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In recent times there has been growing public and media interest in the potential health effects of the repeated head impacts experienced by players in high-intensity contact sports such as rugby, boxing and American football.
Warning against generalised conclusions
In particular, commentators have frequently sought a direct connection between these sports and a variety of degenerative brain diseases and psychiatric conditions, including chronic traumatic encephalopathy (CTE), Alzheimer’s disease, dementia and depression.
In a new report published on the website of the BokSmart National Rugby Safety Programme, a group of South African medical researchers have reviewed the body of existing scientific evidence that might shed some light on the question of whether there is actually a direct link between rugby-related concussion injuries and such diseases.
Read: Sports concussions: myths and facts
The authors note that until now, CTE has only been identified in a small number of former rugby players and while they acknowledge that there could be a possible connection between the illness, concussion and cumulative head impacts, they warn against drawing generalised conclusions from limited data and emphasise that it is “impetuous to definitively interpret the previous case studies as reliable evidence supporting an integral role of sport-related concussions in the development and progression of CTE”.
They point out that there is currently no direct evidence “to accurately quantify or contextualize the plausible risk of CTE derived from contact sport” and that the role of concussion and less severe (sub-concussive) head impacts in the development of CTE is “ill-defined and unknown”.
Read: Did repeat concussions in rugby cause Joost's MND?
While concussion is common in many contact sports, including rugby, the moderate to severe traumatic brain injuries (TBI) that may well play a role in conditions like Alzheimer’s disease, Parkinson’s disease, motor neuron disease (also known as Lou Gehrig’s disease), dementia and depression, are less so.
On par with professional ice hockey
Thus the evidence for degenerative brain conditions that result from TBI may not be solely or directly related to concussions contracted while playing contact sports. The latter often involve milder forms of brain injury instead of TBI and “a direct causative link between chronic neurodegenerative disorders and rugby union has not yet been established”.
On average, between 1.4 and 4.0 concussions occur per 1000 professional rugby union players – an incidence rate that is higher than that for American football, but on par with professional ice hockey.
In South Africa between 2008 and 2011, catastrophic TBIs occurred at a rate of 0.19 per 100,000 junior rugby players and 0.62 for every 100,000 senior players, leading to a total of four deaths.
Read: Rugby players' head injuries linked to brain decline
According to the report, there are numerous and complex external and internal (e.g. genetic) contributing factors which influence the disorders in question, making it “impossible to isolate a single causative mechanism, such as concussion”.
In conclusion, the researchers argue that “presently no definitive statements on the relationships between repetitive concussions and sub-concussive impacts and neurological disorders can be made”.
They add that “recent media attention on CTE and head impacts can undermine the on-going efforts of concussion awareness and education, especially at this infantile stage of our understanding of the underlying mechanisms of CTE and other neurological disorders”.
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