Chronic traumatic encephalopathy is not a real disease

Fluid biomarkers of chronic traumatic brain injury

Traumatic brain injury (TBI) is a leading cause of long-term disability across the world. Evidence for the usefulness of imaging and fluid biomarkers to predict outcomes and screen for the need to monitor complications in the acute stage is steadily increasing. Still, many people experience symptoms such as fatigue and cognitive and motor dysfunction in the chronic phase of TBI, where objective assessments for brain injury are lacking. Consensus criteria for traumatic encephalopathy syndrome, a clinical syndrome possibly associated with the neurodegenerative disease chronic traumatic encephalopathy, which is commonly associated with sports concussion, have been defined only recently. However, these criteria do not fit all individuals living with chronic consequences of TBI. The pathophysiology of chronic TBI shares many similarities with other neurodegenerative and neuroinflammatory conditions, such as Alzheimer disease. As with Alzheimer disease, advancements in fluid biomarkers represent one of the most promising paths for unravelling the chain of pathophysiological events to enable discrimination between these conditions and, with time, provide prediction modelling and therapeutic end points. This Review summarizes fluid biomarker findings in the chronic phase of TBI (≥6 months after injury) that demonstrate the involvement of inflammation, glial biology and neurodegeneration in the long-term complications of TBI. We explore how the biomarkers associate with outcome and imaging findings and aim to establish mechanistic differences in biomarker patterns between types of chronic TBI and other neurodegenerative conditions. Finally, current limitations and areas of priority for future fluid biomarker research are highlighted.

Neuropsychological Evaluation in Traumatic Brain Injury

Neuropsychological evaluations can be helpful in the aftermath of traumatic brain injury. Cognitive functioning is assessed using standardized assessment tools and by comparing an individual's scores on testing to normative data. These evaluations examine objective cognitive functioning as well as other factors that have been shown to influence performance on cognitive tests (eg, psychiatric conditions, sleep) in an attempt to answer a specific question from referring providers. Referral questions may focus on the extent of impairment, the trajectory of recovery, or ability to return to work, sport, or the other previous activity.

Chronic Traumatic Encephalopathy as the Course of Alzheimer's Disease

This editorial investigates chronic traumatic encephalopathy (CTE) as a course of Alzheimer's disease (AD). CTE is a debilitating neurodegenerative disease that is the result of repeated mild traumatic brain injury (TBI). Many epidemiological studies show that experiencing a TBI in early or middle life is associated with an increased risk of dementia later in life. Chronic traumatic encephalopathy (CTE) and Alzheimer's disease (AD) present a series of similar neuropathological features that were investigated in this work like recombinant tau into filaments or the accumulation and aggregation of Aβ protein. However, these two conditions differ from each other in brain-blood barrier damage. The purpose of this review was to evaluate information about CTE and AD from various articles, focusing especially on new therapeutic possibilities for the improvement in cognitive skills.

Public Chronic Traumatic Encephalopathy Knowledge: Sources, Accuracy and Confidence

ABSTRACT

The goal of this study was to examine the general public's level of accuracy and confidence in knowledge of chronic traumatic encephalopathy (CTE), as well as information sources. This study also explored how these factors affected comfort in allowing children to play a high-contact sport. This study utilized online surveys and included 529 participants. Overall, CTE knowledge accuracy was 48.02% (standard deviation = 0.23). Inaccuracies regarding the etiology and diagnosis of CTE were most common, whereas the symptoms and lack of treatments for CTE were more widely known. Despite overall low CTE knowledge accuracy, CTE knowledge confidence was positively correlated with comfort in allowing children to play a high-contact sport (r = 0.199, P ≤ 0.001). Participants identified television/movies followed by web sites and social media as the most utilized CTE information sources. These results further support the need for clinicians and researchers to address misconceptions about CTE.

Chronic traumatic encephalopathy (CTE)-features and forensic considerations

Chronic traumatic encephalopathy (CTE) is a neurodegenerative condition, in which the only known cause is exposure to repeated episodes of blunt head trauma. It most often occurs in professional and amateur athletes who have had frequent and repetitive cranial impacts during contact sports, but may also be found in victims of domestic violence, military personnel exposed to explosive devices and in individuals with severe epilepsy. The pathognomonic pathological findings are of neurofibrillary tangles and pretangles in the depths of the cerebral sulci caused by perivascular accumulation of phosphorylated Tau (pTau). Cases may be high profile requiring an evaluation of whether the neuropathological findings of CTE can be related to injuries previously sustained on the sporting field. Failure to examine the brain or to adequately sample appropriate areas at autopsy may lead to cases being overlooked and to an underestimation of the incidence of this condition in the community. Performing immunohistochemical staining for pTau in three areas from the neocortex has been found to be a useful screening tool for CTE. Ascertaining whether there is a history of head trauma, including exposure to contact sports, as a standard part of forensic clinical history protocols will help identify at-risk individuals so that Coronial consideration of the need for brain examination can be appropriately informed. Repetitive head trauma, particularly from contact sport, is being increasingly recognized as a cause of significant preventable neurodegeneration.

Chronic Traumatic Encephalopathy as a Preventable Environmental Disease

In this Perspective we explore the evolution of our understanding of chronic traumatic encephalopathy (CTE) and its relationship with repetitive head injury. As with many neurodegenerative conditions, there is an imperfect correspondence between neuropathology and clinical phenotype, but unlike other neurodegenerative diseases, CTE has a discrete and easily modifiable risk factor: exposure to repetitive head injury. Consequently, evaluation of the evidence regarding exposure to repetitive head injury and CTE risk should be undertaken using public or occupational health frameworks of medical knowledge. The current debate over the existence of CTE as a disease of concern is fuelled in part by immediate medico-legal considerations, and the involvement of high-profile athletes, with inevitable media interest. Moving beyond this debate has significant potential to address and reduce disease impact in the near future, and provide novel insights into mechanisms underlying abnormal protein accumulation in CTE and other neurodegenerative diseases.

Adverse Health and Psychosocial Repercussions in Retirees from Sports Involving Head Trauma: Looking at the Sport of Boxing

Academic scholarship has steadily reported unfavourable clinical findings on the sport of boxing, and national medical bodies have issued calls for restrictions on the sport. Yet, the positions taken on boxing by medical bodies have been subject to serious discussions. Beyond the medical and legal writings, there is also literature referring to the social and cultural features of boxing as ethically significant. However, what is missing in the bioethical literature is an understanding of the boxers themselves. This is apart from their brain injuries, the debates about the degenerative brain disease known as chronic traumatic encephalopathy (CTE), and related issues about the disease. This article argues that the lives of boxers, their relationships, their careers, and their futures, also requires its own research, particularly in telling stories about their lives, and those lives and futures which boxing affects. The article uses two approaches. First, to imagine a more enduring “whole of life viewpoint” by using an extended future timeframe. Second, to consider perspectives of a person’s significant others. After reviewing the boxing literature, the article discusses social settings and then explores the hidden social relationships in life after boxing. With these longer time and close relationship viewpoints, three important themes emerge: family and kinship; age, stage and career; and the effects of boxing fatalities. These analyses are used in conjunction with relevant clinical findings which complement the telling of stories to improve medical information, and engages professional and public empathy for people’s experience of illness and difficulties in coping.

Frequency and Predictors of Traumatic Encephalopathy Syndrome in a Prospective Cohort of Retired Professional Athletes

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 consensus diagnoses, and identify predictors that increase the likelihood of TES diagnosis. Participants were 85 retired professional contact sport athletes from a prospective cohort at the University of Texas Southwestern Medical Center and the University of Texas at Dallas. Participants ranged in age from 23 to 79 (M = 55.95, SD = 13.82) and obtained 7 to 19 years of education (M = 16.08, SD = 1.03). Retirees were either non-Hispanic white (n = 62) or African-American (n = 23). Retired athletes underwent a standard clinical evaluation, which included a clinical interview, neurological exam, neuroimaging, neuropsychological testing, and consensus diagnosis of normal, mild cognitive impairment, or dementia. TES criteria were applied to all 85 athletes, and frequencies of diagnoses were compared. Fourteen predictors of TES diagnosis were evaluated using binary logistic regressions, and included demographic, neuropsychological, depression symptoms, and head-injury exposure variables. A high frequency (56%) of TES was observed among this cohort of retired athletes, but 54% of those meeting criteria for TES were diagnosed as cognitively normal via consensus diagnosis. Games played in the National Football League (OR = 0.993, p = 0.087), number of concussions (OR = 1.020, p = 0.532), number of concussions with loss of consciousness (OR = 1.141 p = 0.188), and years playing professionally (OR = 0.976, p = 0.627) were not associated with TES diagnosis. Degree of depressive symptomatology, as measured by the total score on the Beck Depression Inventory-II, was the only predictor of TES diagnosis (OR = 1.297, p < 0.001). Our results add to previous findings underscoring the risk for false positive diagnosis, highlight the limitations of the TES criteria in clinical and research settings, and question the relationship between TES and head-injury exposure. Future research is needed to examine depression in retired professional athletes.

Mild Chronic Traumatic Encephalopathy Neuropathology in People With No Known Participation in Contact Sports or History of Repetitive Neurotrauma

It has been asserted that chronic traumatic encephalopathy (CTE) pathology is only present in former athletes and others who have been exposed to repetitive concussions, subconcussive blows, or both. We hypothesized that CTE pathology would be present in men who had no known history of repetitive neurotrauma. Comprehensive medical record reviews and health surveys completed by a family member were available for the 8 men in this case series, none of whom had known exposure to repetitive neurotrauma but 2 of whom had a history of traumatic brain injury (TBI). Postmortem tissue was immunostained for hyperphosphorylated tau (p-tau) to assess for CTE pathology, Braak stage, and aging-related p-tau. The neuropathologist was blind to age, personal history, and clinical history. Six of the 8 cases (75%) showed p-tau in neurons, astrocytes, and cell processes around small blood vessels in an irregular pattern at the depths of the cortical sulci. The changes were focal and limited in terms of overall extent, and some of the cases had a clearer pattern of pathology and some could be considered equivocal. Two of the 8 cases had a history of TBI and one of them showed CTE pathology. Five of the 6 cases with no known history of neurotrauma appeared to meet consensus criteria for CTE. This study adds to the emerging literature indicating that CTE pathology is present in people not known to have experienced multiple concussions or subconcussive blows to the head.

Examining the Progressive Behavior and Neuropathological Outcomes Associated with Chronic Repetitive Mild Traumatic Brain Injury in Rats

While the physical and behavioral symptomologies associated with a single mild traumatic brain injury (mTBI) are typically transient, repetitive mTBIs (RmTBI) have been associated with persisting neurological deficits. Therefore, this study examined the progressive changes in behavior and the neuropathological outcomes associated with chronic RmTBI through adolescence and adulthood in male and female Sprague Dawley rats. Rats experienced 2 mTBIs/week for 15 weeks and were periodically tested for changes in motor behavior, cognitive function, emotional disturbances, and aggression. Brain tissue was examined for neuropathological changes in ventricle size and presentation of Iba1 and GFAP. We did not see progressively worse behavioral impairments with the accumulation of injuries or time, but did find evidence for neurological and functional change (motor disturbance, reduced exploration, reduced aggression, alteration in depressive-like behavior, deficits in short-term working memory). Neuropathological assessment of RmTBI animals identified an increase in ventricle size, prolonged changes in GFAP, and sex differences in Iba1, in the corpus callosum, thalamus, and medial prefrontal cortex. Telomere length reduced exponentially as the injury load increased. Overall, chronic RmTBI did not result in accumulating behavioral impairment, and there is a need to further investigate progressive behavioral changes associated with repeated injuries in adolescence and young adulthood.

A Decision-Analytic Approach to Addressing the Evidence About Football and Chronic Traumatic Encephalopathy

Doubts can be raised about almost any assertion that a particular exposure can lead to an increase in a given adverse health effect. Even some of the most well-accepted causal associations in public health, such as that linking cigarette smoking to increased lung cancer risk, have intriguing research questions remaining to be answered. The inquiry whether an exposure causes a disease is never wholly a yes/no question but ought to follow from an appraisal of the weight of evidence supporting the positive conclusion in light of any coherent theories casting doubt on this evidence and the data supporting these. More importantly, such an appraisal cannot be made sensibly without considering the relative consequences to public health and economic welfare of specific actions based on unwarranted credulity (false positives) versus unwarranted skepticism (false negatives). Here we appraise the weight of evidence for the premise that repeated head impacts (RHIs) in professional football can increase the incidence of chronic traumatic encephalopathy (CTE) and, in turn, cause a variety of cognitive and behavioral symptoms. We first dismiss four logical fallacies that should not affect the appraisal of the weight of evidence. We then examine four alternative hypotheses in which RHI is not associated with CTE or symptoms (or both), and we conclude that the chances are small that the RHI→ CTE→ symptoms link is coincidental or artifactual. In particular, we observe that there are many specific interventions for which, even under a skeptical appraisal of the weight of evidence, the costs of a false positive are smaller than the false negative costs of refusing to intervene.

Chronic Traumatic Encephalopathy: A Brief Overview

Chronic Traumatic Encephalopathy (CTE) is a debilitating neurodegenerative disease, which has been increasingly reported in athletes, especially American football players, as well as military veterans in combat settings, commonly as a result of repetitive mild traumatic brain injuries (TBIs). CTE has a unique neuropathological signature comprised of accumulation of phosphorylated tau (p-tau) in sulci and peri-vascular regions, microgliosis, and astrocytosis. As per most recent disease classification, the disease manifests itself in four different stages, characterized by widespread tauopathy. Clinically, CTE has a more subtle presentation, as patients often present with two distinct phenotypes, with one subtype initially presenting with affective changes, and the other subtype with more cognitive impairment. On a genetic basis, there are no clear risk factor genes. Although ApoE4 carriers have been reported to suffer more severe outcome post TBI. As there are no disease modifying regimen for CTE, the newly developed TBI treatments, if administered in a time sensitive manner, can offer a potential viable option. Prevention is another key strategy that needs to be implemented in various sports and military settings. Providing education for safe practice techniques, such as safe tackling and hitting, and providing ready access to full neuropsychiatric assessment by team physician could have measurable benefits. The combination of advanced of research techniques including neuroimaging, as well as increasing public awareness of CTE, offers promising vistas for research advancement.

Traumatic brain injury: neuropathological, neurocognitive and neurobehavioral sequelae

Traumatic brain injury (TBI) causes substantial neurological disabilities and mental distress. Annual TBI incidence is in magnitude of millions, making it a global health challenge. Categorization of TBI into severe, moderate and mild by scores on the Glasgow coma scale (GCS) is based on clinical grounds and standard brain imaging (CT). Recent research focused on repeated mild TBI (sport and non-sport concussions) suggests that a considerable number of patients have long-term disabling neurocognitive and neurobehavioral sequelae. These relate to subtle neuronal injury (diffuse axonal injury) visible only by using advanced neuroimaging distinguishing microstructural tissue damage. With advanced MRI protocols better characterization of TBI is achievable. Diffusion tensor imaging (DTI) visualizes white matter pathology, susceptibility weight imaging (SWI) detects microscopic bleeding while functional magnetic resonance imaging (fMRI) provides closer understanding of cognitive disorders etc. However, advanced imaging is still not integrated in the clinical care of patients with TBI. Patients with chronic TBI may experience many somatic disorders, cognitive disturbances and mental complaints. The underlying pathophysiological mechanisms occurring in TBI are complex, brain injuries are highly heterogeneous and include neuroendocrine dysfunctions. Post-traumatic neuroendocrine dysfunctions received attention since the year 2000. Occurrence of TBI-related hypopituitarism does not correlate to severity of the GCS scores. Complete or partial hypopituitarism (isolated growth hormone (GH) deficiency as most frequent) may occur after mild TBI equally as after moderate-to-severe TBI. Many symptoms of hypopituitarism overlap with symptoms occurring in patients with chronic TBI, i.e. they have lower scores on neuropsychological examinations (cognitive disability) and have more symptoms of mental distress (depression and fatigue). The great challenges for the endocrinologist are: (1) detection of hypopituitarism in patients with TBI prospectively (in the acute phase and months to years after TBI), (2) assessment of the extent of cognitive impairment at baseline, and (3) monitoring of treatment effects (alteration of cognitive functioning and mental distress with hormone replacement therapy). Only few studies recently suggest that with growth hormone (rhGH) replacement in patients with chronic TBI and with abnormal GH secretion, cognitive performance may not change while symptoms related to depression and fatigue improve. Stagnation in post-TBI rehabilitation progress is recommended as a signal for clinical suspicion of neuroendocrine dysfunction. This remains a challenging area for more research.

Historical perspectives on evolving operational definitions of concussive brain injury: From railway spine to sport-related concussion

Objective: Concussion is a clinical syndrome of biomechanically induced alteration in brain function. The historical derivation of current operational definitions of uncomplicated concussive brain injury based on acute injury variables especially posttraumatic amnesia (PTA) vs. symptom presence (no PTA) are reviewed.Methods: Major milestones from 150 plus years of concussion research include (a) railway spine; (b) traumatic neurosis; (c) duration of loss of consciousness predicting severity of brain injury; (d) early neuropsychological studies; (e) sport related concussion; and (f) chronic traumatic encephalopathy.Results: After initial organic explanations proved untenable, 19th century conceptions of concussion were operationally defined from symptom presence, attributed primarily to psychogenic (emotional, motivational, and/or predispositional) causes. In the 1930s, duration of PTA was linked to brain injury severity via outcome studies. Concussion (as defined by PTA < 1 h) was later found to cause a transient lowering of neuropsychological test scores in memory and executive function. In the 1990s, organizational definitions of sport-related concussion began to include biomechanical events without PTA that produced symptoms. Such events have not been linked to neuropsychological impairment.Conclusions: Two differing operational definitions of concussion are in the current use, involving the presence vs. absence of PTA. These two groupings are not clinically similar, although they are currently being widely treated as such. Operational definitions of concussion should address both minimum and maximums for duration of PTA, initial Glasgow Coma Scale score, complications, and symptom presence.