Publications by authors named "McDonald Bc"

Article Synopsis
  • The decline in vehicle emissions highlights the increasing role of Volatile Organic Compounds (VOCs) from Volatile Chemical Products (VCP), but their complex chemistry poses challenges for accurate modeling.
  • Researchers developed a new chemical mechanism called RACM2B-VCP to better represent VOC emissions from VCP sources, specifically in urban settings like Los Angeles.
  • Model evaluations show promising results, indicating that over 50% of anthropogenic VOC reactivity and ozone enhancement in the area is linked to VCP emissions, despite some remaining discrepancies in the model's overall VOC reactivity predictions.
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Cancer-related cognitive impairment (CRCI) is a broad term encompassing subtle cognitive problems to more severe impairment. CRCI severity is influenced by host, disease, and treatment factors and affects patients prior to, during, and following cancer treatment. The National Cancer Institute (NCI) Symptom Management and Health-Related Quality of Life Steering Committee (SxQoL SC) convened a Clinical Trial Planning Meeting (CTPM) to review the state of the science on CRCI and to develop both Phase II/III intervention trials aimed at improving cognitive function in cancer survivors with non-central nervous system (CNS) disease and longitudinal studies to understand the trajectory of cognitive impairment and contributing factors.

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Background: Physical activity can improve cognition; however, little is known regarding the relationships between longitudinal objectively measured physical activity, cognition, and inflammation in older breast cancer survivors.

Methods: Older (aged 60 years and older) breast cancer survivors (n = 216) and frequency-matched noncancer control participants (n = 216) were assessed at baseline (presystemic therapy for survivors) and annually for up to 5 years. Assessments included hip-worn actigraphs worn for 7 days, neuropsychological tests, the Functional Assessment of Cancer Therapy-Cognitive Function perceived cognitive impairment subscale, and circulating levels of C-reactive protein and interleukin-6.

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Identification of genetic alleles associated with both Alzheimer's disease (AD) and concussion severity/recovery could help explain the association between concussion and elevated dementia risk. However, there has been little investigation into whether AD risk genes associate with concussion severity/recovery, and the limited findings are mixed. We used AD polygenic risk scores (PRS) and genotypes to investigate any such associations in the NCAA-DoD Grand Alliance CARE Consortium (CARE) dataset.

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Structural neuroimaging data have been used to compute an estimate of the biological age of the brain (brain-age) which has been associated with other biologically and behaviorally meaningful measures of brain development and aging. The ongoing research interest in brain-age has highlighted the need for robust and publicly available brain-age models pre-trained on data from large samples of healthy individuals. To address this need we have previously released a developmental brain-age model.

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Purpose: We evaluated whether plasma Alzheimer disease (AD)-related biomarkers were associated with cancer-related cognitive decline among older breast cancer survivors.

Methods: We included survivors aged 60-90 years with primary stage 0-III breast cancers (n = 236) and frequency-matched noncancer control paricipant (n = 154) who passed a cognitive screen and had banked plasma specimens. Participants were assessed at baseline (presystemic therapy) and annually for up to 60 months.

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Purpose: Cancer survivors commonly report cognitive declines after cancer therapy. Due to the complex etiology of cancer-related cognitive decline (CRCD), predicting who will be at risk of CRCD remains a clinical challenge. We developed a model to predict breast cancer survivors who would experience CRCD after systematic treatment.

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Prior studies have shown that people of color (POC) in the United States are exposed to higher levels of pollution than non-Hispanic White people. We show that the city of Denver, Colorado, displays similar race- and ethnicity-based air pollution disparities by using a combination of high-resolution satellite data, air pollution modeling, historical demographic information, and areal apportionment techniques. TROPOMI NO columns and modeled PM concentrations from 2019 are higher in communities subject to redlining.

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The COVID-19 stay-at-home orders issued in the United States caused significant reductions in traffic and economic activities. To understand the pandemic's perturbations on US emissions and impacts on urban air quality, we developed near-real-time bottom-up emission inventories based on publicly available energy and economic datasets, simulated the emission changes in a chemical transport model, and evaluated air quality impacts against various observations. The COVID-19 pandemic affected US emissions across broad-based energy and economic sectors and the impacts persisted to 2021.

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Article Synopsis
  • The study investigates white matter microstructural changes in the hippocampal cingulum bundle among Korean older adults with varying cognitive conditions, including Alzheimer's disease (AD), mild cognitive impairment (MCI), and those who are cognitively normal (CN).
  • Results revealed that both AD and MCI participants exhibited greater measures of radial diffusivity (RD), mean diffusivity (MD), and axial diffusivity (AxD), along with reduced fractional anisotropy (FA) compared to CN individuals.
  • The findings indicate a correlation between poorer white matter integrity in the cingulum bundle and worse cognitive performance and higher amyloid burden, aligning with previous research focused on predominantly European populations.
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We present an empirically benchmarked framework for sex-specific normative modeling of brain morphometry that can inform about the biological and behavioral significance of deviations from typical age-related neuroanatomical changes and support future study designs. This framework was developed using regional morphometric data from 37,407 healthy individuals (53% female; aged 3-90 years) following a comparative evaluation of eight algorithms and multiple covariate combinations pertaining to image acquisition and quality, parcellation software versions, global neuroimaging measures, and longitudinal stability. The Multivariate Factorial Polynomial Regression (MFPR) emerged as the preferred algorithm optimized using nonlinear polynomials for age and linear effects of global measures as covariates.

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The extent to which emission control technologies and policies have reduced anthropogenic NO emissions from motor vehicles is large but uncertain. We evaluate a fuel-based emission inventory for southern California during the June 2021 period, coinciding with the Re-Evaluating the Chemistry of Air Pollutants in CAlifornia (RECAP-CA) field campaign. A modified version of the Fuel-based Inventory of Vehicle Emissions (FIVE) is presented, incorporating 1.

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Understanding the interrelationships of brain function as measured by resting-state magnetic resonance imaging and neuropsychological/behavioral measures in Alzheimer's disease is key for advancement of neuroimaging analysis methods in clinical research. The edge time-series framework recently developed in the field of network neuroscience, in combination with other network science methods, allows for investigations of brain-behavior relationships that are not possible with conventional functional connectivity methods. Data from the Indiana Alzheimer's Disease Research Center sample (53 cognitively normal control, 47 subjective cognitive decline, 32 mild cognitive impairment, and 20 Alzheimer's disease participants) were used to investigate relationships between functional connectivity components, each derived from a subset of time points based on co-fluctuation of regional signals, and measures of domain-specific neuropsychological functions.

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Understanding the interrelationships of brain function as measured by resting-state magnetic resonance imaging and neuropsychological/behavioral measures in Alzheimer's disease is key for advancement of neuroimaging analysis methods in clinical research. The edge time-series framework recently developed in the field of network neuroscience, in combination with other network science methods, allows for investigations of brain-behavior relationships that are not possible with conventional functional connectivity methods. Data from the Indiana Alzheimer's Disease Research Center sample (53 cognitively normal control, 47 subjective cognitive decline, 32 mild cognitive impairment, and 20 Alzheimer's disease participants) were used to investigate relationships between functional connectivity components, each derived from a subset of time points based on co-fluctuation of regional signals, and measures of domain-specific neuropsychological functions.

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Purpose: To identify trajectories of depressive symptoms in older breast cancer survivors and demographic, psychosocial, physical health, and cancer-related predictors of these trajectories.

Methods: Recently diagnosed nonmetastatic breast cancer survivors (n = 272), ages 60-98 years, were evaluated for depressive symptoms (Center for Epidemiological Studies Depression Scale, CES-D; scores ≥16 suggestive of clinically significant depressive symptoms). CES-D scores were analyzed in growth-mixture models to determine depression trajectories from baseline (post-surgery, pre-systemic therapy) through 3-year annual follow-up.

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Purpose: Cancer-related cognitive impairment (CRCI) has been associated with altered brain activation after chemotherapy in areas related to working memory. Hence, improving working memory capacity and associated brain activation might aid in the recovery of CRCI. In this study, we investigated the potential of a mindfulness-based intervention (MBI) to impact working memory-related brain activation.

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Article Synopsis
  • Los Angeles experiences significant air pollution from ozone and particulate matter, which hasn't improved much over the last ten years despite reduced emissions from vehicles.
  • Recent airborne measurements revealed a complex mix of volatile organic compounds (VOCs) in the area, with ethanol and terpenoids being the most prevalent sources.
  • Comparing these measurements with existing emission inventories highlighted inconsistencies in the data, especially concerning biogenic and volatile chemical product emissions, while transportation-related VOCs showed better alignment.
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Cancer-related cognitive impairment (CRCI) affects a large proportion of cancer survivors and has significant negative effects on survivor function and quality of life (QOL). Treatments for CRCI are being developed and evaluated. Memory and attention adaptation training (MAAT) is a cognitive-behavioral therapy (CBT) demonstrated to improve CRCI symptoms and QOL in previous research.

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Volatile chemical products (VCP) are an increasingly important source of hydrocarbon and oxygenated volatile organic compound (OVOC) emissions to the atmosphere, and these emissions are likely to play an important role as anthropogenic precursors for secondary organic aerosol (SOA). While the SOA from VCP hydrocarbons is often accounted for in models, the formation, evolution, and properties of SOA from VCP OVOCs remain uncertain. We use environmental chamber data and a kinetic model to develop SOA parameters for 10 OVOCs representing glycols, glycol ethers, esters, oxygenated aromatics, and amines.

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Article Synopsis
  • - Identifying early biomarkers for Alzheimer's disease (AD) is crucial for effective treatments, with cerebral blood flow (CBF) being a potential indicator as it typically decreases in older adults with AD compared to healthy peers.
  • - A study involving 77 older adults investigated the relationship between CBF, hypertension, and AD-related factors like the APOEε4 gene and tau and amyloid levels using advanced imaging techniques.
  • - Results showed that changes in CBF are linked to tau and amyloid aggregation, with some relationships influenced by hypertension or APOEε4 status, highlighting the need for more research on CBF as an early biomarker for AD.
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There have been no published genome-wide studies of the genetics of cancer- and treatment-related cognitive decline (CRCD); the purpose of this study is to identify genetic variants associated with CRCD in older female breast cancer survivors. Analyses included white non-Hispanic women with non-metastatic breast cancer aged 60+ ( = 325) and age-, racial/ethnic group-, and education-matched controls ( = 340) with pre-systemic treatment and one-year follow-up cognitive assessment. CRCD was evaluated using longitudinal domain scores on cognitive tests of attention, processing speed, and executive function (APE), and learning and memory (LM).

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Background: Cancer and its treatments may accelerate aging in survivors; however, research has not examined epigenetic markers of aging in longer term breast cancer survivors. This study examined whether older breast cancer survivors showed greater epigenetic aging than noncancer controls and whether epigenetic aging related to functional outcomes.

Methods: Nonmetastatic breast cancer survivors (n = 89) enrolled prior to systemic therapy and frequency-matched controls (n = 101) ages 62 to 84 years provided two blood samples to derive epigenetic aging measures (Horvath, Extrinsic Epigenetic Age [EEA], PhenoAge, GrimAge, Dunedin Pace of Aging) and completed cognitive (Functional Assessment of Cancer Therapy-Cognitive Function) and physical (Medical Outcomes Study Short Form-12) function assessments at approximately 24 to 36 and 60 months after enrollment.

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Brain gray matter (GM) reductions have been reported after breast cancer chemotherapy, typically in small and/or cross-sectional cohorts, most commonly using voxel-based morphometry (VBM). There has been little examination of approaches such as deformation-based morphometry (DBM), machine-learning-based brain aging metrics, or the relationship of clinical and demographic risk factors to GM reduction. This international data pooling study begins to address these questions.

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Background: Immune activation/inflammation markers (immune markers) were tested to explain differences in neurocognition among older breast cancer survivors versus noncancer controls.

Methods: Women >60 years old with primary breast cancer (stages 0-III) (n = 400) were assessed before systemic therapy with frequency-matched controls (n = 329) and followed annually to 60 months; blood was collected during annual assessments from 2016 to 2020. Neurocognition was measured by tests of attention, processing speed, and executive function (APE).

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Background: White matter (WM) microstructural changes in the hippocampal cingulum bundle (CBH) in Alzheimer's disease (AD) have been described in cohorts of largely European ancestry but are lacking in other populations.

Methods: We assessed the relationship between CBH WM integrity and cognition or amyloid burden in 505 Korean older adults aged ≥55 years, including 276 cognitively normal older adults (CN), 142 mild cognitive impairment (MCI), and 87 AD, recruited as part of the Korean Brain Aging Study for the Early Diagnosis and Prediction of Alzheimer's disease (KBASE) at Seoul National University.

Results: Compared to CN, AD and MCI subjects showed decreased WM integrity in the bilateral CBH.

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