Biomarkers.

Background: [F]MK-6240 was developed for PET imaging of AD tau pathology, but the exact molecular signature of specific binding remains unclear. This study quantified levels of four phospho-tau forms and total tau in postmortem brain tissues from [F]MK-6240 imaged cases to investigate associations with antemortem [F]MK-6240 PET.

Methods: This study included four participants from the Wisconsin ADRC or WRAP with antemortem [F]MK-6240 and [C]PiB PET imaging and postmortem brain tissue obtained on average 32-months after imaging (Table 1).

Biomarkers.

Background: Specific PSEN1 mutations cause early-onset AD but their effects on blood biomarker levels are unknown. We evaluated autopsy-confirmed individuals affected by six different PSEN1 mutations; two of known (L381V, C410Y) and three (A426P/E318G, M233L, and V261I) of unknown pathogenic status. The sixth patient had Autosomal Dominant AD (ADAD) not yet genotyped.

Biomarkers.

Background: Given the increasing usage of plasma biomarkers for Alzheimer's disease (AD) studies, it is necessary to better understand relationships between plasma biomarker and PET and MR imaging outcomes, particularly within the AT(N) framework.

Method: We evaluated plasma samples from 233 subjects (age 74.05.

Biomarkers.

Background: Tau PET thresholds should detect early tau deposition and predict cognitive decline. We evaluated the relationships between the BETTH-derived sensitivity and specificity tau thresholds (Gogola et al, doi:10.2967/jnumed.

Biomarkers.

Background: Plasma phospho-tau217 (p-tau217) is a promising blood-based biomarkers for Alzheimer's disease (AD). However, the accessibility of pTau217 tests for both research and clinical applications has been constrained. Previous studies focused on highly-phenotyped cohorts that differ substantially from the wider population.

Biomarkers.

Background: Phosphorylated tau proteins accumulate in pathological aggregates which define neurodegenerative tauopathies, including Alzheimer's disease (AD). Insight into the early stages of tau polymerization/aggregation, including early hyperphosphorylation events, is critical for identification of biomarkers of incipient disease as well as novel therapy targets.

Method: We analyzed postmortem tissue sections of hippocampus from AD cases and middle frontal gyrus from non-AD cases with mainly 4R tau isoforms (progressive supranuclear palsy, PSP; corticobasal degeneration, CBD; aging related tau astrogliopathy, ARTAG) or 3R tau (Pick's disease, PiD).

Biomarkers.

Background: Imaging and plasma biomarkers are widely used in Alzheimer's disease (AD) observational studies and clinical trials. Due to the lack of racial or ethnic diversity in earlier studies, a more complete understanding of biomarker differences across racialized groups is needed. Further, results from the few previous studies have disagreed on both the magnitude and direction of AD biomarker differences in racialized groups.

Biomarkers.

Background: Amyloid β (Aβ) deposition in the brain is a pathological hallmark of Alzheimer's disease (AD). While immunoprecipitation-mass spectrometry (IP-MS) stands out as an accurate method for quantifying blood-based Aβ peptides, its major limitations such as prolonged sample preparation, extensive analysis time, large specimen volume, and high costs, present opportunities for improvement. Consequently, we aimed to develop a novel plasma IP-MS Aβ assay that employs simplified and significantly shorter analytical procedures, along with much-reduced sample volumes.

Biomarkers.

Background: High-resolution and high-contrast postmortem MRI can unveil structural abnormalities overlooked by antemortem MRI, making it well-suited for targeted pathology assessments. In community cohorts, limbic-predominant age-related TDP-43 encephalopathy (LATE) pathology is linked with smaller amygdala [Makkinejad 2019 Neurobiol Aging] and hippocampal volumes [Josephs 2015 Ann Neurol]. Whether a similar association exists in Down syndrome (DS) remains unexplored.

Alzheimer's Imaging Consortium.

Background: [18F]MK-6240 was developed for PET imaging of AD tau pathology, but the exact molecular signature of specific binding remains unclear. This study quantified levels of four phospho-tau forms and total tau in postmortem brain tissues from [18F]MK-6240 imaged cases to investigate associations with antemortem [18F]MK-6240 PET.

Methods: This study included four participants from the Wisconsin ADRC or WRAP with antemortem [18F]MK-6240 and [11C]PiB PET imaging and postmortem brain tissue obtained on average 32-months after imaging (Table 1).

Alzheimer's Imaging Consortium.

Background: Employing a custom 60-channel single-transmit/32-channel receive Tic-Tac-Toe (TTT) coil in 7T MRI imaging has enhanced the resolution and contrast for identifying White Matter Hyperintensities (WMHs), which are critical markers in Alzheimer's disease and related dementias (AD/ADRD).

Method: The method involves resecting the left hemisphere of the brain, excluding the cerebellum, followed by embalming in 10% formalin. 1.

Multi-analyte proteomic analysis identifies blood-based neuroinflammation, cerebrovascular and synaptic biomarkers in preclinical Alzheimer's disease.

Background: Blood-based biomarkers are gaining grounds for the detection of Alzheimer's disease (AD) and related disorders (ADRDs). However, two key obstacles remain: the lack of methods for multi-analyte assessments and the need for biomarkers for related pathophysiological processes like neuroinflammation, vascular, and synaptic dysfunction. A novel proteomic method for pre-selected analytes, based on proximity extension technology, was recently introduced.

A streamlined, resource-efficient immunoprecipitation-mass spectrometry method for quantifying plasma amyloid-β biomarkers in Alzheimer's disease.

High-performance, resource-efficient methods for plasma amyloid-β (Aβ) quantification in Alzheimer's disease are lacking; existing mass spectrometry-based assays are resource- and time-intensive. We developed a streamlined mass spectrometry method with a single immunoprecipitation step, an optimized buffer system, and ≤75% less antibody requirement. Analytical and clinical performances were compared with an in-house reproduced version of a well-known two-step assay.

Implementation and Assessment of Tau Thresholds in Non-Demented Individuals as Predictors of Cognitive Decline in Tau Imaging Studies.

Background: Tau accumulation in Alzheimer's disease is associated with short term clinical progression and faster rates of cognitive decline in individuals with high amyloid-β deposition. Defining an optimal threshold of tau accumulation predictive of cognitive decline remains a challenge.

Objective: We tested the ability of regional tau PET sensitivity and specificity thresholds to predict longitudinal cognitive decline.

Multi-analyte proteomic analysis identifies blood-based neuroinflammation, cerebrovascular and synaptic biomarkers in preclinical Alzheimer's disease.

Background: Blood-based biomarkers are gaining grounds for Alzheimer's disease (AD) detection. However, two key obstacles need to be addressed: the lack of methods for multi-analyte assessments and the need for markers of neuroinflammation, vascular, and synaptic dysfunction. Here, we evaluated a novel multi-analyte biomarker platform, NULISAseq CNS disease panel, a multiplex NUcleic acid-linked Immuno-Sandwich Assay (NULISA) targeting ~120 analytes, including classical AD biomarkers and key proteins defining various disease hallmarks.

Correlating hippocampal and amygdala volumes with neuropathological burden in neurodegenerative diseases using 7T postmortem MRI.

Numerous research groups worldwide have focused on postmortem imaging to bridge the resolution gap between clinical neuroimaging and neuropathology data. We developed a standardized protocol for brain embedding, imaging, and processing, facilitating alignment between antemortem MRI, postmortem MRI, and pathology to observe brain atrophy and structural damage progression over time. Using 7T postmortem ex vivo MRI, we explore the potential correlation of amygdala and hippocampal atrophy with neuropathological burden in both Down syndrome (DS) and Alzheimer's disease (AD) cohorts.

Alzheimer blood biomarkers: practical guidelines for study design, sample collection, processing, biobanking, measurement and result reporting.

Alzheimer's disease (AD), the most common form of dementia, remains challenging to understand and treat despite decades of research and clinical investigation. This might be partly due to a lack of widely available and cost-effective modalities for diagnosis and prognosis. Recently, the blood-based AD biomarker field has seen significant progress driven by technological advances, mainly improved analytical sensitivity and precision of the assays and measurement platforms.

The Role of NRF2 in Cerebrovascular Protection: Implications for Vascular Cognitive Impairment and Dementia (VCID).

Vascular cognitive impairment and dementia (VCID) represents a broad spectrum of cognitive decline secondary to cerebral vascular aging and injury. It is the second most common type of dementia, and the prevalence continues to increase. Nuclear factor erythroid 2-related factor 2 (NRF2) is enriched in the cerebral vasculature and has diverse roles in metabolic balance, mitochondrial stabilization, redox balance, and anti-inflammation.

Novel ultrasensitive immunoassay for the selective quantification of tau oligomers and related soluble aggregates.

Introduction: Tau aggregation into paired helical filaments and neurofibrillary tangles is characteristic of Alzheimer's disease (AD) and related disorders. However, biochemical assays for the quantification of soluble, earlier-stage tau aggregates are lacking. We describe an immunoassay that is selective for tau oligomers and related soluble aggregates over monomers.

Application of robust regression in translational neuroscience studies with non-Gaussian outcome data.

Linear regression is one of the most used statistical techniques in neuroscience, including the study of the neuropathology of Alzheimer's disease (AD) dementia. However, the practical utility of this approach is often limited because dependent variables are often highly skewed and fail to meet the assumption of normality. Applying linear regression analyses to highly skewed datasets can generate imprecise results, which lead to erroneous estimates derived from statistical models.

Association Between β-Amyloid Accumulation and Incident Dementia in Individuals 80 Years or Older Without Dementia.

Background And Objectives: While the highest prevalence of dementia occurs in individuals older than 80 years, most imaging studies focused on younger populations. The rates of β-amyloid (Aβ) accumulation and the effect of Alzheimer disease (AD) pathology on progression to dementia in this age group remain unexplored. In this study, we examined the relationship between changes in Aβ deposition over time and incident dementia in nondemented individuals followed during a period of 11 years.

The cell-specific roles of Nrf2 in acute and chronic phases of ischemic stroke.

Ischemic stroke refers to the sudden loss of blood flow in a specific area of the brain. It is the fifth leading cause of mortality and the leading cause of permanent disability. The transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) controls the production of several antioxidants and protective proteins and it has been investigated as a possible pharmaceutical target for reducing harmful oxidative events in brain ischemia.

Biostatistical Estimation of Tau Threshold Hallmarks (BETTH) Algorithm for Human Tau PET Imaging Studies.

A methodology for determining tau PET thresholds is needed to confidently detect early tau deposition. We compared multiple threshold-determining methods in participants who underwent either F-flortaucipir or F-MK-6240 PET scans. F-flortaucipir ( = 798) and F-MK-6240 ( = 216) scans were processed and sampled to obtain regional SUV ratios.

Astrocyte reactivity influences amyloid-β effects on tau pathology in preclinical Alzheimer's disease.

An unresolved question for the understanding of Alzheimer's disease (AD) pathophysiology is why a significant percentage of amyloid-β (Aβ)-positive cognitively unimpaired (CU) individuals do not develop detectable downstream tau pathology and, consequently, clinical deterioration. In vitro evidence suggests that reactive astrocytes unleash Aβ effects in pathological tau phosphorylation. Here, in a biomarker study across three cohorts (n = 1,016), we tested whether astrocyte reactivity modulates the association of Aβ with tau phosphorylation in CU individuals.