Publications by authors named "Samuel Lockhart"

Apolipoprotein E () ε4 is a genetic risk factor for Alzheimer's disease (AD). Social support may confer protection against cognitive decline even in the presence of ε4. We examined the relationship among ε4 allele(s) carrier status, social support (overall and sub-sources), and cognition in 115 older adults (72.

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Background: Multidomain lifestyle interventions may have the potential to slow biological aging as captured by deficit accumulation frailty indices. We describe the distribution and composition of the 49-component frailty index (FI) developed by the U.S.

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  • Adverse psychosocial factors like stress and loneliness can affect gene expression related to inflammation and cognitive decline, suggesting that people facing these challenges may experience higher levels of CTRA gene expression.
  • In participants with normal cognition and mild cognitive impairment (MCI), a sense of eudaimonic well-being (EWB) was linked to lower levels of CTRA gene expression, indicating its potential protective role against stress.
  • Coping strategies varied based on cognitive status, influencing the relationship with CTRA gene expression, while loneliness did not significantly affect gene expression in this low-loneliness group.
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  • Cognitive resilience is when people don't show mental decline even if they have signs of Alzheimer's in their brains.
  • Measuring cognitive resilience is tricky because it can't be seen directly, and one common method used might give wrong results.
  • The new method we suggest uses machine learning to improve how we measure cognitive resilience, making it more accurate and relying less on guesses about the data.
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The objectives of this study were to investigate the variable factors associated with cognitive function and cortical atrophy and estimated variable importance of those factors in affecting cognitive function and cortical atrophy in patients with EOAD and LOAD. Patients with EOAD (n = 40), LOAD (n = 34), and healthy volunteers with normal cognition were included (n = 65). All of them performed 3T MRI, [F]THK5351 PET (THK), [F]flutemetamol PET (FLUTE), and detailed neuropsychological tests.

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Introduction: Microtubule (MT) stability is crucial for proper neuronal function. Understanding MT dysregulation is critical for connecting amyloid beta (Aβ) and tau-based degenerative events and early changes in presymptomatic Alzheimer's disease (AD). Herein we present positron emission tomography (PET) imaging properties of our MT-PET radiotracer, [C]MPC-6827, in multiple established AD mouse models.

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Background: A screening tool sensitive to Alzheimer's disease (AD) risk factors, such as amyloid-β (Aβ) deposition, and subtle cognitive changes, best elicited by complex everyday tasks, is needed.

Objective: To determine if grocery shopping performance could differentiate older adults at elevated risk of developing AD (OAer), older adults at low risk of developing AD (OAlr), and young adults (YA), and if amount of Aβ deposition could predict grocery shopping performance in older adults (OA).

Methods: Twenty-one OAer (78±5 years), 33 OAlr (78±5 years), and 28 YA (31±3 years) performed four grocery shopping trials, with the best and worst performances analyzed.

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Introduction: We evaluated associations between plasma and neuroimaging-derived biomarkers of Alzheimer's disease and related dementias and the impact of health-related comorbidities.

Methods: We examined plasma biomarkers (neurofilament light chain, glial fibrillary acidic protein, amyloid beta [Aβ] 42/40, phosphorylated tau 181) and neuroimaging measures of amyloid deposition (Aβ-positron emission tomography [PET]), total brain volume, white matter hyperintensity volume, diffusion-weighted fractional anisotropy, and neurite orientation dispersion and density imaging free water. Participants were adjudicated as cognitively unimpaired (CU; N = 299), mild cognitive impairment (MCI; N = 192), or dementia (DEM; N = 65).

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Alzheimer's Disease (AD) is the most common cause of dementia, although multiple pathologies are found in nearly half of the cases with clinically diagnosed AD. Prion diseases, such as Creutzfeldt-Jakob disease (CJD), are rare causes of dementia and typically manifest as a rapidly progressive dementia, where symptom onset to dementia most often occurs over the course of months. In this brief report, we describe a patient's typically progressive dementia with a precipitous decline at the end of their life who, on neuropathological evaluation, was found to have multiple neurodegenerative proteinopathies as well as spongiform encephalopathy due to CJD.

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Background: The preclinical Alzheimer's cognitive composite (PACC) was developed for in-person administration to capture subtle cognitive decline. At the outset of the COVID-19 pandemic, cognitive testing was increasingly performed remotely by telephone or video administration. It is desirable to have a harmonized composite measurement derived from both in-person and remote assessments for identifying cognitive changes and to examine its relationship with common neuroimaging biomarkers.

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Mediterranean diets may be neuroprotective and prevent cognitive decline relative to Western diets; however, the underlying biology is poorly understood. We assessed the effects of Western versus Mediterranean-like diets on RNAseq-generated transcriptional profiles in lateral temporal cortex and their relationships with longitudinal changes in neuroanatomy, circulating monocyte gene expression, and observations of social isolation and anxiety in 38 socially-housed, middle-aged female cynomolgus macaques (Macaca fascicularis). Diet resulted in differential expression of seven transcripts (FDR < 0.

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  • Blood-based mitochondrial bioenergetic profiling is a practical and low-risk method for studying mitochondrial function and energy metabolism using human blood samples.
  • The study employs two respirometric techniques to assess mitochondrial bioenergetics in peripheral blood mononuclear cells and platelets, revealing that female participants exhibit significantly higher respiration rates than male participants, even after adjusting for other variables.
  • Findings highlight the importance of considering sex differences in mitochondrial bioenergetic profiles, particularly in the context of human health and aging research.
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Background: Frontotemporal dementia (FTD) represents a collection of neurobehavioral and neurocognitive syndromes that are associated with a significant degree of clinical, pathological, and genetic heterogeneity. Such heterogeneity hinders the identification of effective biomarkers, preventing effective targeted recruitment of participants in clinical trials for developing potential interventions and treatments. In the present study, we aim to automatically differentiate patients with three clinical phenotypes of FTD, behavioral-variant FTD (bvFTD), semantic variant PPA (svPPA), and nonfluent variant PPA (nfvPPA), based on their structural MRI by training a deep neural network (DNN).

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Background: Capturing a measure of movement quality during a complex walking task may indicate the earliest signs of detrimental changes to the brain due to beta amyloid (Aβ) deposition and be a potential differentiator of older adults at elevated and low risk of developing Alzheimer's disease. This study aimed to determine: 1) age-related differences in gait speed, stride length, and gait smoothness while transitioning from an even to an uneven walking surface, by comparing young adults (YA) and older adults (OA), and 2) if gait speed, stride length, and gait smoothness in OA while transitioning from an even to an uneven walking surface is influenced by the amount of Aβ deposition present in an OA's brain.

Methods: Participants included 56 OA (>70 years of age) and 29 YA (25-35 years of age).

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  • Mediterranean diets may help protect against cognitive decline and are linked to beneficial changes in gene expression related to inflammation in the brain compared to Western diets.
  • Research involving middle-aged female cynomolgus macaques compared the effects of these two diets on gene expression, MRI results, and behaviors like social isolation and anxiety.
  • Results showed that a Mediterranean diet led to lower levels of pro-inflammatory genes and higher expressions of transcripts associated with anti-inflammatory pathways, emphasizing the potential neuroprotective benefits of this dietary pattern.
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Introduction: Retinal vascular network changes may reflect the integrity of the cerebral microcirculation, and may be associated with cognitive impairment.

Methods: Associations of retinal vascular measures with cognitive function and MRI biomarkers were examined amongst Multi-Ethnic Study of Atherosclerosis (MESA) participants in North Carolina who had gradable retinal photographs at Exams 2 (2002 to 2004, n = 313) and 5 (2010 to 2012, n = 306), and detailed cognitive testing and MRI at Exam 6 (2016 to 2018).

Results: After adjustment for covariates and multiple comparisons, greater arteriolar fractal dimension (FD) at Exam 2 was associated with less isotropic free water of gray matter regions (β = -0.

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Studies over the last 100 years have suggested a link between inflammation, infectious disease, and Alzheimer's Disease (AD). Understanding how the immune system changes during the development of AD may facilitate new treatments. Here, we studied an aging cohort who had been assessed for AD pathology with amyloid positron emission tomography and cognitive testing, and conducted high dimensional flow cytometry on peripheral blood mononuclear and cerebrospinal fluid cells.

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The microtubule (MT) instability observed in Alzheimer's disease (AD) is commonly attributed to hyperphosphorylation of the MT-associated protein, tau. PET imaging offers an opportunity to gain critical information about MT changes with the onset and development of AD and related dementia. We developed the first brain-penetrant MT PET ligand, [C]MPC-6827, and evaluated its imaging utility in vervet monkeys.

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Objectives: Alzheimer's disease (AD) is characterised by amyloid-beta accumulation (A), tau aggregation (T) and neurodegeneration (N). Vascular (V) burden has been found concomitantly with AD pathology and has synergistic effects on cognitive decline with AD biomarkers. We determined whether cognitive trajectories of AT(N) categories differed according to vascular (V) burden.

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Introduction: Adverse psychosocial exposure is associated with increased proinflammatory gene expression and reduced type-1 interferon gene expression, a profile known as the conserved transcriptional response to adversity (CTRA). Little is known about CTRA activity in the context of cognitive impairment, although chronic inflammatory activation has been posited as one mechanism contributing to late-life cognitive decline.

Methods: We studied 171 community-dwelling older adults from the Wake Forest Alzheimer's Disease Research Center who answered questions via a telephone questionnaire battery about their perceived stress, loneliness, well-being, and impact of COVID-19 on their life, and who provided a self-collected dried blood spot sample.

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Purpose: To reduce the total scan time of multiple postlabeling delay (multi-PLD) pseudo-continuous arterial spin labeling (pCASL) by developing a hierarchically structured 3D convolutional neural network (H-CNN) that estimates the arterial transit time (ATT) and cerebral blow flow (CBF) maps from the reduced number of PLDs as well as averages.

Methods: A total of 48 subjects (38 females and 10 males), aged 56-80 years, compromising a training group (n = 45) and a validation group (n = 3) underwent MRI including multi-PLD pCASL. We proposed an H-CNN to estimate the ATT and CBF maps using a reduced number of PLDs and a separately reduced number of averages.

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Article Synopsis
  • - The study investigates small extracellular vesicles (sEVs) derived from brain cells in blood to find potential biomarkers for Alzheimer's disease (AD) by analyzing microRNA (miRNA) levels in older adults with varying cognitive abilities.
  • - Researchers isolated sEVs from participants with normal cognition, mild cognitive impairment (MCI), and AD, revealing that miRNA expression patterns significantly differentiated between these groups and correlated with brain imaging results.
  • - The findings suggest that analyzing miRNAs in sEVs provides a promising, non-invasive blood-based method for detecting and monitoring Alzheimer's disease progression.
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Type 2 diabetes (T2D) is a heritable metabolic disorder. While population studies have identified hundreds of common genetic variants associated with T2D, the role of rare (frequency < 0.1%) protein-coding variation is less clear.

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Accurate measurement of Alzheimer's disease (AD) pathology in older adults without significant clinical impairment is critical to assessing intervention strategies aimed at slowing AD-related cognitive decline. The U.S.

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