (P<0.001) to values in controls. Concentrations of neurochemicals choline and myo-inositol that were higher pretransplant compared with controls (P=0.001 and P<0.001, respectively) also normalized post-transplant (P<0.001 and P<0.001, respectively). FA increased (P=0.001) and MD decreased (P<0.001) post-transplant.

CONCLUSIONS

Certain brain abnormalities in CKD are reversible and normalize with kidney transplantation. Further studies are needed to understand the mechanisms underlying these brain abnormalities and to explore interventions to mitigate them even in patients who cannot be transplanted.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

Cognitive Impairment and Imaging Correlates in End Stage Renal Disease, NCT01883349.

Can the Timed Up & Go Test and Montreal Cognitive Assessment predict outcomes in patients waitlisted for renal transplant?

PURPOSE

Frail patients who undergo renal transplantation (RT) have more complications; however, little is known if these patients can sustain the wait to RT. We used the Timed Up and Go Test (TUGT) and Montreal Cognitive Assessment (MoCA) to determine outcomes of RT candidates.

METHODS

In this retrospective study, 526 RT candidates underwent TUGT and MoCA (2015-2019) and were divided into "favorable" (transplanted or remained on the list) or "unfavorable" (not listed, removed from list, or died) outcome. Demographics, education, language, comorbidities, dialysis type, use of a walking device, TUGT, and MoCA were compared by outcome.

RESULTS

Overall, 230 patients (43.7%) passed TUG, 268 (51%) passed MoCA, 133 (25.3%) passed both, and 161 (30.6%) failed both tests. Multivariate analysis demonstrated age ≥ 65 (OR 1.58, CI 1.03-2.43), cardiac disease (OR 3.09, CI 2.02-4.72), ≥36 months on dialysis (OR 1.80, CI 1.24-2.69), EPTS < 20% at time of MoCA (OR 0.26, CI 0.07-0.98), and failing TUGT (OR 2.14, CI 1.43-3.19) were associated with unfavorable outcome. Failing MoCA was not associated with outcome.

CONCLUSIONS

MoCA test results were not associated with RT waitlist outcomes; however, passing the TUGT was associated with receiving RT or remaining on the list. Additional studies are needed to validate this and determine outcome after RT.

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.

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

BACKGROUND

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

DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS

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

RESULTS

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

CONCLUSION

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

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.

The Contribution of Kidney Disease to Cognitive Impairment in Patients with Type 2 Diabetes

PURPOSE OF REVIEW

This review focuses on the relationships between diabetes, cognitive impairment, and the contribution of kidney disease.

RECENT FINDINGS

We review the independent contributions of parameters of kidney disease, including albuminuria, glomerular filtration, bone/mineral metabolism, and vitamin D synthesis, on cognitive performance in patients with diabetes. Potential pathophysiologic mechanisms underlying these associations are discussed highlighting gaps in existing knowledge. Finally, effects of the dialysis procedure on the brain and cognitive performance are considered. Emphasis is placed on novel non-invasive screening tools with the potential to preserve cerebral perfusion during hemodialysis and limit cognitive decline in patients with diabetic ESKD. Patients with type 2 diabetes and advanced chronic kidney disease suffer a higher prevalence of cognitive impairment. This is particularly true in patients with diabetes and end-stage kidney disease (ESKD).

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.

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.

An interdisciplinary approach to the older transplant patient: strategies for improving clinical outcomes

PURPOSE OF REVIEW

To describe the latest investigations into the role of frailty and assessment of other aging-related issues in the solid organ transplant candidate and recipient. This information is relevant for all involved in the care of transplant patients, but is especially relevant in infectious diseases, given the increased burden of infection seen in older and frailer patients.

RECENT FINDINGS

The Fried Frailty Phenotype (FFP) and Short Performance Physical Battery (SPPB) are well validated tools for measuring frailty in older adults. Recently, these frailty tools have also been used to predict a range of clinical outcomes in adults with endstage organ disease undergoing advanced therapies including mechanical circulatory device (MCSD) or transplantation including death on the waiting list, length of hospital stay, need for readmission, infection, and death. Frailty may also be estimated by chart review and comorbidity assessment. Other aging-related evaluations of interest are cognitive function, sarcopenia, and nutritional status. The strength of association for each tool varies by the type of end organ disease, although there are many findings in common across organ types.

SUMMARY

As trends in the aging of the population continue to impact transplant and MCSD candidates and recipients, it is increasingly important for providers to be cognizant of the methods for assessment of aging-associated dysfunction including frailty and sarcopenia.

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.

The relationship between cognitive function and having diabetes in patients treated with hemodialysis

PURPOSE

Patients undergoing maintenance hemodialysis (MHD) have a higher prevalence of cognitive impairment and inferior cognitive performance than the general population, and those with cognitive impairment are at higher risk of death than those without cognitive impairment. Having diabetes has been associated with an increased risk of cognitive decline in end-stage kidney disease patients treated with peritoneal dialysis or kidney transplant. However, these findings may not extend to the hemodialysis population. Thus, we aim to investigate the relationship between having diabetes and cognitive function in MHD patients.

METHODS

This was a cross-sectional study. A total of 203 patients treated with MHD from two blood purification centers were enrolled as subjects. The Chinese version of the Montreal Cognitive Assessment (MoCA) was utilized to assess cognitive function.

RESULTS

MHD patients with diabetes had a significantly higher prevalence of global cognitive impairment and inferior performance in global cognition, visuospatial/executive function, naming, language, abstraction and orientation tasks compared with those without diabetes. According to the multiple linear analyses, having diabetes was significantly associated with lower global cognitive function, naming, and language scores, with β coefficients and 95% CIs of -1.30 [ -2.59, -0.01], -0.25 [-0.47, -0.02], and -0.32 [-0.58, -0.07], respectively (all P < 0.05). Having diabetes could not independently predict an increased risk of global cognitive impairment.

CONCLUSIONS

In MHD patients, having diabetes is significantly associated with lower cognitive function scores. Medical staff should evaluate early and focus on the decline of cognitive function in MHD patients with diabetes, in order to achieve early diagnosis and early intervention.

Impact of the donor-recipient gender matching on the graft survival from live donors

Background

Several factors such as recipient age, BMI, serum cratinine, and positive history of dialysis are important in predicting graft survival among kidney transplant recipients. One factor affecting the transplant outcomes is donors and recipients gender, which is usually ignored.

Methods

A total of 1113 kidney transplant recipients were studied in this retrospective cohort study. Several factors were taken into account for graft survival and outcomes such as donors and recipients gender and age in addition to common recipient factors like cratinine, eGFR, BMI, and positive history of dialysis.

Results

The most successful transplant based on donor-recipient gender was observed in male donor to male recipient, and then male donor to female recipient. In female transplant recipients, level of serum cratinine and eGFR, positive dialysis history before transplant, and low donor hemoglobin level can be considered as good prognostic factors recommended for kidney transplant survival.

Conclusions

Our results suggested gender matching for kidney transplant. Only in some exceptional conditions, male donor to female recipient kidney transplant may be successful and female donors to male recipients are not suggested, especially in aged patients with the history of dialysis.

Exploration of symptom experience in kidney transplant recipients based on symptoms experience model

PURPOSE

Kidney transplant recipients suffer from a variety of symptoms, and symptom management is crucial in improving their quality of life (QOL). Accordingly, this study aims to identify the symptoms experienced by kidney transplant recipients and examine the relationship amongst antecedents, symptom experience and QOL of recipients in China.

METHODS

A total of 300 kidney transplant recipients were investigated in one of the most first-rate hospitals in China by asking them to fill out a self-designed general questionnaire, the Symptom Experience Scale, the Sense of Coherence Scale (Chinese version), the Revised Life Orientation Test (Chinese version) and the 36-item Short Form Health Survey (Chinese version).

RESULTS

Kidney transplant recipients experienced multiple symptoms that were frequent, severe and bothersome. The final model showed significant consistency with the data. In the QOL model, post-transplant time, complications, immunosuppressive agents and sense of coherence explained 30.7% of the variance of symptom experience. Moreover, habitual residence, economic burden, post-transplant time, kidney function, optimism and symptom experience accounted for 70.6% of the variance on QOL.

CONCLUSIONS

We can explain the relationship between antecedents, symptom experience and QOL amongst Chinese kidney transplant recipients by using Symptoms Experience Model. Clinicians and caregivers can manage the recipient's symptoms during follow-up from psychological, physical and medication management perspectives. Improving sense of coherence, maintaining optimism and managing symptoms are essential for enhancing QOL.

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.

Brain metabolic alterations in patients with long-term calcineurin inhibitor therapy after liver transplantation

BACKGROUND

Calcineurin inhibitor (CNI) neurotoxicity after liver transplantation might be due to impairment of the cerebral metabolism.

AIMS

To investigate CNI-related alterations of brain metabolite distributions and associations between cognitive function and brain metabolism in patients with long-term CNI treatment after liver transplantation.

METHODS

Eighty-two patients (19 CNI free, 34 CNI low-dose and 29 standard-dose CNI immunosuppression) 10 years after liver transplantation and 32 adjusted healthy controls underwent nonlocalised brain phosphorus magnetic resonance spectroscopy (MRS) and single voxel proton MRS in the parietal white matter to estimate brain metabolite contents. The MRS results were correlated with psychometric data assessing cognitive function.

RESULTS

Phosphorus metabolite concentrations with the exception of phosphocreatine (PCr) were reduced in patients compared to controls. Particularly, patients with low-dose CNI therapy showed a significant decrease in adenosine triphosphate (0.209 ± 0.012 vs 0.222 ± 0.010; P < 0.001) and a significant increase in PCr (0.344 ± 0.026 vs 0.321 ± 0.017; P < 0.001) compared to controls. Myo-Inositol in the CNI free group (2.719 ± 0.549 institutional unit [iu]) was significantly lower compared to controls (3.181 ± 0.425 iu; P = 0.02), patients on low-dose (3.130 ± 0.513 iu; P < 0.05) and standard-dose CNI therapy (3.207 ± 0.632 iu; P < 0.02). Glutamate and glutamine levels correlated negatively with cognitive function (Repeatable Battery for the Assessment of Neuropsychological Status Total Scale: R = -0.362, P = 0.029).

CONCLUSION

Long-term CNI therapy after liver transplantation might be associated with alterations of brain metabolites.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

DISCUSSION

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

Subclinical Cognitive Impairment and Listing for Kidney Transplantation

BACKGROUND AND OBJECTIVES

Cognitive impairment is common in patients with kidney disease and can affect physicians' perception and/or patients' ability to complete the pretransplant evaluation. We examined whether cognitive impairment influences the likelihood for transplant listing and whether patients with cognitive impairment take longer to be listed.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We conducted a single-center longitudinal cohort study. Patients presenting for their index kidney transplant evaluation were screened for cognitive impairment using the Montreal Cognitive Assessment. A score <26 indicated cognitive impairment. The transplant selection committee was blinded to the scores. Kaplan-Meier analysis assessed time to active listing by level of cognition. A Cox proportional hazards model that included age, sex, race/ethnicity, smoking, coronary artery disease, and diabetes was constructed to evaluate the association between Montreal Cognitive Assessment score and listing for transplant.

RESULTS

In total, 349 patients who underwent Montreal Cognitive Assessment testing at their initial visit were included in the analysis. Patients with cognitive impairment were more likely to be older, black, and smokers. The time to listing in patients with cognitive impairment was longer than the time to listing in those with no cognitive impairment (median time, 10.6 versus 6.3 months; log rank test P=0.01). Cognitive impairment was independently associated with a lower likelihood of being listed for transplant (hazard ratio, 0.93 per unit lower Montreal Cognitive Assessment score; 95% confidence interval, 0.88 to 0.99; P=0.02). A lower proportion of patients with cognitive impairment were listed compared with patients without cognitive impairment at 1 month (2% versus 11%), 6 months (17% versus 37%), and 1 year (23% versus 41%), (P<0.001 for all).

CONCLUSIONS

Cognitive impairment is associated with a lower likelihood of being listed for kidney transplant, and is associated with longer time to transplant listing.

Solid organ transplantation in older adults. Infectious and other age-related considerations

In the U.S., older adults aged 65 or above comprise nearly one quarter of the solid organ transplant (SOT) waitlists, and the number of transplants performed in this age group continues to increase. There are no specific guidelines for the assessment and follow up of the older SOT candidate or recipient. Older adults are at increased risk of infectious complications after SOT. Despite these complications and even with the use of suboptimal donors, overall outcomes are favorable. We provide an overview to specific consideration as they relate to the older SOT candidate and recipient.

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.

Montreal Cognitive Assessment for cognitive assessment in chronic kidney disease: a systematic review

INTRODUCTION

There is evidence in the literature that cognitive impairment is more prevalent in individuals with chronic kidney disease (CKD) than in the general population. The Montreal Cognitive Assessment (MoCA) is an instrument with a good application profile for cognitive evaluation of patients with CKD-like impairments. The objective of this study is to perform a systematic review of MoCA use in the context of CKD.

METHOD

The keywords "Montreal Cognitive Assessment", "Kidney Disease" and "Chronic Kidney Disease" were used to search the databases. The inclusion criteria were: a) empirical articles; b) approach to cognitive impairment in CKD; c) papers in Portuguese and English.

RESULTS

The studies were mostly cross-sectional, published in medical journals, with research carried out mostly in Europe. About 45% of the studies had samples of less than 150 participants and variations in the prevalence of cognitive impairment were found ranging from 28.9% to 74.6%. The cutoff point for the identification of the impairment presented variation between the studies.

DISCUSSION

The results' analysis demonstrates the need for more complete studies on MoCA scoring and adaptation in its different versions. We recommend to the health professionals who will use the results in the clinical setting that the interpretation of the results be made in the light of studies more related to the context lived by the patients.

CONCLUSIONS

The instrument is efficient to be used in several stages and treatment modalities of the disease. We point to the need to adapt a cut-off point for the instrument in the different translations of the instrument.

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.

Cognitive function among long-term survivors of heart transplantation

BACKGROUND

Cognitive impairment is documented early after heart transplantation (HTx), but we lack data on cognitive function beyond the fourth year post-transplant. Against the background of good long-term survival, this knowledge is necessary to improve clinical care throughout the entire post-transplant period.

METHODS

We assessed cognitive function with a neuropsychological test battery in a sample of HTx recipients ≥16 years post-transplant. To improve clinical utility, we also applied adapted consensus criteria for Mild Cognitive Impairment (MCI). Furthermore, we explored sociodemographic and clinical characteristics possibly related to cognitive function.

RESULTS

Thirty-seven subjects were included 20.3 (±3.8) years after HTx. Mean age was 57.5 (±14.2) years, and 18.9% were women. Up to 38.9% exhibited impaired test performance (ie, performance at least 1.5 standard deviations below the normative mean) on several individual cognitive measures, especially on measures of processing speed, executive functions, memory, and language functions. One subject was diagnosed with dementia, and 30.1% qualified for MCI. Those with MCI had lower hemoglobin than those without.

CONCLUSIONS

A substantial proportion of long-term survivors of HTx might be cognitively impaired. The level of impairment appears comparable to what is defined as MCI in the literature. Modifiable factors related to cognitive impairment might exist.

Discrepancies between Perceived and Measured Cognition in Kidney Transplant Recipients: Implications for Clinical Management

BACKGROUND

Cognitive impairment is common in kidney transplant (KT) recipients and affects quality of life, graft survival, morbidity, and mortality. Failure to identify patients with cognitive impairment can withhold appropriate and timely intervention. This study determines whether measured cognition with standard screening tools offers any advantage over perceived cognition in screening transplant patients for cognitive impairment.

METHODS

Cognition was assessed in 157 KT recipients using the Montreal Cognitive Assessment (MoCA; measured cognition). In addition, transplant physicians and nurse coordinators were asked to rate transplant recipients' level of cognition after routine clinical interactions (perceived cognition). Physicians and nurses were blind to MoCA scores. Perceived cognition scores were compared to MoCA scores.

RESULTS

Perceived cognition scores fairly correlated with MOCA scores (γ = 0.24, p = 0.001 for physicians and γ = 0.33, p < 0.0001 for nurses). Physician scores moderately correlated with nurses scores (κ = 0.44, p < 0.0001). Clinical perception had a low accuracy for identifying patients with cognitive impairment (sensitivity 66% for physicians, 65% for nurses), and those without cognitive impairment (specificity 67% for physicians, 76% for nurses).

CONCLUSION

Clinical perception is inaccurate at detecting cognitive impairment in KT recipients. Objective tests should be considered to screen KT recipients for cognitive impairment.