John Hart's research while affiliated with University of Texas Southwestern Medical Center and other places

Publications (137)

Article
Objective: Estimating when full time care will be needed in Alzheimer’s Clinical Syndrome (ACS) is difficult. This is due to limited research identifying the factors associated with loss of independent living (LOI), which may differ across dementia stages. Thus, we examined which clinical and neuropsychological factors predict LOI in the early-to-m...
Article
Objective High Definition transcranial Direct Current Stimulation (HD-tDCS) has been shown to improve cognitive performance in individuals with chronic traumatic brain injury (TBI), although electrophysiological mechanisms remain unclear. Methods Veterans with TBI underwent active anodal (N = 15) vs sham (N = 10) HD-tDCS targeting the pre-suppleme...
Article
Few studies have examined an association between mild traumatic brain injury (mTBI) and Alzheimer’s disease (AD). For this reason, we compared an AD dementia group with an mTBI history (n = 10) to a matched AD control group (n = 20) on measures of cognitive function, cerebral glucose metabolism, and markers of amyloid and tau deposition. Only a tre...
Article
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Several important questions regarding cognitive aging and dementia in older people with multiple sclerosis (PwMS) are the focus of this narrative review: Do older PwMS have worse cognitive decline compared to older people without MS? Can older PwMS develop dementia or other neurodegenerative diseases such as Alzheimer’s disease (AD) that may be acc...
Conference Paper
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Objective: We examined the therapeutic effects on word finding difficulty in persons with multiple sclerosis (PwMS) using high-definition transcranial direct current stimulation (HD-tDCS) targeting the pre-Supplementary Motor Area (pre-SMA). Background: Word finding difficulty is prevalent in PwMS and can impact communication, job performance, and...
Article
Background: Life expectancy (LE) following Alzheimer's disease (AD) is highly variable. The literature to date is limited by smaller sample sizes and clinical diagnoses. Objective: No study to date has evaluated predictors of AD LE in a retrospective large autopsy-confirmed sample, which was the primary objective of this study. Methods: Partic...
Conference Paper
Full-text available
Anodal high definition transcranial direct current stimulation (HD-tDCS) targeting the pre-supplementary motor area/dorsal anterior cingulate cortex (pre-SMA/dACC) has recently been shown to improve verbal and executive functions in veterans with chronic traumatic brain injury (cTBI), but the underlying mechanisms remain unknown. We examined electr...
Article
Anodal high definition transcranial direct current stimulation (HD-tDCS) targeting the pre-supplementary motor area/dorsal anterior cingulate cortex (pre-SMA/dACC) has recently been shown to improve verbal retrieval deficits in veterans with chronic traumatic brain injury (TBI)[42], but predictors of treatment response are unclear. We hypothesized...
Article
Objective We explored the course of neuropsychiatric symptoms (NPS) in autopsy-confirmed Alzheimer’s disease (ad) subjects with and without a history of TBI (TBI+ vs. TBI-), expecting that TBI history may be associated with NPS severity over time. Method Data from 1532 individuals (age 50+) with autopsy-confirmed ad were obtained from the National...
Article
Objective Concussion symptoms are non-specific and various symptom inventories are influenced by sex, even in the absence of injury. The Texas Postconcussion Symptom Inventory (TPSI) is a new 66-item concussion-related symptom measure with three empirically-derived indices (Cognitive, Neuropsychiatric, and Somatic). We evaluated if symptom reportin...
Article
Objective Self-report scales are commonly used to evaluate non-specific symptoms following concussion. While several scales have been developed, few were created using a systematic process and most contain several ambiguous items that may be misinterpreted. To address this, a new theoretically-based, multidimensional measure was designed to assess...
Article
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We report a patient who has cognitive sequalae including verbal retrieval deficits after severe traumatic brain injury (TBI). The cortico-caudate-thalamic circuit involving the pre-Supplementary Motor Area (pre-SMA) has been proposed to underlie verbal retrieval functions. We hypothesized that High Definition-transcranial Direct Current Stimulation...
Article
Emotional processing and cognitive control are implicated as being dysfunctional in posttraumatic stress disorder (PTSD) and targeted in cognitive processing therapy (CPT), a trauma-focused treatment for PTSD. The N2 event-related potential has been interpreted in the context of emotional processing and cognitive control. In this analysis of second...
Article
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Traumatic encephalopathy syndrome (TES) is proposed to represent the long-term impact of repetitive head-injury exposure and the clinical manifestation of chronic traumatic encephalopathy (CTE). This study aimed to evaluate the frequency of TES in a cohort of retired professional contact sport athletes, compare the frequency of TES to clinical cons...
Article
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Introduction Prior Go/NoGo studies have localized specific regions and EEG spectra for which traditional approaches have distinguished between Go and NoGo conditions. A more detailed characterization of the spatial distribution and timing of the synchronization of frequency bands would contribute substantially to the clarification of neural mechani...
Preprint
Full-text available
A bstract The neural underpinnings of inhibitory control, an executive cognitive control function, has been a topic of interest for several decades due to both its clinical significance and the maturation of cognitive science disciplines. Behavioral, imaging, and electrophysiological studies suggest that the pre-supplementary motor area (preSMA) se...
Article
Background: Traumatic brain injury (TBI) is a known risk factor for neurodegenerative dementias such as Alzheimer disease (AD); however, the potential risk of mild cases of TBI, such as concussions, remains unclear. Objective: To explore whether a small sample of retired professional athletes with a diagnosis of mild cognitive impairment (MCI)-t...
Poster
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Mechanistic theories of the N400 event-related potential—a neural correlate indexing semantic processing in the brain—implicate the roles of prediction, priming, and bottom-up sensory integration in language comprehension; however, mechanisms explaining volitional aspects of semantic meaning construction are not fully understood. To explore this, p...
Article
To test the hypothesis that semantic processes are represented in multiple subsystems, we recorded electroencephalogram (EEG) as we elicited object memories using the modified Semantic Object Retrieval Test, during which an object feature, presented as a visual word [VW], an auditory word [AW], or a picture [Pic], was followed by a second feature a...
Article
Objective To determine whether subjects with chronic traumatic encephalopathy (CTE) and dementia have distinct clinical features compared to subjects with pathologically confirmed Alzheimer’s disease (AD). Methods Among 339 subjects assessed for CTE in the National Alzheimer’s Coordinating Center dataset, 6 subjects with CTE and 25 subjects with A...
Article
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West Nile Virus (WNV) can result in clinically severe neurologic disease. There is no treatment for WNV infection, but administration of anti-WNV polyclonal human antibody has demonstrated efficacy in animal models. We compared Omr-IgG-am, an immunoglobulin product with high titers of anti-WNV antibody, with intravenous immunoglobulin (IVIG) and no...
Article
Recent discovery of chronic traumatic encephalopathy in former National Football League (NFL) players has led to a surge of papers investigating cognitive functioning in these former athletes. This critical review of the literature focused on the neuropsychological functioning in these ageing athletes, and included 22 articles published between 201...
Article
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Post‐traumatic stress disorder (PTSD) is a debilitating condition that may develop after experiencing a traumatic event. Combat exposure increases an individual's chance of developing PTSD, making veterans especially susceptible to the disorder. PTSD is characterized by dysregulated emotional networks, memory deficits, and a hyperattentive response...
Article
Chronic verbal retrieval deficits have been noted in traumatic brain injury (TBI), but no U.S. Food and Drug Administration-approved interventions are available. The present study investigated whether 10 sessions of 20 min of 1 mA anodal high-definition transcranial direct current stimulation (HD-tDCS) targeting pre-supplementary motor area/dorsal...
Preprint
Full-text available
A bstract Prior Go/NoGo studies have localized specific regions and EEG spectra for which traditional approaches have distinguished between Go and NoGo conditions. A more detailed characterization of the spatial distribution and timing of the synchronization of frequency bands would contribute substantially to the clarification of neural mechanisms...
Article
Traumatic brain injuries (TBI) have received widespread media attention in recent years as being a risk factor for the development of dementia and chronic traumatic encephalopathy (CTE). This has sparked fears about the potential long-term effects of TBI of any severity on cognitive aging, leading to a public health concern. This article reviews th...
Article
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Alzheimer's disease (AD) is the most common cause of neurodegenerative cognitive impairment, defined by abnormal accumulations of amyloid-β and tau. Approaches directly targeting these proteins have not resulted in a disease modifying therapy. Neurovascular unit dysfunction is a feature of AD offering an alternative target for intervention. Sildena...
Article
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Objective: The aim of the current study is to examine whether concussion history and years played are linearly associated with cognitive outcomes in retired National Football League (NFL) players. Method: Thirty-five retired NFL players over the age of 50 who had sustained at least one concussion completed a clinical interview and brief neuropsy...
Article
Our team previously reported event-related potential (ERP) and hyperarousal patterns from a study of one construction battalion of the U.S. Naval Reserve who served during the 1991 Persian Gulf War. We sought to replicate these findings in a sample that was more representative of the entire Gulf War-era veteran population, including male and female...
Article
Background: Traumatic brain injury (TBI) with loss of consciousness (LOC) has been associated with earlier onset of mild cognitive impairment, frontotemporal dementia, Parkinson's disease, and Alzheimer's disease (AD), but has not been examined as a risk factor for earlier onset of dementia with Lewy bodies (DLB). Objective: The purpose of this...
Article
To investigate differences in inhibitory control and processing speed over the life span, participants in 7- to 8-, 10- to 11-, 12- to 15-, 18- to 25-, and 54- to 80-year-old age cohorts completed a Go/No-Go task requiring varying levels of semantic categorization. Discriminant function analysis of correct rejection rates (CRRs), hit rates (HRs), a...
Article
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Objective: To examine whether history of traumatic brain injury (TBI) is associated with more rapid progression from mild cognitive impairment (MCI) to Alzheimer's disease (AD). Method: Data from 2,719 subjects with MCI were obtained from the National Alzheimer's Coordinating Center. TBI was categorized based on presence (TBI+) or absence (TBI-)...
Article
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The dorsal anterior cingulate cortex (dACC) has been identified as a core region affected by many disorders, representing a promising target for neuromodulation. High Definition-transcranial Direct Current Stimulation (HD-tDCS) is a non-invasive neuromodulation technique that has already shown promising outcomes and has been tested to engage deeper...
Article
Objective: To evaluate whether a history of traumatic brain injury (TBI) with reported loss of consciousness (LOC) is a risk factor for earlier onset of Alzheimer's disease (AD) in an autopsy-confirmed sample. Method: Data from 2,133 participants with autopsy-confirmed AD (i.e., at least Braak neurofibrillary tangle stages III to VI and CERAD ne...
Article
The hemodynamic response function (HRF), a model of brain blood-flow changes in response to neural activity, reflects communication between neurons and the vasculature that supplies these neurons in part by means of glial cell intermediaries (e.g., astrocytes). Intact neural-vascular communication might play a central role in optimal cognitive perf...
Article
Objective The feasibility and reliability of neuropsychological assessment at a distance have been demonstrated, but the validity of this testing medium has not been adequately demonstrated. The purpose of this study was to determine the ability of video teleconferencing administration of neuropsychological measures (teleneuropsychology) in discrim...
Article
Background: The objective was to test whether repetitive Transcranial Magnetic Stimulation (rTMS) just prior to Cognitive Processing Therapy (CPT) would significantly improve the clinical outcome compared to sham rTMS prior to CPT in veterans with PTSD. Methods: Veterans 18-60 years of age with current combat-related PTSD symptoms were randomize...
Article
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Traumatic brain injury (TBI) is often considered to be a risk factor for the later development of neurodegenerative conditions, but some findings do not support a link. Differences in research methods, clinical samples, and limitations encountered when assessing and documenting TBI details likely contribute to the mixed reports in the literature. D...
Article
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Objective: Medical history information regarding prior traumatic brain injury (TBI) usually relies on self-report, although little is known about the reliability of this information with regard to injuries sustained years or decades earlier. Even less is known about the reliability of self-reported medical history information in older individuals...
Article
Multiple sclerosis (MS) involves damage to white matter microstructures. This damage has been related to grey matter function as measured by standard, physiologically-nonspecific neuroimaging indices (i.e., blood-oxygen-level dependent signal [BOLD]). Here, we used calibrated functional magnetic resonance imaging and diffusion tensor imaging to exa...
Article
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As with other medical events, concussion history is typically dependent upon self-report, although little is known about the accuracy or reliability of such information. We assessed the reliability of lifetime self-reported concussion histories from 27 retired players from the National Football League (NFL) at baseline and one to two years later. T...
Article
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Fibromyalgia is a disorder characterized by widespread musculoskeletal pain frequently accompanied by other symptoms such as fatigue. Moderate improvement from pharmacological and non-pharmacological treatments have proposed non-invasive brain stimulation techniques such as transcranial direct current stimulation (tDCS) to the occipital nerve (more...
Article
Background: The anterior cingulate cortex (ACC) has been implicated in both cognitive and emotional processing, with cognitive information proposed to be processed through the dorsal/caudal ACC and emotional information through the rostral/ventral ACC. Objective: The objective of this study is to investigate the role of the dorsal anterior cingu...
Article
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Growing evidence suggests that cognitive control processes are impaired in amnestic mild cognitive impairment (aMCI); however the nature of these alterations needs further examination. The current study examined differences in electroencephalographic theta and alpha power related to cognitive control processes involving response execution and respo...
Article
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Tinnitus is the perception of a sound in the absence of a corresponding external sound source. Research has suggested that functional abnormalities in tinnitus patients involve auditory as well as non-auditory brain areas. Transcranial electrical stimulation (tES), such as transcranial direct current stimulation (tDCS) to the dorsolateral prefronta...
Article
Gulf War veterans meeting criteria for Haley Syndrome 2 of Gulf War illness endorse a particular constellation of symptoms that include difficulty with processing information, word-finding, and confusion. To explore the neural basis of their word-finding difficulty, we assessed event-related potentials (ERPs) associated with semantic memory retriev...
Article
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Objective: This study examined whether a history of traumatic brain injury (TBI) is associated with earlier onset of Alzheimer disease (AD), independent of apolipoprotein ε4 status (Apoe4) and gender. Method: Participants with a clinical diagnosis of AD (n = 7625) were obtained from the National Alzheimer's Coordinating Center Uniform Data Set,...
Article
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Individuals who have suffered a traumatic brain injury (TBI) often have word retrieval deficits; however, the underlying neural mechanisms of such deficits are yet to be clarified. Previous studies in normal subjects have shown that during a word retrieval task, there is a 750 ms event-related potential (ERP) divergence detected at the left fronto-...
Article
Using diffusion tensor imaging (DTI), we assessed the relationship of white matter integrity and performance on the Boston Naming Test (BNT) in a group of retired professional football players and a control group. We examined correlations between fractional anisotropy (FA) and mean diffusivity (MD) with BNT T-scores in an unbiased voxel-wise analys...
Article
Recently, techniques to non-invasively modulate specific brain areas gained popularity in the form of transcranial direct current stimulation (tDCS) and high-definition transcranial direct current stimulation. These non-invasive techniques have already shown promising outcomes in various studies with healthy subjects as well as patient populations....
Article
This study examined whether history of traumatic brain injury (TBI) is associated with increased risk and earlier onset of mild cognitive impairment (MCI). Subjects with MCI (n = 3,187) and normal cognition (n = 3,244) were obtained from the National Alzheimer's Coordinating Center database. TBI was categorized based on lifetime reported TBI with l...
Article
We examined the effects of amnestic mild cognitive impairment (aMCI) on behavioral (response times and error rates) and scalp-recorded event-related potential (ERP) measures of response execution and inhibition, using Go/NoGo tasks involving basic and superordinate semantic categorization. Twenty-five aMCI (16 F; 68.5±8 years) and 25 age- and gende...
Article
Veterans with posttraumatic stress disorder (PTSD) underwent a systematic evaluation to determine which factors were associated with the degree of functional status. Demographic information, self-report scales, and symptom ratings performed by trained evaluators were investigated in multiple regression models to determine their contribution to func...
Article
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Multiple sclerosis (MS) results in inflammatory damage to white matter microstructure. Prior research using blood-oxygen-level dependent (BOLD) imaging indicates MS-related alterations to brain function. What is currently unknown is the extent to which white matter microstructural damage influences BOLD signal in MS. Here we assessed changes in par...
Article
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Objective: We retrospectively examined whether a history of traumatic brain injury (TBI) is associated with an earlier age of symptom onset and diagnosis in a large sample of patients with behavioural variant frontotemporal dementia (bvFTD). Methods: Data on patients with bvFTD (n=678) were obtained from the National Alzheimer's Coordinating Cen...
Article
Cognitive slowing is a core neuropsychological symptom of Multiple Sclerosis (MS). We aimed to assess the extent to which cognitive slowing in MS was predicted by changes in dorsolateral prefrontal networks. We assessed patients with relapsing-remitting MS and healthy controls (HCs) on measures of processing speed. Participants underwent a function...
Article
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To our knowledge, this is the first study to show an association between concussion, cognition, and anatomical structural brain changes across the age spectrum in former National Football League athletes. To assess the relationship of hippocampal volume, memory performance, and the influence of concussion history in retired National Football League...
Article
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Background. Despite the proven efficacy of acyclovir (ACV) therapy, herpes simplex encephalitis (HSE) continues to cause substantial morbidity and mortality. Among patients with HSE treated with ACV, the mortality rate is approximately 14%–19%. Among survivors, 45%–60% have neuropsychological sequelae at 1 year. Thus, improving therapeutic approach...
Article
Deficits in semantic memory in individuals with amnestic mild cognitive impairment (aMCI) have been previously reported, but the underlying neurobiological mechanisms remain to be clarified. We examined event-related potentials (ERPs) associated with semantic memory retrieval in 16 individuals with aMCI as compared to 17 normal controls using the S...
Conference Paper
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Scholars have long been interested in the differing reward preferences between government and business leaders. The present study explored the differential neural underpinnings using fMRI of incentive anticipation and outcome during a monetary incentive delay (MID) task in executive-level leaders from government and business organizations. Seven ma...
Article
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Numerous studies have found evidence for corticolimbic theta band electroencephalographic (EEG) oscillations in the neural processing of visual stimuli perceived as threatening. However, varying temporal and topographical patterns have emerged, possibly due to varying arousal levels of the stimuli. In addition, recent studies suggest neural oscilla...
Article
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Posterior cortical atrophy (PCA) is a neurodegenerative syndrome dominated by deterioration of higher visual function (particularly visuospatial and visuoperceptual abilities). It is most commonly due to Alzheimer's disease pathology, but may also be caused by dementia with Lewy bodies, corticobasal degeneration or Creutzfeldt-Jakob disease. Patien...