What is the evidence for chronic concussion-related changes in retired athletes: Behavioural, pathological and clinical outcomes?

The Florey Institute of Neuroscience and Mental Health, , Heidelberg, Australia.
British Journal of Sports Medicine (Impact Factor: 5.03). 04/2013; 47(5):327-30. DOI: 10.1136/bjsports-2013-092248
Source: PubMed


The purpose of this paper was to review the current state of evidence for chronic traumatic encephalopathy (CTE) in retired athletes and to consider the potential differential diagnoses that require consideration when retired athletes present with cognitive and psychiatric problems.
MEDLINE, CINAHL, EMBASE, Mosby's Index, PsycEXTRA, PsycINFO and Scopus. Key words included CTE, dementia pugilistica, punch drunk syndrome, traumatic encephalopathy, CTE, repetitive head injury, sports concussion, multiple concussions, chronic concussions, subconcussive blow and sports-related traumatic brain injury.
At present, there are no published epidemiological, cross-sectional or prospective studies relating to modern CTE. Owing to the nature of the published studies, being case reports or pathological case series, it is not possible to determine the causality or risk factors with any certainty. As such, the speculation that repeated concussion or subconcussive impacts cause CTE remains unproven. The extent to which age-related changes, psychiatric or mental health illness, alcohol/drug use or coexisting dementing illnesses contribute to this process is largely unaccounted for in the published literature.
At present, the interpretation of causation in the modern CTE case studies should proceed cautiously. The causal assumptions require further prospective or longitudinal studies on the topic.

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Available from: Paul McCrory, Apr 27, 2014
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    • "In some cases, the neurologic consequences may extend across the life course (Kerr et al., 2012, 2014; McCrory et al., 2013a; Seichepine et al., 2013). Ongoing efforts to reduce the public health burden of concussions from sport span multiple levels, ranging from attempting to modify individual safety behaviors to changing the rules of sports to reduce exposure to potentially injurious head impacts (Benson et al., 2013; Graham et al., 2014; McCrory et al., 2013b). "
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    ABSTRACT: Concussions from sport present a substantial public health burden given the number of youth, adolescent and emerging adult athletes that participate in contact or collision sports. Athletes who fail to report symptoms of a suspected concussion and continue play are at risk of worsened symptomatology and potentially catastrophic neurologic consequences if another impact is sustained during this vulnerable period. Understanding why athletes do or do not report their symptoms is critical for developing efficacious strategies for risk reduction. Psychosocial theories and frameworks that explicitly incorporate context, as a source of expectations about the outcomes of reporting and as a source of behavioral reinforcement, are useful in framing this problem. The present study quantifies the pressure that athletes experience to continue playing after a head impact-from coaches, teammates, parents, and fans-and assesses how this pressure, both independently and as a system, is related to future concussion reporting intention. Participants in the study were 328 male and female athletes from 19 teams competing in one of seven sports (soccer, lacrosse, basketball, softball, baseball, volleyball, field hockey) at four colleges in the northeast region of the United States. Results found that more than one-quarter of the sample had experienced pressure from at least one source to continue playing after a head impact during the previous year. Results of a latent profile mixture model indicated that athletes who experienced pressure from all four of the measured sources were significantly more likely to intend to continue playing in the future than were athletes who had not experienced pressure from all sources, or only pressure from coaches and teammates. These findings underscore the importance of designing interventions that address the system in which athletes make decisions about concussion reporting, including athletes' parents, rather than focusing solely on modifying the individual's reporting cognitions. Copyright © 2015. Published by Elsevier Ltd.
    Social Science [?] Medicine 06/2015; 134. DOI:10.1016/j.socscimed.2015.04.011 · 2.89 Impact Factor
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    • "It has been suggested that factors other than repetitive head impacts could also be responsible for this pattern of pathology. The most commonly suggested alternative explanations include substance abuse and the normal degenerative process of aging (McCrory et al. 2007, 2013). Although it is true that cause-and-effect relationships between the number of head impacts or amount of brain trauma and the extent of pathology of CTE have yet to be established, there are good reasons to reject these alternative explanations. "
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    ABSTRACT: Free access to article: Chronic traumatic encephalopathy (CTE) is a neurodegenerative disease that is most often identified in postmortem autopsies of individuals exposed to repetitive head impacts, such as boxers and football players. The neuropathology of CTE is characterized by the accumulation of hyperphosphorylated tau protein in a pattern that is unique from that of other neurodegenerative diseases, including Alzheimer's disease. The clinical features of CTE are often progressive, leading to dramatic changes in mood, behavior, and cognition, frequently resulting in debilitating dementia. In some cases, motor features, including parkinsonism, can also be present. In this review, the historical origins of CTE are revealed for the first time and an overview of the current state of knowledge of CTE is provided, including the neuropathology, clinical features, proposed clinical and pathological diagnostic criteria, potential in vivo biomarkers, known risk factors, and treatment options.
    Annual Review of Clinical Psychology 01/2015; 11(1). DOI:10.1146/annurev-clinpsy-032814-112814 · 12.67 Impact Factor
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    • "See Supplementary Fig. 3 for effect size maps. other risk factors that are currently confusing the picture of the persistent effects of concussion on brain health (Mccrory et al., 2013). Further, multiple neurocognitive and brain integrity variables were correlated with the uncovered white matter abnormalities , which further emphasizes the clinical pertinence of the current findings. "
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    ABSTRACT: Sports-related concussions have been shown to lead to persistent subclinical anomalies of the motor and cognitive systems in young asymptomatic athletes. In advancing age, these latent alterations correlate with detectable motor and cognitive function decline. Until now, the interacting effects of concussions and the normal ageing process on white matter tract integrity remain unknown. Here we used a tract-based spatial statistical method to uncover potential white matter tissue damage in 15 retired athletes with a history of concussions, free of comorbid medical conditions. We also investigated potential associations between white matter integrity and declines in cognitive and motor functions. Compared to an age- and education-matched control group of 15 retired athletes without concussions, former athletes with concussions exhibited widespread white matter anomalies along many major association, interhemispheric, and projection tracts. Group contrasts revealed decreases in fractional anisotropy, as well as increases in mean and radial diffusivity measures in the concussed group. These differences were primarily apparent in fronto-parietal networks as well as in the frontal aspect of the corpus callosum. The white matter anomalies uncovered in concussed athletes were significantly associated with a decline in episodic memory and lateral ventricle expansion. Finally, the expected association between frontal white matter integrity and motor learning found in former non-concussed athletes was absent in concussed participants. Together, these results show that advancing age in retired athletes presenting with a history of sports-related concussions is linked to diffuse white matter abnormalities that are consistent with the effects of traumatic axonal injury and exacerbated demyelination. These changes in white matter integrity might explain the cognitive and motor function declines documented in this population.
    Brain 09/2014; 137(11):2997-3011. DOI:10.1093/brain/awu236 · 9.20 Impact Factor
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