The AFL's Concussion Research and Innovation Director, Catherine Willmott, shares a glimpse into her latest research into sports-related concussion.
The landscape of sports-related concussion (SRC) and mild traumatic brain injury (mTBI) is undergoing rapid, evidence-driven transformation.
For psychology professionals – particularly clinical neuropsychologists and sport and exercise psychologists – there are more scientific findings available than ever before. However, translation of this plethora of information into policy and evidence-based care remains a challenge.
Today, the field demands sophisticated diagnostic reasoning, an embrace of multidisciplinary collaboration and an understanding of the evolving international guidelines.
Ahead of her keynote at the upcoming APS College of Clinical Neuropsychologists (CCN) Conference, Adjunct Associate Professor Catherine Willmott MAPS, Concussion Research and Innovation Director at AFL, and lead of the mTBI stream at the Monash-Epworth Rehabilitation Research Centre at Monash University, shares her insights from a 30-year career spent at the intersection of clinical practice, neurotrauma research and education.
“Working in mild traumatic brain injury or concussion is just as challenging, if not more challenging, than severe traumatic brain injury because it can be difficult to quantify the injury,” says Willmott.
“It’s often not evident on imaging. Typically, we're talking about functional disturbances in the brain and no evidence of structural pathology or changes on a standard clinical CT/MRI brain scan.”
The challenge of shifting definitions
Another challenge facing psychologists and researchers alike is the lack of uniformity in terminology, says Willmott.
The terms 'mild traumatic brain injury', 'concussion', 'sport-related concussion', and 'mild head injury' are frequently used interchangeably in common parlance, yet they can carry distinct definitions depending on the framework adopted.
“It’s complicated,” she says. “You’ve got studies that are purporting to be measuring the same cohorts, but they're actually not. And then obviously the research informs clinical care. So that's problematic.”
Currently, bodies such as the Concussion in Sport Group (CISG) – which meets every four years to undertake a range of systematic reviews and develop a global consensus statement – and the American Congress of Rehabilitation Medicine (ACRM) are operating under different criteria, she adds.
The ACRM definition of “mild TBI” requires a biomechanically plausible mechanism of action plus at least one of:
i) one or more clinical signs,
ii) at least two acute symptoms and a clinical examination or laboratory finding; or
iii) and neuroimaging evidence,
However, the CISG definition of sport-related concussion does not require observable signs, with reports of symptoms following an impact that transmits an impulsive force to the brain that cannot be explained by other factors sufficient.
“And so as researchers, it's incumbent upon us now when we're doing research to be really clear about what criteria we use. In order to demonstrate that an intervention or treatment works or you're mapping recovery, you need to know what population it has been studied in to determine likely generalisation to other populations.”
This nuance extends to considering demographic factors, such as sex and gender differences, and how they might contribute to results.
Willmott notes that her current research collaboration with the Victorian Department of Health and La Trobe University is exploring, among other questions, why higher rates of concussion are sometimes documented in female athletes.
“We don't know if it's actually that they're having more injuries or that, as some previous literature would suggest, women are more likely to report medical symptoms than men. What are the nuances around that? What is neurobiological that might relate to concussion risk in terms of physiological factors, and what is a psychosocial result of women reporting differently?”
Unpacking persistent symptoms
For the majority of athletes at both the elite and community levels, symptoms typically resolve within a two-four week window.
“There are, of course, some people who take longer to recover following a sport-related concussion. We start saying that they've got persistent post-concussion symptoms at around 4 weeks or greater than four weeks post injury,” says Willmott. “But it's interesting – the factors that can be contributing to the persistence of symptoms are multidimensional, including issues that predate the injury.”
Elite competitions, such as the AFL, enforce strict, graded return-to-play (RTP) processes with mandatory minimum staged recovery periods and milestones for medical clearance before progression to the next step.
This is currently a minimum of 12 days at the elite level, though the average recovery often tracks closer to three weeks or longer, and 21 days in community football, with longer periods considered for those in certain circumstances.
For children and adolescents, the priority shifts strictly to a "return-to-learn" model in the first instance.
"They've got to be back at school full-time with no academic accommodations before they'd even consider going back to sport," she says.
However, when symptoms linger beyond the one-month mark, psychologists must transition to assessing for persistent post-concussion symptoms.
Willmott emphasises that managing these prolonged cases requires examining a complex web of pre-existing, injury-related and post-injury factors, such as:
- Personal history of migraines or headaches prior to injury
- Ongoing vestibular dysfunction
- Neck or other physical pain resulting from the collision
- Concurrent psychosocial stressors or pre-existing mental health conditions.
“Taking an extensive clinical history is the most important part of the diagnostic formulation,” says Willmott. “There's no test that will just tell you the answer. It’s a process of diagnostic reasoning. And so, it's important to use validated symptom scales and neuropsychological tests appropriate to the population and context.”
Crucially, the early stages of concussion management are less about intensive psychological intervention and more about structured psychoeducation, she adds. Reassuring an anxious patient/player that initial acute symptoms are normal and expected to spontaneously resolve can mitigate secondary psychological distress.
Additionally, modern rehabilitation literature supports shifting the focus from complete symptom eradication to symptom tolerance and progressive activity despite lingering symptoms.
"Our i-RECOveR multidisciplinary concussion treatment program is led by Associate Professor Adam McKay, involving MERRC staff and students, [has] physiotherapy provided by the Neurological Rehabilitation Group and adjunct medical care that's focused on returning to activities and managing symptoms. It has been shown to be effective in a single case series, and is now being replicated in an RCT."
Debunking myths and misconceptions
One of the most vital roles for psychology professionals is protecting vulnerable or anxious clients from misinformation. The heavy media saturation surrounding the potential long-term neurodegenerative risks of collision sports has created a climate of heightened anxiety for some past and present players.
Willmott is particularly concerned about the widespread misconception that Chronic Traumatic Encephalopathy (CTE) can be diagnosed in living patients.
“CTE is a neuropathological change in the brain that can only be seen at autopsy,” says Willmott. “In living people, you cannot diagnose someone with CTE or even probable CTE because you can't see that neuropathological change in the brain until you cut it, section it and stain it.”
She references recent literature in Nature Medicine highlighting that the clinical criteria for Traumatic Encephalopathy Syndrome (TES) – often conflated with CTE in public discourse – lack specificity and have low predictive value for actual post-mortem CTE pathology.
Willmott says danger of this overreach is worth highlighting. When living patients are prematurely given a deterministic, non-reversible diagnosis, clinicians may not investigate treatable factors that may well improve quality of life, she says.
“We have to stay in the evidence-based domain,” she says.
While it’s important to take players/patient’s symptoms and distress seriously, she says: "The last thing we want to do is have a situation where a player is told that their diagnosis is CTE, and no other options are investigated when a relatively straightforward intervention maybe could provide some relief."
Future innovations
Despite these challenges, the horizon for clinical neuropsychology in sport is exceptionally bright, driven by landmark initiatives such as the AFL Brain Health Initiative, which Willmott established.
"We are incredibly lucky to have players who speak up and advise us on the research, but very much also our players association – the AFL Players Association – are incredibly supportive of this initiative as well. The AFL doctors and club psychologists are further critical to the success of the BHI research program.
This prospective, longitudinal clinical research program tracks players from their status as a current AFL or AFLW player, throughout their professional careers and into retirement. By collecting long-term data on these players, Willmott and her fellow researchers hope to identify athlete, injury, health, lifestyle and environmental factors that can influence long-term brain health in collision sport athletes.
Through her work at Monash University and the AFL, Willmott has collaborated with others in neuroscience to investigate genetic and physiological biomarkers.
“We've previously looked at genetic risk factors for recovery after moderate to severe traumatic brain injury. There are numerous candidate biomarkers. And, as yet, we don't even really have clearly defined ones to predict outcomes following severe traumatic brain injury. The concussion end of the spectrum is more nuanced.
"But it looks like there will be some candidate biomarkers that will be more useful for supporting the initial diagnosis of a concussion.
"And then there are different biomarkers that look like they're going to have more use in tracking recovery over time and looking at how the neurophysiological changes in the brain are recovering over time that might persist beyond symptom experience."
If validated and governed with appropriate consent/privacy safeguards, these insights would possibly help to inform return-to-play times, she adds.
"There are certainly not yet one or two definitive clinical biomarkers that we'd look at introducing into clinical practice right now, but I think there may be in the not-too-distant future.”
Recently, Willmott was also involved in the development of Headgear Standards for Australian football that involves manufacturers having their product tested in a crash-lab and then subsequently certified to the standards.
“One product has far been certified so dar and is now being trialled on the field. The hope is that such a product can reduce the force applied to the brain in the event of a head impact, as measured by instrumented mouthguards with accelerometers, and also reduce the risk of concussion injury.”
Achieving these milestones, however, is impossible in a silo. Willmott underscores that the best practice of neurotrauma care is fundamentally multi-disciplinary.
Psychologists must actively liaise with sports medicine physicians, general practitioners, physiotherapists, neurologists, neurosurgeons and other specialists to piece together the complete clinical picture.
The AFL's concussion guidelines are developed by its Chief Medical Officer, Dr Michael Makdissi, an internationally renowned sports medicine physician, with consultation across a range of disciplines to incorporate evidence-based best practices.
"We are incredibly lucky to have him. He has been one of the major contributors to those international concussion in sport consensus meeting processes and is very influential in taking the field further in terms of innovation and research.
“Additionally, we have clinical neuropsychologist, Dr Jonathan Reyes, AFL Concussion Research Lead; clinical psychologists Dr Kate Hall, AFL Head of Mental Health and Wellbeing; and Associate Professor Suzie Cosh, AFL Mental Health & Wellbeing Research Lead, as investigators on the Brain Health Initiative. The team bring a wealth of clinical and research experience to these roles.”
For psychologists looking to build a dynamic career, Willmott says the sporting field offers a rare, multi-faceted path.
“This field opens up an incredible opportunity for neuropsychologists at the intersection of working across clinical work, academia and research, and education,” says Willmott. “You're undertaking research to inform the guidelines for the management of players and to enhance clinical care... and then you're educating the players and the community. The AFL industry is seeking to develop increasing opportunities for neuropsychologists to work across clinical and research roles in the sport.”
The APS College of Clinical Neuropsychologists Conference features a comprehensive look at these themes, including a practical clinical workshop examining neuropsychology in sport, and an expert research panel focusing on long-term outcomes. Willmott is involved in both.
For registration and full program details, visit the official CCN 2026 Conference Agenda.