Bicarbonate, blood pressure, and executive function in pediatric CKD-is there a link?

Neurocognitive deficits may not resolve following pediatric kidney transplantation

BACKGROUND

Pediatric chronic kidney disease (CKD) patients are at risk for cognitive deficits with worsening disease progression. Limited, existing cross-sectional studies suggest that cognitive deficits may improve following kidney transplantation. We sought to assess cognitive performance in relationship to kidney transplantation and kidney-specific medical variables in a sample of pediatric kidney transplant patients who provided cross-sectional and longitudinal observations.

METHODS

A retrospective chart review was conducted in patients who completed pre- and/or post-transplant neurocognitive testing at the University of Iowa from 2015-2021. Cognitive outcomes were investigated with developmentally appropriate, standardized measures. Mixed linear models estimated the impact of transplant status on cognitive function (z-scores). Subsequent post-hoc t-tests on change scores were limited to patients who had provided pre- and post-transplant assessments.

RESULTS

Thirty eight patients underwent cognitive assessments: 10 had both pre- and post-transplant cognitive assessments, 11 had pre-transplant assessments only, and 17 had post-transplant data only. Post-transplant status was associated with significantly lower full-scale IQ and slower processing speed compared to pre-transplant status (estimate = -0.32, 95% confidence interval [CI] = -0.52: -0.12; estimate = -0.86, CI = -1.17: -0.55, respectively). Post-hoc analyses confirmed results from the mixed models (FSIQ change score = -0.34, 95% CI = -0.56: -0.12; processing speed change score = -0.98, CI = -1.28: -0.68). Finally, being ≥80 months old at transplant was associated with substantially lower FSIQ compared to being <80 months (estimate = -1.25, 95% CI = -1.94: -0.56).

CONCLUSIONS

Our results highlight the importance of monitoring cognitive function following pediatric kidney transplant and identify older transplant age as a risk factor for cognitive deficits.

Overview of the findings and advances in the neurocognitive and psychosocial functioning of mild to moderate pediatric CKD: perspectives from the Chronic Kidney Disease in Children (CKiD) cohort study

The Chronic Kidney Disease in Children (CKiD) prospective cohort study was designed to address the neurocognitive, growth, cardiovascular, and disease progression of children and adolescents with mild to moderate CKD. The study has had continuous funding from NIDDK for 17 years and has contributed significant advances in pediatric CKD. The goals of this educational review are threefold: (1) to provide an overview of the neurocognitive and psychosocial studies from CKiD to date; (2) to provide best practice recommendations for those working with the neurocognitive and psychosocial aspects of pediatric CKD based on CKiD findings; and (3) to help chart future goals and directives for both research and clinical practice. This collection of 22 empirical studies has produced a number of key findings for children and adolescents with mild to moderate CKD. While various studies suggest a relatively positive presentation for this population as a whole, without evidence of significant impairment or deterioration, findings do indicate the presence of neurocognitive dysfunction, emotional-behavioral difficulties, and lower quality of life for many children with CKD. These findings support the promotion of best practices that are accompanied by additional future clinical and research initiatives with this patient population.

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.

The Similarities and Differences Between Glomerular vs. Non-glomerular Diagnoses on Intelligence and Executive Functions in Pediatric Chronic Kidney Disease: A Brief Report

Pediatric chronic kidney disease (CKD) appears to be a heterogeneous group of conditions, but this heterogeneity has not been explored with respect to its impact on neurocognitive functioning. This study investigated the neurocognitive functioning of those with glomerular (G) vs. non-glomerular (NG) diagnoses. Data from the North American CKiD Study were employed and the current study included 1,003 children and adolescents with mild to moderate CKD. The G Group included 260 participants (median age = 14.7 years) and the NG Group included 743 individuals (median age = 9.0 years). Neurocognitive measures assessed IQ, inhibitory control, attention regulation, problem solving, working memory, and overall executive functioning. Data from all visits were included in the linear mixed model analyses. After adjusting for sociodemographic and CKD-related covariates, results indicated no differences between the diagnostic groups on measures of IQ, problem solving, working memory, and attention regulation. There was a trend for the G group to receive better parent ratings on their overall executive functions (p < 0.07), with a small effect size being present. Additionally, there was a significant G group X hypertension interaction (p < 0.003) for inhibitory control, indicating that those with both a G diagnosis and hypertension performed more poorly than the NG group with hypertension. These findings suggest that the separation of G vs. NG CKD produced minimal, but specific group differences were observed. Ongoing examination of the heterogeneity of pediatric CKD on neurocognition, perhaps at a different time point in disease progression or using a different model, appears warranted.

Neurocognition in Pediatric Chronic Kidney Disease: A Review of Data From the Chronic Kidney Disease in Children (CKiD) Study

Pediatric chronic kidney disease (CKD) is associated with deficits in neurocognitive functioning, ranging from mild to severe, and correlated with the severity of kidney disease. Clinical variables that are associated with neurocognitive deficits include lower kidney function, hypertension, proteinuria, and metabolic acidosis. Commonly reported neurocognitive difficulties include academic underachievement and deficits in attention regulation and executive function as well as somewhat lower intellectual abilities compared with peer and normative data. Although often mild, these neurocognitive deficits may have broad implications for quality of life and likely contribute to both poorer high school graduation rates and long-term underemployment in the adult CKD population. The presence of neurocognitive deficits in predialytic CKD has been well characterized, but further longitudinal research is warranted to describe cognitive changes as children progress from early stage CKD to kidney replacement therapy. Such studies should include both cognitive and neuroimaging evaluations to better inform the impact of CKD progression on neurocognitive outcomes.

The pressure's on: understanding neurocognitive and psychological associations with pediatric hypertension to inform comprehensive care

The prevalence of hypertension is increasing in pediatric populations. While clinical data and practice guidelines identify the impact of hypertension on organ dysfunction and emphasize the importance for end-organ damage screening, the bidirectional effects of pediatric hypertension on neurocognitive and psychological outcomes are understudied. The objective of this review is to highlight the association between hypertension and cognition, attention, learning, and mental health in children and adolescents. In doing so, this review provides a framework and toolkit to integrate neuropsychology and psychology into the screening and management stages of pediatric hypertension. By recognizing the effects of hypertension on cognition, behavior, and mental health, screenings and interventions can be implemented to proactively and comprehensively improve the health outcomes for children with blood pressure concerns.

Acidosis, cognitive dysfunction and motor impairments in patients with kidney disease

Metabolic acidosis, defined as a plasma or serum bicarbonate concentration <22 mmol/L, is a frequent consequence of chronic kidney disease (CKD) and occurs in ~10–30% of patients with advanced stages of CKD. Likewise, in patients with a kidney transplant, prevalence rates of metabolic acidosis range from 20% to 50%. CKD has recently been associated with cognitive dysfunction, including mild cognitive impairment with memory and attention deficits, reduced executive functions and morphological damage detectable with imaging. Also, impaired motor functions and loss of muscle strength are often found in patients with advanced CKD, which in part may be attributed to altered central nervous system (CNS) functions. While the exact mechanisms of how CKD may cause cognitive dysfunction and reduced motor functions are still debated, recent data point towards the possibility that acidosis is one modifiable contributor to cognitive dysfunction. This review summarizes recent evidence for an association between acidosis and cognitive dysfunction in patients with CKD and discusses potential mechanisms by which acidosis may impact CNS functions. The review also identifies important open questions to be answered to improve prevention and therapy of cognitive dysfunction in the setting of metabolic acidosis in patients with CKD.