Gray matter volume and white matter lesions in chronic kidney disease: exploring the association with depressive symptoms

Indoxyl Sulfate Administration during Pregnancy Contributes to Renal Injury and Increased Blood-Brain Barrier Permeability

Rates of pregnancy-related acute kidney injury (PR-AKI) have increased in the U.S over the past two decades, but how PR-AKI affects the blood-brain barrier (BBB) is understudied. AKI is associated with increased amounts of uremic toxins, like indoxyl sulfate (I.S), whose chronic administration leads to BBB and cognitive changes. This study's objective was to determine if (1) PR-AKI increases I.S and (2) if administration of I.S during pregnancy elicits renal injury and/or increases BBB permeability. From gestational day (GD) 11 to GD19, Sprague Dawley rats were given either 100 or 200 mg/kg body-weight dose of I.S. PR-AKI was induced on GD18 via 45 min bilateral renal ischemic reperfusion surgery. On GD18, metabolic cage metrics and metabolic waste was collected and on GD19 blood pressure, and BBB permeability (by Evan's Blue infusion) were measured. I.S and creatinine were measured in both urine and circulation, respectively. One-way ANOVA or student t-tests were performed using GraphPad Prism with a p < 0.05 significance. I.S and PR-AKI led to oliguria. I.S administration led to increased BBB permeability compared to normal pregnant and PR-AKI animals. These results suggest that I.S administration during pregnancy leads to increased BBB permeability and evidence of renal injury comparable to PR-AKI animals.

An Investigation of the Relationship Between Carotid Artery Stenosis and White Matter Hyperintensities

Introduction White matter hyperintensities (WMHs) are frequently detected on magnetic resonance imaging (MRI) with age. Although the etiology of WMH has not been fully explained, it was reported to be associated with internal carotid artery (ICA) stenosis as well as small vessel diseases. The number and volume of these lesions might increase in cases of internal carotid artery (ICA) stenosis. The present study aimed to calculate the localization and volumes of white matter lesions in the VolBrain Program and investigate the relationship between age and sex in patients with symptomatic and asymptomatic internal carotid artery stenosis. Methods MRI scans of patients with carotid stenosis with T1-weighted and fluid-attenuated inversion recovery (FLAIR) sequences were performed retrospectively for the present study, which had a retrospective design. The patients were divided into two groups (<70% and ≥70%) because endovascular intervention was considered in patients with asymptomatic stenosis over 70%. Digital subtraction angiography was used to detect carotid artery stenosis. They were also divided into four groups. According to laterality and degree of stenosis, ICA stenosis was separated as those with <70% stenosis on both sides (group 1), right side ICA <70%, left side ≥70% stenosis (group 2), right side ICA ≥70%, left side <70% stenosis (group 3), and ≥70% stenosis on both sides (group 4). A total of 102 patient images were selected that met the inclusion criteria. The measurements of white matter lesion volumes were made using the LesionBrain application in the VolBrain Program. Results The MRI of 82 patients (mean age: 65.55 ± 9.28 years), 28 females and 54 males, were used in the present study. According to LesionBrain Analysis, the total WMH volume was seen in the first and third groups at most. When analyzed in regional terms, stenosis was mostly detected in the first and third groups in the periventricular region. WMH volume was less in all areas in group 4. When examined according to the number of lesions, the most lesions were detected in the third group in the juxtacortical region. When the difference between the groups was examined, a significant difference was detected only in the volume change in the deep white region (p=0.011). No significant differences were found between WMH volumes and age and gender (p>0.05). Conclusion Stenosis of the external internal carotid artery might cause hypoperfusion and silent embolization in the brain. As a result, as well as pathological conditions in cortical areas, ischemic areas in the white matter might also cause cognitive disorders.

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.

Segmental Abnormalities of White Matter Microstructure in End-Stage Renal Disease Patients: An Automated Fiber Quantification Tractography Study

Background and Purpose: End-stage renal disease (ESRD) results in extensive white matter abnormalities, but the specific damage segment cannot be identified. This study aimed to determine the segmental abnormalities of white matter microstructure in ESRD and its relationship with cognitive and renal function indicators. Methods: Eighteen ESRD patients and 19 healthy controls (HCs) were prospectively recruited. All participants underwent DTI and clinical assessments. Automatic fiber quantification (AFQ) was applied to generate bundle profiles along 16 main white matter tracts. We compared the DTI parameters between groups. Besides, we used partial correlation and multiple linear regression analyses to explore the associations between white matter integrity and cognitive performance as well as renal function indicators. Results: In the global tract level, compared to HCs, ESRD patients had greater MD, AD, and RD values and lower FA value in several fibers (P < 0.05, FDR correction). In the point-wise level, extensive damage existed in specific locations of different fiber tracts, particularly in the left hemisphere (P < 0.05, FDR correction). Among these tracts, the mean AD values of the left cingulum cingulate correlated negatively with MoCA score. Urea and UA level were independent predictors of the AD value of superior component of the left corticospinal. Besides, urea level was the independent predictors of mean MD value of left anterior thalamic radiation (ATR). Conclusion: White matter fiber tract damage in ESRD patients may be characterized by abnormalities in its specific location, especially in the left hemisphere. Aberrational specific located fibers were related to cognitive impairment and renal dysfunction.

Prevalence of white matter hyperintensities increases with age

White matter hyperintensities (WMHs) that arise with age and/or atherosclerosis constitute a heterogeneous disorder in the white matter of the brain. However, the relationship between age-related risk factors and the prevalence of WMHs is still obscure. More clinical data is needed to confirm the relationship between age and the prevalence of WMHs. We collected 836 patients, who were treated in the Renmin Hospital, Hubei University of Medicine, China from January 2015 to February 2016, for a case-controlled retrospective analysis. According to T2-weighted magnetic resonance imaging results, all patients were divided into a WMHs group (n = 333) and a non-WMHs group (n = 503). The WMHs group contained 159 males and 174 females. The prevalence of WMHs increased with age and was associated with age-related risk factors, such as cardiovascular diseases, smoking, drinking, diabetes, hypertension and history of cerebral infarction. There was no significant difference in sex, education level, hyperlipidemia and hyperhomocysteinemia among the different age ranges. These findings confirm that age is an independent risk factor for the prevalence and severity of WMHs. The age-related risk factors enhance the occurrence of WMHs.

Reduced estimated glomerular filtration rate is associated with depressive symptoms in elder Chinese: A population-based cross-sectional study

Depression has been associated with chronic kidney disease (CKD). However, few studies have examined whether such association exist in average older individuals with mild to moderate reduced kidney function. This study investigated the association between reduced estimated glomerular filtration rate (eGFR) and depressive symptoms in Chinese older population. Data was obtained from the Rugao Longevity and Ageing Study conducted in Jiangsu, China. Cockcroft-Gault (CG) equation was used to calculate eGFR. Depressive symptoms were defined by using Chinese version of 15-item Geriatric Depression Scale (GDS-15). The prevalence of depressive symptoms was 9.9% among 1749 elderly participants aged 70-84 years. Many elderly had a mild to moderate reduced renal function (84.3%, 57.1% in stage2 CKD and 27.2% in stage3 CKD, respectively). The overall GDS-15 score showed an upward trend with decreasing of eGFR (p < 0.05). Furthermore, a moderate decline of eGFR (in stage3 CKD) was significantly associated with increased risk of depressive symptoms even after adjusting for confounders (OR = 1.71, 95%CI 1.05-2.77, P = 0.03). Elder had no depressive symptoms if their eGFR was normal or mildly reduced. Our results suggest that a moderate decrease of eGFR (stage3 CKD) was independently associated with depressive symptoms in general Chinese elderly.