Neurofilament Light Concentrations Research Articles

Plasma biomarkers in chronic single moderate-severe traumatic brain injury.

Blood biomarkers are an emerging diagnostic and prognostic tool that reflect a range of neuropathological processes following traumatic brain injury (TBI). Their effectiveness in identifying long-term neuropathological processes after TBI is unclear. Studying biomarkers in the chronic phase is vital because elevated levels in TBI might result from distinct neuropathological mechanisms during acute and chronic phases. Here, we examine plasma biomarkers in the chronic period following TBI and their association with amyloid and tau PET, white matter microarchitecture, brain age and cognition. We recruited participants ≥40 years of age who had suffered a single moderate-severe TBI ≥10 years previously between January 2018 and March 2021. We measured plasma biomarkers using single molecule array technology [ubiquitin C-terminal hydrolase L1 (UCH-L1), neurofilament light (NfL), tau, glial fibrillary acidic protein (GFAP) and phosphorylated tau (P-tau181)]; PET tracers to measure amyloid-β (18F-NAV4694) and tau neurofibrillary tangles (18F-MK6240); MRI to assess white matter microstructure and brain age; and the Rey Auditory Verbal Learning Test to measure verbal-episodic memory. A total of 90 post-TBI participants (73% male; mean = 58.2 years) were recruited on average 22 years (range = 10-33 years) post-injury, and 32 non-TBI control participants (66% male; mean = 57.9 years) were recruited. Plasma UCH-L1 levels were 67% higher {exp(b) = 1.67, P = 0.018, adjusted P = 0.044, 95% confidence interval (CI) [10% to 155%], area under the curve = 0.616} and P-tau181 were 27% higher {exp(b) = 1.24, P = 0.011, adjusted P = 0.044, 95% CI [5% to 46%], area under the curve = 0.632} in TBI participants compared with controls. Amyloid and tau PET were not elevated in TBI participants. Higher concentrations of plasma P-tau181, UCH-L1, GFAP and NfL were significantly associated with worse white matter microstructure but not brain age in TBI participants. For TBI participants, poorer verbal-episodic memory was associated with higher concentration of P-tau181 {short delay: b = -2.17, SE = 1.06, P = 0.043, 95% CI [-4.28, -0.07]; long delay: bP-tau = -2.56, SE = 1.08, P = 0.020, 95% CI [-4.71, -0.41]}, tau {immediate memory: bTau = -6.22, SE = 2.47, P = 0.014, 95% CI [-11.14, -1.30]} and UCH-L1 {immediate memory: bUCH-L1 = -2.14, SE = 1.07, P = 0.048, 95% CI [-4.26, -0.01]}, but was not associated with functional outcome. Elevated plasma markers related to neuronal damage and accumulation of phosphorylated tau suggest the presence of ongoing neuropathology in the chronic phase following a single moderate-severe TBI. Plasma biomarkers were associated with measures of microstructural brain disruption on MRI and disordered cognition, further highlighting their utility as potential objective tools to monitor evolving neuropathology post-TBI.

Nutritional Optimization for Brain Health in Contact Sports: A Systematic Review and Meta-Analysis on Long-Chain ω-3 Fatty Acids and Neurofilament Light

Accumulating evidence has highlighted the acute and chronic impact of repetitive subconcussive head impacts (rSHIs) in contact sports. Neurofilament-light (Nf-L), a brain-derived biomarker of neuroaxonal injury, elevates in concert with rSHI. Recently, long-chain ω-3 polyunsaturated fatty acids (LC ω-3 PUFAs) supplementation has been suggested to mitigate brain injury from rSHI as reflected by attenuation of Nf-L concentrations within contact sport athletes. Using a systematic review with a meta-analysis, we aimed to determine the effect of LC ω-3 PUFA supplementation on Nf-L concentrations in athletes routinely exposed to rSHI. Electronic databases (PubMed and CINAHL) were searched from inception through January 2024. One-stage meta-analysis of individual participant-level data was used to detect changes in Nf-L concentrations between LC ω-3 PUFA and control/placebo (PL) groups from baseline to midseason (MS) and postseason (PS). Least square means (±SE) for Nf-L change from baseline were compared by treatment group for MS/PS using contrast t tests. Significance was set a priori at adjusted P ≤ 0.05. Of 460 records identified, 3 studies in collegiate American football players (n = 179; LC ω-3 PUFA = 105, PL = 71) were included in the meta-analysis. Compared with PL, the change in Nf-L concentrations was statistically similar at MS [mean difference (MD) = –1.66 ± 0.82 pg·mL–1, adjusted P = 0.09] and significantly lower at PS (MD = –2.23 ± 0.83 pg·mL–1, adjusted P = 0.02) in athletes following LC ω-3 PUFA supplementation. Our findings demonstrate preliminary support for the prophylactic administration of LC ω-3 PUFA in contact sport athletes exposed to rSHI; however, further research is required to determine the effective dosage required.This trial was registered at OSF (DOI: https://doi.org/10.17605/OSF.IO/EY5QW).

Neurofilament light (NfL) concentrations in patients with epilepsy with recurrent isolated seizures: Insights from a clinical cohort study

PurposeTo detect possible neuronal damage due to recurrent isolated seizures in patients with epilepsy in a clinical routine setting. MethodsWe measured the serum concentrations of neurofilament light chain (sNfL) in 46 outpatients with an at least monthly occurrence (self-reported) of generalized tonic-clonic seizures in the six months prior to the study and in 49 patients who had been seizure free (self-reported) for at least one year. We assigned the patients with seizure activity into groups with moderate and high seizure frequency. We measured sNfL with a highly sensitive single molecule array (Simoa). ResultsThe majority (94 %) of all patients with epilepsy had sNfL values within the age adjusted reference ranges of our laboratory. Three patients with and three patients without seizure activity (each 3 %) showed elevated sNfL concentrations. Age adjusted sNfL concentrations did not differ significantly between patients with and without seizure activity in the total sample or in the female subgroup. In contrast, NfL concentrations were significantly higher in male patients with seizure activity and highest in the subgroup of those with high seizure activity, but were only above the reference range in two patients. sNfL concentrations did not differ between focal and generalized epilepsies and between genetic and structural etiologies. ConclusionsThe sNfL concentrations in patients with epilepsy and healthy patients did not differ significantly. The finding of higher sNfL concentrations in males with self-reported seizure activity should be viewed with utmost caution because the difference was small and only two male patients showed sNfL concentrations above the reference range.

Blood biomarkers for neuroaxonal injury and astrocytic activation in chemotherapy-induced peripheral neuropathy.

Chemotherapy-induced peripheral neuropathy (CIPN) is a troublesome side effect in patients exposed to taxanes in the treatment of cancer and may affect quality of life dramatically. Here we assessed whether serum levels of neurofilament light (NfL) and tau (two neuroaxonal injury biomarkers) and glial fibrillary acidic protein (GFAP, a biomarker for astrocytic activation) correlate with the development of CIPN in the adjuvant setting of early breast cancer. Using ultrasensitive single molecule array technology, serum levels of NfL, GFAP, and tau were measured before and every 3 weeks in 10 women receiving adjuvant EC (epirubicin 90 mg/m² and cyclophosphamide 600 mg/m²) every 3 weeks × 3, followed by weekly paclitaxel 80 mg/m² × 9-12 weeks after surgery due to early breast cancer. CIPN was graded according to the NCI Common Terminology Criteria for Adverse Events (CTCAE v5.0) and the questionnaire EORTC QLQ CIPN-20. Serum levels of GFAP increased successively during cycles of EC. NfL increased instead in response to the treatment of paclitaxel. NfL and GFAP continued to rise throughout exposure of cumulatively higher doses of paclitaxel and were reduced 3 months after the end of chemotherapy. Serums levels of tau were marginally affected by exposure to chemotherapy. Women with worse symptoms of CIPN had higher concentrations of NfL than women with mild symptoms of CIPN. NfL and GFAP are promising biomarkers to identify women at risk of developing CIPN. Larger prospective studies are now needed.

Association of Plasma Amyloid, P-Tau, GFAP, and NfL With CSF, Clinical, and Cognitive Features in Patients With Dementia With Lewy Bodies.

Plasma β-amyloid-1-42/1-40 (Aβ42/40), phosphorylated-tau (P-tau), glial fibrillary acidic protein (GFAP), and neurofilament light (NfL) have been widely examined in Alzheimer disease (AD), but little is known about their reflection of copathologies, clinical importance, and predictive value in dementia with Lewy bodies (DLB). We aimed to evaluate associations of these biomarkers with CSF amyloid, cognition, and core features in DLB. This cross-sectional multicenter cohort study with prospective component included individuals with DLB, AD, and healthy controls (HCs), recruited from 2002 to 2020 with an annual follow-up of up to 5 years, from the European-Dementia With Lewy Bodies consortium. Plasma biomarkers were measured by single-molecule array (Neurology 4-Plex E kit). Amyloid status was determined by CSF Aβ42 concentrations, and cognition was assessed by Mini-Mental State Examination (MMSE). Biomarker differences across groups, associations with amyloid status, and clinical core features were assessed by analysis of covariance. Associations with cognitive impairment and decline were assessed by linear regression and linear mixed-effects models. In our cohort consisting of 562 individuals (HC n = 89, DLB n = 342, AD n = 131; 250 women [44.5%], mean [SD] age of 71 [8] years), sex distribution did not differ between groups. Patients with DLB were significantly older, and had less years of education and worse baseline cognition than HC, but not AD. DLB participants stratified for amyloid status differed significantly in plasma Aβ42/40 ratio (decreased in amyloid abnormal: β = -0.008, 95% CI -0.016 to -0.0003, p = 0.01) and P-tau (increased in amyloid abnormal, P-tau181: β = 0.246, 95% CI 0.011-0.481; P-tau231: β = 0.227, 95% CI 0.035-0.419, both p < 0.05), but not in GFAP (β = 0.068, 95% CI -0.018 to 0.153, p = 0.119), and NfL (β = 0.004, 95% CI -0.087 to 0.096, p = 0.923) concentrations. Higher baseline GFAP, NfL, and P-tau concentrations were associated with lower MMSE scores in DLB, and GFAP and NfL were associated with a faster cognitive decline (GFAP: annual change of -2.11 MMSE points, 95% CI -2.88 to -1.35 MMSE points, p < 0.001; NfL: annual change of -2.13 MMSE points, 95% CI -2.97 to -1.29 MMSE points, p < 0.001). DLB participants with parkinsonism had higher concentrations of NfL (β = 0.08, 95% CI 0.02-0.14, p = 0.006) than those without. Our study suggests a possible utility of plasma Aβ42/40, P-tau181, and P-tau231 as a noninvasive biomarkers to assess amyloid copathology in DLB, and plasma GFAP and NfL as monitoring biomarkers for cognitive symptoms in DLB.

Relationships between PET and blood plasma biomarkers in corticobasal syndrome.

Corticobasal syndrome (CBS) can result from underlying Alzheimer's disease (AD) pathologies. Little is known about the utility of blood plasma metrics to predict positron emission tomography (PET) biomarker-confirmed AD in CBS. A cohort of eighteen CBS patients (8amyloid beta [Aβ]+; 10Aβ-) and 8 cognitively unimpaired (CU) individuals underwent PET imaging and plasma analysis. Plasma concentrations were compared using a Kruskal-Wallis test. Spearman correlations assessed relationships between plasma concentrations and PET uptake. CBS Aβ+ group showed a reduced Aβ42/40 ratio, with elevated phosphorylated tau (p-tau)181, glial fibrillary acidic protein (GFAP), and neurofilament light (NfL) concentrations, while CBS Aβ- group only showed elevated NfL concentration compared to CU. Both p-tau181 and GFAP were able to differentiate CBS Aβ- from CBS Aβ+ and showed positive associations with Aβ and tau PET uptake. This study supports use of plasma p-tau181 and GFAP to detect AD in CBS. NfL shows potential as a non-specific disease biomarker of CBS regardless of underlying pathology. Plasma phosphorylated tau (p-tau)181 and glial fibrillary acidic protein (GFAP) concentrations differentiate corticobasal syndrome (CBS) amyloid beta (Aβ)- from CBS Aβ+. Plasma neurofilament light concentrations are elevated in CBS Aβ- and Aβ+ compared to controls. Plasma p-tau181 and GFAP concentrations were associated with Aβ and tau positron emission tomography (PET) uptake. Aβ42/40 ratio showed a negative correlation with Aβ PET uptake.

Chronic consequences of ischemic stroke: Profiling brain injury and inflammation in a mouse model with reperfusion.

Stroke is a pervasive and debilitating global health concern, necessitating innovative therapeutic strategies, especially during recovery. While existing literature often focuses on acute interventions, our study addresses the uniqueness of brain tissue during wound healing, emphasizing the chronic phase following the commonly used middle cerebral artery (MCA) occlusion model. Using clinically relevant endpoints in male and female mice such as magnetic resonance imaging (MRI) and plasma neurofilament light (NFL) measurement, along with immunohistochemistry, we describe injury evolution. Our findings document significant alterations in edema, tissue remodeling, and gadolinium leakage through MRI. Plasma NFL concentration remained elevated at 30 days poststroke. Microglia responses are confined to the region adjacent to the injury, rather than continued widespread activation, and boron-dipyrromethene (BODIPY) staining demonstrated the persistent presence of foam cells within the infarct. Additional immunohistochemistry highlighted sustained B and T lymphocyte presence in the poststroke brain. These observations underscore potentially pivotal roles played by chronic inflammation brought on by the lipid-rich brain environment, and chronic blood-brain barrier dysfunction, in the development of secondary neurodegeneration. This study sheds light on the enduring consequences of ischemic stroke in the most used rodent stroke model and provides valuable insights for future research, clinical strategies, and therapeutic development.

#2929 Plasma levels of brain injury markers NfL and GFAP are independently predicted by glomerular filtration rate in patients with chronic kidney disease

Abstract Background and Aims Patients with chronic kidney disease (CKD) have a high prevalence of cerebrovascular disease and cognitive impairment. The aim of the present study was to measure brain injury biomarkers in plasma in a cohort of patients with CKD stages 3 and 4, without a diagnosis of cerebrovascular disease, and to determine factors that independently predicted plasma levels of these biomarkers. Method This was a cross-sectional cohort study including 110 patients with CKD stages 3 and 4, and 55 healthy, matched, controls, recruited from the outpatient clinic at Sahlgrenska university hospital, Gothenburg, Sweden. None of the included study subjects had a diagnosis of cerebrovascular disease, cognitive impairment, or any other neurological disease. Plasma concentrations of neurofilament light (NfL), glial fibrillary acidic protein (GFAP) and phosphorylated Tau (p-Tau231) were analyzed with ultrasensitive single molecule array (SIMOA). Measured GFR (mGFR) was determined by plasma clearance of ⁵¹Cr-EDTA. Values are medians [interquartile range]. For linear regression analyses standardised beta coefficients (β) are presented. Results Characteristics of CKD patients and healthy controls are presented in Table 1. Plasma concentrations of NfL (37.5 [22.1-47.5] vs. 13.4 [10.5-16.7] ng/L, p &amp;lt; 0.001), p-Tau231 (25.7 [19.1-38.7] vs. 13.9 [10.5-16.3] ng/L, p &amp;lt; 0.001) and GFAP (190 [140-281] vs. 153 [116-211] ng/L, p = 0.001) were significantly elevated in patients with CKD vs. controls. In CKD patients, mGFR showed statistically significant inverse correlations to plasma concentrations of NfL, p-Tau231, and GFAP (Table 2). In multiple regression analyses, mGFR was associated with plasma levels of NfL (β = −0.457, p &amp;lt; 0.001) and GFAP (β = −0.322, p &amp;lt; 0.001) independently of diabetes, age, troponin-T, b-hemoglobin, and aortic pulse-wave velocity. However, mGFR was not significantly associated with plasma levels of p-Tau231 in a multiple regression analysis. Conclusion Plasma levels of brain injury markers NfL, p-Tau231 and GFAP were elevated in patients with CKD stages 3 and 4, without a history of cerebrovascular disease, compared to healthy controls. Furthermore, mGFR independently predicted plasma concentrations of NfL and GFAP in multiple regression models. These results raise the possibility that reduced GFR per se may be associated with subclinical brain injury.

Acute-Phase Neurofilament Light and Glial Fibrillary Acidic Proteins in Cerebrospinal Fluid Predict Long-Term Outcome After Severe Traumatic Brain Injury.

This study investigated trajectory profiles and the association of concentrations of the biomarkers neurofilament light (NfL) and glial fibrillary acidic protein (GFAP) in ventricular cerebrospinal fluid (CSF) with clinical outcome at 1 year and 10-15 years after a severe traumatic brain injury (sTBI). This study included patients with sTBI at the Neurointensive Care Unit at Sahlgrenska University Hospital, Gothenburg, Sweden. The injury was regarded as severe if patients had a Glasgow Coma Scale ≤ 8 corresponding to Reaction Level Scale ≥ 4. CSF was collected from a ventricular catheter during a 2-week period. Concentrations of NfL and GFAP in CSF were analyzed with enzyme-linked immunosorbent assay. The Glasgow Outcome Scale (GOS) was used to assess the 1-year and 10-15-year outcomes. After adjustment for age and previous neurological diseases, logistic regression was performed for the outcomes GOS 1 (dead) or GOS 2-5 (alive) and GOS 1-3 (poor) or GOS 4-5 (good) versus the independent continuous variables (NfL and GFAP). Fifty-three patients with sTBI were investigated; forty-seven adults are presented in the article, and six children (aged 7-18 years) are described in Supplement 1. The CSF concentrations of NfL gradually increased over 2 weeks post trauma, whereas GFAP concentrations peaked on days 3-4. Increasing NfL and GFAP CSF concentrations increased the odds of GOS 1-3 outcome 1 year after trauma (odds ratio [OR] 1.73, 95% confidence interval [CI] 1.07-2.80, p = 0.025; and OR 1.61, 95% CI 1.09-2.37, p = 0.016, respectively). Similarly, increasing CSF concentrations of NfL and GFAP increased the odds for GOS 1-3 outcome 10-15 years after trauma (OR 2.04, 95% CI 1.05-3.96, p = 0.035; and OR 1.60, 95% CI 1.02-2.00, p = 0.040). This study shows that initial high concentrations of NfL and GFAP in CSF are both associated with higher odds for GOS 1-3 outcome 1 year and 10-15 years after an sTBI, implicating its potential usage as a prognostic marker in the future.

Change in Enlarged Perivascular Spaces over Time and Associations with Outcomes After Traumatic Brain Injury.

Enlarged perivascular spaces (EPVs) can be seen on magnetic resonance imaging (MRI) scans in various neurological diseases, including traumatic brain injury (TBI). EPVs have been associated with cognitive dysfunction and sleep disturbances; however, their clinical significance remains unclear. The goal of this study was to identify MRI burden of EPVs over time following TBI and to explore their relationship with postinjury outcomes. Individuals with TBI underwent postinjury data collection at Day 1 (blood), 2 weeks (blood, MRI, outcomes), and 6 months (blood, MRI, outcomes). EPV burden was assessed using T1 and FLAIR sequences on representative slices in the centrum semiovale, basal ganglia, and midbrain. Serum blood was assayed to measure concentrations of neurofilament light (NfL) and glial fibrillary acidic protein (GFAP). Thirty-two participants with TBI were included (mean age 36.8 years, 78% male, 50% White). Total EPVs count did not significantly change from 2 weeks (23.5 [95% confidence interval or CI = 22.0-32.0]) to 6 months (26.0 [95% CI = 22.0-30.0], p = 0.16). For self-reported measures of sleep, there were no significant associations between EPVs count and Insomnia Severity Index (2 weeks: β = -0.004; 95% CI = -0.094, 0.086; 6 months: β = 0.002; 95% CI = -0.122, 0.125) or the subset of sleep questions on the Rivermead Post-Concussion Symptoms Questionnaire (2 weeks: β = -0.005; 95% CI = -0.049, 0.039; 6 months: β = -0.019; 95% CI = -0.079, 0.042). Functional outcome, determined by 6 months incomplete recovery (Glasgow Outcome Scale-Extended [GOS-E < 8]) versus complete recovery (GOS-E = 8), was significantly associated with a higher number of EPVs at 2 weeks (odds ratio = 0.94, 95% CI = 0.88-0.99). Spearman correlations showed no significant relationship between EPVs count and GFAP or NfL. This study used commonly acquired MRI sequences to quantify EPVs and investigated their utility as a potential imaging biomarker in TBI. Given the minimal change in EPVs over time, this period may not be long enough for potential recovery or may indicate that EPVs are structural findings that do not significantly change over time.

Comprehensive analysis of brain injury parameters in a preclinical porcine model of acute liver failure.

Acute liver failure (ALF) is defined as acute loss of liver function leading to hepatic encephalopathy associated with a high risk of patient death. Brain injury markers in serum and tissue can help detect and monitor ALF-associated brain injury. This study compares different brain injury parameters in plasma and tissue along with the progression of ALF. ALF was induced by performing an 85% liver resection. Following the resection, animals were recovered and monitored for up to 48 h or until reaching the predefined endpoint of receiving standard medical therapy (SMT). Blood and serum samples were taken at Tbaseline, T24, and upon reaching the endpoint (Tend). Control animals were euthanized by exsanguination following plasma sampling. Postmortem brain tissue samples were collected from the frontal cortex (FCTx) and cerebellum (Cb) of all animals. Glial fibrillary acidic protein (GFAP) and tau protein and mRNA levels were quantified using ELISA and qRT-PCR in all plasma and brain samples. Plasma neurofilament light (NFL) was also measured using ELISA. All ALF animals (n = 4) were euthanized upon showing signs of brain herniation. Evaluation of brain injury biomarkers revealed that GFAP was elevated in ALF animals at T24h and Tend, while Tau and NFL concentrations were unchanged. Moreover, plasma glial fibrillary acidic protein (GFAP) levels were negatively correlated with total protein and positively correlated with both aspartate transaminase (AST) and alkaline phosphatase (AP). Additionally, lower GFAP and tau RNA expressions were observed in the FCTx of the ALF group but not in the CB tissue. The current large animal study has identified a strong correlation between GFAP concentration in the blood and markers of ALF. Additionally, the protein and gene expression analyses in the FCTx revealed that this area appears to be susceptible, while the CB is protected from the detrimental impacts of ALF-associated brain swelling. These results warrant further studies to investigate the mechanisms behind this process.

Higher levels of brain injury biomarker tau are associated with unfavorable outcomes in patients supported with ECMO following cardiac arrest

AimWe sought to determine if higher plasma levels of brain injury biomarkers neurofilament light (NfL), phosphorylated tau 181 (pT181), tau, and ubiquitin C-terminal hydrolase L1 (UCHL1) were associated with unfavorable outcomes in children supported on extracorporeal membrane oxygenation (ECMO) with and without preceding cardiac arrest. MethodsWe conducted a secondary analysis of a two-center prospective observational study of ECMO patients 0-<18 years. Plasma concentrations of NfL, pT181, tau, and UCHL1 were measured on ECMO days 1, 2 and 3. Unfavorable outcome was defined as in-hospital mortality or discharge Pediatric Cerebral Performance Category (PCPC) >2 with decline from baseline PCPC among survivors. ResultsAmong 88 children on ECMO, mean tau levels were significantly higher on each of the first three ECMO days in children who underwent extracorporeal cardiopulmonary resuscitation (ECPR) compared to those with non-ECPR cardiac arrest or with no cardiac arrest preceding ECMO. Higher ECMO day 1 tau levels were significantly associated with increased hazard of unfavorable outcome in unadjusted (HR, 1.35, 95% CI 1.09–1.66) and adjusted (HR, 1.42; 95% CI 1.13–1.79) models. Higher levels of NfL or pT181 were not associated with increased hazard for unfavorable outcome in multivariable models.UCHL1 values were outside of detectable limits and thus deferred from analysis. ConclusionsLevels of tau were significantly associated with increased hazard of death or unfavorable neurologic outcome in unadjusted and adjusted models. Biomarkers of brain injury, particularly tau, may aid in detection of neurologic injury and neuroprognostication in patients on ECMO with and without preceding cardiac arrest.

Serum neurofilament light for detecting disease activity in individual patients in multiple sclerosis: A 48-week prospective single-center study

Background: Serum neurofilament light (sNfL) reflects neuroaxonal damage and is now used as an outcome in treatment trials of relapsing-remitting multiple sclerosis (RRMS). However, the diagnostic properties of sNfL for monitoring disease activity in individual patients warrant further investigations. Method: Patients with suspected relapse and/or contrast-enhancing lesions (CELs) were consecutively included and performed magnetic resonance imaging (MRI) of the brain at baseline and weeks 28 and 48. Serum was obtained at baseline and 2, 4, 8, 16, 24, and 48 weeks. Neurofilament light concentration was measured using Single molecule array technology. Results: We included 44 patients, 40 with RRMS and 4 with clinically isolated syndrome. The median sNfL level peaked at 2 weeks post-baseline (14.6 ng/L, interquartile range (IQR); 9.3–31.6) and reached nadir at 48 weeks (9.1 ng/L, IQR; 5.5–15.0), equivalent to the median sNfL of controls (9.1 ng/L, IQR; 7.4–12). A baseline Z-score of more than 1.1 (area under the curve; 0.78, p < 0.0001) had a sensitivity of 81% and specificity of 70% to detect disease activity. Conclusion: One out of five patients with relapse and/or CELs did not change significantly in post-baseline sNfL levels. The utility of repeated sNfL measurements to monitor disease activity is complementary rather than a substitute for clinical and MRI measures.

The impact of kidney function on plasma neurofilament light and phospho-tau 181 in a community-based cohort: the Shanghai Aging Study

BackgroundThe blood-based biomarkers are approaching the clinical practice of Alzheimer’s disease (AD). Chronic kidney disease (CKD) has a potential confounding effect on peripheral protein levels. It is essential to characterize the impact of renal function on AD markers.MethodsPlasma phospho-tau181 (P-tau181), and neurofilament light (NfL) were assayed via the Simoa HD-X platform in 1189 dementia-free participants from the Shanghai Aging Study (SAS). The estimated glomerular filter rate (eGFR) was calculated. The association between renal function and blood NfL, P-tau181 was analyzed. An analysis of interactions between various demographic and comorbid factors and eGFR was conducted.ResultsThe eGFR levels were negatively associated with plasma concentrations of NfL and P-tau181 (B = − 0.19, 95% CI − 0.224 to − 0.156, P < 0.001; B = − 0.009, 95% CI − 0.013 to -0.005, P < 0.001, respectively). After adjusting for demographic characteristics and comorbid diseases, eGFR remained significantly correlated with plasma NfL (B = − 0.010, 95% CI − 0.133 to − 0.068, P < 0.001), but not with P-tau181 (B = − 0.003, 95% CI − 0.007 to 0.001, P = 0.194). A significant interaction between age and eGFR was found for plasma NfL (Pinteraction < 0.001). In participants ≥ 70 years and with eGFR < 60 ml/min/1.73 m2, the correlation between eGFR and plasma NfL was significantly remarkable (B = − 0.790, 95% CI − 1.026 to − 0,554, P < 0.001).ConclusionsConsidering renal function and age is crucial when interpreting AD biomarkers in the general aging population.

Poor olfaction prior to cardiac surgery: Association with cognition, plasma neurofilament light, and post-operative delirium.

Post-operative delirium (POD) affects up to 50% of cardiac surgery patients, with higher incidence in older adults. There is increasing need for screening tools that identify individuals most vulnerable to POD. Here, we examined the relationship between pre-operative olfaction and both incident POD and POD severity in patients undergoing cardiac surgery. We also examined cross-sectional relationships between baseline olfaction, cognition, and plasma neurofilament light (NfL). Individuals undergoing cardiac surgery (n=189; mean age=70years; 75% men) were enrolled in a clinical trial of cerebral autoregulation monitoring. At baseline, odor identification performance (Brief Smell Identification Test), cognitive performance, and plasma concentrations of NfL levels (Simoa™ NF-Light Assay) were measured. Delirium was assessed with the Confusion Assessment Method (CAM) or CAM-ICU, and delirium severity was assessed using the Delirium Rating Scale-Revised-98. The association of baseline olfaction, delirium incidence, and delirium severity was examined in regression models adjusting for age, duration of cardiopulmonary bypass, logistic European System for Cardiac Operative Risk Evaluation (EuroSCORE), and baseline cognition. Olfactory dysfunction was present in 30% of patients, and POD incidence was 44%. Pre-operative olfactory dysfunction was associated with both incident POD (OR=3.17, p=0.001) and greater severity of POD after cardiac surgery (OR=3.94 p<0.001) in models adjusted for age, duration of bypass, and a surgical risk score. The addition of baseline cognition attenuated the strength of the association, but it remained significant for incident POD (OR=2.25, p=0.04) and POD severity (OR 2.10, p=0.04). Poor baseline olfaction was associated with greater baseline cognitive dysfunction (p<0.001) and increased baseline plasma NfL concentrations (p=0.04). Neither age, cognition, nor baseline NFL concentration modified the association of impaired olfaction and delirium outcomes. Olfactory assessment may be a useful pre-surgical screening tool for the identification of patients undergoing cardiac surgery at increased risk of POD. Identifying those at highest risk for severe delirium and poor cognitive outcomes following surgery would allow for earlier intervention and pre-operative rehabilitation strategies, which could ultimately impact the functional disability and morbidity associated with POD.

Characterizing the Relationship Between Arterial Carbon Dioxide Trajectory and Serial Brain Biomarkers with Central Nervous System Injury During Veno-Venous Extracorporeal Membrane Oxygenation: A Prospective Cohort Study

BackgroundCentral nervous system (CNS) injury following initiation of veno-venous extracorporeal membrane oxygenation (VV-ECMO) is common. An acute decrease in partial pressure of arterial carbon dioxide (PaCO2) following VV-ECMO initiation has been suggested as an etiological factor, but the challenges of diagnosing CNS injuries has made discerning a relationship between PaCO2 and CNS injury difficult.MethodsWe conducted a prospective cohort study of adult patients undergoing VV-ECMO for acute respiratory failure. Arterial blood gas measurements were obtained prior to initiation of VV-ECMO, and at every 2–4 h for the first 24 h. Neuroimaging was conducted within the first 7–14 days in patients who were suspected of having neurological injury or unable to be examined because of sedation. We collected blood biospecimens to measure brain biomarkers [neurofilament light (NF-L); glial fibrillary acidic protein (GFAP); and phosphorylated-tau 181] in the first 7 days following initiation of VV-ECMO. We assessed the relationship between both PaCO2 over the first 24 h and brain biomarkers with CNS injury using mixed methods linear regression. Finally, we explored the effects of absolute change of PaCO2 on serum levels of neurological biomarkers by separate mixed methods linear regression for each biomarker using three PaCO2 exposures hypothesized to result in CNS injury.ResultsIn our cohort, 12 of 59 (20%) patients had overt CNS injury identified on head computed tomography. The PaCO2 decrease with VV-ECMO initiation was steeper in patients who developed a CNS injury (− 0.32%, 95% confidence interval − 0.25 to − 0.39) compared with those without (− 0.18%, 95% confidence interval − 0.14 to − 0.21, P interaction < 0.001). The mean concentration of NF-L increased over time and was higher in those with a CNS injury (464 [739]) compared with those without (127 [257]; P = 0.001). GFAP was higher in those with a CNS injury (4278 [11,653] pg/ml) compared with those without (116 [108] pg/ml; P < 0.001). The mean NF-L, GFAP, and tau over time in patients stratified by the three thresholds of absolute change of PaCO2 showed no differences and had no significant interaction for time.ConclusionsAlthough rapid decreases in PaCO2 following initiation of VV-ECMO were slightly greater in patients who had CNS injuries versus those without, data overlap and absence of relationships between PaCO2 and brain biomarkers suggests other pathophysiologic variables are likely at play.

Serum GFAP, NfL, and tau concentrations are associated with worse neurobehavioral functioning following mild, moderate, and severe TBI: a cross-sectional multiple-cohort study.

The purpose of this study was to examine whether blood-based biomarkers associate with neurobehavioral functioning at three time points following traumatic brain injury (TBI). Participants were 328 United States service members and veterans (SMVs) prospectively enrolled in the Defense and Veterans Brain Injury Center-Traumatic Brain Injury Center of Excellence (DVBIC-TBICoE) 15-Year Longitudinal TBI Study, recruited into three groups: uncomplicated mild TBI (MTBI, n = 155); complicated mild, moderate, severe TBI combined (STBI, n = 97); non-injured controls (NIC, n = 76). Participants were further divided into three cohorts based on time since injury (≤12 months, 3-5 years, and 8-10 years). Participants completed the Minnesota Multiphasic Personality Inventory-2-Restructured Format (MMPI-2-RF) and underwent blood draw to measure serum concentrations of glial fibrillary acidic protein (GFAP), neurofilament light (NfL), and tau. A total of 11 MMPI-2-RF scales were examined (e.g., depression, anxiety, anger, somatic, cognitive symptoms). Stepwise hierarchical regression models were conducted within each group. Significant associations were found between biomarkers and MMPI-2-RF scales (all p < 0.05; R2Δ > 0.10). GFAP was inversely related to (a) neurological complaints in the MTBI group at ≤12 months, (b) demoralization, anger proneness in the STBI group at ≤12 months, and (c) head pain complaints in the STBI group at 8-10 years. NfL was (a) related to low positive emotions in the NIC group; and inversely related to (b) demoralization, somatic complaints, neurological complaints, cognitive complaints in the MTBI group at ≤12 months, (c) demoralization in the STBI group at ≤12 months, and (d) demoralization, head pain complaints, stress/worry in the STBI group at 3-5 years. In the STBI group, there were meaningful findings (R2Δ > 0.10) for tau, NFL, and GFAP that did not reach statistical significance. Results indicate worse scores on some MMPI-2-RF scales (e.g., depression, stress/worry, neurological and head pain complaints) were associated with lower concentrations of serum GFAP, NfL, and tau in the sub-acute and chronic phase of the recovery trajectory up to 5 years post-injury, with a reverse trend observed at 8-10 years. Longitudinal studies are needed to help elucidate any patterns of association between blood-based biomarkers and neurobehavioral outcome over the recovery trajectory following TBI.

Association of perioperative plasma concentration of neurofilament light with delirium after cardiac surgery: a nested observational study

BackgroundNeurofilament light is a blood-based biomarker of neuroaxonal injury that can provide insight into perioperative brain vulnerability and injury. Prior studies have suggested that increased baseline and postoperative concentrations of neurofilament light are associated with delirium after noncardiac surgery, but results are inconsistent. Results have not been reported in cardiac surgery patients, who are among those at highest risk for delirium. We hypothesised that perioperative blood concentrations of neurofilament light (both baseline and change from baseline to postoperative day 1) are associated with delirium after cardiac surgery. MethodsThis study was nested in a trial of arterial blood pressure targeting during cardiopulmonary bypass using cerebral autoregulation metrics. Blood concentrations of neurofilament light were measured at baseline and on postoperative day 1. The primary outcome was postoperative delirium. Regression models were used to examine the associations between neurofilament light concentration and delirium and delirium severity, adjusting for age, sex, race, logistic European System for Cardiac Operative Risk Evaluation, bypass duration, and cognition. ResultsDelirium occurred in 44.6% of 175 patients. Baseline neurofilament light concentration was higher in delirious than in non-delirious patients (median 20.7 pg ml−1 [IQR 16.1–33.2] vs median 15.5 pg ml−1 [IQR 12.1–24.2], P<0.001). In adjusted models, greater baseline neurofilament light concentration was associated with delirium (odds ratio, 1.027; 95% confidence interval, 1.003–1.053; P=0.029) and delirium severity. From baseline to postoperative day 1, neurofilament light concentration increased by 42%, but there was no association with delirium. ConclusionsBaseline neurofilament light concentration, but not change from baseline to postoperative day 1, was associated with delirium after cardiac surgery.

Plasma Alzheimer biomarker correlates of cerebrovascular disease in adults with Down syndrome

AbstractBackgroundBy age 40 over 90% of adults with Down syndrome (DS) develop Alzheimer’s disease (AD) pathology and most progress to dementia. Despite having fewer systemic vascular risk factors than neurotypical adults, recent studies demonstrate evidence of significant cerebrovascular disease in individuals with DS that track with the clinical progression of AD, suggesting a role for cerebrovascular disease that is not attributable solely to exposure to vascular risk factors. In the current study, we examined the codependency between white matter hyperintensity (WMH) volume, a marker of small vessel cerebrovascular disease, and AD pathophysiology, indexed with plasma AD biomarkers, in adults with DS.MethodOne hundred eighty‐seven participants from the Alzheimer Biomarkers Consortium – Down Syndrome (mean[SD] = 45.1[9.4] years) with available MRI and plasma biomarker data were included in the study. Whole‐brain WMH volumes were derived from T2‐weighted FLAIR MRI scans with in‐house software and plasma p‐tau217, Aβ42/Aβ40, and neurofilament light (NfL) concentrations were measured with SIMOA assays. Separate general linear models tested the association of WMH volume with each of the three biomarker concentrations; subsequent models were stratified by age, based on the median (46 years old).ResultHigher WMH volume was associated with increased p‐tau217 and NfL concentrations but not with Aβ. In stratified analyses, the association between WMH and NfL concentration was stronger in younger adults than in older adults whereas the association between WMH and p‐tau217 concentration was stronger in older adults than in younger adults.ConclusionOur findings suggest a co‐dependency of cerebrovascular disease with tau pathology and neurodegeneration in adults with Down syndrome. Cerebrovascular disease may promote neurodegenerative changes in early adulthood and tau changes in later adulthood. The additional or alternative possibility that tau and neurodegeneration promote white matter changes cannot be ruled out in these cross sectional analyses. Future work will address the relative temporal emergence of these markers in adults with DS.

Development of a targeted proteomic assay for the quantitation of neurofilament light in cerebrospinal fluid: Correlation with Simoa‐based quantitation across neurodegenerative diseases and centres

AbstractBackgroundCerebrospinal fluid (CSF) neurofilament light (NfL) is a dynamic biomarker of neurodegeneration that is used for supporting clinical diagnosis and monitoring disease‐modifying therapies. Development of new analytical tests has been limited, with quantitation of NfL in biomarker studies largely restricted to immunoassay methods. Targeted mass spectrometry is a highly specific technique that can be easily translated into existing proteomic and clinical pathology laboratories. In this multi‐centre study, we have developed two targeted mass spectrometry assays which were compared to Simoa, the gold standard method for NfL quantitation. The developed methods included immunocapture of intact NfL protein or specific peptides (immune‐peptide capture) prior to targeted proteomic analyses. We discuss the development, validation and merits of each technology to quantitate NfL in CSF from healthy controls and several neurodegenerative diseases.MethodCSF was collected from patients with a range of neurological diseases at the National Hospital for Neurology and Neurosurgery (London, UK). Clinical diagnosis was determined by their treating clinician according to consensus clinical criteria. NfL concentrations were measured by Simoa (Quanterix, USA) and two immunoprecipitation‐targeted mass spectrometry (IP‐MS) assays developed by a collaboration between UCL and Washington University in St Louis. To evaluate replication of results across centres and mass spectrometry approaches, results were compared using Spearman’s correlation analysis and Bland‐Altman testing.ResultsA high correlation was observed for CSF NfL levels between Simoa and both IP‐MS assays (immune‐peptide capture, r = 0.90, P&lt;0.0001 and immune‐protein capture, r = 0.88, P&lt;0.0001). Relative differences in mean NfL concentration between clinical groups remained the same across the analytical methods, with the highest and lowest NfL concentrations observed in the Huntington’s disease and the healthy control groups respectively. Interestingly, differences in the extent of correlation between Simoa and IP‐MS were observed between the different clinical groups (r = 0.37 ‐ 0.94).ConclusionImmunoprecipitation‐targeted mass spectrometry quantitation of NfL correlates highly with NfL Simoa measures across a range of neurodegenerative and neuroinflammatory diseases, and is replicable between laboratories using different immunoprecipitation‐targeted mass spectrometry approaches.