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INTRODUCTION: This study investigates the effect of apolipoprotein E (APOE) genotype on neurology plasma biomarkers in cognitively healthy Super‐Seniors. METHODS: Three hundred seventy plasma specimens from Super‐Senior participants ≥ 85 years old, who have never been diagnosed with dementia, cancer, diabetes, cardiovascular, or major pulmonary disease, were analyzed on the Quanterix Simoa HD‐X analyzer using commercial Neurology 4‐plex E and phosphorylated tau (p‐tau)181 assays. RESULTS: Eighty (22%) participants were APOE ε4 carriers and 290 (73%) were non‐carriers. No significant differences were found between APOE ε4 carriers and non‐carriers regarding age, sex, or Mini‐Mental State Examination scores. In APOE ε4 carriers, plasma amyloid beta 42/40 was lower and p‐tau181 and glial fibrillary acidic protein were higher compared to non‐APOE ε4 carriers. After adjusting for demographic variables, p‐tau181 was the only biomarker to remain significantly associated with APOE ε4 carrier status. DISCUSSION: APOE ε4 genotype modifies plasma p‐tau181 concentration in seniors resilient to age‐related clinical disease, suggesting that some Super‐Seniors may have Alzheimer's disease pathology without progressing to cognitive decline. Highlights: Healthy seniors enable identification of associations that may be masked by disease.Plasma phosphorylated tau (p‐tau)181 concentrations associate with apolipoprotein E (APOE) ε4 carriership in healthy seniors.APOE should be accounted for when interpreting p‐tau181, regardless of disease. [ABSTRACT FROM AUTHOR]

Blood biomarkers have the potential to transform diagnosis and prognosis for multiple neurological indications. Establishing normative data is a critical benchmark in the analytical validation process. Normative data are important in children as little is known about how brain development may impact potential biomarkers. The objective of this study is to generate pediatric reference intervals (RIs) for serum neurofilament light (NfL), an axonal marker, and glial fibrillary acidic protein (GFAP), an astrocytic marker. Serum from healthy children and adolescents aged 1 to <19 years were obtained from the Canadian Laboratory Initiative on Pediatric Reference Intervals (CALIPER) cohort. Serum NfL (n=300) and GFAP (n=316) were quantified using Simoa technology, and discrete RI (2.5th and 97.5th percentiles) and continuous RI (5th and 95th percentiles) were generated. While there was no association with sex, there was a statistically significant (p<0.0001) negative association between age and serum NfL (Rho −0.400) and GFAP (Rho −0.749). Two statistically significant age partitions were generated for NfL: age 1 to <10 years (lower, upper limit; 3.13, 20.6 pg/mL) and 10 to <19 years (1.82, 7.44 pg/mL). For GFAP, three statistically significant age partitions were generated: age 1 to <3.5 years (80.4, 601 pg/mL); 3.5 to <11 years (50.7, 224 pg/mL); and 11 to <19 years (26.2, 119 pg/mL). Taken together with the literature on adults, NfL and GFAP display U-shaped curves with high levels in infants, decreasing levels during childhood, a plateau during adolescence and early adulthood and increasing levels in seniors. These normative data are expected to inform future pediatric studies on the importance of age on neurological blood biomarkers. [ABSTRACT FROM AUTHOR]

Background: Informative, readily accessible plasma biomarkers of pathology, neuroinflammation, and neurodegeneration in Alzheimer's disease (AD) could enhance targeted approaches to AD trial design and treatment. In post‐hoc analyses, we examined whether plasma biomarkers (Aβ1‐40, Aβ1‐42, total tau, p‐tau‐181, NfL, and GFAP) predicted 48‐week change in cognitive (ADAS‐Cog11), global function (CDR‐SB), and volumetric MRI (6 cortical regions and 2 whole brain measures) outcomes in T2 Protect AD, a phase‐2 placebo‐controlled RCT of troriluzole in mild‐to‐moderate AD (NCT03605667). Method: At least one baseline biomarker measurement was available for 319 of 350 trial participants, forming the analytic sample. No significant treatment effects were found in T2 Protect AD (Feldman 2021, JPAD 8(4):s46); thus, treatment arms were pooled for this analysis. Baseline levels of, and 48‐week changes in, plasma biomarkers were assessed for association with 48‐week change in outcomes using linear regression adjusted for relevant covariates. Combinations of baseline plasma biomarkers that best predicted 48‐week decline on the ADAS‐Cog11 and CDR‐SB were identified using LASSO regression. Statistical significance level was 5%; p‐values were Bonferroni corrected for multiple comparisons. Result: Participant characteristics are presented in Table 1. Higher baseline plasma NfL predicted greater 48‐week decline on ADAS‐Cog11 (p = 0.026) and CDR‐SB (p = 0.048; Fig. 1A). LASSO revealed that the combination of baseline plasma NfL, total tau, and Aβ42/40 ratio best predicted 48‐week decline on ADAS‐Cog11, whereas baseline NfL alone best predicted 48‐week decline on CDR‐SB. Regarding MRI outcomes, baseline NfL predicted increase in ventricular volume (p = 0.018; Fig 1A). Baseline NfL, GFAP, and p‐tau‐181 each predicted 48‐week decline in mid‐temporal cortical volume (all p<0.02; Fig.1B); LASSO results were similar. The only significant association between 48‐week biomarker change and clinical outcomes was between increased plasma NfL and worsening CDR‐SB. Conclusion: Elevated baseline plasma NfL predicted greater 48‐week decline on cognitive, global function, and MRI measures in a clinical trial of mild‐to‐moderate AD. Furthermore, greater increase in plasma NfL over time was associated with greater clinical decline. Plasma NfL is an easily accessible biomarker that may enhance AD clinical trial design and treatment strategies. Acknowledgement: Trial funding by Biohaven Pharmaceuticals; data and trial coordination by the Alzheimer's Disease Cooperative Study (ADCS). [ABSTRACT FROM AUTHOR]

Hypoxic ischaemic brain injury after resuscitation from cardiac arrest is associated with dismal clinical outcomes. To date, most clinical interventions have been geared towards the restoration of cerebral oxygen delivery after resuscitation; however, outcomes in clinical trials are disappointing. Therefore, alternative disease mechanism(s) are likely to be at play, of which the response of the innate immune system to sterile injured tissue in vivo after reperfusion has garnered significant interest. The innate immune system is composed of three pillars: (i) cytokines and signalling molecules; (ii) leucocyte migration and activation; and (iii) the complement cascade. In animal models of hypoxic ischaemic brain injury, pro‐inflammatory cytokines are central to propagation of the response of the innate immune system to cerebral ischaemia–reperfusion. In particular, interleukin‐1 beta and downstream signalling can result in direct neural injury that culminates in cell death, termed pyroptosis. Leucocyte chemotaxis and activation are central to the in vivo response to cerebral ischaemia–reperfusion. Both parenchymal microglial activation and possible infiltration of peripherally circulating monocytes might account for exacerbation of an immunopathological response in humans. Finally, activation of the complement cascade intersects with multiple aspects of the innate immune response by facilitating leucocyte activation, further cytokine release and endothelial activation. To date, large studies of immunomodulatory therapies have not been conducted; however, lessons learned from historical studies using therapeutic hypothermia in humans suggest that quelling an immunopathological response might be efficacious. Future work should delineate the precise pathways involved in vivo in humans to target specific signalling molecules. [ABSTRACT FROM AUTHOR]

Background: Prognostication is very important to clinicians and families during the early management of severe traumatic brain injury (sTBI), however, there are no gold standard biomarkers to determine prognosis in sTBI. As has been demonstrated in several diseases, early measurement of serum metabolomic profiles can be used as sensitive and specific biomarkers to predict outcomes. Methods: We prospectively enrolled 59 adults with sTBI (Glasgow coma scale, GCS ≤ 8) in a multicenter Canadian TBI (CanTBI) study. Serum samples were drawn for metabolomic profiling on the 1st and 4th days following injury. The Glasgow outcome scale extended (GOSE) was collected at 3- and 12-months post-injury. Targeted direct infusion liquid chromatography-tandem mass spectrometry (DI/LC–MS/MS) and untargeted proton nuclear magnetic resonance spectroscopy (1H-NMR) were used to profile serum metabolites. Multivariate analysis was used to determine the association between serum metabolomics and GOSE, dichotomized into favorable (GOSE 5–8) and unfavorable (GOSE 1–4), outcomes. Results: Serum metabolic profiles on days 1 and 4 post-injury were highly predictive (Q2 > 0.4–0.5) and highly accurate (AUC > 0.99) to predict GOSE outcome at 3- and 12-months post-injury and mortality at 3 months. The metabolic profiles on day 4 were more predictive (Q2 > 0.55) than those measured on day 1 post-injury. Unfavorable outcomes were associated with considerable metabolite changes from day 1 to day 4 compared to favorable outcomes. Increased lysophosphatidylcholines, acylcarnitines, energy-related metabolites (glucose, lactate), aromatic amino acids, and glutamate were associated with poor outcomes and mortality. Discussion: Metabolomic profiles were strongly associated with the prognosis of GOSE outcome at 3 and 12 months and mortality following sTBI in adults. The metabolic phenotypes on day 4 post-injury were more predictive and significant for predicting the sTBI outcome compared to the day 1 sample. This may reflect the larger contribution of secondary brain injury (day 4) to sTBI outcome. Patients with unfavorable outcomes demonstrated more metabolite changes from day 1 to day 4 post-injury. These findings highlighted increased concentration of neurobiomarkers such as N-acetylaspartate (NAA) and tyrosine, decreased concentrations of ketone bodies, and decreased urea cycle metabolites on day 4 presenting potential metabolites to predict the outcome. The current findings strongly support the use of serum metabolomics, that are shown to be better than clinical data, in determining prognosis in adults with sTBI in the early days post-injury. Our findings, however, require validation in a larger cohort of adults with sTBI to be used for clinical practice. [ABSTRACT FROM AUTHOR]