Concussion was defined by the “Zurich Group” of medical and neurological experts at the 4th International Conference on Concussion in Sport (2012) as *“a complex pathophysiological process affecting the brain, induced by biomechanical forces”*¹.

Traumatic brain injury (TBI) is a major global public health issue, imposing both a substantial personal and economic burden. Each year, more than 3.5 million people are affected by TBI². Survivors and their families endure long-term challenges, while society faces significant healthcare costs and productivity losses³. Importantly, TBI has also been implicated as a potential risk factor for later neurodegenerative disorders, including Alzheimer’s disease⁴–¹⁰. Despite this burden, no treatment has proven effective, even after multiple phase III clinical trials¹¹–¹³.

In sport, the scale of the problem is clear. In the United States, approximately 175,000 children and adolescents aged 0–19 present to hospital annually with sport-related concussions¹⁵. Up to 15% may remain symptomatic for two years or longer, with lasting performance decline following their last concussion. Biomarker-based diagnostics are emerging as an important approach to more comprehensively assess brain function after concussion¹⁶.

Among children aged 0–14 years in the United States each year, TBI accounts for an estimated:

• 3,000 deaths
• 29,000 hospitalisations
• 400,000 emergency department visits

TBI is the leading cause of disability in young people in the U.S. However, most outcome data are drawn from limited case series or regional studies rather than large-scale, systematic investigations¹⁷. Evidence further suggests that TBI may predispose children and adults alike to later neurodegenerative disorders, including Alzheimer’s disease¹⁸–²⁴.

Notably, brain injuries can be more concerning in children than in professional athletes. Unlike other injuries where younger bodies typically heal faster, paediatric brain trauma often heals more slowly and may lead to longer-lasting deficits²⁵.

The impact of TBI extends beyond the injured individual, affecting families and caregivers. Partners of survivors frequently report higher levels of stress, anxiety, and depression, as well as lower quality of life compared to the general population²⁶. They are particularly distressed by personality and behavioural changes, including aggression, disinhibition, or loss of motivation²⁷.

Updated 2014 Australian guidelines for sports-related concussion highlight five key complications²⁸:

1. Impaired performance and increased risk of further injury – slowed reaction times and cognitive deficits may heighten the risk of re-injury.
2. Acute, progressive diffuse cerebral oedema – also known as “second impact syndrome,” where repeated trauma can trigger fatal brain swelling if the initial injury was not recognised.
3. Prolonged symptoms – 5–10% of athletes take more than 10 days to recover, and approximately 1% continue to experience symptoms beyond three months.
4. Mental health issues – retired athletes show a two- to threefold increased risk of clinical depression.
5. Cumulative cognitive decline (Chronic Traumatic Encephalopathy, CTE) – recurrent head trauma is linked to progressive deterioration in brain function.

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