Serum Sodium and Cognition in Older Community-Dwelling Men

The association between urinary sodium and the risk of dementia: Evidence from a population-based cohort study

BACKGROUND

Sodium intake reduction is crucial for cardiovascular health, however, its lasting impact on dementia remains unclear.

METHODS

We included 458,577 UK Biobank participants without dementia at baseline. We estimated 24-h urinary sodium (E24hUNa) using spot urinary parameters and obtained the incidence of all-cause dementia, Alzheimer's disease, and vascular dementia from multiple sources.

RESULTS

The mean E24hUNa was 3.0 g (1st-99th percentile: 1.5 g-5.1 g). Over a mean follow-up of 13.6 years, 7886 (1.7 %) participants developed all-cause dementia, including 3763 (0.8 %) Alzheimer's disease and 1851 (0.4 %) vascular dementia. In the restricted cubic spline model, we identify a potential cutoff of 3.13 g for E24hUNa, below which each 1 g decrease in E24hUNa was associated with 21 % (95 % confidence interval [CI] 1.11-1.34) higher all-cause dementia risk and 35 % (95 % CI 1.11-1.63) higher vascular dementia risk (P-value <0.001 for non-linearity). The hazard ratios were 1.15 (95 % CI, 1.07-1.24) for all-cause dementia and 1.21 (95 % CI 1.04-1.40) for vascular dementia among individuals with E24hUNa below 3.13 g compared to those with E24hUNa higher than 3.13 g.

LIMITATIONS

One of the major limitations is the estimation of 24-h urinary sodium with spot urine samples.

CONCLUSIONS

An E24hUNa level below 3.13 g, equivalent to 3.37 g daily sodium intake, is associated with increased risks of all-cause and vascular dementia. This exploratory study suggests a potential lower limit below which the risk of dementia increases with a lower sodium level. Future studies are necessary to validate our findings.

Magnesium and Cognitive Health in Adults: A Systematic Review and Meta-Analysis

Magnesium (Mg) plays a key role in neurological functioning and manifestations. However, the evidence from randomized controlled trials (RCTs) and cohorts on Mg and cognitive health among adults has not been systematically reviewed. We aimed to examine the associations of various Mg forms (supplements, dietary intake, and biomarkers) with cognitive outcomes by summarizing evidence from RCTs and cohorts. PubMed, Embase, PsycINFO, and the Cochrane Central Register of Controlled Trials were searched for relevant peer-reviewed articles published up to May 3, 2024. Three random-effects models were performed, when appropriate, to evaluate the relationship between Mg and cognitive outcomes: 1) linear meta-regression, 2) nonlinear (quadratic) meta-regression, and 3) meta-analysis using Mg variables categorized based on pre-existing recommendations. Three RCTs and 12 cohort studies were included in this systematic review. Evidence from the limited number of RCTs was insufficient to draw conclusions on the effects of Mg supplements. Cohort studies showed inconsistent dose-response relationships between dietary Mg and cognitive disorders, with high heterogeneity across populations. However, consistent U-shape associations of serum Mg with all-cause dementia and cognitive impairment were found in cohorts, suggesting an optimal serum Mg concentration of ∼0.85 mmol/L. This nonlinear association was detected in meta-regression (Pquadratic = 0.003) and in meta-analysis based on the reference interval of serum Mg (0.75-0.95 mmol/L) [<0.75 compared with 0.85 mmol/L: pooled hazard ratio (HR) = 1.43; 95% confidence interval (CI) = 1.05, 1.93; >0.95 compared with 0.85 mmol/L: pooled HR = 1.30; 95% CI = 1.03, 1.64]. More evidence from RCTs and cohorts is warranted. Future cohort studies should evaluate various Mg biomarkers and collect repeated measurements of Mg intake over time, considering different sources (diet or supplements) and factors affecting absorption (for example, calcium-to-Mg intake ratio). This systematic review was preregistered in PROSPERO (CRD42023423663).

Effects of dietary intervention on human diseases: molecular mechanisms and therapeutic potential

Diet, serving as a vital source of nutrients, exerts a profound influence on human health and disease progression. Recently, dietary interventions have emerged as promising adjunctive treatment strategies not only for cancer but also for neurodegenerative diseases, autoimmune diseases, cardiovascular diseases, and metabolic disorders. These interventions have demonstrated substantial potential in modulating metabolism, disease trajectory, and therapeutic responses. Metabolic reprogramming is a hallmark of malignant progression, and a deeper understanding of this phenomenon in tumors and its effects on immune regulation is a significant challenge that impedes cancer eradication. Dietary intake, as a key environmental factor, can influence tumor metabolism. Emerging evidence indicates that dietary interventions might affect the nutrient availability in tumors, thereby increasing the efficacy of cancer treatments. However, the intricate interplay between dietary interventions and the pathogenesis of cancer and other diseases is complex. Despite encouraging results, the mechanisms underlying diet-based therapeutic strategies remain largely unexplored, often resulting in underutilization in disease management. In this review, we aim to illuminate the potential effects of various dietary interventions, including calorie restriction, fasting-mimicking diet, ketogenic diet, protein restriction diet, high-salt diet, high-fat diet, and high-fiber diet, on cancer and the aforementioned diseases. We explore the multifaceted impacts of these dietary interventions, encompassing their immunomodulatory effects, other biological impacts, and underlying molecular mechanisms. This review offers valuable insights into the potential application of these dietary interventions as adjunctive therapies in disease management.

Serum sodium improvement: change in Comprehensive Geriatric Assessment parameters in geriatric patients with hyponatremia

BACKGROUND

Hyponatremia presents with symptoms considered age-associated in the elderly. We assess the change in Comprehensive Geriatric Assessment (CGA) parameters after hyponatremia improvement in hospitalized geriatric patients.

METHODS

We took 100 hyponatremic and same number of eunatremic geriatric patients (> 60 years) who were comorbidity, presenting-complaints, and age-matched. Four CGA parameters were utilized, the new Hindi Mental State Examination (HMSE), Barthel's index of activities of daily living (ADL), Timed up and go Test (TUG), and handgrip strength by hand dynamometer (HG). We analyzed these at admission and discharge, and their relationship with change in sodium levels.

RESULTS

Average age was 68.1 ± 5.8 years, with males constituting 75%. The CGA parameters demonstrated worse values amongst the hyponatremia than the normonatremia group. Severe hyponatremia group showed worse CGA scores in comparison with moderate and mild. With improvement in sodium level, the improvements in ADL, TUG, and HMSE scores were greater in the hyponatremia group (8.8 ± 10.1, 2.2 ± 2.5, and 1.7 ± 2.3 respectively) in comparison to the normonatremia reference group (4.7 ± 9.0, 1 ± 2.0, and 0.7 ± 1.3 respectively, P < 0.05).

CONCLUSION

Our study is the first utilizing HMSE to assess change in cognitive ability with improvement in serum sodium levels in the Indian elderly. Hyponatremic patients show worse baseline CGA parameters, and hyponatremia severity correlates with worse motor and cognitive function. Improvement in the serum sodium level improves the CGA parameters. Correction of hyponatremia in the geriatric age group significantly impacts life quality.

Associations of Hyponatremia with Cognition Function and All-Cause Mortality: Post Hoc Analysis of the Systolic BP Intervention Trial

Key Points

Incident hyponatremia is associated with probable dementia. Incident hyponatremia does not seem to be associated with mild cognitive impairment or death.

Background

Acute neurologic effects of severe hyponatremia are well-known. However, the long-term association of hyponatremia with cognitive impairment is unclear.

Methods

In this post hoc analysis of the Systolic Blood Pressure Intervention Trial, we examined whether incident hyponatremia is a risk factor of mild cognitive impairment (MCI) or probable dementia (PD). In those with baseline serum sodium level ≥130 mmol/L, we defined incident hyponatremia in the first 6 months as a Systolic Blood Pressure Intervention Trial safety alert for serum sodium level <130 mmol/L from randomization to the 6-month visit. In multivariate Cox regression models adjusted for baseline cognitive function and other variables, we related incident hyponatremia in the first 6 months with subsequent MCI or PD in 8540 participants with cognitive outcomes data and with all-cause mortality (ACM) in 9135 participants with mortality data.

Results

Incident hyponatremia in the first 6 months was noted in 116 participants (1.4%). Older age, female sex, non-Black race, lower body mass index, and randomization to intensive systolic BP control were associated with incident hyponatremia. Compared with those without hyponatremia, those with incident hyponatremia had higher risk of PD (2.1 versus 0.9 events/100 person-years; hazard ratio [HR], 3.08; 95% confidence interval [CI], 1.48 to 6.41) but not MCI (3.1 versus 3.6 events/100 person-years; HR, 0.95; 95% CI, 0.54 to 1.68) and the composite of MCI/PD (5.0 versus 4.2 events/100 person-years; HR, 1.28; 95% CI, 0.82 to 2.0). There were no significant differences in ACM (HR, 1.84; 95% CI, 0.90 to 3.73).

Conclusions

Biologic plausibility for the association of incident hyponatremia with PD but not MCI or death is unclear. The association of incident hyponatremia with PD could reflect a chance finding or noncausal biologic association or causal relationship.

Altered consciousness mediates the effect of hypernatremia, but not hyponatremia, on mortality among patients observed in the ICU

Purpose

Dysnatremias - hypernatremia and hyponatremia - may be associated with mortality through their impact on altered consciousness. We examined the mediating effect of decreased consciousness on the relationship between dysnatremia and mortality.

Methods

Among 195,568 critically ill patients in the United States contained in the eICU database, we categorized serum sodium into bands of 5mEq/L. Using causal mediation analysis, we compared bands in the hypernatremia and hyponatremia ranges to a reference band of 135-139mEq/L to determine the proportion of mortality mediated by decreased consciousness as determined by the Glasgow Coma Score (GCS).

Results

Both hyponatremia (OR [95%CI] for bands: <120mEq/L: 1.58 [1.26-1.97]; 120-<125mEq/L: 1.92 [1.64-2.25]; 125-<130mEq/L: 1.76 [1.60-1.93]; 130-<135mEq/L: 1.32 [1.24-1.41]) and hypernatremia (OR [95%CI] for bands: 140-<145mEq/L: 1.12 [1.05-1.19]; 145-<150mEq/L: 1.89 [1.70-2.11]; ≥150mEq/L: 1.86 [1.57-2.19]) were significantly associated with increased mortality. GCS mediated the effect of hypernatremia on mortality risk (Proportion mediated [95%CI]: 140-144mEq/L: 0.38 [0.23 to 0.89]; 145-149mEq/L: 0.27 [0.22 to 0.34]; ≥150mEq/L: 0.53 [0.41 to 0.81]) but not hyponatremia (proportion mediated 95%CI upper bound <0.05 for all bands).

Conclusion

Decreased consciousness mediates the association between increased mortality and hypernatremia, but not hyponatremia. Further studies are needed to explore neurologic mechanisms and directionality in this relationship.

The Association between Dysnatraemia during Hospitalisation and Post-COVID-19 Mental Fatigue

COVID-19 may induce short- and long-term cognitive failures after recovery, but the underlying risk factors are still controversial. Here, we investigated whether (i) the odds of experiencing persistent cognitive failures differ based on the patients' disease course severity and sex at birth; and (ii) the patients' electrolytic profile in the acute stage represents a risk factor for persistent cognitive failures. We analysed data from 204 patients suffering from COVID-19 and hospitalised during the first pandemic wave. According to the 7-point WHO-OS scale, their disease course was classified as severe or mild. We investigated the presence of persistent cognitive failures collected after hospital discharge, while electrolyte profiles were collected during hospitalisation. The results showed that females who suffered from a mild course compared to a severe course of COVID-19 had a higher risk of presenting with persistent mental fatigue after recovery. Furthermore, in females who suffered from a mild course of COVID-19, persistent mental fatigue was related to electrolyte imbalance, in terms of both hypo- and hypernatremia, during hospitalisation in the acute phase. These findings have important implications for the clinical management of hospitalised COVID-19 patients. Attention should be paid to potential electrolyte imbalances, mainly in females suffering from mild COVID-19.

Dietary sodium/potassium intake and cognitive impairment in older patients with hypertension: Data from NHANES 2011-2014

This study aimed to assess the relationship between dietary sodium/potassium intake and cognition in elderly individuals with hypertension. We designed a cross-sectional study based on the 2011-2014 National Health and Nutrition Examination Survey (NHANES) 2011-2014. A multivariable-logistic regression analysis was performed to analyze the relationship between sodium/potassium intake and cognitive impairment. Restricted cubic spline (RCS) based on regression analysis to assess the nonlinear dose-response relationship between dietary sodium intake and cognitive performance. Out of the 2276 participants included in this study, 1670 patients had hypertension. Compared with the lowest quartile of dietary sodium intake, the lowest weighted odds ratio of cognitive impairment in DSST was observed in Q4 (OR = 0.45, 0.29-0.70), and a similar trend was observed in AFT (OR = 0.34, 0.18-0.65). After adjusting the covariates, the lowest weighted multivariable-adjusted OR of cognitive impairment in DSST were also observed in Q4 (OR = 0.47, 0.26-0.84) compared with the lowest quartile of dietary sodium intake. The RCS results showed that dietary sodium intake was U-shaped and associated with the risk of cognitive impairment in the DSST (P_{non-linearity}  = 0.0067). In addition, no significant association was observed between dietary potassium intake and different dimensions of cognitive performance. In conclusion, excessively high and low low dietary sodium were associated with impairment of specific processing speed, sustained attention, and working memory for elderly patients with hypertension in the United States. However, no association was observed between dietary potassium intake and cognition.

Hyponatremia and Cancer: From Bedside to Benchside

Hyponatremia is the most common electrolyte disorder encountered in hospitalized patients. This applies also to cancer patients. Multiple causes can lead to hyponatremia, but most frequently this electrolyte disorder is due to the syndrome of inappropriate antidiuresis. In cancer patients, this syndrome is mostly secondary to ectopic secretion of arginine vasopressin by tumoral cells. In addition, several chemotherapeutic drugs induce the release of arginine vasopressin by the hypothalamus. There is evidence that hyponatremia is associated to a more negative outcome in several pathologies, including cancer. Many studies have demonstrated that in different cancer types, both progression-free survival and overall survival are negatively affected by hyponatremia, whereas the correction of serum [Na⁺] has a positive effect on patient outcome. In vitro studies have shown that cells grown in low [Na⁺] have a greater proliferation rate and motility, due to a dysregulation in intracellular signalling pathways. Noteworthy, vasopressin receptors antagonists, which were approved more than a decade ago for the treatment of euvolemic and hypervolemic hyponatremia, have shown unexpected antiproliferative effects. Because of this property, vaptans were also approved for the treatment of polycystic kidney disease. In vitro evidence indicated that this family of drugs effectively counteracts proliferation and invasivity of cancer cells, thus possibly opening a new scenario among the pharmacological strategies to treat cancer.

Serum sodium, cognition and incident dementia in the general population

BACKGROUND

Low serum sodium may be associated with cognitive impairment and dementia in the general population, but the data remain inconclusive. Therefore, we aimed to determine the association of low serum sodium with cognitive function and incident dementia in the general population.

METHODS

Participants from a prospective population-based cohort were eligible if data on serum sodium (collected between 1997 and 2008), dementia prevalence and dementia incidence were available (follow-up until 2018). Global cognitive function was assessed with the Mini-Mental State Examination (MMSE) and the general cognitive factor (G-factor, derived from principal component analysis of individual tests). Linear regression and Cox proportional-hazards models were used to assess associations of standardised continuous and categorised low serum sodium (mean - 1.96*SD: cut-off of 137 mmol/L) with overall cognitive function and incident dementia, respectively.

RESULTS

In all, 8,028 participants free of dementia at baseline (mean age 63.6 years, 57% female, serum sodium 142 ± 2 mmol/L), including 217 participants with low serum sodium, were included. Cross-sectionally, continuous serum sodium and/or low serum sodium were not associated with the MMSE or G-factor. However, participants with low serum sodium performed worse on the Stroop and Purdue Pegboard tests. During a median follow-up of 10.7 years, 758 subjects developed dementia. Continuous serum sodium (hazard ratio (HR) 0.98, 95% confidence interval (CI) 0.92;1.05) and low serum sodium (HR 1.27, 95% CI 0.90;1.79) were not associated with a higher risk of incident dementia.

CONCLUSION

We identified no significant associations of low serum sodium with overall cognitive functioning and risk of dementia. However, low serum sodium-including levels above the clinical cut-off for hyponatremia-was associated with impairments in selected cognitive domains including attention and psychomotor function.

Hyponatremic Cognitive Dysfunction Resulting from Drug-Drug-Gene Interaction between Sertraline and Cannabidiol in an Intermediate CYP2C19 Metabolizer Patient

Background: Pharmacogenomics (PGx) can provide more precision in determining causation of adverse drug reactions (ADRs) from drug-drug-gene interaction clinical application. Case Summary: Patient was an intermediate CYP2C19 metabolizer on stable therapy taking a low but therapeutic dose of sertraline for depression and anxiety over a period of 20 years. The patient then became hyponatremic and cognitively impaired after addition of cannabidiol (CBD) to this sertraline regimen. The proposed mechanism was drug-drug-gene interaction of CBD further inhibiting the CYP2C19 metabolism of sertraline and increasing drug exposure to produce moderate to severe hyponatremia and subsequent cognitive dysfunction. Practice Implications: Pharmacogenomics (PGx) testing may assist in etiology of patient symptoms from adverse drug reactions (ADRs) or drug-drug interactions by combining these with detection and application of drug-gene interactions. This case shows inhibition of CYP2C19 by CBD to further increase sertraline exposure, producing hyponatremia and subsequent cognitive dysfunction through CYP2C19 phenoconversion by CBD.

Approach to the Patient: Hyponatremia and the Syndrome of Inappropriate Antidiuresis (SIAD)

Hyponatremia is the most common electrolyte disturbance seen in clinical practice, affecting up to 30% of acute hospital admissions, and is associated with significant adverse clinical outcomes. Acute or severe symptomatic hyponatremia carries a high risk of neurological morbidity and mortality. In contrast, chronic hyponatremia is associated with significant morbidity including increased risk of falls, osteoporosis, fractures, gait instability, and cognitive decline; prolonged hospital admissions; and etiology-specific increase in mortality. In this Approach to the Patient, we review and compare the current recommendations, guidelines, and literature for diagnosis and treatment options for both acute and chronic hyponatremia, illustrated by 2 case studies. Particular focus is concentrated on the diagnosis and management of the syndrome of inappropriate antidiuresis. An understanding of the pathophysiology of hyponatremia, along with a synthesis of the duration of hyponatremia, biochemical severity, symptomatology, and blood volume status, forms the structure to guide the appropriate and timely management of hyponatremia. We present 2 illustrative cases that represent common presentations with hyponatremia and discuss the approach to management of these and other causes of hyponatremia.

The Assessment of Baseline Comprehensive Geriatric Assessment Parameters in Geriatric Patients With Varying Severity of Hyponatremia at a Tertiary Care Center

Background and objective

The prevalence of hyponatremia is estimated to be significantly higher in the geriatric age group compared to non-geriatric patients. The clinical symptoms of hyponatremia are often subtle and interpreted as age-related in geriatric patients. In this study, we aimed to perform the baseline comprehensive geriatric assessment (CGA) among a group of geriatric population with hyponatremia.

Methods

We utilized four simple CGA parameters: the Hindi Mental State Examination (HMSE) to assess the cognition, the Barthel Index for Activities of Daily Living (ADL) for assessing the level of independence, the Timed Up and Go (TUG) test for risk of fall evaluation, and handgrip (HG) strength by hand dynamometer for frailty. All CGA parameters were analyzed at admission among 100 geriatric patients (>60 years old), and an assessment of their relationship with the severity of hyponatremia was done. An equal number of age-, comorbidity-, and reason for acute presentation-matched hyponatremic patients were enrolled as controls. The student’s t-test and analysis of variance (ANOVA) were used for evaluation. Ethical clearance was obtained from the Institutional Ethics Committee, All India Institute of Medical Sciences, Rishikesh, and informed consent from patients or next of kin was taken before enrollment.

Results

The mean age of the study population was 68.1 ± 5.8 years, with a male-to-female ratio of 3:1. All CGA parameters tested showed lower values among hyponatremic patients compared to normonatremic patients, although only ADL (71.6 ± 12.3 vs. 76.7 ± 11.5, p=0.001) and HMSE (23.4 ± 3.1 vs. 24.4 ± 2.4, p=0.01) were statistically significant. All parameters were found to be worse in the severe group compared to moderate and mild groups, but significance was found only for TUG (17.9 ± 3.4 vs. 16.4 ± 4.2 vs. 14.6 ± 3.5, p=0.003, with higher values indicating worse status) and HMSE (21.1 ± 4.0 vs. 22.6 ± 2.8 vs. 24.1 ± 2.5, p=0.0007).

Conclusion

Based on our findings, hyponatremic patients have poor baseline CGA parameter values, and the severity of hyponatremia correlates with poor motor and cognitive functions. Hence, the prompt recognition and correction of hyponatremia should be prioritized in the elderly as both these parameters significantly impact the quality of life in this population. As the severity of hyponatremia increases, the elderly tend to have a higher incidence of the two main geriatric giants: impaired cognition and falls.

Cognitive Impairment in Acute Heart Failure: Narrative Review

Cognitive impairment (CI) represents a common but often veiled comorbidity in patients with acute heart failure (AHF) that deserves more clinical attention. In the AHF setting, it manifests as varying degrees of deficits in one or more cognitive domains across a wide spectrum ranging from mild CI to severe global neurocognitive disorder. On the basis of the significant negative implications of CI on quality of life and its overwhelming association with poor outcomes, there is a compelling need for establishment of detailed consensus guidelines on cognitive screening methods to be systematically implemented in the population of patients with heart failure (HF). Since limited attention has been drawn exclusively on the field of CI in AHF thus far, the present narrative review aims to shed further light on the topic. The underlying pathophysiological mechanisms of CI in AHF remain poorly understood and seem to be multifactorial. Different pathophysiological pathways may come into play, depending on the clinical phenotype of AHF. There is some evidence that cognitive decline closely follows the perturbations incurred across the long-term disease trajectory of HF, both along the time course of stable chronic HF as well as during episodes of HF exacerbation. CI in AHF remains a rather under recognized scientific field that poses many challenges, since there are still many unresolved issues regarding cognitive changes in patients hospitalized with AHF that need to be thoroughly addressed.

DASH diet adherence and cognitive function: Multi-ethnic study of atherosclerosis

BACKGROUND AND AIMS

The Adherence to the Dietary Approaches to Stop Hypertension (DASH) diet has been associated with better cognitive function in studies of predominantly White participants; few studies have examined this association in diverse cohorts. Our objective was to examine the association between the DASH diet and cognitive function in the diverse Multi-Ethnic Study of Atherosclerosis (MESA) cohort.

METHODS

Among 4169 MESA participants, we evaluated prospectively, the association between DASH diet adherence and cognitive function. Participants completed a food frequency questionnaire at baseline (2000-2002) and cognitive function was assessed using the Cognitive Abilities Screening Instrument (CASI), Digit Symbol Coding (DSC), and Digit Span (DS) at Exam 5 in 2010-2012 and Exam 6 (2016-2019). Regression analyses were used to evaluate the association between quintiles of DASH diet adherence with CASI, DSC, and DS performance and decline, adjusting for potential confounders. Effect modification by hypertension, diabetes, race/ethnicity, acculturation, and exercise were evaluated.

RESULTS

DASH diet adherence was not associated with cognitive performance or decline for any of the measures. There were no differences by racial/ethnic groups, with the exception that Hispanic participants reporting greater DASH diet adherence, performed worse on DS at Exam 5 (p = 0.05). Components of the DASH diet were differentially correlated with test performance: increased consumption of nuts/legumes was associated with better performance on the CASI at Exam 5 (p = 0.003) and Exam 6 (p = 0.007). Increased consumption of whole grains was associated with better DSC performance at Exam 5 (p = 0.04) and better DS performance at Exam 6 (p = 0.01).

CONCLUSIONS

DASH diet adherence was nominally associated with cognitive function with a suggestion of differences by race/ethnicity. Future work should examine more closely, the relationships between racial and ethnic groups and the impact of diet on cognitive function.

Hyponatremia and Oxidative Stress

Hyponatremia, i.e., the presence of a serum sodium concentration ([Na+]) < 136 mEq/L, is the most frequent electrolyte imbalance in the elderly and in hospitalized patients. Symptoms of acute hyponatremia, whose main target is the central nervous system, are explained by the "osmotic theory" and the neuronal swelling secondary to decreased extracellular osmolality, which determines cerebral oedema. Following the description of neurological and systemic manifestations even in mild and chronic hyponatremia, in the last decade reduced extracellular [Na+] was associated with detrimental effects on cellular homeostasis independently of hypoosmolality. Most of these alterations appeared to be elicited by oxidative stress. In this review, we focus on the role of oxidative stress on both osmolality-dependent and -independent impairment of cell and tissue functions observed in hyponatremic conditions. Furthermore, basic and clinical research suggested that oxidative stress appears to be a common denominator of the degenerative processes related to aging, cancer progression, and hyponatremia. Of note, low [Na+] is able to exacerbate multiple manifestations of senescence and to decrease progression-free and overall survival in oncologic patients.

Sodium Intensity Changes Differ Between Relaxation- and Density-Weighted MRI in Multiple Sclerosis

Introduction: The source of Tissue Sodium Concentration (TSC) increase in Multiple Sclerosis (MS) remains unclear, and could be attributed to altered intracellular sodium concentration or tissue microstructure. This paper investigates sodium in MS using three new MRI sequences. Methods: Three sodium scans were acquired at 4.7 T from 30 patients (11 relapsing-remitting, 10 secondary-progressive, 9 primary-progressive) and 9 healthy controls including: Density-Weighted (NaDW), with very short 30° excitation for more accurate TSC measurement; Projection Acquisition with Coherent MAgNetization (NaPACMAN), designed for enhanced relaxation-based contrast; and Soft Inversion Recovery FLuid Attenuation (NaSIRFLA), developed to reduce fluid space contribution. Signal was measured in both lesions (n = 397) and normal appearing white matter (NAWM) relative to controls in the splenium of corpus callosum and the anterior and posterior limbs of internal capsule. Correlations with clinical and cognitive evaluations were tested over all MS patients. Results: Sodium intensity in MS lesions was elevated over control WM by a greater amount for NaPACMAN (75%) than NaDW (35%), the latter representing TSC. In contrast, NaSIRFLA exhibited lower intensity, but only for region specific analysis in the SCC (-7%). Sodium intensity in average MS NAWM was not significantly different than control WM for either of the three scans. NaSIRFLA in the average NAWM and specifically the posterior limb of internal capsules positively correlated with the Paced Auditory Serial Addition Test (PASAT). Discussion: Lower NaSIRFLA signal in lesions and ~2× greater NaPACMAN signal elevation over control WM than NaDW can be explained with a demyelination model that also includes edema. A NAWM demyelination model that includes tissue atrophy suggests no signal change for NaSIRFLA, and only slightly greater NAWM signal than control WM for both NaDW and NaPACMAN, reflecting experimental results. Models were derived from previous total and myelin water fraction study in MS with T2-relaxometry, and for the first time include sodium within the myelin water space. Reduced auditory processing association with lower signal on NaSIRFLA cannot be explained by greater demyelination and its modeled impact on the three sodium MRI sequences. Alternative explanations include intra- or extracellular sodium concentration change. Relaxation-weighted sodium MRI in combination with sodium-density MRI may help elucidate microstructural and metabolic changes in MS.

Serum sodium in relation to various domains of cognitive function in the elderly US population

Background

Recent evidence suggests that sodium imbalances may be associated with cognitive impairment; however, the association between specific domains of cognition remains unclear. This study examines the association between serum sodium levels and immediate and delayed verbal memory as measured by the CERAD Word Learning Test (CERAD WLT), executive function as measured by the Animal Fluency test (AFT), and sustained attention, working memory, and processing speed as measured by the Digit Symbol Substitution test (DSST) in the elderly population of the US aged 60 and older who participated in the 2011–2014 National Health and Nutrition Examination Surveys (n = 2,541).

Methods

Cognitive function tests were performed by trained interviewers and sodium levels were measured using indirect ion selective electrode methodology.

Results

After adjusting for all covariates, quintiles of CERAD WLT scores showed significant positive associations with log-transformed sodium levels (Immediate recall (IR) β = 4.25 (SE = 1.83, p-value 0.027); Delayed recall (DR) β = 6.54 (SE = 1.82, p-value 0.001)). Compared to normal sodium levels, hyponatremia was significantly associated with lower CERAD WLT-IR (β = -0.34, SE = 0.15, p-value 0.035) and CERAD WLT-DR scores (β -0.48, SE = 0.10, p-value < 0.001) and showed borderline significance with AFT scores (β = = -0.38, SE = 0.19, p-value 0.052). Hypernatremia did not show any significant relationships with cognitive test scores, compared to normal sodium levels.

Conclusions

Our cross-sectional study showed that lower sodium levels were associated with cognitive change, especially regarding memory and executive function.

[Hyponatremia - causes, diagnostic evaluation and treatment]

Intact osmoregulation prevents osmotic gradients thereby limiting cell swelling and shrinking. Hyponatremia is a state of an osmole-free water excess compared to the amounts of solutes and clinical management of hyponatremic patients requires pathophysiology-oriented approaches to select appropriate treatments. Clinicians need to assess the patient's volume status to differentiate hyponatremia with volume depletion, expansion or normovolemia, respectively. In addition, work-up includes differentiation between acute and chronic and asymptomatic and symptomatic hyponatremia. Estimation of free water-clearance helps predicting Serum-Na⁺ changes and is important to prevent overcorrection of hyponatremia. Water restriction, hypertonic salt, urea, V2-receptor-blockers and recently sodium glucose cotransporter 2 (SGLT2) inhibitors were employed to treat patients with hyponatremia.

Lower serum sodium levels predict poor clinical outcomes in patients with insomnia

Background

The association between lower serum sodium levels and the clinical outcomes of insomnia patients remains unclear. We explored whether lower serum sodium is associated with poor clinical outcomes in patients with insomnia.

Methods

We retrospectively enrolled patients with a diagnosis of insomnia from January 2011 to December 2012. We divided participants into three groups according to initial serum sodium level: tertile 1 (< 138 mmol/L), tertile 2 (138.0–140.9 mmol/L), and tertile 3 (≥ 141.0 mmol/L). To calculate the relative risk of death, hazard ratios (HRs) and 95% confidence intervals (CIs) were obtained using Cox proportional hazard models.

Results

A total of 412 patients with insomnia were included, of whom 13.6% (n = 56) had hyponatremia. Patients with lower serum sodium concentrations were older and had lower hemoglobin, calcium, phosphorus, and albumin levels. At the median follow-up of 49.4 months, 44 patients had died and 62 experienced acute kidney injury (AKI). Kaplan-Meier analysis showed significantly higher mortality in patients in the lowest tertile for serum sodium. The lowest tertile of the serum sodium level and the AKI were associated with all-cause mortality. However, the lowest tertile of the serum sodium level was not significantly associated with AKI.

Conclusions

The lowest tertile of the serum sodium level was associated with a higher mortality rate in insomnia patients. Our results suggest that the serum sodium level could serve as a prognostic factor in insomniacs; patients with lower sodium levels require particular care.

Impairment of Neurocognitive Functioning, Motor Performance, and Mood Stability in Hospitalized Patients With Euvolemic Moderate and Profound Hyponatremia

BACKGROUND

The impact of chronic moderate and profound hyponatremia on neurocognitive performance, motor skills, and mood stability has not been investigated systematically so far, and results regarding mild to moderate hyponatremia are inconsistent. Furthermore, it is not known whether treatment has an effect on outcome in these patients.

METHODS

A total of 130 hospitalized patients with confirmed euvolemic hyponatremia (<130 mEq/L) were subjected to a test battery (Mini-Mental State Examination, DemTect, Trail-Making Tests A and B, Beck Depression Inventory, Timed-up-and-go Test) before and after treatment; additionally, 50 normonatremic group-matched patients served as reference group.

RESULTS

The scores of all tested domains were significantly worse in the hyponatremia group (median serum sodium [Na⁺] 122 (119-126) mEq/L) as compared to the reference group (P <0.001), and the odds of obtaining a pathological test result increased markedly with more profound hyponatremic states (odds ratios between 5.0 and 21.8 in the group with Na⁺ <120 mEq/L compared to reference group). Inversely, treatment led to a significant amelioration of all test results with medium to large effect sizes. Linear regression models revealed the increment of Na⁺ as an important predictor of test outcome.

CONCLUSION

We demonstrate a clear association between lower levels of Na⁺ beyond mild hyponatremia and impairment of neurocognitive and motor performance as well as mood disorders. Our analysis further suggests a causal role of hyponatremia in this context. However, there are apparent differences between the distinct tested domains warranting further investigations.

Prevalence of hyponatremia among older inpatients in a general hospital

PURPOSE

This study aimed to explore the incidence, clinical features, etiology, and mortality of hyponatremia in older inpatients and thus provide preliminary data for an epidemiological study.

METHODS

Hospitalized older patients diagnosed with hyponatremia at the First Medical Center of PLA General Hospital during January 2013-December 2016 were stratified by serum sodium concentrations into mild (130- < 135 mmol/L), moderate (125- < 130 mmol/L) and severe hyponatremia groups (< 125 mmol/L). Etiologies, medication histories, hospitalization times, and outcomes were analyzed.

RESULTS

During the indicated period, 4364 older patients with hyponatremia were hospitalized, including 2934 men and 1430 women with an average age of 84.6 ± 3.5 years (range 80-104 years). The prevalence of hyponatremia was 24.7%. An analysis of common primary diseases identified respiratory diseases as the most frequent (25.0%), followed by tumors (23.1%), cardiovascular diseases (19.9%), central nervous system diseases (8.9%), and orthopedic diseases (6.1%). PPIs (59.7%), loop diuretics (57.4%), potassium-preserving diuretics (29.5%), ACEIs/ARBs (20.0%), thiazide diuretics (12.5%), and NSAIDs (12.4%) were the drugs most commonly associated with hyponatremia. The in-hospital mortality rate was 11.7%. Aggravated hyponatremia led to a prolonged hospitalization time. Moreover, when compared with mild hyponatremia, moderate and severe hyponatremia were associated with significant increases in in-hospital mortality (ORs 1.89 and 2.66, respectively; 95% CIs 1.54-2.33 and 2.06-3.43, respectively; P < 0.01).

CONCLUSIONS

Hyponatremia is a common complication in hospitalized older patients and is caused mainly by respiratory diseases, tumors, and cardiovascular diseases. Given the correlation between the degree of hyponatremia and prognosis, the early and accurate identification and treatment of this condition can reduce the associated morbidity and mortality.

Neurological dysfunction after cardiac surgery and cardiac intensive care admission: A narrative review part 2: Cognitive dysfunction after critical illness; potential contributors in surgery and intensive care; pathogenesis; and therapies to prevent/treat perioperative neurological dysfunction

Severe cognitive decline and cognitive dysfunction has been attributed to patient's stay in the cardiovascular intensive care unit. Prolonged mechanical ventilation, long duration of stay, sedation protocols, and sleep deprivation contribute to patients developing neurocognitive disorder after intensive care admission and it is associated with poor clinical outcomes. Trauma of surgery, stress of critical care, and administration of anaesthesia evoke a systemic inflammatory response and trigger neuroinflammation and oxidative stress. Anaesthetic agents modulate the function of the GABA receptors. The persistence of these effects in the postoperative period promotes development of cognitive dysfunction. A number of drugs are under investigation to restrict or prevent this cognitive decline.

Impact of Resolution of Hyponatremia on Neurocognitive and Motor Performance in Geriatric Patients

This observational study investigated the impact of hyponatremia resolution on the results of a comprehensive geriatric assessment (CGA) in 150 patients with age ≥70 years and serum sodium <130 mEq/L. The test battery including Barthel index of Activities of Daily Living (ADL) and various tests of neurocognitive function, motor performance and mood stability was applied on admission and at discharge. Changes of individual test results (Δ) were analyzed and normonatremic patients matched for age, gender, and ADL served as reference group. Most CGA test results improved. The improvement was more pronounced in the hyponatremia group with respect to ADL (ΔADL: 14.3 ± 17.1 vs. 9.8 ± 14.7; p = 0.002) and MMSE (ΔMMSE: 1.8 ± 3.0 vs. 0.7 ± 1.9; p = 0.002). Effect sizes were small (i.e., >0.2) in the overall analysis for ΔADL and ΔMMSE and moderate (i.e., >0.5) for ΔMMSE in the euvolemic subgroup. Beneficial effects on ΔADL and ΔMMSE were only observed in the subgroup of patients in which [Na⁺] was raised by >5 mEq/L and multivariable linear regression analysis confirmed [Na⁺] increase to be an independent predictor of MMSE improvement. Resolution of hyponatremia has a beneficial impact on the geriatric patients' overall functional status, in particular in euvolemic cases.

Osmoregulation Performance and Kidney Transplant Outcome

BACKGROUND

Kidney transplant recipients have an impaired ability to dilute urine but seldom develop baseline hyponatremia before ESRD. Although hyponatremia is a risk factor for adverse events in CKD and in kidney transplant recipients, it remains unclear whether subtler alterations in osmoregulation performance are associated with outcome.

METHODS

We studied a single-center prospective cohort of 1258 kidney transplant recipients who underwent a water-loading test 3 months after transplant to determine osmoregulation performance. Measured GFR (mGFR) was performed at the same visit. A group of 164 healthy candidates for kidney donation served as controls. We further evaluated the association of osmoregulation performance with transplantation outcomes and subsequent kidney function.

RESULTS

Unlike controls, most kidney transplant recipients failed to maintain plasma sodium during water loading (plasma sodium slope of -0.6±0.4 mmol/L per hour in transplant recipients versus -0.12±0.3 mmol/L per hour in controls; P<0.001). Steeper plasma sodium reduction during the test independently associated with the composite outcome of all-cause mortality and allograft loss (hazard ratio [HR], 1.73 per 1 mmol/L per hour decrease in plasma sodium; 95% confidence interval [95% CI], 1.23 to 2.45; P=0.002) and allograft loss alone (HR, 2.04 per 1 mmol/L per hour decrease in plasma sodium; 95% CI, 1.19 to 3.51; P=0.01). The association remained significant in a prespecified sensitivity analysis excluding patients with hyperglycemia. In addition, a steeper plasma sodium slope 3 months after transplantation independently correlated with lower mGFR at 12 months (β=1.93; 95% CI, 0.46 to 3.41; P=0.01).

CONCLUSIONS

Reduced osmoregulation performance occurs frequently in kidney transplant recipients and is an independent predictor of renal outcome.

Serum Sodium and Pulse Pressure in SPRINT

BACKGROUND

High dietary sodium intake may induce a small, yet physiologically relevant rise in serum sodium concentration, which associates with increased systolic blood pressure. Cellular data suggest that this association is mediated by increased endothelial cell stiffness. We hypothesized that higher serum sodium levels were associated with greater arterial stiffness in participants in the Systolic Blood Pressure Intervention Trial (SPRINT).

METHODS

Multivariable linear regression was used to examine the association between baseline serum sodium level and (i) pulse pressure (PP; n = 8,813; a surrogate measure of arterial stiffness) and (ii) carotid-femoral pulse wave velocity (CFPWV; n = 591 in an ancillary study to SPRINT).

RESULTS

Baseline mean ± SD age was 68 ± 9 years and serum sodium level was 140 ± 2 mmol/L. In the PP analysis, higher serum sodium was associated with increased baseline PP in the fully adjusted model (tertile 3 [≥141 mmol] vs. tertile 2 [139-140 mmol]; β = 0.87, 95% CI = 0.32 to 1.43). Results were similar in those with and without chronic kidney disease. In the ancillary study, higher baseline serum sodium was not associated with increased baseline CFPWV in the fully adjusted model (β = 0.35, 95% CI = -0.14 to 0.84).

CONCLUSIONS

Among adults at high risk for cardiovascular events but free from diabetes, higher serum sodium was independently associated with baseline arterial stiffness in SPRINT, as measured by PP, but not by CFPWV. These results suggest that high serum sodium may be a marker of risk for increased PP, a surrogate index of arterial stiffness.

Allostasis and the Clinical Manifestations of Mild to Moderate Chronic Hyponatremia: No Good Adaptation Goes Unpunished

When homeostatic regulatory systems are unable to maintain a normal serum sodium concentration, the organism must adapt to demands of a disordered internal environment, a process known as "allostasis." Human cells respond to osmotic stress created by an abnormal serum sodium level with the same adaptations used by invertebrate organisms that do not regulate body fluid osmolality. To avoid intolerable changes in their volume, cells export organic osmolytes when exposed to a low serum sodium concentration and accumulate these intracellular solutes when serum sodium concentration increases. The brain's adaptation to severe hyponatremia (serum sodium < 120 mEq/L) has been studied extensively. However, adaptive responses occur with less severe hyponatremia and other tissues are affected; the consequences of these adaptations are incompletely understood. Recent epidemiologic studies have shown that mild (sodium, 130-135 mEq/L) and moderate (sodium, 121-129 mEq/L) chronic hyponatremia, long thought to be inconsequential, is associated with adverse outcomes. Adaptations of the heart, bone, brain, and (possibly) immune system to sustained mild to moderate hyponatremia may adversely affect their function and potentially the organism's survival. This review explores what is known about the consequences of mild to moderate chronic hyponatremia and the potential benefits of treating this condition.