Publications by authors named "Steven E Arnold"

Article Synopsis
  • The study investigates how metabolic changes in the locus coeruleus (LC) relate to Alzheimer's disease (AD) and cognitive decline, raising questions about their progression and significance over time.
  • Using FDG-PET imaging, researchers analyzed LC metabolism in 604 ADNI participants and found that metabolic activity was higher in early preclinical stages, indicating potential cognitive resilience, but lower in later stages alongside cognitive impairment.
  • The results suggest that increased metabolism in the LC during early AD could help maintain memory function, while decreased levels in advanced stages may reflect neurodegenerative processes impacting cognition.
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Objectives: This study explores the potential of developing digital biomarkers from wearables for monitoring individuals with Alzheimer's Disease and Related Dementias, focusing on the feasibility of using Apple Watches for tracking health and behaviors in older adults with cognitive impairment.

Method: Data collection used the Amissa Health technology stack, which passively collects time-series data from smartwatches and provides a high-frequency cloud database for secure data storage, query, and visualization by clinicians and researchers. The platform consists of i) AmissaWear, a software app that runs on smartwatches and sends information to a cloud database using a secure API; and ii) AmissaOrbis, a centralized cloud portal for the collected data.

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The tauopathies are defined by pathological tau protein aggregates within a spectrum of clinically heterogeneous neurodegenerative diseases. The primary tauopathies meet the definition of rare diseases in the United States. There is no approved treatment for primary tauopathies.

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The TAR DNA Binding Protein 43 (TDP-43) has been implicated in the pathogenesis of human neurodegenerative diseases and exhibits hallmark neuropathology in amyotrophic lateral sclerosis (ALS). Here, we explore its tractability as a plasma biomarker of disease and describe its localization and possible functions in the cytosol of platelets. Novel TDP-43 immunoassays were developed on three different technical platforms and qualified for specificity, signal-to-noise ratio, detection range, variation, spike recovery and dilution linearity in human plasma samples.

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Biological and clinical heterogeneity is a major challenge in research for developing new treatments for Alzheimer's disease (AD). AD may be defined by its amyloid beta and tau pathologies, but we recognize that mixed pathologies are common, and that diverse genetics, central nervous system (CNS) and systemic pathophysiological processes, and environmental/experiential factors contribute to AD's diverse clinical and neuropathological features. All these factors are rational targets for therapeutic development; indeed, there are hundreds of candidate pharmacological, dietary, neurostimulation, and lifestyle interventions that show benefits in homogeneous laboratory models.

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Introduction: Sodium phenylbutyrate and taurursodiol (PB and TURSO) is hypothesized to mitigate endoplasmic reticulum stress and mitochondrial dysfunction, two of many mechanisms implicated in Alzheimer's disease (AD) pathophysiology.

Methods: The first-in-indication phase 2a PEGASUS trial was designed to gain insight into PB and TURSO effects on mechanistic targets of engagement and disease biology in AD. The primary clinical efficacy outcome was a global statistical test combining three endpoints relevant to disease trajectory (cognition [Mild/Moderate Alzheimer's Disease Composite Score], function [Functional Activities Questionnaire], and total hippocampal volume on magnetic resonance imaging).

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Background: Proteomics offers potential for detecting and monitoring anorexia nervosa (AN) and its variant, atypical AN (atyp-AN). However, research has been limited by small protein panels, a focus on adult AN, and lack of replication.

Methods: In this study, we performed Olink multiplex profiling of 92 inflammation-related proteins in females with AN/atyp-AN ( = 64), all of whom were ≤90% of expected body weight, and age-matched healthy control individuals ( = 44).

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Objective: To examine the associations of renin-angiotensin system (RAS) inhibitor use with postmortem brain insulin signaling and neuropathology.

Methods: Among Religious Orders Study participants, 150 deceased and autopsied older individuals (75 with diabetes matched to 75 without by age at death, sex, and education) had measurements of insulin receptor substrate-1 (IRS-1) and RAC-alpha serine/threonine protein kinase (AKT1) collected in the prefrontal cortex using ELISA and immunohistochemistry. Alzheimer's disease (AD), brain infarcts, and cerebral vessel pathology data were assessed by systematic neuropathologic evaluations.

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Objectives: To longitudinally characterize disease-relevant CSF and plasma biomarkers in individuals at risk for genetic prion disease up to disease conversion.

Methods: This single-center longitudinal cohort study has followed known carriers of pathogenic variants at risk for prion disease, individuals with a close relative who died of genetic prion disease but who have not undergone predictive genetic testing, and controls. All participants were asymptomatic at first visit and returned roughly annually.

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Background: Evidence links lifestyle factors with Alzheimer's disease (AD). We report the first randomized, controlled clinical trial to determine if intensive lifestyle changes may beneficially affect the progression of mild cognitive impairment (MCI) or early dementia due to AD.

Methods: A 1:1 multicenter randomized controlled phase 2 trial, ages 45-90 with MCI or early dementia due to AD and a Montreal Cognitive Assessment (MoCA) score of 18 or higher.

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Neurofilament light (NfL) concentration in cerebrospinal fluid (CSF) and blood serves as an important biomarker in neurology drug development. Changes in NfL are generally assumed to reflect changes in neuronal damage, while little is known about the clearance of NfL from biofluids. We observed an NfL increase of 3.

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Liquid Chromatography Mass Spectrometry (LC-MS) is a powerful method for profiling complex biological samples. However, batch effects typically arise from differences in sample processing protocols, experimental conditions, and data acquisition techniques, significantly impacting the interpretability of results. Correcting batch effects is crucial for the reproducibility of omics research, but current methods are not optimal for the removal of batch effects without compressing the genuine biological variation under study.

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Cerebrospinal fluid (CSF) matrix biomarkers have become increasingly valuable surrogate markers of neuropsychiatric diseases in research and clinical practice. In contrast, CSF cells have been rarely investigated due to their relative scarcity and fragility, and lack of common collection and cryopreservation protocols, with limited exceptions for neurooncology and primary immune-based diseases like multiple sclerosis. the advent of a microfluidics-based multi-omics approach to studying individual cells has allowed for the study of cellular phenotyping, intracellular dynamics, and intercellular relationships that provide multidimensionality unable to be obtained through acellular fluid-phase analyses.

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Objective: To examine associations of serum insulin and related measures with neuropathology and cognition in older persons.

Methods: We studied 192 older persons (96 with diabetes and 96 without, matched by sex and balanced by age-at-death, education, and postmortem interval) from a community-based, clinical-pathologic study of aging, with annual evaluations including neuropsychological testing (summarized into global cognition and 5 cognitive domains) and postmortem autopsy. We assessed serum insulin, glucose, leptin, adiponectin, hemoglobin A1C, advanced glycation-end products (AGEs), and receptors for advanced glycation-end products, and calculated the Homeostasis Model Assessment of Insulin Resistance (HOMA-IR) and adiponectin-to-leptin ratio.

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Introduction: While Alzheimer's disease (AD) is defined by amyloid-β plaques and tau tangles in the brain, it is evident that many other pathophysiological processes such as inflammation, neurovascular dysfunction, oxidative stress, and metabolic derangements also contribute to the disease process and that varying contributions of these pathways may reflect the heterogeneity of AD. Here, we used a previously validated panel of cerebrospinal fluid (CSF) biomarkers to explore the degree to which different pathophysiological domains are dysregulated in AD and how they relate to each other.

Methods: Twenty-five CSF biomarkers were analyzed in individuals with a clinical diagnosis of AD verified by positive CSF AD biomarkers (AD, = 54) and cognitively unimpaired controls negative for CSF AD biomarkers (CU-N, = 26) using commercial single- and multi-plex immunoassays.

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Vascular dysfunction is increasingly recognized as an important contributor to the pathogenesis of Alzheimer's disease. Alterations in vascular endothelial growth factor (VEGF) pathways have been implicated as potential mechanisms. However, the specific impact of VEGF proteins in preclinical Alzheimer's disease and their relationships with other Alzheimer's disease and vascular pathologies during this critical early period remain to be elucidated.

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Alzheimer's disease (AD) and related dementias (ADRD) is a complex disease with multiple pathophysiological drivers that determine clinical symptomology and disease progression. These diseases develop insidiously over time, through many pathways and disease mechanisms and continue to have a huge societal impact for affected individuals and their families. While emerging blood-based biomarkers, such as plasma p-tau181 and p-tau217, accurately detect Alzheimer neuropthology and are associated with faster cognitive decline, the full extension of plasma proteomic changes in ADRD remains unknown.

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Importance: Genetic prion disease is a universally fatal and rapidly progressive neurodegenerative disease for which genetically targeted therapies are currently under development. Preclinical proofs of concept indicate that treatment before symptoms will offer outsize benefit. Though early treatment paradigms will be informed by the longitudinal biomarker trajectory of mutation carriers, to date limited cases have been molecularly tracked from the presymptomatic phase through symptomatic onset.

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A growing literature suggests that plasma levels of tau phosphorylated at amino acid 217 (pTau217) performs similarly to cerebrospinal fluid (CSF) biomarkers and PET imaging to detect amyloid pathology and to provide diagnostic and prognostic information in Alzheimer's disease (AD), but a significant limiting factor thus far has been a lack of widely available immunoassays. We evaluated a novel pTau217 S-PLEX® assay developed by Meso Scale Discovery (MSD; Rockville, MD) in plasma from 131 individuals with AD confirmed by CSF biomarkers and controls. Technical performance of the assay was excellent with an LLOQ of 1.

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Objectives: Determine if biomarkers of Alzheimer's disease and neural injury may play a role in the prediction of delirium risk.

Methods: In a cohort of older adults who underwent elective surgery, delirium case-no delirium control pairs (N = 70, or 35 matched pairs) were matched by age, sex and vascular comorbidities. Biomarkers from CSF and plasma samples collected prior to surgery, including amyloid beta (Aβ) , Aβ , total (t)-Tau, phosphorylated (p)-Tau , neurofilament-light (NfL), and glial fibrillary acid protein (GFAP) were measured in cerebrospinal fluid (CSF) and plasma using sandwich enzyme-linked immunosorbent assays (ELISAs) or ultrasensitive single molecule array (Simoa) immunoassays.

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Background: Alzheimer's disease (AD) is a complicated condition involving multiple metabolic and immunologic pathophysiological processes that can occur with the hallmark pathologies of amyloid-β, tau, and neurodegeneration. Metformin, an anti-diabetes drug, targets several of these disease processes in in vitro and animal studies. However, the effects of metformin on human cerebrospinal fluid (CSF) and plasma proteins as potential biomarkers of treatment remain unexplored.

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Alzheimer's disease (AD) is a complex and heterogeneous neurodegenerative disorder with contributions from multiple pathophysiological pathways. One of the long-recognized and important features of AD is disrupted cerebral glucose metabolism, but the underlying molecular basis remains unclear. In this study, unbiased mass spectrometry was used to survey CSF from a large clinical cohort, comparing patients who are either cognitively unimpaired (CU; n = 68), suffering from mild-cognitive impairment or dementia from AD (MCI-AD, n = 95; DEM-AD, n = 72), or other causes (MCI-other, n = 77; DEM-other, n = 23), or Normal Pressure Hydrocephalus (NPH, n = 57).

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