[Cognitive impairment and chronic kidney disease: which links?]

Neuropathy - Exponent of Accelerated Involution in Uremia: The Role of Carbamylation

Premature loss of functional integrity of the nervous system in chronic renal failure (CRF) as a consequence of persistent biological activities of the general uremic milieu is almost identical to its structural and functional involution during the process of physiological ageing, but disproportionate and independent of chronological age. In the hyperuremic status of CRF (urea - carbamide), forced carbamylation, as a non-enzymatic post-translational modification (NEPTM) of proteins and amino acids, by changing their biological properties and decreasing proteolysis capacity, represents pathogenetic potential of intensified molecular ageing and accelerated, pathological involution. Physiological predisposition and the exposure of neuropathy before complications of other organs and organ systems in CRF, due to the simultaneous and mutually pathogenetically related uremic lesion and the tissue and vascular segment of the nervous system, direct interest towards proteomic analytical techniques of quantification of carbamylated products as biomarkers of uremic neurotoxicity. Hypothetically, identical to the already established applications of other NEPTM products in practice, they have the potential of clinical methodology in the evaluation of uremic neuropathy and its contribution to the general prediction, but also to the change of the conventional CRF classification. In addition, the identification and therapeutic control of the substrate of accelerated involution, responsible for the amplification of not only neurological but also general degenerative processes in CRF, is attractive in the context of the well-known attitude towards aging.

Uremic Toxic Blood-Brain Barrier Disruption Mediated by AhR Activation Leads to Cognitive Impairment during Experimental Renal Dysfunction

BACKGROUND

Uremic toxicity may play a role in the elevated risk of developing cognitive impairment found among patients with CKD. Some uremic toxins, like indoxyl sulfate, are agonists of the transcription factor aryl hydrocarbon receptor (AhR), which is widely expressed in the central nervous system and which we previously identified as the receptor of indoxyl sulfate in endothelial cells.

METHODS

To characterize involvement of uremic toxins in cerebral and neurobehavioral abnormalities in three rat models of CKD, we induced CKD in rats by an adenine-rich diet or by 5/6 nephrectomy; we also used AhR^-/- knockout mice overloaded with indoxyl sulfate in drinking water. We assessed neurologic deficits by neurobehavioral tests and blood-brain barrier disruption by SPECT/CT imaging after injection of ^99mTc-DTPA, an imaging marker of blood-brain barrier permeability.

RESULTS

In CKD rats, we found cognitive impairment in the novel object recognition test, the object location task, and social memory tests and an increase of blood-brain barrier permeability associated with renal dysfunction. We found a significant correlation between ^99mTc-DTPA content in brain and both the discrimination index in the novel object recognition test and indoxyl sulfate concentrations in serum. When we added indoxyl sulfate to the drinking water of rats fed an adenine-rich diet, we found an increase in indoxyl sulfate concentrations in serum associated with a stronger impairment in cognition and a higher permeability of the blood-brain barrier. In addition, non-CKD AhR^-/- knockout mice were protected against indoxyl sulfate-induced blood-brain barrier disruption and cognitive impairment.

CONCLUSIONS

AhR activation by indoxyl sulfate, a uremic toxin, leads to blood-brain barrier disruption associated with cognitive impairment in animal models of CKD.

Age, preoperative higher serum cortisol levels, and lower serum acetylcholine levels predict delirium after percutaneous coronary intervention in acute coronary syndrome patients accompanied with renal dysfunction

BACKGROUND

The objective of the study is to investigate the incidence and risk factors of delirium after percutaneous coronary intervention (PCI) in acute coronary syndrome (ACS) patients accompanied with renal dysfunction.

MATERIALS AND METHODS

This was a prospective and cohort study, performed in a medical center from July 2014 to June 2017, which enrolled ACS patients accompanied with renal dysfunction who were treated with PCI. Univariate analysis and binary logistic regression analysis was used to determine the incidence and risk factors of delirium.

RESULTS

Data were analyzed from 119 patients. The 7-day incidence of delirium after PCI in ACS patients accompanied with renal dysfunction was 15.97% (n = 19/119). The binary logistic regression analysis results indicate that age (odd ratio [OR] 1.463; 95% confidence interval [CI] 1.070-2.001; P = 0.017), preoperative higher serum cortisol (COR) (OR 1.025; 95% CI 1.002-1.048; P = 0.030), and lower serum acetylcholine (Ach) (OR 0.965; 95% CI 0.937-0.993; P = 0.016) were significant differences in delirium and nondelirium groups.

CONCLUSIONS

Age, preoperative higher serum COR levels, and lower serum Ach levels were independent risk factors for delirium after PCI in ACS patients accompanied with renal dysfunction.

Cognitive impairment of patients with chronic renal disease on hemodialysis and its relationship with sociodemographic and clinical characteristics

Cognitive impairment and dementia commonly occur in individuals with chronic kidney disease, especially in advanced stages, but are still poorly diagnosed.

OBJECTIVE

To evaluate the cognitive ability of patients with chronic kidney disease on hemodialysis and its relationship with sociodemographic and clinical characteristics.

METHODS

A cross-sectional study was carried out in a Renal Replacement Therapy Unit in the interior of the State of São Paulo involving 99 patients. The data were collected through an individual interview, using the Sociodemographic and Clinical Characterization questionnaires and the Addenbrooke's Cognitive Examination - Revised (ACE-R) questionnaire.

RESULTS

Participants were predominantly male, with a mean age of 54.68 years. The mean ACE-R score was 64.26 points, and 76.76% of patients had lower-than-expected scores, suggesting the presence of cognitive impairment. A moderate, negative correlation was found between total score on the ACE-R and age (r= -0.38, p≤0.001), a moderate positive correlation with years of education (r=0.52, p≤0.001), and a weak positive correlation of total score with hemodialysis time (r=0.26, p≤0.001).

CONCLUSION

A relationship was found between cognitive ability and age, years of education and hemodialysis time, suggesting that individuals who were older, had less education and longer hemodialysis time presented greater cognitive impairment.

Cognitive Impairment in Chronic Kidney Disease: Vascular Milieu and the Potential Therapeutic Role of Exercise

Chronic kidney disease (CKD) is considered a model of accelerated aging. More specifically, CKD leads to reduced physical functioning and increased frailty, increased vascular dysfunction, vascular calcification and arterial stiffness, high levels of systemic inflammation, and oxidative stress, as well as increased cognitive impairment. Increasing evidence suggests that the cognitive impairment associated with CKD may be related to cerebral small vessel disease and overall impairment in white matter integrity. The triad of poor physical function, vascular dysfunction, and cognitive impairment places patients living with CKD at an increased risk for loss of independence, poor health-related quality of life, morbidity, and mortality. The purpose of this review is to discuss the available evidence of cerebrovascular-renal axis and its interconnection with early and accelerated cognitive impairment in patients with CKD and the plausible role of exercise as a therapeutic modality. Understanding the cerebrovascular-renal axis pathophysiological link and its interconnection with physical function is important for clinicians in order to minimize the risk of loss of independence and improve quality of life in patients with CKD.