Diabetes Mellitus is Associated With Higher Serum Neurofilament Light Chain Levels in the General US Population

The relationship between triglyceride-glucose index and serum neurofilament light chain: Findings from NHANES 2013-2014

BACKGROUND

The Triglyceride-Glucose (TyG) index has become a reliable indicator for evaluating the level of insulin resistance, a pivotal factor in both metabolic and neurodegenerative disorders. Serum neurofilament light chain (sNfL) serves as a responsive biomarker for detecting neuroaxonal injury. Despite this, the interplay between the TyG index and sNfL levels has not been sufficiently investigated. The aim of this research is to scrutinize the correlation between TyG index and sNfL levels across a substantial, population-based cohort.

METHODS

Our study involved an examination of the dataset from the 2013-2014 round of the National Health and Nutrition Examination Survey (NHANES), encompassing a total of 2029 enrolled subjects. The TyG index was calculated using fasting triglycerides and glucose levels. Multivariable linear regression models were conducted to evaluate the relationship between TyG index and sNfL levels, adjusting for potential confounders such as age, sex, race, BMI, hypertension, stroke, congestive heart failure, alcohol consumption and NHHR (Non-High-Density Lipoprotein Cholesterol to High-Density Lipoprotein Cholesterol Ratio). Nonlinear associations were investigated using regression models based on restricted cubic splines (RCS).

RESULTS

Both the unadjusted and adjusted regression analyses revealed a substantial positive correlation between the TyG index and ln-sNfL levels. After accounting for all covariates, each unit increase in the TyG index was associated with a 0.15 (95% CI: 0.02-0.27, p =  0.04) increase in ln-sNfL levels. RCS analysis revealed a nonlinear relationship, with a threshold around a TyG index value of 9.63, beyond which ln-sNfL levels increased more rapidly. The association was consistent across subgroups.

CONCLUSION

Our study links higher TyG index with increased sNfL levels, indicating insulin resistance's role in neuroaxonal injury. The nonlinear relationship implies a heightened risk of neurodegeneration beyond a certain insulin resistance threshold. This underscores the need for early metabolic interventions to prevent neurodegenerative processes.

Association between serum neurofilament light chain levels and grip strength among US adults: a cross-sectional study using National Health and Nutrition Examination Survey data from 2013 to 2014

OBJECTIVE

We aimed to investigate the relationship between serum neurofilament light chain (NfL) and grip strength using data from the 2013-2014 US National Health and Nutrition Examination Survey (NHANES).

DESIGN

Secondary analysis of cross-sectional, population-based data.

SETTING

NHANES sample, 2013-2014.

PARTICIPANTS

We studied 1925 participants aged 20-75 years.

OUTCOME MEASURES AND ANALYSIS

We applied a multivariable generalised linear regression model, adjusted for several potential confounders, and restrictive cubic spline models to evaluate the association between serum NfL and grip strength. Subgroup analyses were conducted using stratified multivariable linear regression analysis.

RESULTS

We included 1925 participants (average age: 44.8±0.44 years) from the NHANES database. Participants with higher serum NfL levels had a significantly higher prevalence of medical conditions (hypertension, diabetes, cardiovascular disorder, chronic kidney disease (CKD) and cancer) compared with those with lower NfL levels (all p<0.001). After adjusting for confounding factors, there was a negative association between serum NfL and grip strength (β=-2.07; 95% CI -3.47, -0.67; p=0.007). In addition, significant interactions were found between NfL and grip strength stratified by age, physical activity and CKD (p value for interaction=0.002, 0.023 and 0.006). The results of the restricted cubic splines (RCS) analysis showed no evidence against a linear association of serum NfL levels with grip strength. (p for non-linearity=0.334).

CONCLUSION

Our study demonstrates a strong, negative and linear correlation between elevated serum NfL levels and grip strength. Notably, our findings indicate that individuals aged between 60 and 75 years, those with physical inactivity and those with CKD exhibit a more pronounced reduction in grip strength with increasing serum NfL levels.

Biochemical use of neurofilament light polypeptide and vitamin B12 in relation to diabetic polyneuropathy in Danish adolescents with type 1 diabetes: a cross-sectional study

INTRODUCTION

The aim of this study was to investigate serum Neurofilament Light polypeptide (NfL) as a biomarker for diabetic polyneuropathy (DPN) in adolescents with type 1 diabetes (T1D). Secondarily, to investigate vitamin B12 (B12) deficiency as a cause for DPN in adolescents with T1D.

RESEARCH DESIGN AND METHODS

Cross-sectional study. Sixty Danish adolescents with T1D (age 15-18 years, diabetes duration >5 years) and 23 age-matched control subjects were included. Based on nerve conduction studies (NCS), intraepidermal nerve fibre density (IENFD) and neurological examination, patients were divided into three groups: (1) T1D without DPN, (2) T1D with subclinical DPN and (3) T1D with confirmed DPN. Blood levels of NfL, B12, B12-binding protein holotranscobalamin (HoloTC) and methylmalonic acid (MMA) were determined.

RESULTS

Twenty-four of the adolescents were without DPN, twenty-one had subclinical DPN and eight had confirmed DPN. NCS was not conducted in three participants and four patients did not have blood samples taken. There were no significant differences in NfL levels or any of the B12 parameters between any of the groups.

CONCLUSIONS

NfL used in a cross-sectional manner was not found useful to distinguish between the adolescents with DPN and those without. Vitamin B12 deficiency did not contribute to neuropathy in Danish adolescents with T1D.

Diabetes and Hypertension at Midlife Predict Increases in Biomarkers of Dementia Among Black Americans

BACKGROUND

Compared to other racial/ethnic groups, Black Americans show accelerated brain aging beginning in midlife and exhibit higher rates and earlier onset of dementia. While these patterns are often viewed as evidence that Black Americans are more vulnerable to Alzheimer's disease, another possibility is that their high risk for chronic vascular pathologies such as high blood pressure and diabetes compromises their brain health. This hypothesis was tested in the present study.

METHODS

Participants included 252 middle-aged Black Americans enrolled in the Family and Community Health Study and living in Iowa or Georgia who had ascertainment of diabetes and hypertension in 2008 and blood drawn in 2008 and 2019. Linear regression models assessed whether hypertension and diabetes were associated with change in neurofilament light chain (NfL), a non-specific biomarker of brain pathology including vascular dementia, and phosphorylated tau181 (p-Tau181), a biomarker of underlying Alzheimer's disease (AD) pathology.

RESULTS

Having a diagnosis of either hypertension or diabetes during middle age was not associated with levels of either p-Tau181 or NfL. However, having a diagnosis of both hypertension and diabetes was robustly associated with higher levels of NfL and increases in NfL over an 11-year period.

CONCLUSIONS

Among Black Americans, comorbid hypertension and diabetes contribute to higher levels of serum NfL, our indicator of neurodegeneration, during late middle age but not with p-Tau181, our indicator of Alzheimer's disease. Rather than being instances of AD, elevated rates of dementia among Black Americans may be largely vascular pathology caused by high rates of diabetes and high blood pressure.

Plastic harmful ingredients reduce the level of neurofilament light chain protein

Population exposure to plastics is increasing, and plasticizers are frequently detected in humans as important ingredients of plastic products. However, patterns of exposure to harmful ingredients of plastics and their effects on neurofilament light chain (NFL), a marker of active brain pathology, are currently inconclusive. Herein, we employed a range of statistical methods to thoroughly investigate the impact of 24 plastic hazardous ingredients and their varying exposure patterns on NFL concentrations in the blood of the general population in 533 participants. Generalized linear model revealed a positive correlation between Mono-isononyl phthalate and Mono (2-Ethyl- 5-Hydroxyhexyl) Phthalate (MEHHP) with NFL. Furthermore, a significant dose-response relationship was observed between MEHHP and NFL, while Butyl paraben and Mono (Hydroxy-Isononyl) Ester exhibited a distinct "inverted U-shaped" nonlinear pattern with NFL. Additionally, Weighted Quantile Sum model allowed us to identify the mixed effects of all 24 plastic hazardous ingredients, with Mono(2-Ethyl-5-Oxohexyl) Phthalate, Mono-isobutyl phthalate, Mon butyl Phthalate, Propyl paraben and Triclosan occupying prominent positions. Finally, the latent profile analysis categorized exposures into high, medium, and low patterns, confirming that higher exposure to plastic hazardous ingredients posed a significant risk factor for elevated NFL levels in the blood. Exposure to plastic hazardous ingredients significantly increases the risk of NFL, the present contributes to early detection and intervention to reduce the incidence of neurodevelopmental disorder.

J-shaped relationship of serum neurofilament light chain with urinary albumin excretion in US adults: NHANES 2013-2014

INTRODUCTION

This study focuses on investigating the relationship between serum neurofilament light chain (sNfL) and urinary albumin-to-creatinine ratio (uACR) among American adults aged 25-75.

METHODS

An analysis was conducted on information gathered from 1741 individuals aged between 25 and 75 who participated in the National Health and Nutrition Examination Survey (NHANES) during the years 2013-2014. Generalized linear models were utilized, and restricted cubic spline (RCS) analysis was conducted to assess a non-linear relationship.

RESULTS

Upon adjusting for multiple variables, a non-linear inverse J-shaped relationship was observed between sNfL and uACR. Compared with individuals in quartile 1 (Q1) of sNfL (2.8-8.3), those with quartile 4 (Q4) (≥19.1) had an adjusted β for uACR of 51.57.

CONCLUSIONS

The study found a J-shaped curve linking sNfL and uACR in American adults, with a turning point around log(sNfL) 2.928 pg/mL.

Relationship between serum neurofilament light chain protein and depression: A nationwide survey and Mendelian randomization study

BACKGROUND

Investigating the link between serum neurofilament protein (sNfL) levels and depression remains an area of limited understanding. This study explores the correlation in US adults and employs Mendelian randomization (MR) to ascertain causality.

METHODS

Our cross-sectional study analyzed data from participants aged 20 and above in the National Health and Nutrition Examination Survey (2013-2014). We employed a weighted multiple logistic regression model to examine the relationship between ln (sNfL) and depression. Restricted cubic splines (RCS) were used to visualize non-linear relationships. Stratified analyses examined associations between ln(sNfL) and depression in different subgroups. Subsequently, we conducted a two-sample bidirectional Mendelian randomization (MR) to assess the causal relationship between sNfL and depression. The inverse variance-weighted (IVW) method was utilized as the primary analysis.

RESULTS

Among 1765 participants (mean age 45.19 years; 49.37 % male), 166 had depression with a Patient Health Questionnaire (PHQ-9) score ≥ 10. After adjusting for covariates, a positive correlation remained between sNfL and depression (OR 1.511, 95 % CI: 1.050-2.175). RCS curves indicated a non-linear association, with a turning point at 2.76 pg/ml. Stratified analyses revealed positive correlations in specific subgroups, with interactions involving age, race, family income, recreational activity, and ln(sNfL). MR using IVW found no significant causal relationship between sNfL and depression genetically (OR = 0.956, 95 % CI: 0.878-1.042), with reverse analysis yielding similar results (OR = 0.897, 95 % CI: 0.756-1.065).

CONCLUSIONS

This cross-sectional study highlights a significant correlation between ln(sNfL) and depression. However, MR results indicate no causal relationship between sNfL and depression.

All-Cause Mortality Differentials by Diabetes Status and Serum Neurofilament Light-Chain Levels in US General Adults

CONTEXT

Neurofilament light chains (sNFLs) increase in patients with diabetes (DM) and are associated with death.

OBJECTIVE

This work aimed to examine whether sNFL mediates associations of DM with all-cause mortality and the extent of interaction or joint relations of sNFL and DM with mortality.

METHODS

This population-based cohort study was conducted using the 2013 to 2014 cycle of the National Health and Nutrition Examination Survey. A total of 2071 adults aged 20 to 75 years with sNFL measurements were included. sNFL was lg-transformed (LgNfl). Participants were included whose LgNfl was higher than 1.48 pg/mL or who were diagnosed with DM. All-cause mortality was the primary outcome obtained through linkage to registries.

RESULTS

During a median follow-up of 6.1years, 85 participants died. Incidence rates (per 1000 person-years [95% CI]) of all-cause mortality were 27.78 (19.98∼35.58) in adults with LgNfl greater than 1.48 pg/mL and DM, 9.01 (1.99∼16.03) in adults with LgNfl greater than 1.48 pg/mL but no DM, 3.07 (1.01∼5.13) in adults with DM and LgNfl less than or equal to 1.48 pg/mL, and 2.21 (1.15∼3.27) in adults without DM and LgNfl less than or equal to 1.48 pg/mL. Significant interaction but not mediation was observed between LgNfl and DM. Compared with adults without DM and LgNfl less than or equal to 1.48 pg/mL, those with DM and LgNfl greater than 1.48 pg/mL had higher risks of all-cause mortality (hazard ratio; 95% CI, 7.06; 3.52∼14.16).

CONCLUSION

In general US adults with DM, elevated sNFLs were associated with higher all-cause mortality specifically, supporting an important role of sNFLs in predicting health outcome in individuals with DM.

Serum neurofilament light chain: a novel biomarker for cardiovascular diseases in individuals without hypertension

Serum neurofilament light chain (sNFL) is a biomarker for axonal injury. Previous studies have linked sNFL levels to cardiovascular risk factors such as diabetes and hypertension, but its association with cardiovascular diseases (CVD) remains unclear. This study aims to explore the association between sNFL and CVD and evaluates its predictive value. Utilizing NHANES 2013-2014 data, this study included 2,035 participants aged ≥ 20 years with measured sNFL quantified using a Siemens immunoassay. CVD was self-reported and included myocardial infarction, stroke, heart failure, coronary heart disease, or angina. Logistic regression models assessed the association between sNFL levels and CVD. The predictive value of sNFL for CVD was evaluated using area under the curve (AUC) and DeLong test. Participants with higher sNFL levels were typically older, male, non-Hispanic white, smokers, and had lower socioeconomic status, higher CVD, hypertension, and diabetes prevalence. Higher sNFL levels were significantly associated with increased odds of CVD (adjusted OR = 1.41, 95% CI: 1.05-1.88). The association was significant in non-hypertensive individuals (OR = 2.72, 95% CI: 1.61-4.62) but not in hypertensive individuals (OR = 1.13, 95% CI: 0.81-1.56). sNFL addition to traditional risk models improved predictive accuracy, especially in non-hypertensive individuals (AUC from 0.827 to 0.856). sNFL levels are significantly associated with CVD in the general population, with a strong predictive value in non-hypertensive individuals. Future longitudinal studies should validate sNFL's efficacy in various populations and explore the underlying mechanisms of its relationship with hypertension and CVD.

Serum Fatty Acid Profiles and Neurofilament Light Chain Levels in the General Population

BACKGROUND

Previous studies have demonstrated associations between fatty acids and neurological disorders. However, no studies have examined the relationship between serum fatty acid levels and serum neurofilament light chain (NfL), a biomarker of neurological disorders.

OBJECTIVES

This study aimed to comprehensively investigate the intricate relationship between 30 serum fatty acids and serum NfL levels in a nationally representative sample of United States adults, using data from the 2013-2014 National Health and Nutrition Examination Survey.

METHODS

Using a cross-sectional analysis, multivariable linear regression models were used to explore the associations between 30 serum fatty acids and serum NfL levels. This analysis involved adjustment for potential confounding variables, including age, sex, race, body mass index (BMI), smoking status, hyperlipidemia, and diabetes, to clarify the association between serum fatty acids and serum NfL levels.

RESULTS

The analysis revealed that certain fatty acids exhibited distinct associations with serum NfL levels. Notably, docosanoic acid (22:0) and tricosanoic acid (C23:0) were found to be inversely associated with serum NfL levels (β = -0.280, 95% confidence interval [CI]: -0.525, -0.035; β = -0.292, 95% CI: -0.511, -0.072). Conversely, palmitoleic acid (16:1n-7) demonstrated a positive association with serum NfL levels (β = 0.125, 95% CI: 0.027, 0.222). Notably, these associations remained significant even after adjustment for potential confounders.

CONCLUSIONS

Individuals with high relative concentrations of certain SFA exhibited decreased serum NfL, whereas those with high relative concentrations of certain monounsaturated fatty acids showed increased serum NfL. These findings contribute to a deeper understanding of the potential impact of serum fatty acids on NfL levels, shedding light on novel avenues for further investigation and potential interventions in the context of neurological health.

Association between aromatic amines and serum neurofilament light chain as a biomarker of neural damage: a cross-sectional study from NHANES

Background

Aromatic amines (AAs) are a group of compounds widely found in chemical industry, tobacco smoke, and during food processing, with established carcinogenic properties. To date, there have been no reports on the potential neurotoxic effects of adult exposure to AAs. Serum neurofilament light chain (sNfL) is a protein released into the bloodstream following nerve axon injury and has been validated as a reliable biomarker for various neurological diseases. However, there has been no research to investigate the relationship between AAs exposure and sNfL.

Methods

In this study, we selected adults (aged ≥20 years) with data on both AAs and sNfL from the National Health and Nutrition Examination Survey (NHANES) conducted in 2013-2014. We used multivariable linear regression models to explore the correlation between urinary AAs and sNfL.

Results

In total, 510 adult participants with an average age of 43.58 ± 14.74 years were included in the study. Our findings indicate that, based on univariate linear regression and between-group comparative analyses, 1-Aminonaphthalene (1-AN), 2-Aminonaphthalene (2-AN), 4-Aminobiphenyl (4-AN) and o-Anisidine (o-ANI) showed a positive correlation with serum neurofilament light chain (P < 0.05). However, multiple linear regression analysis revealed that only 2-AN exhibited a positive correlation with serum neurofilament light chain (P < 0.05), while the correlations of other compounds with serum neurofilament light chain became non-significant.

Conclusion

Although our cross-sectional study fails to establish causal relationships or determine clinical significance, the findings indicate a potential association between adult exposure to AAs, notably 2-AN, and nerve damage. Consequently, further research is needed to explore the connection between AAs exposure, sNfL, and neurological conditions in adults.

[Highly selective sodium-glucose co-transporter type 2 inhibitor empagliflozin as means of brain protection in conditions of chronic brain dyscirculation]

BACKGROUND

Chronic brain dyscirculation is one of the frequent type 2 diabetes mellitus (DM) complications and leads to patients' disability. Sodium-glucose co-transporter type 2 inhibitors (SGLT-2i) have been proven to have advantages for cardiovascular system, but their effect on the central nervous system (CNS) has not been studied enough.

AIM

To study empagliflozin effect on CNS damage functional and laboratory parameters in patients with type 2 DM and, under experimental conditions, to investigate the mechanisms of the drug neurotropic effect.

MATERIALS AND METHODS

The clinical part of the study included patients with type 2 DM on metformin monotherapy (n=39). Patients with a target glycated hemoglobin level formed the "MET" group (n=19), in patients with a non-target glycated hemoglobin level empagliflozin was co-administered for the following 6 months (the "MET+EMPA" group, n=20). Healthy volunteers comprised the control group (n=16). The cognitive status and neuron-specific enolase (NSE) and neurofilament light chains (NLC) concentration were studied. DM was modeled in rats, thereafter the rats were treated with empagliflozin for 8 weeks. Microglia activation was assessed using anti-Iba-1 antibodies and morphological changes in neurons when stained by the Nissl method.

RESULTS

Both in the "MET+EMPA" and the "MET" groups cognitive deficits were observed, according to the Montreal Cognitive Assessment (MOCA) (24.0 (23.0; 27.0) and 25.0 (21.0; 27.0) points) and the Mini-Mental State Examination (MMSE) (23.75 (23.0; 27.0) and 25.0 (21.0; 27.0) points). Empagliflozin therapy led to the cognitive status normalization after 6 months (26.5 (24.0; 27.0) points according to the MOCA scale and 27.5 (24.0; 28.0) points according to the MMSE). Initially, all patients had a significant increase of NSE (3.60 (2.66; 3.76) ng/ml in the "MET" group, 3.22 (2.94; 3.54) ng/ml in the "MET+EMPA» group, 2.72 (2.13; 2.72) ng/ml in the «Control» group) and NLC (4.50 (3.31; 5.56) ng/ml in the «MET» group, 5, 25 (3.75; 6.25) ng/ml in the «MET+EMPA» group comparing with 3.50 (2.25; 3.50) ng/ml in the «Control» group). Empagliflozin therapy led to a significant decrease in NLC already after 3 months (3.80 (3.25; 3.87) ng/ml), without significant influence on the NSE level. In the experiment, DM was characterized by an increased number of activated microgliocytes and destructured neurons and a decreased number of neurons with a normal structure. Empagliflozin therapy was accompanied by a decrease in the number of immunopositive microgliocytes in the CA1 zone of the hippocampus and an increase in the number of structured neurons.

CONCLUSION

Type 2 diabetes mellitus is characterized by functional and biochemical changes in the central nervous system even under satisfactory glycemic control. Therapy with empagliflozin has a neuroprotective effect, manifested in an improvement in cognitive status and a decrease in NLC level. Empagliflozin reduces neuronal damage and abnormal microglial activation.

Impact of amyloid and cardiometabolic risk factors on prognostic capacity of plasma neurofilament light chain for neurodegeneration

BACKGROUND

Plasma neurofilament light chain (NfL) is a blood biomarker of neurodegeneration, including Alzheimer's disease. However, its usefulness may be influenced by common conditions in older adults, including amyloid-β (Aβ) deposition and cardiometabolic risk factors like hypertension, diabetes mellitus (DM), impaired kidney function, and obesity. This longitudinal observational study using the Alzheimer's Disease Neuroimaging Initiative cohort investigated how these conditions influence the prognostic capacity of plasma NfL.

METHODS

Non-demented participants (cognitively unimpaired or mild cognitive impairment) underwent repeated assessments including the Alzheimer's Disease Assessment Scale-Cognitive subscale (ADAS-Cog) scores, hippocampal volumes, and white matter hyperintensity (WMH) volumes at 6- or 12-month intervals. Linear mixed-effect models were employed to examine the interaction between plasma NfL and various variables of interest, such as Aβ (evaluated using Florbetapir positron emission tomography), hypertension, DM, impaired kidney function, or obesity.

RESULTS

Over a mean follow-up period of 62.5 months, participants with a mean age of 72.1 years (n = 720, 48.8% female) at baseline were observed. Higher plasma NfL levels at baseline were associated with steeper increases in ADAS-Cog scores and WMH volumes, and steeper decreases in hippocampal volumes over time (all p-values < 0.001). Notably, Aβ at baseline significantly enhanced the association between plasma NfL and longitudinal changes in ADAS-Cog scores (p-value 0.005) and hippocampal volumes (p-value 0.004). Regarding ADAS-Cog score and WMH volume, the impact of Aβ was more prominent in cognitively unimpaired than in mild cognitive impairment. Hypertension significantly heightened the association between plasma NfL and longitudinal changes in ADAS-Cog scores, hippocampal volumes, and WMH volumes (all p-values < 0.001). DM influenced the association between plasma NfL and changes in ADAS-Cog scores (p-value < 0.001) without affecting hippocampal and WMH volumes. Impaired kidney function did not significantly alter the association between plasma NfL and longitudinal changes in any outcome variables. Obesity heightened the association between plasma NfL and changes in hippocampal volumes only (p-value 0.026).

CONCLUSION

This study suggests that the prognostic capacity of plasma NfL may be amplified in individuals with Aβ or hypertension. This finding emphasizes the importance of considering these factors in the NfL-based prognostic model for neurodegeneration in non-demented older adults.

The association between joint Serum Neurofilament Light Chain and type 2 diabetes with all-cause and cardiovascular mortality in US adults: a longitudinal study of NHANES

BACKGROUND

In the past, there has been a clear conclusion regarding the sole impact of serum neurofilament light chain (sNfL) levels or type 2 diabetes mellitus (DM) on the risk of death. However, the combined effect of sNfL levels and type 2 DM on all-cause and cardiovascular mortality is still uncertain.

METHODS

This study was a prospective cohort study based on data from the National Health and Nutrition Examination Survey (NHANES). The sNfL levels were measured through immunological methods using blood samples collected during the survey. The diagnosis of diabetes was based on rigorous criteria, and participants' mortality data were followed up until December 31, 2019. Firstly, we separately examined the effects of sNfL and type 2 DM on all-cause and cardiovascular mortality, and finally studied the comprehensive impact of the combination of sNfL and type 2 DM on the risk of mortality. Cumulative Kaplan-Meier curves, multivariate logistic regression and sensitivity analysis were incorporated throughout the entire study.

RESULTS

Participants in the highest quartile of sNfL were observed. Multivariable COX regression model showed that increased sNfL levels and type 2 DM were respectively associated with an increased risk of all-cause and cardiovascular mortality. Furthermore, elevated sNfL levels were significantly associated with an increased risk of all-cause mortality and cardiovascular mortality after adjustment for confounding factors. When considering both elevated sNfL levels and type 2 DM, individuals had a significantly increased risk of mortality. Sensitivity analysis confirmed the robustness of the findings.

CONCLUSIONS

These results suggest that elevated levels of sNfL and type 2 DM are associated with an increased risk of all-cause and cardiovascular mortality, and that participants with increased sNfL levels associated with type 2 DM have higher all-cause mortality and cardiovascular mortality.

Negative association of serum neurofilament light chain with estimated glomerular filtration rate levels and the impact of gender

Background

The relationship between kidney function and brain function is complex and poorly understood. This study aims to investigate the association between serum neurofilament light chain (sNfL) and levels of estimated glomerular filtration rate (eGFR), offering new insights into their interactions.

Methods

Data from the national health and nutrition examination survey (NHANES) in 2013-2014, linked with national death index records, were used. Participants who met specific criteria were analyzed. Baseline characteristics were stratified by tertiles of sNfL levels and compared using weighted Kruskal-Wallis and chi-square tests. Weighted linear regression models, both unadjusted and adjusted, evaluated the relationship between log sNfL and eGFR. Subgroup and interaction analyses validated the findings. Restricted cubic spline, scatter plots, and Spearman correlation confirmed the relationship between log sNfL and eGFR.

Results

A total of 2,038 eligible participants were included. Higher sNfL levels were significantly associated with lower eGFR (p < 0.01). The highest sNfL tertile had a significantly higher mortality rate (p < 0.01). Fully adjusted multivariable weighted linear regression showed a significant negative correlation between log sNfL and eGFR (per 10-unit increase; β = -0.07, 95% CI: -0.10 to -0.04, p < 0.01). Subgroup analyses consistently supported this negative correlation (p < 0.01). Interaction analysis revealed a significant gender difference (p = 0.032), with males showing a - 0.06 (-0.09, -0.04) decrease and females a - 0.07 (-0.11, -0.04) decrease in log sNfL per 10-unit increase in eGFR. Restricted cubic spline confirmed a linear relationship (p-non-linear = 0.121), and the Spearman correlation coefficient was -0.45. Females had slightly lower log sNfL levels compared to males at equivalent eGFR levels.

Conclusion

A significant negative correlation was found between log sNfL and eGFR levels. Gender influenced the degree of this negative association. Further research is needed to validate these findings and elucidate their underlying mechanisms.

Elevated serum neurofilament light chain levels are associated with hepatic encephalopathy in patients with cirrhosis

Increasing evidences implicate vital role of neuronal damage in the development of hepatic encephalopathy (HE). Neurofilament light chain (NfL) is the main frame component of neurons and is closely related to axonal radial growth and neuronal structural stability. We hypothesized that NfL as a biomarker of axonal injury may contribute to early diagnosis of HE. This study recruited 101 patients with liver cirrhosis, 10 healthy individuals, and 7 patients with Parkinson's disease. Minimal hepatic encephalopathy (MHE) was diagnosed using psychometric hepatic encephalopathy score. Serum NfL levels were measured by the electrochemiluminescence immunoassay. Serum NfL levels in cirrhotic patients with MHE were significantly higher than cirrhotic patients without MHE, and increased accordingly with the aggravation of HE. Serum NfL levels were associated with psychometric hepatic encephalopathy score, Child-Pugh score, model for end-stage liver disease score, and days of hospitalization. Additionally, serum NfL was an independent predictor of MHE (odds ratio of 1.020 (95% CI 1.005-1.034); P = 0.007). The discriminative abilities of serum NfL were high for identifying MHE (AUC of 0.8134 (95% CI 0.7130-0.9219); P ˂ 0.001) and OHE (AUC of 0.8852 (95% CI 0.8117-0.9587); P ˂ 0.001). Elevated serum NfL levels correlated with the presence of MHE and associated with the severity of HE, are expected to be a biomarker in patients with cirrhosis. Our study suggested that neuronal damage may play a critical role in the development of HE.

Neuroprotective Effects of Bexarotene and Icariin in a Diabetic Rat Model

Objective Type 2 diabetes mellitus (T2DM), a chronic metabolic disorder affecting over 400 million people globally, is increasingly recognized for its detrimental impact on the central nervous system. T2DM is linked to neurodegenerative diseases like Alzheimer's and vascular dementia. This study investigates the neuroprotective effects of bexarotene and icariin in a T2DM rat model, focusing on brain-derived neurotrophic factor (BDNF), glial fibrillary acidic protein (GFAP), and neurofilament-light chain (NfL) levels. Methods Before the study, rats underwent fasting blood glucose tests, lipid profile assessments, and general health evaluations, followed by a high-fat diet for two weeks and a single streptozotocin dose (35 mg/kg). Rats with fasting blood glucose levels ≥250 mg/dl were classified as diabetes mellitus (DM) and continued on the high-fat diet throughout the experiment. Forty-seven male Wistar Albino rats were divided into six groups: a healthy control group, a DM control group, a DM group treated with bexarotene, a DM group treated with icariin, and two DM groups treated with combinations of low and high doses of bexarotene and icariin. After the 45-day treatment, blood samples were collected under thiopental sodium anesthesia, with HbA1c (glycosylated hemoglobin) and hematological parameters analyzed within eight hours, and serum stored at -80°C for further analysis. The animals were then euthanized, and brain tissues were harvested, frozen, and stored at -80°C until further examination. Brain tissues were analyzed for BDNF, GFAP, and NfL levels using ELISA (enzyme-linked immunosorbent assay). For comparing multiple groups, the Kruskal-Wallis test was applied to nonparametric data, and one-way ANOVA was used for parametric data, followed by Bonferroni's post hoc test for pairwise comparisons. Statistical significance was determined with two-tailed tests at p < 0.05. Results Significant changes in GFAP levels were observed across groups (p < 0.001). The DM control group showed the highest GFAP levels, while treatment groups exhibited reductions. The DM control group also showed the highest BDNF levels, while treatment groups exhibited reductions. The DM control group showed the lowest NfL levels, while treatment groups exhibited increments. Conclusion This study highlights the neuroprotective potential of bexarotene and icariin in a diabetic rat model, evidenced by significant changes in GFAP levels. The lack of significant changes in BDNF and NfL suggests that longer study durations may be necessary to observe these effects. Future research should include extended study periods, larger sample sizes, varied dosages, and comprehensive behavioral assessments to better understand the therapeutic potential of these agents.

Serum neurofilament light chain levels are associated with depression among US adults: a cross-sectional analysis among US adults, 2013-2014

BACKGROUND

Serum neurofilament light chain (sNfL) has been identified as a biomarker for neurologic diseases. However, sNfL remains unknown to be responsible for depression.

AIMS

The aim of this research was to explore the relationship between sNfL levels and depression in US adults.

METHODS

In this cross-sectional survey of the general population, we investigated representative data involving 10,175 participants from the 2013-2014 cycle of the National Health and Nutrition Examination Survey (NHANES). Depression was diagnosed using the Patient Health Questionnaire-9 (PHQ-9). The effect of related factors on depression was analyzed by conducting a univariate analysis. Stratified analysis was utilized to detect the stability and sensitivity of the relationship. After adjusting for race, education, marital status, smoking status, body mass index (BMI), sleep duration, income, and a history of hypertension, sedentary behavior and stroke, multivariable linear regression was performed to demonstrate the correlation between sNfL and depression.

RESULTS

A total of 1301 individuals between the ages of 20 and 75 were involved in this investigation, of which 108 (8.3%) were diagnosed with depression. A significant positive correlation between sNfL and depression among adults in the US was observed by conducting univariable analyses. After adjusting for confounding factors, the multivariate analyses indicated that elevated sNfL levels might play a pivotal role in the development of depression (odds ratio (OR) = 3.0; 95% confidence interval (CI): (1.5, 6.1), P = 0.002).

CONCLUSION

These results indicated that sNfL is closely linked to depression in a nationally representative individual. However, further studies are needed to confirm the biological mechanism as well as the clinical implications of sNfL and depression.

The limited role of serum neurofilament light chain in predicting pain severity of patients with diabetic polyneuropathy

Pain is one of many complaints expressed by patients with diabetic polyneuropathy. However, no objective measure for pain severity has been available. Neurofilament light chains have been widely used for assessing axonal damage in the neuronal system. Hence, we sought to investigate whether neurofilament light chains can serve as a marker reflecting pain severity in diabetic polyneuropathy. We enrolled the patients with diabetic polyneuropathy. Serum concentrations of neurofilament light chain were then measured using a single-molecule array. Pain severity was evaluated using painDETECT and the Brief Pain Inventory. Moreover, laboratory results including, serum creatinine, HbA1c, and glomerular filtration rate. A correlation test was used to analyze each variable. A total of 42 patients were enrolled. Neurofilament light chain levels were unable to reflect current neuropathic pain severity. However, high levels of neurofilament light chain were a significant predictor of poor diabetes control (r = 0.41; p = 0.02) and kidney damage (r = 0.45; p = 0.01). Serum levels of neurofilament light chain could not reflect current pain severity but was strongly associated with kidney dysfunction and poor diabetes control. Other biomarkers that could predict pain severity need to be uncovered.

Diagnostic value of neurofilaments in differentiating motor neuron disease from multifocal motor neuropathy

OBJECTIVE

To evaluate the performance of serum neurofilament light chain (NfL) and cerebrospinal fluid (CSF) phosphorylated neurofilament heavy chain (pNfH) as diagnostic biomarkers for the differentiation between motor neuron disease (MND) and multifocal motor neuropathy (MMN).

METHODS

This retrospective, monocentric study included 16 patients with MMN and 34 incident patients with MND. A subgroup of lower motor neuron (MN) dominant MND patients (n = 24) was analyzed separately. Serum NfL was measured using Ella automated immunoassay, and CSF pNfH was measured using enzyme-linked immunosorbent assay. Area under the curve (AUC), optimal cutoff values (Youden's index), and correlations with demographic characteristics were calculated.

RESULTS

Neurofilament concentrations were significantly higher in MND compared to MMN (p < 0.001), and serum NfL and CSF pNfH correlated strongly with each other (Spearman's rho 0.68, p < 0.001). Serum NfL (AUC 0.946, sensitivity and specificity 94%) and CSF pNfH (AUC 0.937, sensitivity 90.0%, specificity 100%) performed excellent in differentiating MND from MMN. Optimal cutoff values were ≥ 44.15 pg/mL (serum NfL) and ≥ 715.5 pg/mL (CSF pNfH), respectively. Similar results were found when restricting the MND cohort to lower MN dominant patients. Only one MMN patient had serum NfL above the cutoff. Two MND patients presented with neurofilament concentrations below the cutoffs, both featuring a slowly progressive disease.

CONCLUSION

Neurofilaments are valuable supportive biomarkers for the differentiation between MND and MMN. Serum NfL and CSF pNfH perform similarly well and elevated neurofilaments in case of diagnostic uncertainty underpin MND diagnosis.

Biomarkers of Neurodegeneration and Alzheimer's Disease Neuropathology in Adolescents and Young Adults with Youth-Onset Type 1 or Type 2 Diabetes: A Proof-of-Concept Study

Adult-onset diabetes increases one's risk of neurodegenerative disease including Alzheimer's disease (AD); however, the risk associated with youth-onset diabetes (Y-DM) remains underexplored. We quantified plasma biomarkers of neurodegeneration and AD in participants with Y-DM from the SEARCH cohort at adolescence and young adulthood (Type 1, n = 25; Type 2, n = 25; 59% female; adolescence, age = 15 y/o [2.6]; adulthood, age = 27.4 y/o [2.2]), comparing them with controls (adolescence, n = 25, age = 14.8 y/o [2.7]; adulthood, n = 21, age = 24.9 y/o [2.8]). Plasma biomarkers, including glial fibrillary acidic protein (GFAP), neurofilament light chain protein (NfL), phosphorylated tau-181 (pTau181), and amyloid beta (Aβ40, Aβ42), were measured via Simoa. A subset of participants (n = 7; age = 27.5 y/o [5.7]) and six controls (age = 25.1 y/o [4.5]) underwent PET scans to quantify brain amyloid and tau densities in AD sensitive brain regions. Y-DM adolescents exhibited lower plasma levels of Aβ40, Aβ42, and GFAP, and higher pTau181 compared to controls (p < 0.05), a pattern persisting into adulthood (p < 0.001). All biomarkers showed significant increases from adolescence to adulthood in Y-DM (p < 0.01), though no significant differences in brain amyloid or tau were noted between Y-DM and controls in adulthood. Preliminary evidence suggests that preclinical AD neuropathology is present in young people with Y-DM, indicating a potential increased risk of neurodegenerative diseases.

Longitudinal Change in Serum Neurofilament Light Chain in Type 2 Diabetes and Early Diabetic Polyneuropathy: ADDITION-Denmark

OBJECTIVE

To investigate the longitudinal development of neurofilament light chain (NfL) levels in type 2 diabetes with and without diabetic polyneuropathy (+/-DPN) and to explore the predictive potential of NfL as a biomarker for DPN.

RESEARCH DESIGN AND METHODS

We performed retrospective longitudinal case-control analysis of data from 178 participants of the Anglo-Danish-Dutch Study of Intensive Treatment in People with Screen-Detected Diabetes in Primary Care-Denmark (ADDITION-Denmark) cohort of people with screen-detected type 2 diabetes. Biobank samples acquired at the ADDITION-Denmark 5- and 10-year follow-ups were analyzed for serum NfL (s-NfL) using single-molecule array, and the results were compared with established reference material to obtain NfL z-scores. DPN was diagnosed according to Toronto criteria for confirmed DPN at the 10-year follow-up.

RESULTS

s-NfL increased over time in +DPN (N = 39) and -DPN participants (N = 139) at levels above normal age-induced s-NfL increase. Longitudinal s-NfL change was greater in +DPN than in -DPN participants (17.4% [95% CI 4.3; 32.2] or 0.31 SD [95% CI 0.03; 0.60] higher s-NfL or NfL z-score increase in +DPN compared with -DPN). s-NfL at the 5-year follow-up was positively associated with nerve conduction studies at the 10-year follow-up (P = 0.02 to <0.001), but not with DPN risk. Areas under the curve (AUCs) for s-NfL were not inferior to AUCs for the Michigan Neuropathy Screening Instrument questionnaire score or vibration detection thresholds. Higher yearly s-NfL increase was associated with higher DPN risk (odds ratio 1.36 [95% CI 1.08; 1.71] per 1 ng/L/year).

CONCLUSIONS

Our findings suggest that preceding s-NfL trajectories differ slightly between those with and without DPN and imply a possible biomarker value of s-NfL trajectories in DPN.

Association between volatile organic compounds and serum neurofilament light chain in US adults

OBJECTIVE

This study aimed to investigate the associations between exposure to blood volatile organic compounds (VOCs) and the level of serum neurofilament light chain (NfL) in adults.

METHODS

We analyzed data from the 2013-2014 National Health and Nutrition Examination Survey (NHANES), including 2008 participants aged 20 to 75 years old. Multiple linear regression models were used to examine the associations between 28 VOCs and NfL after adjusting for multiple potential confounders. Restricted cubic spline (RCS) was used to examine the potential non-linear associations.

RESULTS

The linear regression models showed that higher levels of 2,5-dimethylfuran (β = 0.042, 95 % confidence interval [CI]: 0.001, 0.096), ethyl acetate (β = 0.118, 95 % CI = 0.008, 0.304), and m-/p-xylene (β = 0.043, 95%CI = 0.012, 0.074) were associated with higher NfL levels. These estimates were largely consistent after adjusting for multiple confounders.

CONCLUSION

The findings of our study suggest a potential association between certain volatile organic compounds (2,5-dimethylfuran, ethyl acetate, and m-/p-xylene) and blood NfL levels, implying that they may have a role in revealing neurodegeneration and influencing neurological health.

Liver fibrosis, NT-ProBNP and mortality in patients with MASLD: A population-based cohort study

BACKGROUND & AIM

Liver fibrosis is the strongest predictor of liver-related mortality in many chronic liver diseases. NT-ProBNP is independently associated with cardiovascular mortality in general population settings. Here, we evaluate the relative contribution of non-invasively identified liver fibrosis and NT-ProBNP on all-cause and cardiovascular mortality in patients with metabolic (dysfunction)-associated steatotic liver disease (MASLD).

METHODS AND RESULTS

Serum NT-ProBNP levels were measured in 4229 patients with MASLD from the general population without a known history of heart failure that participated in the 1999-2004 cycles of the National Health and Nutrition Examination Survey. Presence of liver fibrosis was estimated using the Fibrosis-4 index (FIB-4). We applied Cox proportional hazard models adjusted for cardiovascular risk factors to evaluate the association between NT-ProBNP and FIB-4 levels and all-cause and cardiovascular mortality through December 2019. Mortality was lower for participants with normal levels of both biomarkers, intermediate if a single biomarker was elevated and highest when both were above the chosen threshold. In the multivariable-adjusted models, both elevated FIB-4 (≥2.67) and elevated NT-ProBNP levels (≥125 pg/ml) were independently associated with higher risks of all-cause mortality (HR 2.2, 95 % CI 1.5-3.2 and HR 1.6, 95 % CI 1.4-2.0, respectively) and cardiovascular mortality (HR 2.1, 95 % CI 1.2-3.7 and HR 2.1, 95 % CI 1.5-2.9, respectively). The associations remained consistent in subgroup analyses based on sex, obesity and age.

CONCLUSIONS

Both FIB-4 and NT-ProBNP are independently associated with higher mortality in patients with MASLD. Their combined use might prove useful to risk-stratify patients in clinical practice.

Association between urinary glyphosate levels and serum neurofilament light chain in a representative sample of US adults: NHANES 2013-2014

BACKGROUND

Glyphosate, the herbicide with the highest global usage, has been found to have links to neurological impairment in some occupational studies. Neurofilament light chain (NfL) is a protein that is released into the bloodstream following neuroaxonal damage and has emerged as a reliable biomarker for various neurological disorders. However, no research has investigated the potential link between glyphosate exposure and neurological damage or serum NfL levels in the general population.

OBJECTIVE

The objective of this study was to assess the possible correlation between glyphosate exposure and serum NfL levels in a population that is representative of the United States.

METHODS

We analyzed data from 597 adults (aged ≥20 years) from the 2013-2014 National Health and Nutrition Examination Survey (NHANES) to explore the potential correlation between urinary glyphosate levels and serum NfL levels.

RESULTS

We found a significant positive association between urinary glyphosate levels and serum NfL levels (ß-coefficient = 0.110; S.E. = 0.040; P = 0.015), indicating that higher levels of glyphosate exposure may be linked to higher levels of neuroaxonal damage. Furthermore, when glyphosate levels were divided into quintiles, we observed a significant trend of increasing mean NfL concentrations with increasing quintiles of glyphosate exposure (P for trend = 0.036). Notably, the association was more pronounced in certain subgroups, including those aged ≥40 years, non-Hispanic whites, and those with a BMI between 25 and 30.

IMPACT STATEMENT

This is the first research to suggest an association between glyphosate exposure and biomarkers indicative of neurological damage in general U.S. adults. If the correlation observed is causal, it raises concerns about the potential effects of glyphosate exposure on neurological health among U.S. adults. The study is noteworthy due to its representation of American adults aged 20 and above, as well as the use of reliable and comprehensive data from the NHANES database.

Recent Advances in Diagnostic, Prognostic, and Disease-Monitoring Biomarkers in Multiple Sclerosis

Multiple sclerosis (MS) is a highly heterogeneous disease. Currently, a combination of clinical features, MRI, and cerebrospinal fluid markers are used in clinical practice for diagnosis and treatment decisions. In recent years, there has been considerable effort to develop novel biomarkers that better reflect the pathologic substrates of the disease to aid in diagnosis and early prognosis, evaluation of ongoing inflammatory activity, detection and monitoring of disease progression, prediction of treatment response, and monitoring of disease-modifying treatment safety. In this review, the authors provide an overview of promising recent developments in diagnostic, prognostic, and disease-monitoring/treatment-response biomarkers in MS.

The potential of blood neurofilament light as a marker of neurodegeneration for Alzheimer's disease

Over the past several years, there has been a surge in blood biomarker studies examining the value of plasma or serum neurofilament light (NfL) as a biomarker of neurodegeneration for Alzheimer's disease. However, there have been limited efforts to combine existing findings to assess the utility of blood NfL as a biomarker of neurodegeneration for Alzheimer's disease. In addition, we still need better insight into the specific aspects of neurodegeneration that are reflected by the elevated plasma or serum concentration of NfL. In this review, we survey the literature on the cross-sectional and longitudinal relationships between blood-based NfL levels and other, neuroimaging-based, indices of neurodegeneration in individuals on the Alzheimer's continuum. Then, based on the biomarker classification established by the FDA-NIH Biomarker Working group, we determine the utility of blood-based NfL as a marker for monitoring the disease status (i.e. monitoring biomarker) and predicting the severity of neurodegeneration in older adults with and without cognitive decline (i.e. a prognostic or a risk/susceptibility biomarker). The current findings suggest that blood NfL exhibits great promise as a monitoring biomarker because an increased NfL level in plasma or serum appears to reflect the current severity of atrophy, hypometabolism and the decline of white matter integrity, particularly in the brain regions typically affected by Alzheimer's disease. Longitudinal evidence indicates that blood NfL can be useful not only as a prognostic biomarker for predicting the progression of neurodegeneration in patients with Alzheimer's disease but also as a susceptibility/risk biomarker predicting the likelihood of abnormal alterations in brain structure and function in cognitively unimpaired individuals with a higher risk of developing Alzheimer's disease (e.g. those with a higher amyloid-β). There are still limitations to current research, as discussed in this review. Nevertheless, the extant literature strongly suggests that blood NfL can serve as a valuable prognostic and susceptibility biomarker for Alzheimer's disease-related neurodegeneration in clinical settings, as well as in research settings.

Serum neurofilament light chain and cognition decline in US elderly: A cross-sectional study

OBJECTIVE

Early identification of cognitive impairment in neurodegenerative diseases like Alzheimer's disease (AD) is crucial. Neurofilament, a potential biomarker for neurological disorders, has gained attention. Our study aims to investigate the relationship between serum neurofilament light (sNfL) levels and cognitive function in elderly individuals in the United States.

METHODS

This cross-sectional study analyzed data from participants aged 60 and above in the National Health and Nutrition Examination Survey (2013-2014). We collected sNfL levels, cognitive function tests, sociodemographic characteristics, comorbidities, and other variables. Weighted multiple linear regression models examined the relationship between ln(sNfL) and cognitive scores. Restricted cubic spline (RCS) visualization explored nonlinear relationships. The stratified analysis examined subgroups' ln(sNfL) and cognitive function association.

RESULTS

The study included 446 participants (47.73% male). Participants with ln(sNfL) levels between 2.58 and 2.81 pg/mL (second quintile) performed relatively well in cognitive tests. After adjusting for multiple factors, ln(sNfL) levels were negatively correlated with cognitive function, with adjusted β (95% CI) as follows: immediate recall test (IRT): -0.763 (-1.301 to -0.224), delayed recall test (DRT): -0.308 (-0.576 to -0.04), animal fluency test (AFT): -1.616 (-2.639 to -0.594), and digit symbol substitution test (DSST): -2.790 (-4.369 to -1.21). RCS curves showed nonlinear relationships between ln(sNfL) and DRT, AFT, with inflection points around 2.7 pg/mL. The stratified analysis revealed a negative correlation between ln(sNfL) and cognition in specific subgroups with distinct features, with an interaction between diabetes and ln(sNfL).

INTERPRETATION

Higher sNfL levels are associated with poorer cognitive function in the elderly population of the United States. sNfL shows promise as a potential biomarker for early identification of cognitive decline.

Elevated plasma neurofilament light chain in immune-mediated neurological disorders (IMND) detected by immunomagnetic reduction (IMR)

BACKGROUND

In cases of immune-mediated neurological disorders (IMND), different syndromes are associated with antibodies against neuronal surface antigens, intra-neuronal antigens, astrocytic aquaporin, and gangliosides. These autoantibodies can be pathogenic or connected to neuroinflammation and resulting neuronal injuries. This study aims to identify a blood biomarker that can detect neuronal damage in individuals with IMND. To this end, we use immunomagnetic reduction (IMR) nanobead technology to measure plasma neurofilament light chain (NfL).

METHODS

The patients with IMND were enrolled in the Chang Gung Memorial Hospital at Keelung from 2018 to 2023. Seronegative patients were excluded based on the results of antibody tests. The healthy controls (HC) were community-dwelling adults from the Northeastern Taiwan Community Medicine Research Cohort (NTCMRC) conducted by the Community Medicine Research Center of the Keelung CGMH from 2020 to 2022. IMR technique detects magnetic susceptibility via measuring magnetic signal reduction caused by antigen-antibody immunocomplex formation on magnetic nanobeads. The plasma level of NfL was determined by the magnetic susceptibility changes in IMR.

RESULTS

The study enrolled 57 IMND patients from the hospital and 73 HC participants from the communities. The plasma NfL was significantly higher in the IMND than in the HC (11.022 ± 2.637 vs. 9.664 ± 2.610 pg/mL, p = 0.004), regardless of age effects on plasma NfL in an analysis of covariance (ANCOVA) (F = 0.720, p = 0.950). In the receiver of operation curve analysis, the area under curve for plasma NfL to discriminate IMND and HC was 0.664 (95% CI = 0.549 to 0.739, p = 0.005). The subgroup analysis of plasma NfL in the IMND patients showed no difference between peripheral immune-mediated neuropathy (IMN) and central immune-mediated encephalomyelitis (IMEM) (11.331 ± 2.895 vs. 10.627 ± 2.260 pg/mL, p = 0.322), nor between tumor and non-tumor IMND (10.784 ± 3.446 vs. 11.093 ± 2.391 pg/mL, p = 0.714). Additionally, the antibody class of ganglioside antibodies in IMN did not have an impact on plasma NfL level (p = 0.857).

CONCLUSION

Plasma NfL measurement is a reliable indicator of axonal injuries in patients with IMND. It is equally effective in detecting nerve injuries in inflammatory peripheral neuropathies and central neuroinflammation. The IMR nanobead technology offers a feasible method of detecting plasma NfL, which helps identify axonal injuries in IMND.

Diabetes: a tipping point in neurodegenerative diseases

Diabetes is associated with an increased risk and progression of Alzheimer's (AD) and Parkinson's (PD) diseases. Conversely, diabetes may confer neuroprotection against amyotrophic lateral sclerosis (ALS). It has been posited that perturbations in glucose and insulin regulation, cholesterol metabolism, and mitochondrial bioenergetics defects may underlie the molecular underpinnings of diabetes effects on the brain. Nevertheless, the precise molecular mechanisms remain elusive. Here, we discuss the evidence from molecular, epidemiological, and clinical studies investigating the impact of diabetes on neurodegeneration and highlight shared dysregulated pathways between these complex comorbidities. We also discuss promising antidiabetic drugs, molecular diagnostics currently in clinical trials, and outstanding questions and challenges for future pursuit.

The Presence and Severity of NAFLD are Associated With Cognitive Impairment and Hippocampal Damage

CONTEXT

Although cognitive impairment in nonalcoholic fatty liver disease (NAFLD) has received attention in recent years, little is known about detailed cognitive functions in histologically diagnosed individuals.

OBJECTIVE

This study aimed to investigate the association of liver pathological changes with cognitive features and further explore the underlying brain manifestations.

METHODS AND PATIENTS

We performed a cross-sectional study in 320 subjects who underwent liver biopsy. Among the enrolled participants, 225 underwent assessments of global cognition and cognitive subdomains. Furthermore, 70 individuals received functional magnetic resonance imaging scans for neuroimaging evaluations. The associations among liver histological features, brain alterations, and cognitive functions were evaluated using structural equation model.

RESULTS

Compared with controls, patients with NAFLD had poorer immediate memory and delayed memory. Severe liver steatosis (odds ratio, 2.189; 95% CI, 1.020-4.699) and ballooning (OR, 3.655; 95% CI, 1.419-9.414) were related to a higher proportion of memory impairment. Structural magnetic resonance imaging showed that patients with nonalcoholic steatohepatitis exhibited volume loss in left hippocampus and its subregions of subiculum and presubiculum. Task-based magnetic resonance imaging showed that patients with nonalcoholic steatohepatitis had decreased left hippocampal activation. Path analysis demonstrated that higher NAFLD activity scores were associated with lower subiculum volume and reduced hippocampal activation, and such hippocampal damage contributed to lower delayed memory scores.

CONCLUSIONS

We are the first to report the presence and severity of NAFLD to be associated with an increased risk of memory impairment and hippocampal structural and functional abnormalities. These findings stress the significance of early cognitive evaluation in patients with NAFLD.

Cornerstone Cellular Pathways for Metabolic Disorders and Diabetes Mellitus: Non-Coding RNAs, Wnt Signaling, and AMPK

Metabolic disorders and diabetes (DM) impact more than five hundred million individuals throughout the world and are insidious in onset, chronic in nature, and yield significant disability and death. Current therapies that address nutritional status, weight management, and pharmacological options may delay disability but cannot alter disease course or functional organ loss, such as dementia and degeneration of systemic bodily functions. Underlying these challenges are the onset of aging disorders associated with increased lifespan, telomere dysfunction, and oxidative stress generation that lead to multi-system dysfunction. These significant hurdles point to the urgent need to address underlying disease mechanisms with innovative applications. New treatment strategies involve non-coding RNA pathways with microRNAs (miRNAs) and circular ribonucleic acids (circRNAs), Wnt signaling, and Wnt1 inducible signaling pathway protein 1 (WISP1) that are dependent upon programmed cell death pathways, cellular metabolic pathways with AMP-activated protein kinase (AMPK) and nicotinamide, and growth factor applications. Non-coding RNAs, Wnt signaling, and AMPK are cornerstone mechanisms for overseeing complex metabolic pathways that offer innovative treatment avenues for metabolic disease and DM but will necessitate continued appreciation of the ability of each of these cellular mechanisms to independently and in unison influence clinical outcome.

The impact of aging and oxidative stress in metabolic and nervous system disorders: programmed cell death and molecular signal transduction crosstalk

Life expectancy is increasing throughout the world and coincides with a rise in non-communicable diseases (NCDs), especially for metabolic disease that includes diabetes mellitus (DM) and neurodegenerative disorders. The debilitating effects of metabolic disorders influence the entire body and significantly affect the nervous system impacting greater than one billion people with disability in the peripheral nervous system as well as with cognitive loss, now the seventh leading cause of death worldwide. Metabolic disorders, such as DM, and neurologic disease remain a significant challenge for the treatment and care of individuals since present therapies may limit symptoms but do not halt overall disease progression. These clinical challenges to address the interplay between metabolic and neurodegenerative disorders warrant innovative strategies that can focus upon the underlying mechanisms of aging-related disorders, oxidative stress, cell senescence, and cell death. Programmed cell death pathways that involve autophagy, apoptosis, ferroptosis, and pyroptosis can play a critical role in metabolic and neurodegenerative disorders and oversee processes that include insulin resistance, β-cell function, mitochondrial integrity, reactive oxygen species release, and inflammatory cell activation. The silent mating type information regulation 2 homolog 1 (Saccharomyces cerevisiae) (SIRT1), AMP activated protein kinase (AMPK), and Wnt1 inducible signaling pathway protein 1 (WISP1) are novel targets that can oversee programmed cell death pathways tied to β-nicotinamide adenine dinucleotide (NAD+), nicotinamide, apolipoprotein E (APOE), severe acute respiratory syndrome (SARS-CoV-2) exposure with coronavirus disease 2019 (COVID-19), and trophic factors, such as erythropoietin (EPO). The pathways of programmed cell death, SIRT1, AMPK, and WISP1 offer exciting prospects for maintaining metabolic homeostasis and nervous system function that can be compromised during aging-related disorders and lead to cognitive impairment, but these pathways have dual roles in determining the ultimate fate of cells and organ systems that warrant thoughtful insight into complex autofeedback mechanisms.

Biological variation estimates for serum neurofilament light chain in healthy subjects

OBJECTIVES

Neurofilament light chain (NfL) is an emerging biomarker of neurodegeneration disorders. Knowledge of the biological variation (BV) can facilitate proper interpretation between serial measurements. Here BV estimates for serum NfL (sNfL) are provided.

METHODS

Serum samples were collected weekly from 24 apparently healthy subjects for 10 consecutive weeks and analyzed in duplicate using the Siemens Healthineers sNfL assay on the Atellica® IM Analyzer. Outlier detection, variance homogeneity analyses, and trend analysis were performed followed by CV-ANOVA to determine BV and analytical variation (CVA) estimates with 95%CI and the associated reference change values (RCV) and analytical performance specifications (APS).

RESULTS

Despite observed differences in sNfL concentrations between males and females, BV estimates remained consistent across genders. Both within-subject BV (CVI) for males (10.7%, 95%CI; 9.2-12.6) and females (9.1%, 95%CI; 7.8-10.9) and between-subject BV (CVG) for males (26.1%, 95%CI; 18.0-45.6) and females (30.2%, 95%CI; 20.9-53.5) were comparable. An index of individuality value of 0.33 highlights significant individuality, indicating the potential efficacy of personalized reference intervals in patient monitoring.

CONCLUSIONS

The established BV estimates for sNfL underscore its potential as a valuable biomarker for monitoring neurodegenerative diseases, offering a foundation for improved decision-making in clinical settings.

Novel fluid biomarkers for mild cognitive impairment: A systematic review and meta-analysis

Mild cognitive impairment (MCI) is a well-established prodromal stage of dementia (e.g., Alzheimer's disease) that is often accompanied by early signs of neurodegeneration. To facilitate a better characterization of the underlying pathophysiology, we assessed the available literature to evaluate potential fluid biomarkers in MCI. Peer-reviewed articles that measured cerebrospinal fluid (CSF) and/or peripheral biomarkers of neuronal injury (total-tau [T-tau], neurofilament light chain [NfL], heart-type fatty acid binding protein [HFABP], neuron-specific enolase, ubiquitin C-terminal hydrolase L1) and/or astroglial pathology (glial fibrillary acidic protein [GFAP], S100 calcium-binding protein B) in MCI and healthy controls were assessed. Group differences were summarized by standardized mean differences (SMDs) and 95% confidence intervals calculated using a random-effects model. Heterogeneity was quantified using I2. A total of 107 studies were included in the meta-analysis and 10 studies were qualitatively reviewed. In CSF, concentrations of NfL (SMD = 0.69 [0.56, 0.83]), GFAP (SMD = 0.41 [0.07, 0.75]), and HFABP (SMD = 0.57 [0.26, 0.89]) were elevated in MCI. In blood, increased concentrations of T-tau (SMD = 0.19 [0.09, 0.29]), NfL (SMD = 0.41 [0.32, 0.49]), and GFAP (SMD = 0.39 [0.23, 0.55]) were found in MCI. Heterogeneity that was identified in all comparisons was explored using meta-regression and subgroup analysis. Elevated NfL and GFAP can be detected in both CSF and peripheral blood. Monitoring these biomarkers in clinical settings may provide important insight into underlying neurodegenerative processes in MCI.

Prediabetes is associated with a higher serum neurofilament light chain level in adolescents

Objective

Serum neurofilament light chain (sNfL) level, which is a biomarker indicative of neuroaxonal damage and cognitive impairment, has been reported in several neurological diseases. There has been a lack of studies on the association between sNfL levels and prediabetes in adolescents. This study investigated whether sNfL levels were higher in adolescents with prediabetes undergoing elective orthopedic surgery.

Methods

The sNfL level was measured in 149 adolescents aged from 12 to 18 years who underwent elective orthopedic surgery at the Hunan Children's Hospital (18 with and 131 without prediabetes). We evaluated the association between prediabetes and sNfL level after adjusting for age, sex, and triglycerides using a multivariable linear regression model.

Results

The prevalence of prediabetes in adolescents was 12.08%. Univariate logistic regression analysis showed that prediabetes was related to sNfL. In multivariate logistic regression analysis, the association between prediabetes with sNfL levels remained significant after adjustment for age, sex, and triglyceride. The relationship between the two was further visualized by a smoothed curve.

Conclusions

Prediabetes is associated with a higher sNfL. Further large-scale and prospective studies are needed to verify the clinical application of sNfL as a monitoring biomarker for adolescent prediabetes in adolescents and to evaluate the performance of sNfL in predicting the incidence of neuropathy and cognitive dysfunction in adolescents with prediabetes.

Serum neurofilament light chain levels are associated with all-cause mortality in the general US population

INTRODUCTION

Serum neurofilament light chain (sNfL) levels are biomarkers of neuro-axonal injury in multiple neurological diseases. Little is known on their potential role as prognostic markers in people without known neurological conditions.

OBJECTIVE

The aim of this study is to evaluate the association between sNfL levels and all-cause mortality in a general population setting.

METHODS

sNfL levels were measured in 2071 people aged 25-75 years from the general US population that participated in the 2013-2014 cycles of the National Health and Nutrition Examination Survey (NHANES). Cognitive function was evaluated in a subset of participants aged 60-75 years using the Consortium to Establish a Registry for Alzheimer's Disease-Word Learning test, the Animal Fluency test and the Digit Symbol Substitution test. We applied Cox proportional hazard models adjusted for several potential confounders to evaluate the association between sNfL and all-cause mortality through December 2019 by linking NHANES data with data from the National Death Index.

RESULTS

In a cross-sectional analysis, higher sNfL levels were associated with worse performance in all three cognitive function tests. Over a median follow-up of 6.1 years, 85 participants died. In a multivariable model adjusted for age, sex, race-ethnicity, diabetes, chronic kidney disease, harmful alcohol consumption, cigarette smoke and prevalent cardiovascular disease, higher sNfL levels were significantly and positively associated with all-cause mortality (HR per unit increase in log-transformed sNfL: 2.46, 95% CI 1.77-3.43, p < 0.001). Results were robust when analyses were stratified according to age, sex, body mass index and kidney function.

CONCLUSION

We found a positive association between sNfL levels and mortality in the general US population. Further studies are needed to understand the biological mechanisms underlying this association.