Sport is one of the most valuable things a child can do. The physical fitness, the discipline, the friendships, the lessons in resilience, teamwork, and how to handle winning and losing – these benefits are real, lasting, and far-reaching. Millions of children and teenagers around the world play contact sports every week, and the vast majority of them will never experience a serious brain injury.
But the science has changed. And parents, coaches, and young athletes deserve to know what it now says. Over the past decade, research has made three things increasingly clear: the developing brain is more vulnerable to head impacts than an adult brain; the cumulative effects of repeated sub-concussive impacts begin building from the very first season of contact sport; and CTE – the progressive neurodegenerative disease previously associated with retired professional athletes in their 50s, 60s, and 70s – has now been found in young amateur athletes as young as 17.
This is not a guide designed to frighten parents or discourage children from sport. It is the opposite: it is a guide designed to ensure that every young athlete who plays contact sport has the protection, the awareness, and the tools they need to play it as safely as possible – for as long as possible.
Why the developing brain is different
The single most important thing to understand about brain safety in youth sport is that a child’s brain is not simply a smaller version of an adult brain. It is a fundamentally different organ at a fundamentally different stage of development – and that difference makes it significantly more vulnerable to injury from head impacts.
The brain is still being built
The human brain does not reach full maturity until approximately the mid-20s. The first five years of life are when the brain experiences the most dramatic growth – roughly 90% of its ultimate size – and the process of brain development continues intensively throughout childhood and adolescence.
A critical part of this development is myelination: the process by which the axons of nerve cells – the long fibres that carry signals from one part of the brain to another – become coated in myelin, a protective fatty sheath that both protects the axon and dramatically accelerates signal transmission. Children have less myelinated brains than adults, meaning the cells in their brains are less well protected, and they are more susceptible to chemical and metabolic changes following an impact and event on a head.
Children can be concussed with less force than adults, and the consequences of that concussion can be both more severe in the short term and more long-lasting than in a fully developed brain.
Brain changes can persist long after symptoms resolve
One of the most important findings from recent research concerns what happens in a young brain after concussion, even when the child appears fully recovered. Children and adolescents who suffer a concussion often recover quickly, but research has increasingly shown that brain connectivity and cognitive function can deteriorate years later.
A September 2025 study from UC Riverside found that a single concussion in early life can lead to lasting changes in white matter – the fibres that serve as communication pathways in the brain – potentially altering brain structure and function throughout an individual’s lifetime. The researchers were clear about the implication: children who experience a concussion should not be declared fully recovered based only on short-term symptom resolution.
This finding fundamentally challenges the common parental and coaching assumption that once symptoms are gone, recovery is complete. For the developing brain, the story may be continuing long after the headache has cleared.
Recovery takes longer in children and adolescents
Recovery may be slower among young children, and people who have had a concussion or other TBI in the past. The timeline for recovery from a concussion in a young athlete is typically longer than in an adult, and varies considerably by age. Research tracking symptom progression across age groups found meaningful differences in recovery trajectories between children aged 5 to 7, 8 to 12, and 13 to 18 years – with adolescents often experiencing more prolonged symptoms than younger children or adults.
Developing brains of children and adolescents are more vulnerable to mild traumatic brain injuries because their axons are not well-myelinated, meaning cells in the brain are not well protected, and they are more susceptible to chemical and metabolic changes.
Girls face a higher concussion risk than boys
In sports where both boys and girls compete separately, girls are 12% more likely to suffer a concussion than boys. The reasons appear to be partly structural – important brain structures that are key for signalling in the brain are narrower and less dense in females, and more likely to be damaged by brain injuries such as concussion. Neck strength also plays a role: on average, girls have less neck muscle mass than boys of the same age and sport, which means the head is less stabilised during sudden movements and impacts.
This is not a reason to restrict girls from sport. It is a reason to ensure that girls’ programmes apply the same – and in some contexts greater – attention to brain safety as boys’ programmes, and to recognise that the risk in girls’ football, girls’ ice hockey, and girls’ floorball is real and must be managed accordingly.
The sub-concussive reality for youth athletes
The conversation about youth sport and brain safety has historically focused on concussion – the diagnosable event that removes a player from the field and initiates a return-to-play protocol. This framing misses the larger issue entirely.
Each year, millions of individuals are exposed to repetitive head impacts through contact sports. These impacts are often non-symptomatic and non-concussive, and can occur thousands of times per year, over the course of decades in some cases.
The science on sub-concussive impacts in youth athletes has advanced dramatically in the last few years – and the findings are sobering.
CTE found in young amateur athletes
A December 2024 Boston University study examined 180 brain donors younger than 30 years, including 148 who had played only at the amateur level. CTE was diagnosed in 70 (38.8%) including one woman who played collegiate soccer. Most were diagnosed with mild CTE (stages I or II). Of those diagnosed, the majority had never played above high school or collegiate level – they were not retired professionals. They were young people who played youth, school, and club sport.
For athletes to develop CTE before the age of 30, it is likely they were exposed to repeated brain trauma from an early age through youth sport. The pathology of CTE, as Professor Ann McKee of the Boston University CTE Centre has emphasised, starts early – not in retirement, but during active playing years, and potentially during the school years that precede them.
CTE is observed in individuals as young as 17. Risk for CTE in exposed individuals is associated with the number of years of exposure to repetitive head impacts and the cumulative force endured.
These findings represent a genuine reframing of who is at risk. The long-held assumption that brain disease from contact sport is a problem for professional athletes in later life is no longer supported by the evidence.
Brain changes from sub-concussive impacts in a single season
You do not need a diagnosis. You do not need a concussion. Research on youth and high school athletes has found measurable neurological changes after a single season of contact sport, in athletes who were never diagnosed with a concussion during that season. The extent of these changes is directly and linearly correlated with the total number of head impacts the athlete experienced.
Many studies have found total number of impacts to be significantly correlated with changes in white matter integrity, changes in balance performance, and cognitive impairment.
In plain terms: a season of contact sport is changing the brains of young athletes who appear perfectly healthy throughout, and the more impacts they experience, the greater the change.
Age of first exposure matters enormously
The research on when contact play begins is among the most consistent and actionable in the entire field. Beginning full-contact sport before the age of 12 is associated with worse long-term cognitive and behavioural outcomes than beginning at 12 or older, even after controlling for total years of play.
Total cumulative lifetime exposure to repetitive brain trauma is the greatest risk factor for CTE. The longer someone plays, their risk of developing CTE doubles every 2.6 years. Starting earlier simply extends the total exposure window – and the data shows that it extends it during the period of greatest brain vulnerability.
Recognising concussion in a young athlete: what to look for
One of the most important practical skills any parent or coach can develop is the ability to recognise the signs of concussion in a young athlete – and to act on them immediately, even when the child says they feel fine.
Concussion signs and symptoms may not show up right away – they may take hours or days to appear or be noticed. Spotting a possible concussion may be harder in young children and some children with disabilities because they may not be able to communicate or express how they feel.
What you see – observable signs
The following can be observed by a parent, coach, or teammate from the sideline. Any one of these signs after a head impact or collision should trigger immediate removal from play:
Appearing dazed, stunned, or confused.
Moving clumsily or losing balance.
Answering questions slowly or giving unclear answers.
Showing behaviour or personality changes (unusual irritability, crying, emotional).
Being unable to recall events just before or after the impact.
Losing consciousness, even briefly – note that fewer than 10% of concussions involve any loss of consciousness, so its absence does not mean no concussion has occurred.
Holding the head or appearing to be in discomfort.
What the child tells you – reported symptoms
Young children may struggle to describe what they are feeling. Older children and teenagers may minimise or conceal symptoms because they want to keep playing. Asking direct, specific questions after any significant impact helps:
Headache or a feeling of pressure in the head
Nausea or vomiting
Dizziness or “everything is spinning”
Feeling foggy, slowed down, or “not right”
Blurry or double vision
Sensitivity to light or noise
Memory problems – not remembering how to get to the field, forgetting the score, asking the same question repeatedly
Feeling more emotional than usual, crying for no obvious reason
Sleep disturbance – sleeping far more or far less than normal
Concussion danger signs – seek emergency care immediately
The following signs require immediate emergency medical attention. Do not wait.
One pupil larger than the other
Extreme drowsiness or inability to be woken
Severe or worsening headache that does not improve
Slurred speech
Repeated vomiting
Seizure or convulsion
Increasing confusion or irritability, unusual behaviour
Neck pain
Weakness or tingling/burning in arms or legs
Deteriorating conscious status
Double vision
The golden rule: when in doubt, sit them out
The most important sentence in this guide is this: if you suspect concussion, remove the young athlete from play immediately and do not allow same-day return under any circumstances. This is not a grey area. Same-day return to play after a suspected concussion is never safe at any age – but it is particularly dangerous in young athletes because of second impact syndrome.
Second impact syndrome: why it matters especially for youth Second impact syndrome occurs when a young athlete who has not fully recovered from a concussion receives a second head impact. The result can be catastrophic: rapid, uncontrolled brain swelling that can cause permanent neurological damage or death. Second impact syndrome is where a young athlete who has previously been concussed receives a second impact either on the same day or up to a week later, resulting in catastrophic outcomes.
Second impact syndrome is essentially exclusive to children and adolescents – it is rarely seen in adults. It is not caused by an especially severe second impact. A relatively minor collision can trigger it in a brain that has not recovered from the first event. The only protection is ensuring full recovery before any return to contact activity.
The child who says “I’m fine, I want to go back in” after a collision may mean it entirely sincerely. Their brain, and their symptoms, are telling a different story. The adult on the sideline is the protection.
Return to play – and return to school
Return to play after a concussion in a young athlete should always be gradual, supervised, and cleared by a qualified healthcare professional. It should never be rushed because of a forthcoming important match, a championship, or social pressure from the team.
The internationally agreed framework follows a graduated six-step protocol, moving from complete rest through light aerobic exercise, sport-specific exercise, non-contact training, full-contact training (medical clearance required), and finally return to competition. Each step should take at least 24 hours, and any return of symptoms at any stage means going back to the previous step.
What is less commonly discussed is return to school – which can be just as important as return to sport for a young athlete. Concussions can be challenging for families, as they impact school performance, sleep, mood and behaviour, and participation in activities. Cognitive rest – reducing mental demands as well as physical ones – is part of the recovery process. This may mean reduced homework load, extended time on tests, breaks during the school day, and reduced screen time. Teachers and school nurses should be informed when a student-athlete has sustained a concussion, so that appropriate academic accommodations can be made.
Most children recover fully within two to four weeks with appropriate management. For some, symptoms persist for longer – a condition called post-concussion syndrome – which requires specialist medical assessment and management.
What parents can do: a practical checklist
This is the most actionable part of this guide. These are the things parents can do – before, during, and after a season – to meaningfully protect their child’s brain.
Before the season
Choose a club that takes brain safety seriously. Ask directly: what is the club’s concussion protocol? Who is responsible for recognising and responding to suspected head injuries? What are the rules around same-day return to play? How do you measure and manage the cumulative brain load and sub-concussive events? A good club will have clear, confident answers, and respective tools, protocols and procedures in place.
Ensure equipment fits correctly. Helmets, headbands, and other protective equipment only work as intended when they fit properly. A helmet that is too loose shifts during contact and provides inconsistent protection. Have equipment checked and fitted at the start of every season – children grow.
Talk to your child about disclosure. Many children hide concussion symptoms because they do not want to let teammates down, do not want to miss a match, or fear being seen as weak. Before the season starts, have an explicit conversation: if something does not feel right after a collision, they must tell you, their coach, or a team official immediately. No match is worth your brain.
During the season
Watch every training session and match with the brain in mind. You are not just watching how your child performs – you are watching how they respond after significant contacts. The observational signs listed above become second nature with practice.
Never pressure a child to play through symptoms. However important the match, however much your child wants to play, however much the team needs them – a child who shows concussion signs must not continue. This is the single most important active choice parents make in youth sport.
Monitor cumulative load, not just concussion events. If your club or team uses head impact sensors, engage with the data. The total number and pattern of impacts across a season gives a picture of brain load that no observation from the sideline can match.
Keep a simple record. Note any significant impacts and events your child experienced – even minor ones that did not produce immediate symptoms. If your child later develops symptoms, or if another impact occurs, having a record of prior events is important medical information.
After a concussion
Follow the return-to-play protocol fully. Do not shortcut it. Do not let the child talk you out of it. Do not let a coach push for earlier return.
Inform the school. Academic adjustments during recovery are not a sign of weakness – they are appropriate medical management.
Seek specialist care if symptoms persist beyond two to three weeks. A paediatrician or sports medicine physician with concussion experience can guide management of prolonged recovery.
Take the long-term view. A young athlete who is protected, managed well, and returned to sport safely after concussion can have a long, enjoyable, and healthy sporting career. A young athlete who returns too soon, sustains repeated concussions, or accumulates unchecked sub-concussive load faces risks that will not become visible until decades later.
What coaches of youth athletes can do
Coaches carry a specific responsibility in youth sport that goes beyond training performance. Brain development in adolescents and teenagers is not fully developed, and damage to still-developing areas of the brain can result in detrimental long-term effects. Every decision a coach makes about training load, contact intensity, and injury response directly affects that development.
Concussion awareness training. Coaches need the knowledge to recognise, respond to, and help prevent concussion.
Establish and enforce a strict same-day removal policy. No ambiguity. No “let’s see how they feel in five minutes.” Any athlete showing concussion signs is removed and does not return that day. This policy must be communicated to players, to parents, and to other coaching staff before the season begins.
Reduce contact repetitions in training. Creating structure and guidance for impact and event exposures, such as non-contact drills, and implementing age restrictions on full contact and number of head impacts and events, focus on physical training for neck and upper torso, are practical steps that directly reduce the sub-concussive load young athletes accumulate in training. Many skills that are currently taught through full-contact repetition can be developed equally well through controlled-contact or technique-only alternatives.
Model the culture you want. If coaches treat head impacts as unremarkable, normalise playing through symptoms, or praise players who “toughened up” after a collision, young athletes will absorb exactly that message. If coaches treat brain safety seriously, remove injured players without hesitation, and communicate openly about why these decisions matter, athletes will absorb that instead.
Consider head impact tracking. A sensor during training and matches provides objective data on impacts and events across the session and season. For youth coaches managing a squad without medical staff on the sideline, this technology provides a layer of oversight that observation alone cannot match.
A note on keeping sport in perspective
None of this information should lead to the conclusion that children should not play contact sport. The physical, social, developmental, and psychological benefits of sport are real and important. Many of the world’s happiest, healthiest, most successful adults played contact sport throughout their childhoods and carry that experience as one of the most formative of their lives.
What the science asks of us is proportionate awareness and intelligent management – not fear. Those who work with or treat young athletes, including coaches, athletic directors, trainers, and school nurses, as well as parents of young athletes, should take precautions to minimise the risk of repeated head trauma. Taking those precautions does not diminish the sport – it ensures that the sport gives young athletes everything it is capable of giving, without taking more than it should.
The goal is not fewer children in sport. The goal is every child in sport, protected by adults who understand the risks and take them seriously.
Summary: the ten most important things
For parents and coaches who want the essentials in one place:
1. The developing brain is more vulnerable to injury than an adult brain and takes longer to recover.
2. CTE has been found in athletes as young as 17 who played only at amateur level. The pathology starts early.
3. A single juvenile concussion can trigger white matter changes that persist throughout life – even after symptoms resolve.
4. Sub-concussive impacts accumulate invisibly and silently across every season of contact sport, with measurable neurological effects regardless of whether any concussion is ever diagnosed.
5. Age of first exposure matters. Beginning full-contact sport before age 12 is associated with worse long-term outcomes. The earlier exposure begins, the longer the cumulative window.
6. Concussion symptoms may not appear for hours or days. Fewer than 10% of concussions involve loss of consciousness. “Looking fine” is not the same as being fine.
7. Second impact syndrome – which can be fatal – is primarily a youth condition. Never allow a young athlete to return to play on the same day as a suspected concussion.
8. Return to play must be gradual, fully supervised, and medically cleared. No exceptions.
9. Girls face a statistically higher concussion risk than boys in comparable sports. Their brain safety deserves the same – and in some contexts greater – attention.
10. Prevention is the only tool available. There is no medication and no cure. The decisions made during childhood and adolescence – about contact exposure, concussion management, and training load – determine the brain health that carries into adult life.
If your child shows concussion danger signs – including one pupil larger than the other, extreme drowsiness, worsening headache, slurred speech, repeated vomiting, or seizures – seek emergency medical care immediately.
ACT Head Impact Tracker is a measurement device. ACT Head Impact Tracker is not a medical device. It does not provide medical advice, diagnostics, or treatment suggestions. In case of suspected head injury, immediately and safely remove the athlete from activity and seek assessment from a licensed medical professional.
For more information, or to buy your sensor, visit