Ageing meets kidney disease

Effect of dietary protein intake on cognitive function in the elderly with chronic kidney disease: analysis of the National Health and Nutrition Examination Survey 2011-2014

BACKGROUND

Cognitive dysfunction is prevalent among the elderly diagnosed with chronic kidney disease (CKD). Low protein diets are used for retarding the progression of CKD in clinical practice. Nonetheless, the impact of dietary protein consumption on cognitive function in this population remains uncertain.

METHODS

We recruited 2306 participants (≥60 years) from 2011 to 2014 National Health and Nutrition Examination Survey (NHANES). 24-h dietary recall questionnaire was utilized to evaluate protein intake. Cognitive function was measured using the Consortium to Establish a Registry for Alzheimer's Disease (CERAD), Animal Fluency Test (AFT), and Digit Symbol Substitution Test (DSST). Participants' characteristics were analyzed, and the interaction between protein consumption and CKD on cognitive impairment were analyzed using a logistic regression model.

RESULTS

We divided participants into three groups based on CKD stages: no CKD, CKD stage G1 to G2 (19%), and CKD stage G3 to G5 (18%). The average protein intake was 0.97 g/(kg·d). In the higher protein intake group, CKD stages G1 to G2 elevated the risk of immediate memory impairment (OR: 2.441, 95% Cl: 1.161-5.132 for protein consumption in 1.0-1.2g/(kg·d); OR: 2.225, 95% Cl: 1.015-4.876 for protein consumption in >1.2 g/(kg·d)). However, no similar resuts were observed in the lower protein intake group. In addition, the interaction between CKD status and protein intake on immediate memory was statistically significant (p = .041).

CONCLUSION

A higher probability of cognitive impairment in the elderly with early-stage CKD may be linked to higher protein intake. Low protein diets may be a potential strategy to release cognitive impairment in the elderly with early-stage CKD.

Inverse association between caffeine intake and albuminuria in US adults: an analysis of NHANES 2005-2016

OBJECTIVES

Albuminuria is a significant biomarker of various kidney diseases and is associated with renal outcome. Recently, caffeine intake has shown potential renoprotective effects. However, the relationship between caffeine intake and albuminuria remains profoundly elusive.

METHODS

We conducted a cross-sectional study aimed to explore the association between caffeine intake and albuminuria in the American adult population using the data acquired from the National Health and Nutrition Examination Survey (NHANES) 2005-2016. Caffeine intake was assessed by 24-h dietary recalls, and albuminuria was assessed by albumin-to-creatinine ratio. Multivariate logistic regression was performed to explore the independent association between caffeine intake and albuminuria. Subgroup analysis and interaction tests were also conducted.

RESULTS

Among 23,060 participants, 11.8% of the individuals exhibited albuminuria, and the prevalence of albuminuria decreased with higher caffeine intake tertiles (Tertile 1: 13%; Tertile 2: 11.9%; Tertile 3: 10.5%; P < 0.001). After adjusted potential confounders, the results of logistic regression indicated that a higher caffeine intake was associated with a decreased risk of albuminuria (OR = 0.903; 95% CI: 0.84, 0.97; P = 0.007), especially in females and the participants aged <60 years and chronic kidney disease stage II.

CONCLUSION

The present study first indicated an inverse correlation between caffeine intake and albuminuria, which further confirmed the potentially protective effects of caffeine on the kidney.

Peripheral inflammation and neurocognitive impairment: correlations, underlying mechanisms, and therapeutic implications

Cognitive impairments, such as learning and memory deficits, may occur in susceptible populations including the elderly and patients who are chronically ill or have experienced stressful events, including surgery, infection, and trauma. Accumulating lines of evidence suggested that peripheral inflammation featured by the recruitment of peripheral immune cells and the release of pro-inflammatory cytokines may be activated during aging and these conditions, participating in peripheral immune system-brain communication. Lots of progress has been achieved in deciphering the core bridging mechanism connecting peripheral inflammation and cognitive impairments, which may be helpful in developing early diagnosis, prognosis evaluation, and prevention methods based on peripheral blood circulation system sampling and intervention. In this review, we summarized the evolving evidence on the prevalence of peripheral inflammation-associated neurocognitive impairments and discussed the research advances in the underlying mechanisms. We also highlighted the prevention and treatment strategies against peripheral inflammation-associated cognitive dysfunction.

Association of nocturia of self-report with estimated glomerular filtration rate: a cross-sectional study from the NHANES 2005-2018

Nocturia is a manifestation of systemic diseases, in which chronic kidney disease (CKD) is an independent predictor of nocturia due to its osmotic diuretic mechanism. However, to our knowledge, previous studies have not examined the association between nocturia and estimated glomerular filtration rate (eGFR). The purpose of this study was to assess the association between nocturia exposure and eGFR in the general US population. This study presents a cross-sectional analysis of the general US population enrolled in the National Health and Nutrition Examination Survey (NHANES) from 2005 to 2018. To account for potential confounding factors, linear regression analysis was conducted to investigate the association between nocturia and eGFR. Stratified analyses and interaction tests were employed to examine the variables of interest. Additionally, sensitivity analyses were conducted across diverse populations. A total of 12,265 individuals were included in the study. After controlling for confounding factors, the results of the linear regression analysis indicated that a single increase in nocturnal voiding frequency was associated with a decrease in eGFR by 2.0 mL/min/1.73 m2. In comparison to individuals with a nocturnal urinary frequency of 0, those who voided 1, 2, 3, 4, and ≥ 5 times at night experienced a decrease in eGFR by 3.1, 5.4, 6.4, 8.6 and 4.0 mL/min/1.73 m2, respectively. Nocturia was found to be associated with a decreased eGFR of 4 mL/min/1.73 m2 when compared to individuals without nocturia. The sensitivity analysis yielded consistent findings regarding the association between nocturia and eGFR in both CKD and non-CKD populations, as well as in hypertensive and non-hypertensive populations. Nevertheless, inconsistent conclusions were observed across various prognostic risk populations within the CKD context. The presence of nocturia and heightened frequency of nocturnal urination have been found to be associated with a decline in eGFR.

Telomere Attrition in Chronic Kidney Diseases

Telomeres are dynamic DNA nucleoprotein structures located at the end of chromosomes where they maintain genomic stability. Due to the end replication problem, telomeres shorten with each cell division. Critically short telomeres trigger cellular senescence, which contributes to various degenerative and age-related diseases, including chronic kidney diseases (CKDs). Additionally, other factors such as oxidative stress may also contribute to accelerated telomere shortening. Indeed, telomeres are highly susceptible to oxidative damage due to their high guanine content. Here, we provide a comprehensive review of studies examining telomere length (TL) in CKDs to highlight the association between TL and the development and progression of CKDs in humans. We then focus on studies investigating TL in patients receiving kidney replacement therapy. The mechanisms of the relationship between TL and CKD are not fully understood, but a shorter TL has been associated with decreased kidney function and the progression of nephropathy. Interestingly, telomere lengthening has been observed in some patients in longitudinal studies. Hemodialysis has been shown to accelerate telomere erosion, whereas the uremic milieu is not reversed even in kidney transplantation patients. Overall, this review aims to provide insights into the biological significance of telomere attrition in the pathophysiology of kidney disease, which may contribute to the development of new strategies for the management of patients with CKDs.

Association between Serum Soluble α-Klotho and Urinary Albumin Excretion in Middle-Aged and Older US Adults: NHANES 2007-2016

(1) Background: Preclinical and clinical studies on the anti-aging effect of α-Klotho are emerging. Urinary albumin excretion (UAE) is a well-known biomarker of kidney injury and generalized damage in the cardiovascular system. However, the potential relationship between α-Klotho and UAE is limited and controversial. This study aimed to quantify this relationship in the general middle-aged and elderly population from the National Health and Nutrition Survey (NHANES) 2007-2016. (2) Methods: Serum α-Klotho was measured by enzyme-linked immunosorbent assay. UAE was assessed by the albumin-to-creatinine ratio (ACR). After adjusting for several confounding variables, the relationship between α-Klotho and ACR was analyzed by weighted multivariable logistic regression, subgroup analysis, and interaction tests. A generalized additive model (GAM) with smooth functions using the two-piecewise linear regression model was used to examine the potential nonlinear relationship between α-Klotho and ACR. (3) Results: Among 13,584 participants aged 40-79 years, we observed an independent and significant negative correlation between α-Klotho and ACR (β = -12.22; 95% CI, -23.91, -0.53, p = 0.0448) by multivariable logistic regression analysis, especially in those with age ≥ 60 years, pulse pressure (PP) ≥ 60 mmHg, hypertension or diabetes. We further discovered the nonlinear relationship between α-Klotho and ACR by GAM, revealing the first negative and then positive correlations with an inflection point of 9.91 pg/mL between α-Klotho and ACR. (4) Conclusions: A dose-response relationship between α-Klotho and ACR was demonstrated, and the negative correlation therein indicated that α-Klotho has potential as a serum marker and prophylactic or therapeutic agent despite its metabolic and effective mechanisms needing to be further explored.