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Traumatic brain injury, collision sports participation, and neurodegenerative disorders: narrative power, scientific evidence, and litigation
  1. G David Batty1,
  2. Jaakko Kaprio2
  1. 1 Department of Epidemiology and Public Health, University College London, London, UK
  2. 2 Institute for Molecular Medicine Finland, University of Helsinki, Helsinki, Finland
  1. Correspondence to Professor G David Batty, Department of Epidemiology and Public Health, University College London, London WC1E 6BT, UK; david.batty{at}

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The present and future burden of neurodegenerative disorder, particularly dementia, for individuals, society, and healthcare systems has been extremely well documented. Dementia currently directly affects around 50 million people globally and, owing to demographic expansion, its prevalence is expected to triple over the following three decades.1 The disappointing results of trials of drug treatments for dementia, and other neurodegenerative disease, such as motor neuron disease (amyotrophic lateral sclerosis) and Parkinson’s disease—particularly curative therapies—bring into sharp focus the need to identify modifiable risk factors. Head injury has been advanced in this regard,2 is common3 and, in principle, has the potential for amelioration via advances in safety legislation and protective technologies.

Operationalising head impact

Head injury severity might be operationalised as a continuum. The traumatic insults occurring at the higher end of this spectrum result from vehicular accidents, assaults, and falls in civilian populations and bomb blasts in the military. Direct trauma to the head is not, however, a prerequisite for a significant brain injury; it can also result from rapid acceleration–deceleration as seen in whiplash-type episodes. Severe head injury may also occur in selected sports, most obviously boxing, mixed martial arts (so called ‘cage fighting’), and professional wrestling,4 5 where the infliction of head trauma is a key objective. In other sports such as soccer, while significant trauma to the head may also occur, typically in elbow-on-head collisions,6 head impact—as it is perhaps most usefully termed—is most likely to result from contact with equipment. Typically, this would be the seemingly innocuous subconcussive ‘heading’ of the ball for its redirection. Of the non-sport activities, similar low-intensity neurological insults might be the product of the percussive movement of the head in accompaniment to contemporary music—so-called ‘head banging’.7

Traumatic head injury and dementia

While the influential 2020 report of the Lancet Commission on dementia—an asystematic, selective, narrative …

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  • Contributors GDB wrote the first draft of the manuscript on which JK made comments.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests GDB is a Deputy Editor for the Journal of Epidemiology and Community Health. This editorial was peer-reviewed.

  • Provenance and peer review Commissioned; externally peer reviewed.