The long-term consequences of sport concussions

Georgia Symons (left) and Will O'Brien (right) are CCS PhD students
in the Monash Trauma Group and both are first authors on papers
investigating concussion in sport. See respectively
Symons et al. paper; O'Brien et al. paper

Australian football is the most popular collision sport in Australia – with an average of 6-7 concussions occurring every 1000 match hours across amateur and professional leagues. Despite this high incidence of mild traumatic brain injury, there has been little study of the long-term neurological damage associated with this sport.

Two recently published studies by the Monash Trauma Group in Central Clinical School's Department of Neuroscience looked at the long-term consequences of concussion on the sporting field. They found that indicators of brain injury in the blood and saliva can be persistently changed for years after the injury.

 

These studies raise further concerns of concussion in sport, following former AFL player, Shaun Smith, receiving a $1.4 million payout after his insurance company found he was “totally and permanently disabled” due to the concussion damages he incurred during his playing career. Additionally, analyses of the brains of Polly Farmer, Danny Frawley, and most recently Shane Tuck have shown that these former footballers had all been suffering from Chronic Traumatic Encephalopathy (CTE) when they died.

In one study, led by PhD student Ms Georgia Symons from the Monash University Department of Neuroscience and published recently in the Journal of Concussion, researchers investigated cognitive, blood, and saliva markers of brain injury in 69 male and 26 female amateur Australian footballers both with and without a history of concussion. These were compared to 49 athletes who had never participated in collision sports.

The study found that, compared to athletes who did not participate in collision sports, Australian footballers had a number of alterations in saliva and blood markers.

One of the main tests was for telomere length, which is commonly implicated in ageing and neurodegenerative diseases such as Alzheimer’s disease. According to Ms Symons, “This is the first evidence of shortened telomeres associated with engaging in collision sports”, adding that the findings “may indicate worse neurological health and older biological age (as opposed to chronological age), and suggest there is cumulative damage associated with both concussive and non-concussive brain injuries in male and female athletes”.

The football players also showed elevated levels in their blood of markers of oxidative stress and axonal injury, both considered long term indicators of brain injury.

Another study, led by PhD student Mr William O’Brien, also from the Monash University Department of Neuroscience and published last month in the Journal of Neurotrauma, studied 65 male and 40 female amateur Australian footballers, of which 58 players reported a prior concussion.

The researchers studied blood levels of two key molecules associated with inflammation, interleukin-1Beta and interleukin 18.

The study found that male footballers with a concussion history had higher levels of these inflammatory markers than those without a prior history. There was also a positive correlation between years of collision sport participation in male footballers with IL-18 levels.

The researchers concluded that both concussions, as well as participation in collision sports, may have chronic inflammatory consequences, and further that there may be a sex difference in this chronic inflammatory response.  “Our findings suggest that in males, mild brain injury may cause persisting inflammation. However, future studies are required to determine whether this contributes to the chronic consequences, such as cognitive deficits and neurodegeneration, which have been linked to a history of mild brain traumas and collision sport participation,” Mr O’Brien said.

While further research is necessary, in particular into whether male and female footballers have different long-term outcomes following mild brain injuries, the findings from these two studies further confirm concerns for the long-term consequences of engaging in Australian football.

See more:

• Symons GF, Clough M, O’Brien WT, et al. Shortened telomeres and serum protein biomarker abnormalities in collision sport athletes regardless of concussion history and sex. Journal of Concussion Vol.4.  https://doi.org/10.1177/2059700220975609
• O'Brien WT, Symons GF, Bain J, et al. Elevated serum interleukin-1β levels in male, but not female, collision sport athletes with a concussion history. J Neurotrauma. 2020 Dec 14. doi: 10.1089/neu.2020.7479.
• Monash Trauma Group in the Department of Neuroscience, Central Clinical School 
• More about Chronic Traumatic Encephalopathy (3:12 mins video by Professor Meng Law)