How Much Do Head Injuries in Youth Sports Really Add Up?

A study published in The BMJ on 25 August 2026 estimates that at least one in four former NFL players who died between 2016 and 2021 had chronic traumatic encephalopathy at death, driven by cumulative impacts across a whole playing career that began in youth sport. No Canadian expert quoted on the findings is telling families to quit sport. They are saying the hits add up, and most of that build-up is preventable.

Key takeaways

Of 878 former NFL players who died between 2016 and 2021, 235 donated their brains, and 215 of those showed the disease.

That sets a floor of about 25 percent even if every non-donor was unaffected. The theoretical ceiling is about 98 percent.

Community brain bank studies put the general population rate under 1 percent.

Six in ten donors with the disease met the clinical criteria for dementia.

Ontario is still the only province with an actual concussion law.

Prevention targets every repetitive impact, not just the obvious collisions.

Football preseason is on, minor hockey registration is open, and researchers have just put a number on a question parents have circled for a decade.

What did the new brain study on former football players find?

High rates in donated NFL brains are not news. The problem has been the denominator, because brain banks fill with players who had worrying symptoms in life and chose to donate, which inflates any percentage drawn from them. This brain study on former football players, from Mass General Brigham, Boston University and the Concussion and CTE Foundation, went after the missing denominator instead.

The team identified every man who played at least one NFL game since 1949 and died between 2008 and 2021, before soft-shell helmet add-ons became common, then narrowed to the 2016 to 2021 window when brain donation was most frequent. In that window 878 former players died, 235 donated their brains, and 215 of those brains showed evidence of the disease. Even assuming nobody who declined to donate was affected, the rate still lands near 25 per cent. Lead author Dr. Daniel Daneshvar of Mass General Brigham called the result a wake-up call and said the team was saddened to see the minimum come out so high.

The severity findings should hold your attention. Roughly six in ten donors with the disease met the clinical criteria for dementia, meaning memory and thinking problems severe enough that they could no longer feed or groom themselves. Worse pathology tracked with a higher chance of dementia before death. For the wider picture, our piece on the risk factors you can actually change covers the ground.

Why do repeated hits to the head matter more than the big collisions?

Because the exposure that drives the disease is total force over a lifetime, and head injuries in youth sports are where that total starts. Daneshvar has been blunt that the impacts these athletes absorbed did not begin in the NFL. They accumulated at college level, at high school level and often in youth leagues, and it is the running total that raises risk.

That reframes the job for a parent, because counting diagnosed injuries misses the point when repeated hits to the head in ordinary practice sit on the same ledger. Former CFL player Tim Fleiszer, who heads the Concussion Legacy Foundation, argues that minor leagues should cut head impacts on developing brains, including the ones that never produce obvious symptoms. Practice volume, drill design and age of first contact are the levers.

Football is not the whole story. The disease has been confirmed in hockey greats including Hall of Famer Bobby Hull, whose brain was examined by Boston University researchers after his death in 2023. Kids arrive by other routes too, which is why our explainer on why e-scooter head injuries in kids spike every summer sits alongside this one.

What are the return to play rules in Canada?

Uneven. Dr. Charles Tator of the Canadian Concussion Centre at Toronto Western Hospital points to Ontario's Rowan's Law as the model. Passed in 2018 and named for Rowan Stringer, an Ottawa high school rugby player who died after multiple head injuries, it puts removal-from-sport and return-to-sport protocols into provincial law.

Tator's point about the rest of the country is that every province has done something on repetitive head injury, so nobody is without safeguards, and yet Ontario remains the only one where the return-to-play rules in Canada carry the force of legislation rather than league policy. The protocol your child plays under therefore depends on the province, the sport and sometimes the club, so ask your league what theirs is.

What should you do when a child takes a hit to the head?

The protocol is short and requires no diagnosis from you. When a child takes a hit to the head, work through it in order.

Remove them from play immediately, the same day, even if they insist they are fine and the hit looked routine. This step has the strongest evidence behind it.

Watch for 24 to 48 hours for headache, nausea, dizziness, light sensitivity, confusion, irritability or sleep changes. Symptoms often arrive hours after the game.

Get them medically assessed before any return to sport, and follow return-to-learn steps for school before return-to-play steps for the field.

Ask your league for its written protocol and practice contact limits, then keep a running note of every knock across the season rather than treating each as a separate event.

Dizziness that keeps returning after a knock deserves proper attention, and our guide to the reasons dizziness keeps returning explains what a clinician rules out.

What happens when you get a child checked after a head knock?

Usually far less drama than parents brace for. When you get a child checked after a head knock, a clinician takes the history, runs a neurological examination and looks for the red flags that call for imaging. Scans are the exception, because most head injuries do not show up on them.

What you leave with is a staged plan covering rest, a graded return to schoolwork, then a graded return to sport with medical clearance at the end, measured in days and weeks. No test can diagnose long-term damage in a living athlete, so the assessment is about recovery and safe return.

Frequently Asked Questions

How long should a child sit out after a hit to the head?

Removal is immediate and same-day, with no return to play that day under any circumstances. After that, return is staged rather than fixed to a set number of days. The standard sequence restores schoolwork before sport, increases activity gradually and ends with medical clearance.

What symptoms after a head knock need same-day medical attention?

Seek urgent assessment for repeated vomiting, a worsening headache, seizure, weakness or numbness, slurred speech, unequal pupils, rising confusion, or a child who is difficult to rouse. Any loss of consciousness warrants same-day review. For an emergency in Canada, call 911 rather than driving to a clinic.

Does headgear prevent long-term brain damage in youth sport?

No equipment on the market is shown to prevent the disease this research measured. Helmets reduce skull fracture and severe injury, and soft-shell add-ons may reduce impact severity. Researchers in this study point instead to cutting the total number of head impacts through practice limits, rule changes and age of first contact.

Is it only the big collisions that matter?

No. The researchers state that prevention should target all repetitive head impacts, not just the ones producing obvious symptoms. Cumulative force across a playing career appears to drive long-term consequences, which is why practice design and impact volume matter as much as the collisions that stop a game.

Can you test a living athlete for long term brain damage?

Not reliably. The disease can only be confirmed by examining brain tissue after death, which is why prevalence estimates have been so contested. No validated test or biomarker exists for living athletes. Canadian research groups are working on imaging approaches, and clinicians treat symptoms rather than diagnose the pathology.

Your next step

If a knock has left something feeling off, whether that is headaches, fogginess, balance trouble or a change in mood, head injuries in youth sports are worth getting looked at rather than waiting out. Find a walk-in clinic with a short wait near you, a family practice for follow-up care, or a physiotherapist for the balance and neck work that often follows a head injury. You can also compare providers across your province. For more on brain health, browse the Medimap Health Hub.

This article is general information and is not medical advice. It does not replace an assessment by a qualified health professional. For a medical emergency, including any head injury with worsening symptoms, call 911.