Sports-related concussions and later effects on the brain

Summary

The most recent findings of a group of experts funded by international sports organizations provided some recommendations on how to reduce concussion in some sports, and the possible link between repeated concussion and Chronic traumatic encephalopathy in professional athletes. However it failed to find a link between consussion and later brain damage, suicide or depression. But in what seems like a contradiction it did notice an increase of mortality due to neurological diseases, dementia and ALS in professional football and soccer players.

Sport Concussions and brain health

The Concussion in Sport Group (CISG), a panel of physicians and researchers funded by the International Olympic Committee and other international sports federations conducted one of its periodical systematical reviews of medical and scientific literature. Based on its research it prepares consensus statements to guide doctors and sport trainers around the world. This Sixth Consensus Statement reached some interesting conclusions and gave several recommendations.

What is port-related concussion?

The panel defined port-related concussion (SRC) as follows:

Sport-related concussion is a traumatic brain injury caused by a direct blow to the head, neck or body resulting in an impulsive force being transmitted to the brain that occurs in sports and exercise-related activities. This initiates a neurotransmitter and metabolic cascade, with possible axonal injury, blood flow change and inflammation affecting the brain. Symptoms and signs may present immediately, or evolve over minutes or hours, and commonly resolve within days, but may be prolonged. CISG (2023)

Recommendations regarding SRC

The CISG recommended several concussion prevention strategies and some rule changes to reduce collisions and gave the outcome in reduced concussion rate observed in controlled trials:

• Ban body checking in child or adolescent ice hockey (Reduction of concussion rate in games by 58%)
• Limiting the number, duration and intensity of contact practices and collision time in practices in American football led to a drop of 64%.
• Mouthguards were responsible for a 28% drop in concussion rate in ice hockey.
• On-field neuromuscular training (NMT) warm-up programmes at least three times per week is linked to a lower rate of concussions in the Rugby Union.

They also provided strong evidence for concussion management strategies such as the benefits of an early return to controlled physical activity and aerobic exercise instead of resting: "The best available evidence shows that recommending strict rest until the complete resolution of concussion-related symptoms is not beneficial following SRC. Relative (not strict) rest, which includes activities of daily living and reduced screen time, is indicated immediately and for up to the first 2 days after injury. Individuals can return to light-intensity physical activity, such as walking that does not more than mildly exacerbate symptoms, during the initial 24–48 hours following a concussion.... The best data on cognitive exertion show that reduced screen use in the first 48 hours after injury is warranted but may not be effective beyond that."

Long Term Effects on the Brain

Low risk of brain diseases

The studies reviewed by the panel found that the outcome was not severe.

• "Former amateur athletes (primarily American football players) are not at increased risk for depression or suicidality during early adulthood or as older adults."
• "Former professional soccer players are not at increased risk for psychiatric hospitalisation during their adult life."
• "Former professional football and soccer players are not at increased risk for death associated with having a psychiatric disorder or as a result of suicide."
• "Former male amateur athletes were not at increased risk for cognitive impairment, neurological disorders or neurodegenerative diseases compared with men from the general population."

But they are affected by dementia and ALS!

In an apparent contradiction, the panel also recognizes that "[for] former professional athletes [the] causes of death reported greater mortality rates from neurological diseases and dementia in former professional American football players and professional soccer players." Both groups also "have greater mortality rates from ALS".

It also admits that most studies are limited in scope and design. Perhaps under-reporting severe effects.

The panel did find that a condition known as Chronic traumatic encephalopathy (first detected in boxers with repetitive brain injury), is also a risk for regular athletes:

It is reasonable to consider extensive exposure to repetitive head impacts, such as that experienced by some professional athletes, as potentially associated with the development of the specific neuropathology described as CTE.

Critics have pointed out their concerns regarding research integrity and conflicts of interest (the sports federations are funding the research), lack of transparency in the proceedings of the panel, and in the selection criteria of its panelists 2.

References and Further Reading

(1) Patricios JS, Schneider KJ, Dvorak J, et al (2023). Consensus statement on concussion in sport: the 6th International Conference on Concussion in Sport–Amsterdam, October 2022. British Journal of Sports Medicine 2023;57:695-711.

(2)The Senate, Australia, Community Affairs References Committee (2023) Concussions and repeated head trauma in contact sports. Senate Printing Unit, Parliament House, Canberra