Role of Vitamin D in Cognitive Function in Chronic Kidney Disease

Prevalence of cognitive impairment and its predictors among chronic kidney disease patients: A systematic review and meta-analysis

BACKGROUND

Cognitive impairment (CI) is common among patients with chronic kidney disease (CKD), and is associated with a poor prognosis. We assessed the prevalence and associated factors of CI in patients with CKD.

METHODS

A systematic review and meta-analysis were conducted by searching PubMed, Embase, and the Web of Science through December 1, 2023. Random effects models were performed with subgroup analyses to further explore the heterogeneity.

RESULTS

50 studies involving 25,289 CKD patients were included. The overall prevalence of CI was 40% (95% confidence interval 33-46). The pooled prevalence of CI was relatively higher in CKD patients from Africa (58%), Asia (44%) and America (37%). Attention and executive dysfunction appeared to be the most common manifestations. The prevalence of CI was higher among patients with hemodialysis (53%) and peritoneal dialysis (39%) than those without dialysis (32%) and post-kidney transplanted (26%). In addition, advanced age, the presence of diabetes and hypertension might increase the risk of CI in CKD patients.

CONCLUSIONS

People with CKD have a high prevalence of CI, especially in patients with hemodialysis. An early and comprehensive screening for CI in CKD patients is needed to improve clinical outcomes.

TRIAL REGISTRATION

Registration number: PROSPERO (CRD42023412864).

Hypovitaminosis D and its relationship with nutritional status and quality of life in patients undergoing haemodialysis

Introduction

Objective: to assess the prevalence of hypovitaminosis D in patients undergoing haemodialysis (HD) and to determine its relationship with nutritional status and quality of life (QoL). Material and methods: 120 patients were included in the study. The Malnutrition-Inflammation Score (MIS) was used to detect nutritional risk. QoL was evaluated by Kidney Disease Quality of Life version 1.2 (KDQOL-SF). Patients were stratified into three groups according to their vitamin D status: sufficiency (≥ 30 ng/dl), insufficiency (29-10 ng/dl) and deficiency (< 10 ng/dl). Results: hypovitaminosis D was detected in 71 % of the patients studied. Multiple linear regression analysis showed that vitamin-D deficiency was the most significant predictor of low KDQOL-SF scores. It explained 21 % of the variance in the Kidney Disease Component Summary, 27 % of that in the Physical Component Summary, and 22 % of that in the Mental Component Summary. Multiple logistic regression analysis showed that only vitamin-D deficiency was significantly associated with malnutrition (OR, 14.6, p < 0.001). Conclusion: HD patients frequently present with hypovitaminosis D. There is a significant correlation between vitamin-D deficiency, poorer nutritional status, and worse QoL in dialysed patients.

Chronic Kidney Disease and Cognitive Impairment: The Kidney-Brain Axis

Background

Cognitive impairment, increasingly recognized as a major social burden, is commonly found in chronic kidney disease (CKD) patients.

Summary

Vascular damage, uremic toxicity, oxidative stress, and peripheral/central inflammation induced by CKD might be involved in brain lesions and ultimately result in cognitive decline. Uncovering the pathophysiology of CKD-associated cognitive impairment is important for early diagnosis and prevention, which undoubtedly prompts innovative pharmacological treatments.

Key Messages

Here, we sequentially review the current understanding and advances in the epidemiology, risk factors, and pathological mechanisms of cognitive impairment in CKD. Furthermore, we summarize the currently available therapeutic strategies for cognitive impairment in CKD.

Association between Cerebral Oxygenation, as Evaluated with Near-Infrared Spectroscopy, and Cognitive Function in Patients Undergoing Hemodialysis

INTRODUCTION

The prevalence of cognitive impairment in patients undergoing hemodialysis (HD) is higher than that in healthy controls. To date, studies on the association between cognitive function and cerebral oxygenation in these patients are limited. Therefore, in this study, we aimed to cross-sectionally investigate the association between cognitive assessment scores and clinical factors, including cerebral oxygenation, in patients undergoing HD.

METHODS

In this observational study, 193 HD patients were included. Cerebral regional oxygen saturation (rSO2) was monitored using an INVOS 5,100c oxygen saturation monitor. Poor cognition was defined as a Mini-Mental State Examination (MMSE) score ≤23. We analyzed the association between MMSE score and clinical factors, including cerebral rSO2.

RESULTS

MMSE score in HD patients included in this study was 26.8 ± 3.3. There were 164 patients (85%) with MMSE score ≥24 and 29 patients (15%) with an MMSE score ≤23. In the patients with MMSE score ≥24, cerebral rSO2 (53.8% ± 8.3%) was significantly higher than that in patients with MMSE score ≤23 (49.5% ± 9.8%; p = 0.013). Multivariable linear regression analysis was performed using the following confounding factors: age, mean blood pressure, cerebral rSO2, HD duration, ultrafiltration rate, hemoglobin, serum Cr, serum calcium, serum phosphate, total cholesterol, high-density lipoprotein cholesterol levels, serum albumin, presence of diabetes mellitus or chronic glomerulonephritis, history of comorbid cardiovascular or cerebrovascular disease, and use of renin-angiotensin-aldosterone system inhibitors or vitamin D analogs. MMSE score was independently and significantly associated with age (standardized coefficient: -0.244) and cerebral rSO2 (standardized coefficient: 0.180).

CONCLUSIONS

MMSE score was independently associated with age (negative effect) and cerebral rSO2 (positive effect) in this cross-sectional study. Further prospective studies are needed to clarify whether maintaining cerebral oxygenation prevents the deterioration of cognitive function in patients undergoing HD.

Low vitamin D levels are associated with cognitive impairment in patients with Hashimoto thyroiditis

BACKGROUND

Cognitive impairment is commonly observed in patients with Hashimoto thyroiditis (HT). Low levels of vitamin D have been correlated with cognitive impairment in non-HT population. We examined the association of vitamin D levels with cognitive impairment in patients with HT.

METHODS

We recruited 194 patients with HT and 200 healthy volunteers. Levels of serum 25-hydroxyvitamin D (25(OH)D) were measured using a competitive protein-binding assay. Cognitive funtion was assessed using Montreal Cognitive Assessment score (MoCA). Subjects with a MoCA scores < 26 are considered as having mild cognitive impairment (MCI). Multivariate analysis was performed using logistic regression models.

RESULTS

Fifty-five HT patients (28.4%) were diagnosed as having MCI. Patients with MCI had significantly lower 25(OH)D levels when compared with patients without MCI (33.9 ± 6.2 vs. 44.3 ± 9.6 nmol/L, P < 0.001). Significant differences in 25(OH)D quartiles of HT patients were observed between the patients with MCI and the patients without MCI (P < 0.001). In multivariate analyses, serum 25(OH)D levels (≤ 34.0 and ≥ 47.1 nmol/L) were significantly associated with cognitive impairment in patients with HT (OR 6.279, 95% CI 2.673-14.834, P < 0.001; OR 0.061, 95% CI 0.008-0.491, P = 0.009, respectively).

CONCLUSION

Our results demonstrate an important association between serum vitamin D levels and cognitive impairment in patients with HT.

Association of cerebral oxygenation with estimated glomerular filtration rate and cognitive function in chronic kidney disease patients without dialysis therapy

Background

A decline in estimated glomerular filtration rate (eGFR) is reportedly associated with increased prevalence rates of cognitive impairment. However, data concerning the association between the cerebral saturation of oxygen (rSO₂) and cognitive function of patients with chronic kidney disease (CKD) is limited. This study aimed to (i) elucidate the clinical factors associating with cerebral rSO₂ and (ii) investigate the association between cerebral rSO2 and cognitive assessment in CKD patients.

Methods

A total of 40 CKD patients not requiring dialysis (26 men and 14 women; mean age, 61.0 ± 2.7 years) were recruited. The numbers of patients at each CKD stage were as follows: G1, 5; G2, 8; G3a, 6; G3b, 5; G4, 11; and G5, 5. Cerebral rSO₂ was monitored at the forehead using the oxygen saturation monitor INVOS 5100C. The cognitive function of each patient was confirmed using the Mini-Mental State Examination (MMSE).

Results

Cerebral rSO₂ levels were significantly higher in CKD patients than in hemodialysis patients (63.8 ± 1.5% vs. 44.9 ± 2.2%, p < 0.001). Multiple regression analysis showed that cerebral rSO₂ was independently associated with eGFR (standardized coefficient: 0.530), serum albumin concentration (standardized coefficient: 0.365), and serum sodium concentration (standardized coefficient: 0.224). Furthermore, MMSE showed a significantly positive correlation with cerebral rSO₂ (r = 0.624, p < 0.001).

Conclusions

Cerebral rSO₂ was affected by eGFR and serum albumin and sodium concentrations in CKD patients. Furthermore, cerebral rSO₂ monitoring, which reflected MMSE scores, might be a useful method for assessing cognitive function in CKD patients.

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.

Protein Nutrition and Malnutrition in CKD and ESRD

Elevated protein catabolism and protein malnutrition are common in patients with chronic kidney disease (CKD) and end-stage renal disease (ESRD). The underlying etiology includes, but is not limited to, metabolic acidosis intestinal dysbiosis; systemic inflammation with activation of complements, endothelin-1 and renin-angiotensin-aldosterone (RAAS) axis; anabolic hormone resistance; energy expenditure elevation; and uremic toxin accumulation. All of these derangements can further worsen kidney function, leading to poor patient outcomes. Many of these CKD-related derangements can be prevented and substantially reversed, representing an area of great potential to improve CKD and ESRD care. This review integrates known information and recent advances in the area of protein nutrition and malnutrition in CKD and ESRD. Management recommendations are summarized. Thorough understanding the pathogenesis and etiology of protein malnutrition in CKD and ESRD patients will undoubtedly facilitate the design and development of more effective strategies to optimize protein nutrition and improve outcomes.

Electrolyte and Acid-Base Disorders in Chronic Kidney Disease and End-Stage Kidney Failure

The kidneys play a pivotal role in the regulation of electrolyte and acid-base balance. With progressive loss of kidney function, derangements in electrolytes and acid-base inevitably occur and contribute to poor patient outcomes. As chronic kidney disease (CKD) has become a worldwide epidemic, medical providers are increasingly confronted with such problems. Adequate diagnosis and treatment will minimize complications and can potentially be lifesaving. In this review, we discuss the current understanding of the disease process, clinical presentation, diagnosis and treatment strategies, integrating up-to-date knowledge in the field. Although electrolyte and acid-base derangements are significant causes of morbidity and mortality in CKD and end-stage renal disease patients, they can be effectively managed through a timely institution of combined preventive measures and pharmacological therapy. Exciting advances and several upcoming outcome trials will provide further information to guide treatment and improve patient outcomes.