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

Patient Perspectives on the Use of Aging Metrics for Kidney Transplant Decision-Making

INTRODUCTION

Frailty and cognitive function are often measured during kidney transplant evaluation. However, patient perspectives on the ethical considerations of this practice are unclear.

RESEARCH QUESTION

What are patient perspectives on the use of aging metrics in kidney transplant decision-making?

DESIGN

One hundred participants who were evaluated for kidney transplantation and were enrolled in an ongoing prospective cohort study (response rate = 61.3%) were surveyed. Participants were informed of the definitions of frailty and cognitive impairment and then asked survey questions regarding the use of these measures of aging to determine kidney transplant candidacy.

RESULTS

Participants (75.6%) thought it was unfair to prevent older adults from receiving a kidney transplant based on age, but there was less agreement on whether it was fair to deny frail (46.5%) and cognitively impaired (45.9%) patients from accessing kidney transplantation. Compared to older participants, younger participants had 5.36-times (95%CI:1.94-14.81) the odds of choosing a hypothetical younger, frail patient to list for kidney transplantation than an older, non-frail patient; they also had 3.56-times (95%CI:1.33-9.56) the odds of choosing the hypothetical frail patient with social support rather than a non-frail patient without social support. Participants disagreed on the use of patient age as a listing criterion; 19.5% ranked it as the fairest and 28.7% as the least fair.

CONCLUSION

The patient views highlighted in this study are an important step toward developing ethical guidelines to ensure fair use of frailty, cognitive function, and chronological age for kidney transplant decision-making.

Medical Distrust Among Kidney Transplant Candidates

BACKGROUND

Medical distrust may hinder kidney transplantation (KT) access. Among KT candidates evaluated for waitlisting, we identified factors associated with high distrust levels and quantified their association with waitlisting.

METHODS

Among 812 candidates (2018-2023), we assessed distrust using the Revised Health Care System Distrust Scale across composite, competence, and values subscales. We used linear regression to quantify the associations between candidate and neighborhood-level factors and distrust scores. We used Cox models to quantify the associations between distrust scores and waitlisting.

RESULTS

At KT evaluation, candidates who were aged 35-49 years (difference = 1.97, 95% CI: 0.78-3.16), female (difference = 1.10, 95% CI: 0.23-1.97), and Black (difference = 1.47, 95% CI: 0.47-2.47) were more likely to report higher composite distrust score. For subscales, candidates aged 35-49 were more likely to have higher competence distrust score (difference = 1.14, 95% CI: 0.59-1.68) and values distrust score (difference = 0.83, 95% CI: 0.05-1.61). Race/ethnicity (Black, difference = 1.42, 95% CI: 0.76-2.07; Hispanic, difference = 1.52, 95% CI: 0.35-2.69) was only associated with higher values distrust scores. Female candidates reporting higher rescaled values distrust scores (each one point) had a lower chance of waitlisting (aHR = 0.78, 95% CI: 0.63-0.98), whereas this association was not observed among males. Similarly, among non-White candidates, each 1-point increase in both rescaled composite (aHR = 0.87, 95% CI: 0.77-0.99) and values (aHR = 0.82, 95% CI: 0.68-0.99) distrust scores was associated with a lower chance of waitlisting, while there was no association among White candidates.

CONCLUSION

Female, younger, and non-White candidates reported higher distrust scores. Values distrust may contribute to the long-standing racial/ethnic and gender disparities in access to KT. Implementing tailored strategies to reduce distrust in transplant care may improve KT access for groups that experience persistent disparities.

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.

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.

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.

Current recommendations regarding evaluation of cognitive functioning in organ transplant candidates

PURPOSE OF REVIEW

Cognitive impairment is associated with negative effects on solid organ transplant candidates, recipients, and their care partners. However, because of the heterogeneity of mechanisms, presentations, and assessment measures, research suggests a wide array of impairments, patterns of impairments, and unclear trajectories posttransplant. This review provides an abbreviated synthesis of recent research on cognitive impairments observed in organ-eligible candidates and potential trajectories through posttransplant, current clinical recommendations regarding integration of assessment into routine clinical transplant practice, as well as recommendations for future research.

RECENT FINDINGS

Transplantation may resolve certain disease-contributing factors to cognitive impairments but also introduces new potential neurocognitive assaults. Recent studies in kidney and lung recipients document continued impairments in subsets of patients, particularly those identified as frail. For liver candidates, new assessment measures of hepatic encephalopathy have been developed and preliminarily tested with potential for translation into routine clinical care. Clinical implications, as well as ethical considerations are discussed.

SUMMARY

Although guidelines agree that cognitive assessment is an important part of the organ transplantation process, many questions remain of how to best assess cognition and intervene when cognitive impairment is identified in transplant populations. Further research should focus on prospective, longitudinal assessments in transplant-eligible populations through posttransplant.

Delirium, changes in cognitive function, and risk of diagnosed dementia after kidney transplantation

Kidney transplant (KT) recipients with delirium, a preventable surgical complication, are likely to reap cognitive benefits from restored kidney function, but may be more vulnerable to longer-term neurotoxic stressors post-KT (i.e., aging, immunosuppression). In this prospective cohort study, we measured delirium (chart-based), global cognitive function (3MS), and executive function (Trail Making Test Part B minus Part A) in 894 recipients (2009-2021) at KT, 1/3/6-months, 1-year, and annually post-KT. Dementia was ascertained using linked Medicare claims. We described repeated measures of cognitive performance (mixed effects model) and quantified dementia risk (Fine & Gray competing risk) by post-KT delirium. Of 894 recipients, 43(4.8%) had post-KT delirium. Delirium was not associated with global cognitive function at KT (difference = -3.2 points, 95%CI: -6.7, 0.4) or trajectories post-KT (0.03 points/month, 95%CI: -0.27, 0.33). Delirium was associated with worse executive function at KT (55.1 s, 95%CI: 25.6, 84.5), greater improvements in executive function <2 years post-KT (-2.73 s/month, 95%CI: -4.46,-0.99), and greater decline in executive function >2 years post-KT (1.72 s/month, 95%CI: 0.22, 3.21). Post-KT delirium was associated with over 7-fold greater risk of dementia post-KT (adjusted subdistribution hazard ratio = 7.84, 95%CI: 1.22, 50.40). Transplant centers should be aware of cognitive risks associated with post-KT delirium and implement available preventative interventions to reduce delirium risk.

Normal pace walking is beneficial to young participants’ executive abilities

Background

Exercise can improve cognitive function. The impact of acute exercise on cognition is related to exercise intensity. This study aimed to explore whether normal walking had a beneficial effect on cognition.

Methods

Compared with standing still, thirty healthy young men walked on a treadmill at a normal pace, and completed the Stroop test. Near-infrared spectroscopy was used to monitor the hemodynamic changes of the prefrontal cortex during the entire experiment.

Results

Studies showed that normal walking did not stimulate higher average cerebral oxygen in the PFC, but the peak cerebral oxygen in cognitive tests during walking was higher (Stroop Word: 2.56 ± 0.43 and 3.80 ± 0.50, P < 0.01, Stroop Color: 2.50 ± 0.37 and 3.66 ± 0.59, P < 0.05, Stroop Color-Word: 4.13 ± 0.55 and 5.25 ± 0.66, P < 0.01, respectively), and better results were achieved in the Stroop Color-Word test, which was reflected in faster reaction times (49.18 ± 1.68 s, 56.92 ± 2.29 s, respectively, P < 0.001) and higher accuracies (46.19 ± 0.69, 44.15 ± 0.91, respectively, P = 0.018).

Conclusion

For healthy young people, even a normal walk is therefore good for cognition.

Impact of Chronic Kidney Disease on Brain Structure and Function

Chronic kidney disease (CKD) affects more than 37 million American adults. Adult-onset CKD is typically attributed to acquired comorbidities such as aging, type II diabetes, and cardiovascular disease. Conversely, congenital abnormalities of the kidney and urinary tract are the most common cause of CKD in children. Both adult and pediatric patients with CKD are at risk for neurocognitive dysfunction, particularly in the domain of executive function. The exact mechanism for neurocognitive dysfunction in CKD is not known; however, it is conceivable that the multisystemic effects of CKD—including hypertension, acidosis, anemia, proteinuria, and uremic milieu—exert a detrimental effect on the brain. Quantitative neuroimaging modalities, such as magnetic resonance imaging (MRI), provide a non-invasive way to understand the neurobiological underpinnings of cognitive dysfunction in CKD. Adult patients with CKD show differences in brain structure; however, much less is known about the impact of CKD on neurodevelopment in pediatric patients. Herein, this review will summarize current evidence of the impact of CKD on brain structure and function and will identify the critical areas for future research that are needed to better understand the modifiable risk factors for abnormal brain structure and function across both pediatric and adult CKD populations.