Query: Repeated concussion leads to dementia

title: Concussion is confusing us all
abstract: It is time to stop using the term concussion as it has no clear definition and no pathological meaning. This confusion is increasingly problematic as the management of 'concussed' individuals is a pressing concern. Historically, it has been used to describe patients briefly disabled following a head injury, with the assumption that this was due to a transient disorder of brain function without long term sequelae. However, the symptoms of concussion are highly variable in duration, and can persist for many years with no reliable early predictors of outcome. Using vague terminology for post traumatic problems leads to misconceptions and biases in the diagnostic process, producing uninterpretable science, poor clinical guidelines and confused policy. We propose that the term concussion should be avoided. Instead neurologists and other healthcare professionals should classify the severity of traumatic brain injury and then attempt to precisely diagnose the underlying cause of post traumatic symptoms.

title: Risk of suicide after a concussion
abstract: Head injuries have been associated with subsequent suicide among military personnel, but outcomes after a concussion in the community are uncertain. We assessed the long term risk of suicide after concussions occurring on weekends or weekdays in the community.  We performed a longitudinal cohort analysis of adults with diagnosis of a concussion in Ontario, Canada, from Apr. 1, 1992,  2012 (a 20 yr period) excluding severe cases that resulted in hospital admission. The primary outcome was the long term risk of suicide after a weekend or weekday concussion.  We identified 235 110 patients with a concussion. Their mean age was 41 years, 52% were men, and most (86% lived in an urban location. A total of 667 subsequent suicides occurred over a median follow up of 9.3 years, equivalent to 31 deaths per 100 000 patients annually or 3 times the population norm. Weekend concussions were associated with a one third further increased risk of suicide compared with weekday concussions (relative risk 1.36, 95% confidence interval 1.14 1.64) The increased risk applied regardless of patients' demographic characteristics, was independent of past psychiatric conditions, became accentuated with time and exceeded the risk among military personnel. Half of these patients had visited a physician in the last week of life.  Adults with a diagnosis of concussion had an increased long term risk of suicide, particularly after concussions on weekends. Greater attention to the long term care of patients after a concussion in the community might save lives because deaths from suicide can be prevented.

title: Concussion, dementia and CTE: are we getting it very wrong?
abstract: There has been a large media interest over the recent years in the long term health effects of concussive injuries sustained by sportsman, culminating in a Hollywood movie 'Concussion' starring Will Smith. Hardly a week goes by without further studies being announced in the media and creating considerable interest in social media. The message is that concussion is a dangerous condition that causes a complex neuropsychiatric disorder, chronic traumatic encephalopathy (CTE) with a neuropsychiatric phenotype of mood change, irritability and suicidal behaviour which develops over time into a neurodegenerative disorder and  Increasing alarm has followed, and it has been suggested that this is not just a disorder of elite sportsman but a problem for youth sport and that even heading a football (soccer) may cause dementia,2 a terrifying prospect for those parents trying to decide whether to allow their children to participate in sports. This journal features, two well conducted studies examining the outcome of elite rugby and ice hockey players. Both studies offer reassuring messages. Macmillan et al3 study of cognitive outcomes in retired Scottish International rugby players, mean age 54 and a mean of 20 years after retirement, found no significant effects of concussion. The ice hockey cohort4 does not have the same number of years of follow up but at least in the short term is similarly reassuring, although the authors are appropriately cautious that the long term follow up data must be awaited. Both studies used opportunistic cohorts and as such selective sampling, non participation and choice of controls will be valid criticisms. But the more important question might be asked, 'Why are these studies seemingly at such odds with the prevailing wind? Part of the problem may be that much of the debate has been played out in mainstream media rather than scientific journals. To tackle this more

title: Post Concussion Experiences of Collegiate Student Athletes
abstract: Sports related concussions are a major public health concern affecting a significant number of collegiate student athletes. Medical and public health research has addressed every aspect of concussion management processes including concussion education, medical diagnosis, recovery, and returning to sport and classroom. This research has led to several best practices for concussion management. Since 2010, the NCAA has mandated that its member institutions maintain concussion management policies and procedures. However, the current recommendations, based primarily on medical research, have been found in quantitative studies of the behaviors and practices of athletic trainers, coaches, and student athletes to be ineffective. To date, no studies have explored the perceptions and experiences of student athletes post concussion. The purpose of this study was to understand student athletes' experiences post concussion and how their experiences compared to concussion management policy. A qualitative research design was utilized to allow for an in depth understanding of the studentathlete's perspective on concussion management. Data were collected from interviews with seven current and former NCAA student athletes from five member institutions representing Division I football, lacrosse, men's soccer, women's soccer, Division II football, and Division III football; and from publicly obtained concussion management documents. The data were analyzed using Tesch's (2013) organizing system and Love's (2003) methods for document analysis. Eight major findings emerged from the data: 1) Symptomology and its effects, 2) Pressure to return, 3) Lack of Knowledge, 4) Inadequate support, 5) No rest, 6) No policy, 7) Double injury, and 8) Inconsistent

title: Diagnosis and management of acute concussion.
abstract: Mild traumatic brain injury (mTBI) or concussion, constitutes a significant percentage of the millions of TBIs sustained in the United States each year. Symptoms are typically short lived, and may correlate to physiologic changes in the acute period after injury. There are many available tools that can be utilized on the sideline as well as in the clinical setting for assessment and diagnosis of concussion. It is important to use validated tests in conjunction with a thorough history and physical examination. Neurocognitive testing may be helpful in the subacute period. Management should begin with removal from risk if a concussion is suspected, and once diagnosis is made, education and reassurance should be provided. Once symptoms have resolved, a graded return to play protocol can be implemented with close supervision and observation for return of symptoms. Management should be tailored to the individual, and if symptoms are prolonged, further diagnostic evaluation may be necessary.

title: Helmet efficacy against concussion and traumatic brain injury: a review.
abstract: Helmets are one of the earliest and most enduring methods of personal protection in human civilization. Although primarily developed for combat purposes in ancient times, modern helmets have become highly diversified to sports, recreation, and transportation. History and the scientific literature exhibit that helmets continue to be the primary and most effective prevention method against traumatic brain injury (TBI) which presents high mortality and morbidity rates in the US. The neurosurgical and neurotrauma literature on helmets and TBI indicate that helmets provide effectual protection against moderate to severe head trauma resulting in severe disability or death. However, there is a dearth of scientific data on helmet efficacy against concussion in both civilian and military aspects. The objective of this literature review was to explore the historical evolution of helmets, consider the effectiveness of helmets in protecting against severe intracranial injuries, and examine recent evidence on helmet efficacy against concussion. It was also the goal of this report to emphasize the need for more research on helmet efficacy with improved experimental design and quantitative standardization of assessments for concussion and TBI, and to promote expanded involvement of neurosurgery in studying the quantitative diagnostics of concussion and TBI. Recent evidence summarized by this literature review suggests that helmeted patients do not have better relative clinical outcome and protection against concussion than unhelmeted patients.

title: Alzheimer's Dementia due to Suspected CTE from Subconcussive Head Impact
abstract: Chronic traumatic encephalopathy (CTE) has been receiving increasing attention due to press coverage of professional football players. The devastating sequelae of CTE compel us to aim for early diagnosis and treatment. However, by current standards, CTE is challenging to diagnose. Clear clinical diagnostic criteria for CTE have not been established. Only recently, pathological diagnostic criteria have been recognized, but postmortem diagnosis is too late. Reliable biomarkers are not available. By imaging criteria, cavum septum pellucidum has been the only consistent identifiable MRI finding. Because of the imprecise nature of diagnosis based on clinical suspicion, physicians must become cognizant of the broad spectrum of presentations of CTE. With this awareness, appropriate workup can be initiated. CTE can present with early symptoms of emotional changes or late symptoms with memory decline and dementia. Here we present an unusual case of a patient with Alzheimer's disease secondary to suspected CTE that stems from subconcussive head impacts presenting with severe memory and MRI changes. Clinicians should be aware of this presentation and consider CTE in their differential diagnoses while undergoing workup of memory disorders.

title: Concussion As a Multi Scale Complex System: An Interdisciplinary Synthesis of Current Knowledge
abstract: Traumatic brain injury (TBI) has been called "the most complicated disease of the most complex organ of the body" and is an increasingly high profile public health issue. Many patients report long term impairments following even "mild" injuries, but reliable criteria for diagnosis and prognosis are lacking. Every clinical trial for TBI treatment to date has failed to demonstrate reliable and safe improvement in outcomes, and the existing body of literature is insufficient to support the creation of a new classification system. Concussion, or mild TBI, is a highly heterogeneous phenomenon, and numerous factors interact dynamically to influence an individual's recovery trajectory. Many of the obstacles faced in research and clinical practice related to TBI and concussion, including observed heterogeneity, arguably stem from the complexity of the condition itself. To improve understanding of this complexity, we review the current state of research through the lens provided by the interdisciplinary field of systems science, which has been increasingly applied to biomedical issues. The review was conducted iteratively, through multiple phases of literature review, expert interviews, and systems diagramming and represents the first phase in an effort to develop systems models of concussion. The primary focus of this work was to examine concepts and ways of thinking about concussion that currently impede research design and block advancements in care of TBI. Results are presented in the form of a multi scale conceptual framework intended to synthesize knowledge across disciplines, improve research design, and provide a broader, multi scale model for understanding concussion pathophysiology, classification, and treatment.

title: The effect of concussion history on cognitive motor integration in elite hockey players
abstract: To observe the effects of concussion history on cognitive motor integration in elite level athletes.  The study included 102 National Hockey League draft prospects (n 51 concussion history [CH] n 51 no history [NC] Participants completed two computer based visuomotor tasks, one involved 'standard' visuomotor mapping and one involved 'nonstandard' mapping in which vision and action were decoupled.  We observed a significant effect of group on reaction time (CH slower) and accuracy (CH worse) but a group by condition interaction only for reaction time (p 0.05) There were no other deficits found. We discussed these findings in comparison to our previous work with non elite athletes.  Previously concussed elite level athletes may have lingering neurological deficits that are not detected using standard clinical assessments.

title: Considerations for Experimental Animal Models of Concussion, Traumatic Brain Injury, and Chronic Traumatic Encephalopathy These Matters Matter
abstract: Animal models of concussion, traumatic brain injury (TBI) and chronic traumatic encephalopathy (CTE) are widely available and routinely deployed in laboratories around the world. Effective animal modeling requires careful consideration of four basic principles. First, animal model use must be guided by clarity of definitions regarding the human disease or condition being modeled. Concussion, TBI, and CTE represent distinct clinical entities that require clear differentiation: concussion is a neurological syndrome, TBI is a neurological event, and CTE is a neurological disease. While these conditions are all associated with head injury, the pathophysiology, clinical course, and medical management of each are distinct. Investigators who use animal models of these conditions must take into account these clinical distinctions to avoid misinterpretation of results and category mistakes. Second, model selection must be grounded by clarity of purpose with respect to experimental questions and frame of reference of the investigation. Distinguishing injury context "inputs" from injury consequences "outputs" may be helpful during animal model selection, experimental design and execution, and interpretation of results. Vigilance is required to rout out, or rigorously control for, model artifacts with potential to interfere with primary endpoints. The widespread use of anesthetics in many animal models illustrates the many ways that model artifacts can confound preclinical results. Third, concordance between key features of the animal model and the human disease or condition being modeled is required to confirm model biofidelity. Fourth, experimental results observed in animals must be confirmed in human subjects for model validation. Adherence to these principles serves as a bulwark against flawed interpretation of results, study replication failure, and confusion in the field. Implementing these principles will advance basic science discovery and accelerate clinical translation to benefit people affected by concussion, TBI, and CTE.