Polygenic risk discriminates Lewy body dementia from Alzheimer's disease.

Introduction: Lewy body dementia (LBD) shares genetic risk factors with Alzheimer's disease (AD), including apolipoprotein E (APOE), but is distinguishable at the genome-wide level. Polygenic risk scores (PRS) may therefore improve diagnostic classification.

Methods: We assessed diagnostic classification using AD-PRS excluding APOE (AD-PRS ), APOE risk score (APOE-RS), and plasma phosphorylated tau 181 (p-tau181), in 83 participants with LBD, 27 with positron emission tomography amyloid beta (Aβ)positive mild cognitive impairment or AD (MCI+/AD), and 57 controls.

Identify biological Alzheimer's disease using a novel nucleic acid-linked protein immunoassay.

Blood-based biomarkers have been revolutionizing the detection, diagnosis and screening of Alzheimer's disease. Specifically, phosphorylated-tau variants (p-tau, p-tau and p-tau) are promising biomarkers for identifying Alzheimer's disease pathology. Antibody-based assays such as single molecule arrays immunoassays are powerful tools to investigate pathological changes indicated by blood-based biomarkers and have been studied extensively in the Alzheimer's disease research field.

Cerebral Microbleeds and Amyloid Pathology Estimates From the Amyloid Biomarker Study.

Importance: Baseline cerebral microbleeds (CMBs) and APOE ε4 allele copy number are important risk factors for amyloid-related imaging abnormalities in patients with Alzheimer disease (AD) receiving therapies to lower amyloid-β plaque levels.

Objective: To provide prevalence estimates of any, no more than 4, or fewer than 2 CMBs in association with amyloid status, APOE ε4 copy number, and age.

Design, Setting, And Participants: This cross-sectional study used data included in the Amyloid Biomarker Study data pooling initiative (January 1, 2012, to the present [data collection is ongoing]).

Depressive Symptoms and Amyloid Pathology.

Importance: Depressive symptoms are associated with cognitive decline in older individuals. Uncertainty about underlying mechanisms hampers diagnostic and therapeutic efforts. This large-scale study aimed to elucidate the association between depressive symptoms and amyloid pathology.

Polygenic risk scores for atrial fibrillation and heart failure and the risk of stroke and dementia.

Atrial fibrillation and heart failure have both been suggested to increase stroke and dementia risk. However, in observational studies, reversed causation and unmeasured confounding may occur. To mitigate these issues, this study aims to investigate if higher genetic risk for atrial fibrillation and heart failure increases dementia and stroke risk.

Short-term variability of Alzheimer's disease plasma biomarkers in a mixed memory clinic cohort.

Background: For clinical implementation of Alzheimer's disease (AD) blood-based biomarkers (BBMs), knowledge of short-term variability, is crucial to ensure safe and correct biomarker interpretation, i.e., to capture changes or treatment effects that lie beyond that of expected short-term variability and considered clinically relevant.

Single- versus two-test criteria for cognitive impairment: associations with CSF and imaging markers in former American football players.

 Cognitive impairment is a core feature of traumatic encephalopathy syndrome (TES), the putative clinical syndrome of chronic traumatic encephalopathy-a neuropathological disease associated with repetitive head impacts (RHI). Careful operationalization of cognitive impairment is essential to improving the diagnostic specificity and accuracy of TES criteria. We compared single- versus two-test criteria for cognitive impairment in their associations with CSF and imaging biomarkers in male former American football players.

MAPPING THE CEREBROSPINAL FLUID PROTEOME IN BIPOLAR DISORDER.

Background: Bipolar disorder (BD) is a severe psychiatric condition with unclear etiology and no established biomarkers. Here, we aimed to characterize the cerebrospinal fluid (CSF) proteome in euthymic BD individuals to identify potential protein biomarkers.

Methods: We employed nano-flow liquid chromatography coupled to high-resolution mass spectrometry to quantify over 2,000 CSF proteins in 374 individuals from two independent clinical cohorts (n=164+89 and 66+55 cases and controls, respectively).

Novel synaptic markers predict early tau pathology and cognitive deficit in an asymptomatic population at risk of Alzheimer's disease.

Cognitive dysfunction in Alzheimer's disease (AD) correlates closely with pathology in the neuronal microtubule-associated protein tau. Tau pathology may spread via neural synapses. In a population of cognitively unimpaired elderly at elevated risk of AD, we investigated four cerebrospinal (CSF) markers of synaptic dysfunction and degeneration.

Association between herpes simplex virus infection and Alzheimer's disease biomarkers: analysis within the MAPT trial.

In vitro and animal studies have suggested that inoculation with herpes simplex virus 1 (HSV-1) can lead to amyloid deposits, hyperphosphorylation of tau, and/or neuronal loss. Here, we studied the association between HSV-1 and Alzheimer's disease biomarkers in humans. Our sample included 182 participants at risk of cognitive decline from the Multidomain Alzheimer Preventive Trial who had HSV-1 plasma serology and an amyloid PET scan.

Plasma biomarkers of amyloid, tau, astrogliosis, and axonal injury in a mixed memory clinic cohort.

Introduction: Studies have shown that blood biomarkers can differentiate dementia disorders. However, the diagnosis of dementia still relies primarily on cerebrospinal fluid and imaging modalities. The new disease-modifying treatments call for more widely applicable biomarkers.

Know your brain aging to know your resilience in neurodegenerative diseases.

This scientific commentary refers to 'Brain aging rejuvenation factors in adults with genetic and sporadic neurodegenerative disease', by Casaletto . (https://doi.org/10.

Cutting through the noise: A narrative review of Alzheimer's disease plasma biomarkers for routine clinical use.

As novel, anti-amyloid therapies have become more widely available, access to timely and accurate diagnosis has become integral to ensuring optimal treatment of patients with early-stage Alzheimer's disease (AD). Plasma biomarkers are a promising tool for identifying AD pathology; however, several technical and clinical factors need to be considered prior to their implementation in routine clinical use. Given the rapid pace of advancements in the field and the wide array of available biomarkers and tests, this review aims to summarize these considerations, evaluate available platforms, and discuss the steps needed to bring plasma biomarker testing to the clinic.

Clinical utility of plasma p-tau217 in identifying abnormal brain amyloid burden in an Asian cohort with high prevalence of concomitant cerebrovascular disease.

Introduction: Using an Asian cohort with high prevalence of concomitant cerebrovascular disease (CeVD), we evaluated the performance of a plasma immunoassay for tau phosphorylated at threonine 217 (p-tau217) in detecting amyloid beta positivity (Aβ+) on positron emission tomography and cognitive decline, based on a three-range reference, which stratified patients into low-, intermediate-, and high-risk groups for Aβ+.

Methods: Brain amyloid status (Aβ- [n = 142] vs Aβ+ [n = 73]) on amyloid PET scans was assessed along with the plasma ALZpath p-tau217 assay to derive three-range reference points for PET Aβ+ based on 90% sensitivity (lower threshold) and 90% specificity (upper threshold).

Results: Plasma p-tau217 (area under the curve [AUC] = 0.

Menopausal hormone therapy is associated with worse levels of Alzheimer's disease biomarkers in APOE ε4-carrying women: An observational study.

Introduction: Menopausal hormone therapy (MHT), along with the apolipoprotein E (APOE) ε4 allele, has been suggested as a possible risk factor for Alzheimer's disease (AD). However, the relationship between MHT and cerebrospinal fluid (CSF) biomarkers is unknown: we investigated this association, and whether APOE ε4 carrier status moderates it.

Methods: In an observational study of 136 cognitively unimpaired female participants (M = 66.

Consuming a modified Mediterranean ketogenic diet reverses the peripheral lipid signature of Alzheimer's disease in humans.

Background: Alzheimer's disease (AD) is a major neurodegenerative disorder with significant environmental factors, including diet and lifestyle, influencing its onset and progression. Although previous studies have suggested that certain diets may reduce the incidence of AD, the underlying mechanisms remain unclear.

Method: In this post-hoc analysis of a randomized crossover study of 20 elderly adults, we investigated the effects of a modified Mediterranean ketogenic diet (MMKD) on the plasma lipidome in the context of AD biomarkers, analyzing 784 lipid species across 47 classes using a targeted lipidomics platform.

Plasma p-tau and neurofilament/p-tau ratio in differentiating Alzheimer's disease from syndromes associated with frontotemporal lobar degeneration.

Introduction: Plasma-based biomarkers have shown promise for clinical implementation, but their accuracy in differentiating Alzheimer's disease (AD) from syndromes associated with frontotemporal lobar degeneration (FTLD) has yet to be fully investigated. This study assessed the potential of plasma biomarkers for differential diagnosis.

Methods: This cohort study included 374 participants (96 AD, 278 FTLD).

Spontaneous and perturbation-based EEG cortical excitability markers are associated with plasma p-tau181 concentration in healthy middle-aged adults.

In early-stage Alzheimer's disease (AD) amyloid-β (Aβ) deposition can induce neuronal hyperactivity, thereby potentially triggering activity-dependent neuronal secretion of phosphorylated tau (p-tau), ensuing tau aggregation and spread. Therefore, cortical excitability is a candidate biomarker for early AD detection. Moreover, lowering neuronal excitability could potentially complement strategies to reduce Aβ and tau buildup.

Vascular endothelial growth factor receptor-1 (FLT1) interactions with amyloid-beta in Alzheimer's disease: A putative biomarker of amyloid-induced vascular damage.

We have identified FLT1 as a protein that changes during Alzheimer's disease (AD) whereby higher brain protein levels are associated with more amyloid, more tau, and faster longitudinal cognitive decline. Given FLT1's role in angiogenesis and immune activation, we hypothesized that FLT1 is upregulated in response to amyloid pathology, driving a vascular-immune cascade resulting in neurodegeneration and cognitive decline. We sought to determine (1) if in vivo FLT1 levels (CSF and plasma) associate with biomarkers of AD neuropathology or differ between diagnostic staging in an aged cohort enriched for early disease, and (2) whether FLT1 expression interacts with amyloid on downstream outcomes, such as phosphorylated tau levels and cognitive performance.

Guidelines for the standardization of pre-analytical variables for salivary biomarker studies in Alzheimer's disease research: An updated review and consensus of the Salivary Biomarkers for Dementia Research Working Group.

There is a pressing need for accessible biomarkers with high diagnostic accuracy for Alzheimer's disease (AD) diagnosis to facilitate widespread screening, particularly in underserved groups. Saliva is an emerging specimen for measuring AD biomarkers, with distinct contexts of use that could complement blood and cerebrospinal fluid and detect various analytes. An interdisciplinary, international group of AD and related dementias (ADRD) researchers convened and performed a narrative review of published studies on salivary AD biomarkers.

Sex differences in the relationships between 24-h rest-activity patterns and plasma markers of Alzheimer's disease pathology.

Background: Although separate lines of research indicated a moderating role of sex in both sleep-wake disruption and in the interindividual vulnerability to Alzheimer's disease (AD)-related processes, the quantification of sex differences in the interplay between sleep-wake dysregulation and AD pathology remains critically overlooked. Here, we examined sex-specific associations between circadian rest-activity patterns and AD-related pathophysiological processes across the adult lifespan.

Methods: Ninety-two cognitively unimpaired adults (mean age = 59.

Plasma phosphorylated tau and neuropsychiatric symptoms in dementia with Lewy bodies.

Introduction: Neuropsychiatric symptoms (NPSs) are common in dementia with Lewy bodies (DLB) but their neurobiological mechanisms are poorly understood.

Methods: NPSs and cognition were assessed annually in participants (DLB n = 222; Alzheimer's disease [AD] n = 125) from the European DLB (E-DLB) Consortium, and plasma phosphorylated tau-181 (p-tau181) and p-tau231 concentrations were measured at baseline.

Results: Hallucinations, delusions, and depression were more common in DLB than in AD and, in a subgroup with longitudinal follow-up, persistent hallucinations and NPSs were associated with lower p-tau181 and p-tau231 in DLB.

The CSF p-tau/β-amyloid 42 ratio correlates with brain structure and fibrillary β-amyloid deposition in cognitively unimpaired individuals at the earliest stages of pre-clinical Alzheimer's disease.

CSF concentrations of β-amyloid 42 (Aβ42) and phosphorylated tau (p-tau) are well-established biomarkers of Alzheimer's disease and have been studied in relation to several neuropathological features both in patients and in cognitively unimpaired individuals. The CSF p-tau/Aβ42 ratio, a biomarker combining information from both pathophysiological processes, has emerged as a promising tool for monitoring disease progression, even at pre-clinical stages. Here, we studied the association between the CSF p-tau/Aβ42 ratio with downstream markers of pre-clinical Alzheimer's disease progression including brain structure, glucose metabolism, fibrillary Aβ deposition and cognitive performance in 234 cognitively unimpaired individuals, who underwent cognitive testing, a lumbar puncture, MRI, 18F-fluorodeoxyglucose and 18F-flutemetamol PET scanning.

Ultrasensitive Protein Aggregate Quantification Assays for Neurodegenerative Diseases on the Simoa Platform.

Nanoscale aggregates play a key role in the pathogenesis of neurodegenerative disorders such as Alzheimer's and Parkinson's disease. However, quantifying these aggregates in complex biological samples, such as biofluids and postmortem brain tissue, has been challenging due to their low concentration and small size, necessitating the development of methods with high sensitivity and specificity. Here, we have developed ultrasensitive assays utilizing the Quanterix Simoa platform to detect α-synuclein, β-amyloid and tau aggregates, including those with common posttranslational modifications such as truncation of α-synuclein and AT8 phosphorylation of tau aggregates.