Association of Kidney Function Biomarkers with Brain MRI Findings: The BRINK Study

Kidney-brain axis in the pathogenesis of cognitive impairment

The kidney-brain axis is a bidirectional communication network connecting the kidneys and the brain, potentially affected by inflammation, uremic toxin, vascular injury, neuronal degeneration, and so on, leading to a range of diseases. Numerous studies emphasize the disruptions of the kidney-brain axis may contribute to the high morbidity of neurological disorders, such as cognitive impairment (CI) in the natural course of chronic kidney disease (CKD). Although the pathophysiology of the kidney-brain axis has not been fully elucidated, epidemiological data indicate that patients at all stages of CKD have a higher risk of developing CI compared with the general population. In contrast to other reviews, we mentioned some commonly used medicines in CKD that may play a pivotal role in the pathogenesis of CI. Revealing the pathophysiology interactions between kidney damage and brain function can reduce the potential risk of future CI. This review will deeply explore the characteristics, indicators, and potential pathophysiological mechanisms of CKD-related CI. It will provide a theoretical basis for identifying CI that progresses during CKD and ultimately prevents and treats CKD-related CI.

Associations between renal function, hippocampal volume, and cognitive impairment in 544 outpatients

Background

Cognitive impairment and brain atrophy are common in chronic kidney disease patients. It remains unclear whether differences in renal function, even within normal levels, influence hippocampal volume (HCV) and cognition. We aimed to investigate the association between estimated glomerular filtration rate (eGFR), HCV and cognition in outpatients.

Methods

This single-center retrospective study enrolled 544 nonrenal outpatients from our hospital. All participants underwent renal function assessment and 3.0 T magnetic resonance imaging (MRI) in the same year. HCV was also measured, and cognitive assessments were obtained. The correlations between eGFR, HCV, and cognitive function were analyzed. Logistic regression analysis was performed to identify the risk factors for hippocampal atrophy and cognitive impairment. Receiver-operator curves (ROCs) were performed to find the cut-off value of HCV that predicts cognitive impairment.

Results

The mean age of all participants was 66.5 ± 10.9 years. The mean eGFR of all participants was 88.5 ± 15.1 mL/min/1.73 m2. eGFR was positively correlated with HCV and with Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) scores. Univariate and multivariate logistic regression analysis showed Age ≥ 65 years, eGFR < 75 mL/min/1.73 m2, Glucose ≥6.1 mmol/L and combined cerebral microvascular diseases were independent risk factors for hippocampal atrophy and Age ≥ 65 years, left hippocampal volume (LHCV) <2,654 mm3 were independent risk factors for cognitive impairment in outpatients. Although initial unadjusted logistic regression analysis indicated that a lower eGFR (eGFR < 75 mL/min/1.73 m2) was associated with poorer cognitive function, this association was lost after adjusting for confounding variables. ROC curve analysis demonstrated that LHCV <2,654 mm3 had the highest AUROC [(0.842, 95% CI: 0.808-0.871)], indicating that LHCV had a credible prognostic value with a high sensitivity and specificity for predicting cognitive impairment compared with age in outpatients.

Conclusion

Higher eGFR was associated with higher HCV and better cognitive function. eGFR < 75 mL/min/1.73 m2 was an independent risk factor for hippocampal atrophy after adjusting for age. It is suggested that even eGFR < 75 mL/min/1.73 m2, lower eGFR may still be associated with hippocampal atrophy, which is further associated with cognitive impairment. LHCV was a favorable prognostic marker for predicting cognitive impairment rather than age.

A nomogram to predict cognitive function impairment in patients with chronic kidney disease: A national cross-sectional survey

Background

Cognitive function impairment (CFI) is common in patients with chronic kidney disease (CKD) and significantly impacts treatment adherence and quality of life. This study aims to create a simplified nomogram for early CFI risk detection.

Methods

Data were obtained from the National Health and Nutrition Examination Survey cycles spanning from 1999 to 2002 and again from 2011 to 2014. Stepwise logistic regression was used to select variables and construct a CFI risk prediction model. Furthermore, C-statistic and Brier Score (BS) assessed model performance. Additionally, Kaplan-Meier survival curves were utilised to assess risk group-death prognosis relationships.

Results

Of the 545 participants in the CKD model development cohort, a total of 146 (26.8 %) had CFI. The final model included the variables of age, race, education, annual family income, body mass index, estimated glomerular filtration rate, serum albumin and uric acid. The model had a C-statistic of 0.808 (95 % confidence interval (CI): 0.769-0.847) and a BS of 0.149. Furthermore, the 5-fold cross-validation internal C-statistic was 0.764 (interquartile range: 0.763-0.807) and BS was 0.154. Upon external validation, the model's C-statistic decreased to 0.752 (95 % CI: 0.654-0.850) and its BS increased to 0.182. The Kaplan-Meier survival curves demonstrated that intermediate-to-high-risk participants had shorter overall survival time than low-risk participants (log-rank test: p = 0.00042).

Conclusions

This study established an effective nomogram for predicting CFI in patients with CKD, which can be used for the early detection of CFI and guide the treatment of patients with CKD.

Magnetic Resonance Imaging and Manganism: A Narrative Review and Laboratory Recommendations

In recent years, a series of articles has been published concerning magnetic resonance imaging (MRI) studies in a group of patients exposed to manganism, specifically factory workers, welders, and individuals with liver diseases, as well as those abusing home-produced ephedrone. Some potential symptoms of manganese toxicity include motor disturbances, neurocognitive problems, sleep disorders, and psychosocial changes. Despite various publications on MRI research in individuals with an elevated risk of manganism, there is a noticeable absence of a comprehensive review in this field. The detection of the accumulation of manganese in the brain through MRI can confirm the diagnosis and guide appropriate treatment. Due to the high cost of determining manganese ion levels in biological material, an additional aim of the manuscript was to identify simple medical laboratory parameters that, when performed concurrently with MRI, could assist in the diagnosis of manganism. Among these types of parameters are the levels of bilirubin, magnesium, liver enzymes, creatinine, hemoglobin, and hematocrit.

Deliverables from Metabolomics in Kidney Disease: Adenine, New Insights, and Implication for Clinical Decision-Making

BACKGROUND

Chronic kidney disease (CKD) presents a persistent global health challenge, characterized by complex pathophysiology and diverse progression patterns. Metabolomics has emerged as a valuable tool in unraveling the intricate molecular mechanisms driving CKD progression.

SUMMARY

This comprehensive review provides a summary of recent progress in the field of metabolomics in kidney disease with a focus on spatial metabolomics to shed important insights to enhancing our understanding of CKD progression, emphasizing its transformative potential in early disease detection, refined risk assessment, and the development of targeted interventions to improve patient outcomes.

KEY MESSAGE

Through an extensive analysis of metabolic pathways and small-molecule fluctuations, bulk and spatial metabolomics offers unique insights spanning the entire spectrum of CKD, from early stages to advanced disease states. Recent advances in metabolomics technology have enabled spatial identification of biomarkers to provide breakthrough discoveries in predicting CKD trajectory and enabling personalized risk assessment. Furthermore, metabolomics can help decipher the complex molecular intricacies associated with kidney diseases for exciting novel therapeutic approaches. A recent example is the identification of adenine as a key marker of kidney fibrosis for diabetic kidney disease using both untargeted and targeted bulk and spatial metabolomics. The metabolomics studies were critical to identify a new biomarker for kidney failure and to guide new therapeutics for diabetic kidney disease. Similar approaches are being pursued for acute kidney injury and other kidney diseases to enhance precision medicine decision-making.

Association of Kidney Function With Dementia and Structural Brain Differences: A Large Population-Based Cohort Study

BACKGROUND

The association between kidney function and dementia risk and the mechanisms underlying this relationship remain unclear.

METHODS

Within the UK Biobank, 191 970 dementia-free participants aged ≥60 (mean age: 64.1 ± 2.9 years) were followed for 16 years to detect incident dementia. Serum creatinine and Cystatin C were measured at baseline to calculate estimated glomerular filtration rate (eGFR, mL/min/1.73 m2). Kidney function was categorized as normal (eGFR ≥ 90), mildly impaired (60 ≤ eGFR < 90), or moderately to severely impaired (eGFR < 60). Dementia was assessed based on self-reported medical history and medical records. During the follow-up, a subsample of 12 637 participants underwent brain MRI scans. Volumes of total brain, gray matter, white matter, hippocampus, and white matter hyperintensities were assessed.

RESULTS

Over the follow-up, 5 327 (2.8%) participants developed dementia. Compared to normal kidney function, there was an increased risk of dementia with moderate to severely impaired kidney function (hazard ratio = 1.53, 95% confidence interval [CI]: 1.32-1.76) but not mildly impaired kidney function. In Laplace regression, dementia onset among people with moderate to severely impaired kidney function occurred 1.53 (95% CI: 0.98-2.08) years earlier than those with normal kidney function. Moderate to severely impaired kidney function was related to significantly lower gray matter volume (β = -0.11, 95% CI: -0.19 to -0.03), but not to other brain magnetic resonance imaging measures.

CONCLUSIONS

Impaired kidney function is associated with about 50% increased risk of dementia and anticipates dementia onset by more than 1.5 years. Brain neurodegeneration may underlie the kidney function-dementia association.

Relationship between chronic kidney disease and cerebral white matter hyperintensities: a systematic review

Background

This systematic review summarizes available evidence on the relationship between white matter hyperintensities (WMH) volumetric quantification on brain MRI scans and chronic kidney disease (CKD).

Methods

The literature search was performed in March 2022 using MEDLINE PubMed Central, Scopus and Web of Science - Publons as search engines. Relevant articles investigating, with a quantitative volumetric approach, the link between WMH and CKD patients were selected.

Results

The database search strategy found 987 articles, after excluding duplicates, the titles and abstracts of the remaining 320 articles were examined. Subsequently 276 articles were excluded as they were not relevant to the topic. Of the 44 articles evaluated for eligibility, 36 were excluded because the quantitative analysis of WMH was not volumetric. Finally, 8 articles were included in this systematic review.

Conclusions

Literature on this topic is extremely heterogeneous in terms of methodology and samples. However, evidence shows that there is a relationship between CKD and WMH volume of the brain. We recommend that quantifiable biomarkers such as estimated glomerular filtration rate (eGFR) and urine albumin to creatinine ratio (UACR) should be included in studies dealing with cerebrovascular disease. The biological and molecular mechanisms underlying cerebrovascular damage in patients with chronic renal failure deserve to be further explored.

CKD, Brain Atrophy, and White Matter Lesion Volume: The Japan Prospective Studies Collaboration for Aging and Dementia

Rationale & Objective

Chronic kidney disease, defined by albuminuria and/or reduced estimated glomerular filtration rate (eGFR), has been reported to be associated with brain atrophy and/or higher white matter lesion volume (WMLV), but there are few large-scale population-based studies assessing this issue. This study aimed to examine the associations between the urinary albumin-creatinine ratio (UACR) and eGFR levels and brain atrophy and WMLV in a large-scale community-dwelling older population of Japanese.

Study Design

Population-based cross-sectional study.

Setting & Participants

A total of 8,630 dementia-free community-dwelling Japanese aged greater than or equal to 65 years underwent brain magnetic resonance imaging scanning and screening examination of health status in 2016-2018.

Exposures

UACR and eGFR levels.

Outcomes

The total brain volume (TBV)-to-intracranial volume (ICV) ratio (TBV/ICV), the regional brain volume-to-TBV ratio, and the WMLV-to-ICV ratio (WMLV/ICV).

Analytical Approach

The associations of UACR and eGFR levels with the TBV/ICV, the regional brain volume-to-TBV ratio, and the WMLV/ICV were assessed by using an analysis of covariance.

Results

Higher UACR levels were significantly associated with lower TBV/ICV and higher geometric mean values of the WMLV/ICV (P for trend = 0.009 and <0.001, respectively). Lower eGFR levels were significantly associated with lower TBV/ICV, but not clearly associated with WMLV/ICV. In addition, higher UACR levels, but not lower eGFR, were significantly associated with lower temporal cortex volume-to-TBV ratio and lower hippocampal volume-to-TBV ratio.

Limitations

Cross-sectional study, misclassification of UACR or eGFR levels, generalizability to other ethnicities and younger populations, and residual confounding factors.

Conclusions

The present study demonstrated that higher UACR was associated with brain atrophy, especially in the temporal cortex and hippocampus, and with increased WMLV. These findings suggest that chronic kidney disease is involved in the progression of morphologic brain changes associated with cognitive impairment.

Association of Kidney Function Measures With Signs of Neurodegeneration and Small Vessel Disease on Brain Magnetic Resonance Imaging: The Atherosclerosis Risk in Communities (ARIC) Study

RATIONALE & OBJECTIVE

Chronic kidney disease (CKD) is a risk factor for cognitive decline, but evidence is limited on its etiology and morphological manifestation in the brain. We evaluated the association of estimated glomerular filtration rate (eGFR) and urinary albumin-creatinine ratio (UACR) with structural brain abnormalities visible on magnetic resonance imaging (MRI). We also assessed whether this association was altered when different filtration markers were used to estimate GFR.

STUDY DESIGN

Cross-sectional study nested in a cohort study.

SETTING & PARTICIPANTS

1,527 participants in the Atherosclerosis Risk in Communities (ARIC) Study.

PREDICTORS

Log(UACR) and eGFR based on cystatin C, creatinine, cystatin C and creatinine in combination, or β2-microglobulin (B2M).

OUTCOMES

Brain volume reduction, infarcts, microhemorrhages, white matter lesions.

ANALYTICAL APPROACH

Multivariable linear and logistic regression models fit separately for each predictor based on a 1-IQR difference in the predictor value.

RESULTS

Each 1-IQR lower eGFR was associated with reduced cortex volume (regression coefficient: -0.07 [95% CI, -0.12 to-0.02]), greater white matter hyperintensity volume (logarithmically transformed; regression coefficient: 0.07 [95% CI, 0.01-0.15]), and lower white matter fractional anisotropy (regression coefficient: -0.08 [95% CI, -0.17 to-0.01]). The results were similar when eGFR was estimated with different equations based on cystatin C, creatinine, a combination of cystatin C and creatinine, or B2M. Higher log(UACR) was similarly associated with these outcomes as well as brain infarcts and microhemorrhages (odds ratios per 1-IQR-fold greater UACR of 1.31 [95% CI, 1.13-1.52] and 1.30 [95% CI, 1.12-1.51], respectively). The degree to which brain volume was lower in regions usually susceptible to Alzheimer disease and LATE (limbic-predominant age-related TDP-43 [Tar DNA binding protein 43] encephalopathy) was similar to that seen in the rest of the cortex.

LIMITATIONS

No inference about longitudinal effects due to cross-sectional design.

CONCLUSIONS

We found eGFR and UACR are associated with structural brain damage across different domains of etiology, and eGFR- and UACR-related brain atrophy is not selective for regions typically affected by Alzheimer disease and LATE. Hence, Alzheimer disease or LATE may not be leading contributors to neurodegeneration associated with CKD.

Association between Kidney Function and the Burden of Cerebral Small Vessel Disease: An Updated Meta-Analysis and Systematic Review

INTRODUCTION

Due to anatomical and functional similarities in microvascular beds, the brain and kidney share distinctive susceptibilities to vascular injury and common risk factors of small vessel disease. The aim of this updated meta-analysis is to explore the association between kidney function and the burden of cerebral small vessel disease (CSVD).

METHODS

PubMed, EMBASE, and Cochrane Library were systematically searched for observational studies that explored the association between the indicators of kidney function and CSVD neuroimaging markers. The highest-adjusted risk estimates and their 95% confidence intervals (CIs) were aggregated using random-effect models.

RESULTS

Twelve longitudinal studies and 51 cross-sectional studies with 57,030 subjects met the inclusion criteria of systematic review, of which 52 were included in quantitative synthesis. According to the pooled results, we found that low estimated glomerular filtration rate (eGFR <60 mL/min/1.73 m2) was associated with cerebral microbleeds (odds ratio (OR) = 1.55, 95% CI = 1.26-1.90), white matter hyperintensities (OR = 1.40, 95% CI = 1.05-1.86), and lacunar infarctions (OR = 1.50, 95% CI = 1.18-1.92), but not with severe perivascular spaces (OR = 1.20, 95% CI = 0.77-1.88). Likewise, patients with proteinuria (OR = 1.75, 95% CI = 1.47-2.09) or elevated serum cystatin C (OR = 1.51, 95% CI = 1.25-1.83) also had an increased risk of CSVD.

CONCLUSION

The association between kidney function and CSVD has been comprehensively updated through this study, that kidney insufficiency manifested as low eGFR, proteinuria, and elevated serum cystatin C was independently associated with CSVD burden.

Association of impaired kidney function with dementia and brain pathologies: A community-based cohort study

INTRODUCTION

The relationship between impaired kidney function (KF), dementia, and brain pathologies remains unclear.

METHODS

A total of 1354 dementia- and kidney disease-free participants including 895 with normal and 459 with impaired KF were followed from 2002 until 2020 (median [interquartile range]: 5 [2-9]) to detect incident dementia. KF was assessed at baseline and categorized as normal or impaired. Over the follow-up, 453 participants died and underwent autopsies for neuropathological assessment.

RESULTS

Compared to those with normal KF, the hazard ratios (95% confidence intervals [CIs]) of those with impaired KF was 1.48 (1.15, 1.90)/1.44 (1.10, 1.88) for dementia/Alzheimer's dementia. Furthermore, impaired KF was related to a significantly higher burden of cerebral amyloid angiopathy (CAA; odds ratio = 1.96, 95% CI: 1.17, 3.30), but not to other brain pathologies.

DISCUSSION

Impaired KF is associated with an increased risk of dementia and Alzheimer's dementia. CAA may underlie, in part, this association.

HIGHLIGHTS

Impaired kidney function (KF) was associated with higher dementia and Alzheimer's dementia risk. Impaired KF anticipated dementia and Alzheimer's dementia onset by more than 1.5 years. Impaired KF was significantly related to a higher burden of cerebral amyloid angiopathy (CAA) but not to other brain pathologies.

Association of kidney function and brain health: A systematic review and meta-analysis of cohort studies

OBJECTIVE

This study aimed to evaluate the bidirectional association between the kidney dysfunction and the brain health, including structural and functional abnormalities.

DESIGN

Systematic review and meta-analysis with network meta-analysis for outcomes with different estimated glomerular filtration rate (eGFR) ranges.

DATA SOURCES

PubMed, Embase database, Cochrane library and Web of Science (up to Dec. 2021).

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Longitudinal studies that provided evidence of the impact of kidney function estimated from eGFR and urine albumin-to-creatinine ratio (UACR) or chronic kidney disease (CKD) on structural and functional brain abnormalities, and those that provided evidence of the opposite relationship. Studies with study population mean age under 18 years old were excluded.

MAIN OUTCOME MEASURES

Two independent reviewers screened the included studies, extracted the data, and assessed the risk of bias. We performed a random-effects meta-analysis and a network meta-analysis for outcomes with compatible data. We assessed the risk of bias using the Newcastle-Ottawa Quality Assessment Scale criteria (NOS). Subgroup and sensitivity analyses were conducted to explore heterogeneity in the meta-analyses. Inconsistency analyses using the node-splitting method were performed to confirm the results of network meta-analysis.

RESULTS

A total of 53 studies with 3037,357 participants were included in the current systematic review. Among these, 16 provided evidence of structural brain abnormalities, and 38 provided evidence of cognitive impairment and dementia. Analysis of evidence of categorical kidney function showed a positive association between kidney dysfunction and cerebral small vessel disease (cSVD) (relative risk (RR) 1.77, 95% confidence interval (CI) 1.40-2.24, I² = 0.0%), but such results were not found in the analyses of evidence where the kidney function was measured as a continuous variable. Meanwhile, analysis of 28 prior longitudinal studies with 194 compatible sets of data showed that the worse kidney function as categorical variables was related to a greater risk of global brain cognitive disorder (RR 1.28, 95% CI 1.20-1.36, I² = 82.5%).

CONCLUSIONS

In this systematic review and meta-analysis, we found a positive association between CKD and functional brain disorders. However, the relationship between the kidney dysfunction and structural abnormalities in the brain remains controversial. As for the opposite relationship, structural brain abnormalities, especially cerebral microbleeds and silent infarction, but not functional brain abnormalities, are associated with worse renal function. In addition, a higher UACR, but not a lower eGFR, was associated with a higher risk of Alzheimer's disease and vascular dementia.

Estimated GFR, Albuminuria, and Physical Function: The Brain in Kidney Disease (BRINK) Cohort Study

Rationale & Objective

Chronic kidney disease (CKD) is associated with impaired physical performance. However, the association between albuminuria, a marker of vascular endothelial dysfunction, and physical performance has not been fully characterized. We hypothesized that estimated glomerular filtration rate (eGFR) and albuminuria would be independently associated with physical performance.

Study Design

Cross-sectional analysis.

Setting & Participants

A total of 571 adults with and without CKD.

Predictors

Creatinine-based eGFR (eGFRCr) and cystatin C-based eGFR (eGFRCysC) and urine albumin to creatinine ratio (UACR).

Outcome

Short Physical Performance Battery (SPPB).

Analytical Approach

Univariate and multivariable logistic regression models were used to examine associations of eGFR and UACR with impaired physical performance.

Results

Of the 571 participants (mean age, 69.3 years), 157 (27.5%) had eGFRCr (mL/min/1.73m2) <30, 276 (48.3%) had eGFRCr 30-<60, and 138 (24.2%) had eGFRCr ≥60; 303 (55.3%) participants had eGFRcysC <30, 141 (25.7%) had eGFRcysC 30-<60, and 104 (19.0%) had eGFRcysC ≥60. Impaired physical performance was observed in 222 (38.9%) participants. Separate univariate analyses showed that lower eGFRCr, lower eGFRCysC, and higher UACR were associated with higher odds of impaired physical performance. In the adjusted model with eGFRCr or eGFRCysC, UACR, and covariates, UACR retained a statistically significant association with impaired physical performance (adjusted odds ratio [OR], 2.04; 95% confidence interval [CI], 1.21-3.47 for UACR from 30-300 mg/g vs <30 mg/g and adjusted OR, 1.93; 95% CI, 1.01-3.69 for UACR >300 mg/g vs <30 mg/g), but eGFRCr and eGFRCysC did not.

Limitations

Cross-sectional analysis, estimated rather than measured GFR.

Conclusions

Only UACR was associated with worse physical performance in the fully adjusted model, suggesting that vascular endothelial function and inflammation may be important mechanisms of decreased physical function. Similar results were found using eGFRCr or eGFRCysC, suggesting that confounding based on muscle mass does not explain the lack of an association between eGFRCr and physical performance.

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.

Covert vascular brain injury in chronic kidney disease

Chronic kidney disease (CKD) contributes to the increased risk of stroke and dementia. Accumulating evidence indicates that structural brain abnormalities, such as cerebral small vessel disease, including white matter hyperintensities, lacunes, perivascular spaces, and cerebral microbleeds, as well as brain atrophy, are common in patients with CKD. All of these imaging findings have been implicated in the development of stroke and dementia. The brain and kidney exhibit similar impairments and promote structural brain abnormalities due to shared vascular risk factors and similar anatomical and physiological susceptibility to vascular injury in patients with CKD. This indicates that kidney function has a significant effect on brain aging. However, as most results are derived from cross-sectional observational studies, the exact pathophysiology of structural brain abnormalities in CKD remains unclear. The early detection of structural brain abnormalities in CKD in the asymptomatic or subclinical phase (covert) should enable stroke risk prediction and guide clinicians on more targeted interventions to prevent stroke in patients with CKD. This article summarizes the currently available clinical evidence linking covert vascular brain injuries with CKD.

The Relationship Between Renal Function and Imaging Markers and Total Burden of Cerebral Small Vessel Disease

BACKGROUND

Previous studies demonstrating the association between renal functions and cerebral small vessel diseases have usually focused on white matter hyperintensity in the general population or lacunar stroke patients. This study aimed to investigate the effects of renal function on imaging markers of cerebral small vessel disease and etiologic subtypes of stroke in patients with acute ischemic stroke or transient ischemic attack.

MATERIALS AND METHODS

A total of 356 consecutive patients with acute ischemic stroke or transient ischemic attack who were admitted to the Stroke Unit and underwent brain magnetic resonance imaging were evaluated. Demographic data, vascular risk factors, stroke etiology, estimated glomerular filtration rate and severity of cerebral small vessel disease markers, and total cerebral small vessel disease burden were evaluated.

RESULTS

There was a significant inverse correlation between estimated glomerular filtration rate and total number of lacunes, periventricular and deep subcortical Fazekas scores, grade of enlarged perivascular spaces in the centrum semiovale, lobar and total cerebral microbleeds, and total cerebral small vessel disease burden. Impaired renal function was an independent risk factor for the presence of lacunes, deep cerebral microbleeds, and increased total burden. Renal function impairment and periventricular white matter hyperintensities were significantly associated with the etiologic subgroup of small vessel occlusion. The results were still significant after the exclusion of patients below 50 years of age.

CONCLUSION

Our results indicate that there is a relationship between renal function impairment and increased total burden, as well as acute ischemic stroke/transient ischemic attack due to small vessel occlusion.

Association Between White Matter Hyperintensities and Chronic Kidney Disease: A Systematic Review and Meta-Analysis

Objectives

Previous studies of the associations between white matter hyperintensities (WMH) and chronic kidney disease (CKD) were still conflicting; therefore, our study aimed to conduct a systematic review of all of the available research on this topic and a meta-analysis of the association between WMH and CKD among observational studies.

Setting and Design

Systematic review and meta-analysis.

Outcome Measures

Severity of WMH.

Methods and Participants

All relevant studies in public databases were examined until 15 November 2020. Two independent reviewers assessed all the included studies using the Cross-Sectional/Prevalence Study Quality (CSSQ) scale, and then literature review and meta-analyses were undertaken.

Results

We pooled the odds ratio (OR) for the presence of WMH, periventricular hyperintensities (PVH), and deep subcortical white matter hyperintensities (DWMH) of patients with CKD vs. non-CKD patients by subgroup analysis, and the results obtained were WMH OR 2.07, 95% CI [1.58, 2.70], PVH OR 2.41, 95% CI [1.90, 3.05], and DWMH OR 2.11, 95% CI [1.60, 2.80], respectively. The main outcome showed that patients with CKD were more likely to have WMH in the brain compared to the normal controls. Another meta-analysis showed a statistically significant decline in renal function in patients with moderate to severe WMH compared with those with no to mild WMH.

Conclusions

The findings indicated that patients with CKD were more likely to experience WMH than demographically matched controls. On the other hand, patients with moderate to severe WMH in the brain had poor renal function more frequently than those with no to mild WMH.

Kidney function, brain morphology and cognition in the elderly: sex differences in the Austrian Stroke Prevention Study

Impaired kidney function is associated with structural brain changes and cognitive dysfunction. In the aging kidney, hemodynamic and structural alterations reduce the glomerular filtration rate (eGFR). Little is known about differences between men and women regarding decline of kidney function and brain damage.

In this community-based study, we assessed associations between the eGFR, focal and diffuse brain abnormalities and cognitive functions. Sex-specific effects were analyzed by interaction terms eGFR x sex on brain structure and cognition. Interactive effects were assessed using mixed-models –stratified by sex.

Overall, 196 women and 129 men (median age 68 years and mean eGFR 73.8±14.9 ml/min/1.73m²) were included. Significant associations existed between eGFR and cortical volume (β: 1.53E-04; SE: 6.72E-05; p=0.023 for neocortex). Sex exerted a significant interactive effect. Only in men, eGFR related to cortical volumes of all lobes and of deep gray matter structures (p= 0.001 for total gray matter, p=0.0004 for neocortex). In the whole group eGFR was not associated with cognition, but men with lower eGFR performed worse on tests for executive function, which, after FDR correction, was not significant.

We conclude, that in community-dwelling middle-aged and elderly individuals, reduced eGFR relates to brain volume loss in men but not in women.

Structural brain abnormalities in children and young adults with severe chronic kidney disease

BACKGROUND

The pathophysiology of neurological dysfunction in severe chronic kidney disease (CKD) in children and young adults is largely unknown. We aimed to investigate brain volumes and white matter integrity in this population and explore brain structure under different treatment modalities.

METHODS

This cross-sectional study includes 24 patients with severe CKD (eGFR < 30) aged 8-30 years (median = 18.5, range = 9.1-30.5) on different therapy modalities (pre-dialysis, n = 7; dialysis, n = 7; transplanted, n = 10) and 21 healthy controls matched for age, sex, and parental educational level. Neuroimaging targeted brain volume using volumetric analysis on T1 scans and white matter integrity with tract-based spatial statistics and voxel-wise regression on diffusion tensor imaging (DTI) data.

RESULTS

CKD patients had lower white matter integrity in a widespread cluster of primarily distal white matter tracts compared to healthy controls. Furthermore, CKD patients had smaller volume of the nucleus accumbens relative to healthy controls, while no evidence was found for abnormal volumes of gray and white matter or other subcortical structures. Longer time since successful transplantation was related to lower white matter integrity. Exploratory analyses comparing treatment subgroups suggest lower white matter integrity and smaller volume of the nucleus accumbens in dialysis and transplanted patients relative to healthy controls.

CONCLUSIONS

Young CKD patients seem at risk for widespread disruption of white matter integrity and to some extent smaller subcortical volume (i.e., nucleus accumbens). Especially patients on dialysis therapy and patients who received a kidney transplant may be at risk for disruption of white matter integrity and smaller volume of the nucleus accumbens.

Fast Independent Component Analysis Algorithm-Based Functional Magnetic Resonance Imaging in the Diagnosis of Changes in Brain Functional Areas of Cerebral Infarction

The aim of this study was to analyze the application value of functional magnetic resonance imaging (FMRI) optimized by the fast independent component correlation algorithm (ICA algorithm) in the diagnosis of brain functional areas in patients with lumbar disc herniation (LDH). An optimized fast ICA algorithm was established based on the ICA algorithm. 50 patients with cerebral infarction were selected as the research objects, and 30 healthy people were selected as the control group. The 50 patients from the observation group were examined by fMRI based on Fast ICA algorithm, while the control group was tested by fMRI based on the routine ICA algorithm. The performances of the two algorithms, the analysis results of the two groups of brain functional areas, cerebral blood flow (CBF), resting state functional connectivity (rsFC), behavioral data, and image data correlation of patients were compared. The results showed that the sensitivity, specificity, and accuracy of Fast ICA algorithm were 97.83%, 89.52%, and 96.27%, respectively, which in the experimental group were greatly better than the control group (88.73%, 72.19%, and 89.72%), showing statistically significant differences (P < 0.05). The maximum Dice coefficient of FAST ICA algorithm was 0.967, and FAST ICA algorithm was better obviously than the traditional ICA algorithm (P < 0.05). The cerebral blood flow of the healthy superior frontal gyrus (SFG) and healthy superior marginal gyrus (SMG) of the observation group with good motor function recovery were 1.02 ± 0.22 and 1.53 ± 0.61, respectively; both indicators showed an increasing trend, and those in the experimental group were much higher in contrast to the control group, showing statistically obvious differences (P < 0.05). Besides, the detection results of cerebral blood flow (CBF) in the healthy SFG and healthy SMG were negatively correlated with the results of connection test B. In summary, the fMRI based on the Fast ICA algorithm showed a good diagnostic effect in the changes of brain functional areas in patients with cerebral infarction. The experimental results showed that the cerebral blood flow in the brain area was related to motor or cognitive function. The results of this study provided a reliable reference for the examination and diagnosis of brain functional areas in patients with cerebral infarction.

Chronic Kidney Disease Associated with Worsening White Matter Disease and Ventricular Enlargement

BACKGROUND

Chronic kidney disease (CKD), a growing public health issue in the elderly, is associated with increased risk of cognitive impairment.

OBJECTIVE

To investigate the mechanisms through which CKD impacts brain health using longitudinal imaging.

METHODS

We identified 97 participants (74 CKD and 23 non-CKD) from the BRINK (BRain IN Kidney Disease), a longitudinal study of CKD with two MRI scans (baseline and 3-year follow-up). We measured the associations between baseline and change in kidney disease biomarkers of estimated glomerular filtration rate (eGFR) and urinary albumin to creatinine ratio (UACR), considered a measure of microvascular inflammation, and imaging outcomes of cortical thickness and ventricular volume from structural MRI, white matter hyperintensities (WMH) volume from FLAIR images, and fractional anisotropy of the corpus callosum (FACC).

RESULTS

There were white matter-specific changes as observed by increased WMH volume and decreased FACC in CKD participants, as well as ventricular volume increase in both CKD and non-CKD groups reflective of aging-related changes. Decline in eGFR was associated with decrease in the FACC, suggesting that subtle early white matter changes due to kidney disease can be captured using DTI. An increase in UACR was associated with increase in ventricular volume.

CONCLUSION

Our results support the role of eGFR as a measure of kidney microvascular disease which is associated with concurrent white matter damage in CKD. Future work is needed to investigate the possible link between endothelial microvascular inflammation (as measured by an increased UACR) and ventricular volume increase.

Diabetes, Albuminuria and the Kidney-Brain Axis

Cognitive decline and kidney disease are significant public health problems that share similar characteristics and risk factors. The pathophysiology of the kidney-brain axis is not completely understood, and studies analysing the relationship between the biomarkers of kidney damage and cognitive impairment show different results. This article focuses on the epidemiological and clinical aspects concerning the association of albuminuria, a marker for endothelial dysfunction and microvascular disease, and cognitive impairment in patients with chronic kidney disease, diabetic kidney disease and end-stage kidney disease. Most studies show a positive relationship between albuminuria and cognitive impairment in all groups, but evidence in type 2 diabetes (T2D) patients is limited. We briefly discuss the mechanisms underlying these associations, such as damage to the microvascular circulation, leading to hypoperfusion and blood pressure fluctuations, as well as increased inflammation and oxidative stress, both in the brain and in the kidneys. Further clinical and epidemiological studies developed to understand the interplay between the kidneys and brain diseases will hopefully lead to a reduction in cognitive impairment in these patients.

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

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

Kidney Function and Cognitive Decline in Older Adults: Examining the Role of Neurodegeneration

BACKGROUND/OBJECTIVES

Cognitive decline associated with impaired kidney function might involve neurodegeneration. Our objectives were to evaluate the longitudinal association between kidney function and cognitive decline in older adults and to assess the involvement of cortical beta-amyloid and hippocampal atrophy (features of Alzheimer's disease (AD)) in this association.

DESIGN

Secondary analysis of the randomized controlled Multidomain Alzheimer Preventive Trial (MAPT).

SETTINGS

Thirteen memory centers (France and Monaco, 2008-2016).

PARTICIPANTS

A total of 1,334 community-dwellers >70 years old without dementia at baseline.

MEASUREMENTS

We estimated glomerular filtration rate (eGFR) from serum creatinine using CKD-Epi equation. Cognition was assessed at baseline, 6, 12, 24, 36, 48, and 60 months using a composite Z-score designed for MAPT. The Clinical Dementia Rating (CDR) score was used to assess cognition and functional independence. We examined the association between eGFR and (1) evolution of the composite cognitive Z-score using mixed-effect models and (2) progression on CDR using Cox models and mixed-effect models. Adjustments were made for age, sex, education, ApoE genotype, cardiovascular risk factors and disease, hippocampal volume (measured with magnetic resonance), and cortical beta-amyloid (measured with positron emission tomography).

RESULTS

Median (IQR) eGFR was 73(60-84) mL/min/1.73 m² . Two hundred sixty-nine participants experienced progression on CDR score during follow-up. eGFR<60 was significantly associated with progression on CDR score (adjusted hazard ratio (aHR) = 1.35, 95% CI 1.01-1.80) and with both the cognitive and functional independence components of CDR, but not with the evolution of the composite cognitive Z-score (adjusted β-coefficient -0.004, 95% CI -0.014; 0.006). Associations were not modified after further adjustment for beta-amyloid (subsample: n = 252) and hippocampal volume (subsample: n = 270).

CONCLUSIONS

We did not find a mild to moderate renal insufficiency to be associated with brain imaging features of AD, and our results do not support the involvement of AD mechanisms in the incidence of cognitive impairment and functional decline associated with chronic kidney disease.

Mechanisms of cognitive dysfunction in CKD

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

Neuropsychological and neuroanatomical phenotype in 17 patients with cystinosis

Background

Cystinosis is a rare autosomal recessive disorder caused by intracellular cystine accumulation. Proximal tubulopathy (Fanconi syndrome) is one of the first signs, leading to end-stage renal disease between the age of 12 and 16. Other symptoms occur later and encompass endocrinopathies, distal myopathy and deterioration of the central nervous system. Treatment with cysteamine if started early can delay the progression of the disease. Little is known about the neurological impairment which occurs later. The goal of the present study was to find a possible neuroanatomical dysmorphic pattern that could help to explain the cognitive profile of cystinosis patients. We also performed a detailed review of the literature on neurocognitive complications associated with cystinosis.

Methods

17 patients (mean age = 17.6 years, [5.4–33.3]) with cystinosis were included in the study. Neuropsychological assessment was performed including intelligence (Intelligence Quotient (IQ) with Wechsler’s scale), memory (Children Memory Scale and Wechsler Memory Scale), visuo-spatial (Rey’s figure test) and visuo-perceptual skills assessments. Structural brain MRI (3 T) was also performed in 16 out of 17 patients, with high resolution 3D T1-weighted, 3D FLAIR and spectroscopy sequences.

Results

Intellectual efficiency was normal in patients with cystinosis (mean Total IQ = 93). However the Perceptual Reasoning Index (mean = 87, [63–109]) was significantly lower than the Verbal Comprehension Index (mean = 100, [59–138], p = 0.003). Memory assessment showed no difference between visual and verbal memory. But the working memory was significantly impaired in comparison with the general memory skills (p = 0.003). Visuospatial skills assessment revealed copy and reproduction scores below the 50th percentile rank in more than 70% of the patients. Brain MRI showed cortical and sub-cortical cerebral atrophy, especially in the parieto-occipital region and FLAIR hypersignals in parietal, occipital and brain stem/cerebellum. Patients with atrophic brain had lower Total IQ scores compared to non-atrophic cystinosis patients.

Conclusions

Patients with cystinosis have a specific neuropsychological and neuroanatomical profile. We suggest performing a systematic neuropsychological assessment in such children aiming at considering adequate management.

Disruption of white matter connectivity in chronic obstructive pulmonary disease

Background

Mild cognitive impairment is a common systemic manifestation of chronic obstructive pulmonary disease (COPD). However, its pathophysiological origins are not understood. Since, cognitive function relies on efficient communication between distributed cortical and subcortical regions, we investigated whether people with COPD have disruption in white matter connectivity.

Methods

Structural networks were constructed for 30 COPD patients (aged 54–84 years, 57% male, FEV₁ 52.5% pred.) and 23 controls (aged 51–81 years, 48% Male). Networks comprised 90 grey matter regions (nodes) interconnected by white mater fibre tracts traced using deterministic tractography (edges). Edges were weighted by the number of streamlines adjusted for a) streamline length and b) end-node volume. White matter connectivity was quantified using global and nodal graph metrics which characterised the networks connection density, connection strength, segregation, integration, nodal influence and small-worldness. Between-group differences in white matter connectivity and within-group associations with cognitive function and disease severity were tested.

Results

COPD patients’ brain networks had significantly lower global connection strength (p = 0.03) and connection density (p = 0.04). There was a trend towards COPD patients having a reduction in nodal connection density and connection strength across the majority of network nodes but this only reached significance for connection density in the right superior temporal gyrus (p = 0.02) and did not survive correction for end-node volume. There were no other significant global or nodal network differences or within-group associations with disease severity or cognitive function.

Conclusion

COPD brain networks show evidence of damage compared to controls with a reduced number and strength of connections. This loss of connectivity was not sufficient to disrupt the overall efficiency of network organisation, suggesting that it has redundant capacity that makes it resilient to damage, which may explain why cognitive dysfunction is not severe. This might also explain why no direct relationships could be found with cognitive measures. Smoking and hypertension are known to have deleterious effects on the brain. These confounding effects could not be excluded.

Prevalence and Risk of Severe Cognitive Impairment in Advanced Chronic Kidney Disease

Background

Our primary goal is to describe the prevalence, severity, and risk of cognitive impairment (CI) by estimated glomerular filtration rate (eGFR, in mL/min/1.73 m2) in a cohort enriched for advanced chronic kidney disease (CKD; eGFR < 45), adjusting for albuminuria, as measured by urine albumin-to-creatinine ratio (UACR, in mg/g). As both eGFR and albuminuria are associated with CI risk in CKD, we also seek to determine the extent that eGFR remains a useful biomarker for risk of CI in those with CKD and concomitant albuminuria.

Methods

Chi-square tests measured the prevalence of severe CI and mild cognitive impairment (MCI) by eGFR level. Logistic regression models and generalized linear models measured risk of CI by eGFR, adjusted for UACR.

Results

Participants were 574 adults with a mean age of 69; 433 with CKD (eGFR < 60, nondialysis) and 141 controls (eGFR ≥ 60). Forty-eight percent of participants with CKD had severe CI or MCI. The prevalence of severe CI was highest (25%) in those with eGFR < 30. eGFR < 30 was only associated with severe CI in those without albuminuria (UACR < 30; OR = 3.3; p = .02) and was not associated with MCI in similar models.

Conclusions

One quarter of those with eGFR < 30 had severe CI. eGFR < 30 was associated with over threefold increased odds of severe CI in those with UACR < 30, but not with UACR > 30, suggesting that eGFR < 30 is a valid biomarker for increased risk of severe CI in those without concomitant albuminuria.

Albuminuria and Cerebral Small Vessel Disease: A Systematic Review and Meta-Analysis

OBJECTIVES

To determine whether albuminuria, a marker of systemic endothelial dysfunction, is associated with cerebral small vessel disease (SVD).

DESIGN

Systematic review following the Meta-analyses Of Observational Studies in Epidemiology guidelines; independent reviewers searched Pubmed/Medline and Scopus, data were extracted, studies were evaluated on quality, and random-effects models were implemented for meta-analysis.

SETTING

Observational studies quantifying an association between albuminuria and cerebral SVD.

PARTICIPANTS

Adults.

MEASUREMENTS

Magnetic resonance imaging-defined markers of cerebral SVD; white matter hyperintensities (WMHs), lacunar infarcts (LIs), cerebral microbleeds (CMBs), and enlarged perivascular spaces (EPVSs).

RESULTS

Of 31 eligible studies comprising 23,056 participants identified, 27 were included in quantitative synthesis. Most of the studies were cross-sectional and of varying quality. On meta-analysis, albuminuria was associated with greater risk of WMHs (odds ratio (OR) = 1.70, 95% confidence interval (CI) = 1.43-2.01; 13,548 subjects, 2,665 cases; I²  = 44%), LIs (OR = 1.86, 95% CI = 1.49-2.31; 12,857 subjects, 998 cases; I²  = 27%), CMBs (OR = 1.78, 95% CI = 1.30-2.43; 7,645 subjects; 748 cases; I²  = 39%), and EPVSs in the basal ganglia (OR = 1.78, 95% CI = 1.02-3.09; 1,388 subjects, 399 cases; I²  = 37%) and centrum semiovale (OR = 3.27, 95% CI = 1.49-7.20; 1,146 subjects, 460 cases; I²  = 66%). Sensitivity analyses for high-quality and general population studies, but also studies controlling for cardiovascular disease risk factors and renal function, confirmed the findings and resolved the moderate heterogeneity and publication bias that were evident in the overall analyses.

CONCLUSION

Albuminuria is independently associated with cerebral SVD, indicating shared microvascular pathology in the kidney and the brain. The results suggest that peripheral systemic microvascular disease biomarkers could be useful in the evaluation of brain microvascular damage.

Reduced White Matter Integrity With Cognitive Impairments in End Stage Renal Disease

Background: End-stage renal disease (ESRD) is a serious public health problem, which can often lead to multiorgan dysfunction, such as cerebrovascular disease and cognitive damage. It is essential to understand cognitive impairment in patients with ESRD to develop better ESRD treatment and prevent further cognitive impairment. Cognitive impairment is believed to be related to structural abnormalities in the brain. Purpose: To investigate white matter microstructural abnormalities in patients with ESRD using TBSS analysis of DTI and to explore the possible mechanisms underlying the impaired cognitive function. Materials and Methods: A TBSS analysis of DTI data was to investigate the microstructural changes in their WM over the whole brain. We chose the white matter tracts or regions with significantly reduced FA as the regions of interest (ROIs), Pearson's correlations were performed between clinical indicators (Mini-Mental State Examination (MMSE), digit span task scores, serum creatinine, blood urea nitrogen and hemodialysis duration) and the mean FA value of the ROIs in the ESRD patients. Results: Lower FA and higher MD, AD and RD values were observed in widespread and symmetrical WM in ESRD patients than healthy controls (HCs), Pearson correlation analysis revealed a significantly positive correlation between the Mini-Mental State Examination (MMSE) scores and FA values in the right corona radiata and left anterior thalamic radiation (ATR) and demonstrated a significantly negative correlation between FA values and the serum creatinine and blood urea nitrogen in the ATR (P < 0.01) in addition, digit span task scores positively correlate with the FA value in the left anterior rather than in the corona radiata. No cluster survived when we adopted the False Discovery Rate (FDR) correction to multiple comparisons. Conclusion: Our study indicate widespread impairment of the white matter in ESRD patients. Damage to the thalamic radiation and corona radiata may affect cognitive function in ESRD patients, the reduced integrity of ATR may tend to affect the working memory while the damage to the corona radiata may involve the executive function impaired in ESRD patients. The accumulation of serum creatinine and blood urea nitrogen may contribute to the WM impairment.

Associations of Early Kidney Disease With Brain Magnetic Resonance Imaging and Cognitive Function in African Americans With Type 2 Diabetes Mellitus

BACKGROUND

Relationships between early kidney disease, neurocognitive function, and brain anatomy are poorly defined in African Americans with type 2 diabetes mellitus (T2DM).

STUDY DESIGN

Cross-sectional associations were assessed between cerebral anatomy and cognitive performance with estimated glomerular filtration rate (eGFR) and urine albumin-creatinine ratio (UACR) in African Americans with T2DM.

SETTING & PARTICIPANTS

African Americans with cognitive testing and cerebral magnetic resonance imaging (MRI) in the African American-Diabetes Heart Study Memory in Diabetes (AA-DHS MIND; n=512; 480 with MRI) and Action to Control Cardiovascular Risk in Diabetes (ACCORD) MIND (n=484; 104 with MRI) studies.

PREDICTORS

eGFR (CKD-EPI creatinine equation), spot UACR.

MEASUREMENTS

MRI-based cerebral white matter volume (WMV), gray matter volume (GMV), and white matter lesion volume; cognitive performance (Mini-Mental State Examination, Digit Symbol Coding, Stroop Test, and Rey Auditory Verbal Learning Test). Multivariable models adjusted for age, sex, body mass index, scanner, intracranial volume, education, diabetes duration, hemoglobin A1c concentration, low-density lipoprotein cholesterol concentration, smoking, hypertension, and cardiovascular disease were used to test for associations between kidney phenotypes and the brain in each study; a meta-analysis was performed.

RESULTS

Mean participant age was 60.1±7.9 (SD) years; diabetes duration, 12.1±7.7 years; hemoglobin A1c concentration, 8.3%±1.7%; eGFR, 88.7±21.6mL/min/1.73m2; and UACR, 119.2±336.4mg/g. In the fully adjusted meta-analysis, higher GMV associated with lower UACR (P<0.05), with a trend toward association with higher eGFR. Higher white matter lesion volume was associated with higher UACR (P<0.05) and lower eGFR (P<0.001). WMV was not associated with either kidney parameter. Higher UACR was associated with lower Digit Symbol Coding performance (P<0.001) and a trend toward association with higher Stroop interference; eGFR was not associated with cognitive tests.

LIMITATIONS

Cross-sectional; single UACR measurement.

CONCLUSIONS

In African Americans with T2DM, mildly high UACR and mildly low eGFR were associated with smaller GMV and increased white matter lesion volume. UACR was associated with poorer processing speed and working memory.