Association between plasma neurofilament light chain (NfL) concentrations and renal impairment.

Background: Neurofilament Light Chain (NfL) is a blood biomarker of axonal injury and neurodegeneration that can be used in a variety of neurological disorders. Despite the potential clinical use of plasma NfL across multiple neurological disorders, there is increasing evidence that underlying comorbidities such as renal impairment associated with chronic kidney disease (CKD) and cardiovascular diseases can increase NfL concentrations. The objective of this study was to determine the relationship between plasma NfL concentrations and renal function (CKD staging) in individuals without known neurological conditions.

Plasma and MRI biomarkers predict post‐mortem tau pathology.

Background: Imaging and plasma markers are used as key indicators of disease for Alzheimer’s disease (AD) but their usefulness in predicting regional tau pathology is relatively understudied. Our objective was to construct predictive models for regional tau pathology measured on postmortem brain tissue using multiple ante‐mortem AD biomarkers. We focused on hippocampal and parietal regions that were immunostained with AT8 and 2E9 that reflect early and advanced aspects of tangle maturity, respectively.

Older predicted age using AI EKG‐based age prediction is associated with higher Alzheimer’s disease neuropathologic change.

Background: There is increasing need for noninvasive biomarkers of Alzheimer’s Disease (AD) neuropathologic change for early detection and intervention through risk‐factor modification and disease‐modifying therapies. One such biomarker is the prediction of chronological age from routine clinical tests such as an electrocardiogram (EKG) to discriminate between observed biological age from chronological age for healthy aging. Deviation of true age from predicted age has been associated with heart failure, hypertension, and coronary heart disease.

Modeling the temporal evolution of mass spectrometry plasma biomarkers.

Background: Plasma Aβ42/40 and p‐tau217 can predict amyloid positivity in cross‐sectional studies. However, it is unclear how plasma biomarkers perform longitudinally, which is important to inform their utility in tracking disease progression. The goal of this study is to describe temporal evolutions of plasma Aβ42/40 and ptau217 ratio (p‐tau217r) measured via mass spectrometry, p‐tau217 measured via an immunoassay, and amyloid PET.

Plasma NfL and GFAP for predicting VCID brain changes in the population.

Background: Vascular contributions to cognitive impairment and dementia (VCID) are often comorbid with Alzheimer’s disease and increase the risk of dementia. Blood‐based biomarkers may be promising for identifying individuals at high risk for VCID due to small vessel disease (SVD).

Method: We included 1709 participants from the Mayo Clinic Study of Aging who had concurrent MRI, plasma neurofilament light chain (NfL) and glial fibrillary acidic protein (GFAP) measured on the HD‐X Simoa Quanterix platform, and clinical dementia rating scale (CDR).

Evaluation of Two Plasma pTau217 Simoa Assays Against Amyloid‐PET.

Background: Tau phosphorylated at threonine 217 (pTau217) is one of the most promising blood‐based biomarkers of Alzheimer’s disease (AD). This study compares the performance of two plasma pTau217 immunoassays on the Simoa platform for detection of abnormal amyloid‐PET.

Method: Plasma samples from 112 individuals without cognitive impairment and 114 with mild cognitive impairment (MCI) or AD related dementia were evaluated.

Effect of kidney function on plasma pTau217 concentrations using different pTau217 assays.

Background: Chronic kidney disease (CKD) has been associated with increased plasma phosphorylated Tau217 (pTau217) concentrations, potentially confounding its utility in the evaluation of Alzheimer's disease (AD). We assessed the association of estimated glomerular filtration rate (eGFR) with plasma pTau217 concentrations measured by various assays.

Method: We included 195 participants from the Mayo Clinic Study of Aging or the Alzheimer’s Disease Research Center with diagnoses of cognitively unimpaired (n=114), mild cognitive impairment (n=70), and AD dementia (n=11).

International Initiative for Harmonization of Plasma Neurofilament light chain NfL clinical reporting in neurodegenerative diseases.

Background: The quantification of neurofilament light chain (NfL) in blood and cerebrospinal fluid (CSF) has proved useful in many contexts, for the diagnosis and prognosis of various neurological disorders. There is, however, a diversity of practices between centers, essentially linked to the context of use (COU), analytical methods, consideration of comorbidities, determination of cut‐points or use of interpretation scales. Finally, for the same biochemical profile, the interpretation and reporting of results may differ from one center to another, raising the question of test commutability.

Amyloid PET Detects the Deposition of Brain Aβ Earlier than CSF Fluid Biomarkers.

Background: Understanding the relationship between AβPET and AβCSF biomarkers will define their potential utility in Aβ treatment. Few longitudinal or neuropathological comparisons have been reported. We assessed the relationship of AβPET and AβCSF biomarkers in a large community cohort.

Approach for developing interpretative cut‐points during implementation of a plasma p‐tau217 assay in the clinical laboratory.

Background: Implementation of Alzheimer disease blood‐based biomarkers (AD BBBs) in the clinical laboratory requires careful evaluation of test performance and selection of interpretative cut‐points to prevent patient misclassification that may lead to further evaluation, misdiagnosis, and/or potentially unnecessary treatment.

Method: Participants with mild cognitive impairment or mild dementia (n = 427) and with an EDTA‐plasma sample available within 6 months of amyloid‐PET imaging were selected through the Mayo Clinic Study of Aging and the Mayo Clinic Alzheimer’s Disease Research Center in Rochester, Minnesota. Amyloid‐PET was performed with C‐Pittsburg Compound B; abnormal amyloid (A+) was defined as Centiloid ≥25 (SUVR≥1.

Patterns in NIA Health Disparities Research Framework Domains and AD‐Plasma Biomarkers.

Background: The NIA Health Disparities Research (NIA‐HD) Framework organizes factors in four domains (i.e., environmental, sociocultural, behavioral, and biological), which work together over the lifetime to influence health and health disparities.

Amyloid Biomarker Discordance in Patients Evaluated for Anti‐Amyloid Therapy.

Background: Evidence for abnormal amyloid‐β (Aβ) plaque accumulation is necessary prior to initiating anti‐amyloid therapy in early symptomatic Alzheimer’s disease (AD). While the clinical trials for lecanemab and related drugs utilized positron emission tomography (PET) to demonstrate brain amyloidosis, current appropriate use recommendations for clinical practice consider PET or cerebrospinal fluid (CSF) biomarkers as satisfactory for this purpose. Here, we present four clinical cases where CSF biomarker results were discordant from amyloid PET, with the potential to result in erroneous treatment targeting.

Plasma and MRI biomarkers predict post‐mortem tau pathology.

Background: Imaging and plasma markers are used as key indicators of disease for Alzheimer’s disease (AD) but their usefulness in predicting regional tau pathology is relatively understudied. Our objective was to construct predictive models for regional tau pathology measured on postmortem brain tissue using multiple ante‐mortem AD biomarkers. We focused on hippocampal and parietal regions that were immunostained with AT8 and 2E9 that reflect early and advanced aspects of tangle maturity, respectively.

Elevated neurofilament light chain associated with cobalt/chromium metal neurotoxicity in a patient with a failed hip implant.

Background: It is known that the heavy metals cobalt and chromium are associated with neurotoxicity. Chromium (Cr) and Cobalt (Co) are both components of metal-on-metal (MoM) implants which can be degraded/fragmented and released into the bloodstream. Neurofilament Light Chain (NfL) is a neuron-specific protein that increases in serum following axonal damage.

Performance of dehydroepiandrosterone sulfate and baseline cortisol in assessing adrenal insufficiency.

Context: Diagnosing adrenal insufficiency (AI) often requires complex testing which can be time consuming and expensive. Dehydroepiandrosterone sulfate (DHEAS) is a promising marker of hypothalamic-pituitary-adrenal (HPA) axis function, however its diagnostic performance has not yet been evaluated in a large-scale study.

Objective: Evaluate the performance of DHEAS and baseline cortisol in assessing AI.

Performance Characteristics of a Calculated Index Control Method for the phi Multianalyte Assay with Algorithmic Analysis.

Background: Multianalyte assays with algorithmic analysis (MAAAs), such as the Prostate Health Index (phi), are increasingly utilized for generating disease risk scores. Currently, imprecision and bias in phi are not directly monitored by quality control (QC) assessment of the index but rather by QC assessment of individual components. This may not be adequately controlling for imprecision and bias in the calculated multicomponent phi value itself.

Can integration of Alzheimer's plasma biomarkers with MRI, cardiovascular, genetics, and lifestyle measures improve cognition prediction?

There is increasing interest in Alzheimer's disease related plasma biomarkers due to their accessibility and scalability. We hypothesized that integrating plasma biomarkers with other commonly used and available participant data (MRI, cardiovascular factors, lifestyle, genetics) using machine learning (ML) models can improve individual prediction of cognitive outcomes. Further, our goal was to evaluate the heterogeneity of these predictors across different age strata.

Defining the Functional Sensitivity for the Siemens Atellica Calcitonin Assay: Insight From a Single-Center Study.

Background: Detectable, and especially rising postthyroidectomy serum calcitonin and carcinoembryonic antigen levels, as per American Thyroid Association guidelines, indicate potential disease presence, requiring frequent calcitonin measurement or imaging for early detection of persistent or recurrent medullary thyroid carcinoma. Thus, defining the clinical cutoff value of detection of calcitonin assays relative to imaging and clinical status is crucial for patient care. This study aimed to evaluate postoperative calcitonin levels using the new Siemens Atellica assay system to determine the most appropriate levels for clinical decision-making.

Optimizing cutpoints for clinical interpretation of brain amyloid status using plasma p-tau217 immunoassays.

Introduction: We aimed to evaluate clinical interpretation cutpoints for two plasma phosphorylated tau (p-tau)217 assays (ALZpath and Lumipulse) as predictors of amyloid status for implementation in clinical practice.

Methods: Clinical performance of plasma p-tau217 against amyloid positron emission tomography status was evaluated in participants with mild cognitive impairment or mild dementia (n = 427).

Results: Using a one-cutpoint approach (negative/positive), neither assay achieved ≥ 90% in both sensitivity and specificity.

Alzheimer Disease Cerebrospinal Fluid Biomarkers in a Tertiary Neurology Practice.

Objective: To evaluate the performance of Alzheimer disease (AD) cerebrospinal fluid (CSF) biomarkers in a tertiary neurology clinic setting with high frequency of non-AD cases, including normal pressure hydrocephalus (NPH).

Methods: There were 534 patients who underwent AD CSF biomarkers (Roche Elecsys Aβ42, p-Tau181, total-Tau) from April 1, 2020, through April 23, 2021. A behavioral neurologist blinded to CSF results assigned a clinical diagnosis retrospectively on the basis of consensus criteria, and a neuroradiologist blinded to the diagnosis and CSF studies graded brain magnetic resonance images for indicators of CSF dynamics disorders.

Head-to-head comparison of four plasma neurofilament light chain (NfL) immunoassays.

Background: Neurofilament Light Chain (NfL) is an emerging blood biomarker of neuro-axonal injury and neurodegeneration with the potential to be used in the clinical management of various neurological conditions. Various NfL immunoassays are in development on high-throughput automated systems, but little information is available related to the comparability between assays. In this study, we performed a head-to-head comparison of four NfL immunoassays using plasma samples from individuals with various neurological conditions.

Acceptable performance of blood biomarker tests of amyloid pathology - recommendations from the Global CEO Initiative on Alzheimer's Disease.

Anti-amyloid treatments for early symptomatic Alzheimer disease have recently become clinically available in some countries, which has greatly increased the need for biomarker confirmation of amyloid pathology. Blood biomarker (BBM) tests for amyloid pathology are more acceptable, accessible and scalable than amyloid PET or cerebrospinal fluid (CSF) tests, but have highly variable levels of performance. The Global CEO Initiative on Alzheimer's Disease convened a BBM Workgroup to consider the minimum acceptable performance of BBM tests for clinical use.