For the first time, conclusive evidence has been found that repeated head trauma leads to chronic traumatic encephalopathy (CTE), an incurable brain disease.

Why it matters: A new study, carried out by nine universities and the Concussion Legacy Foundation, determined athletes in contact sports are 68 times more likely to develop CTE than the general public.

• The researchers are calling on sports and government bodies to implement prevention and mitigation efforts, especially for children, who are "too young to legally consent to any potential long-term risks."
• "It is time to include repetitive head impacts and CTE among child protection efforts like exposure to lead, mercury, smoking and sunburns," said co-author Adam Finkel of the University of Michigan.

The backdrop: This report comes amid a flurry of CTE-related news, as the shadow it casts across the sports world continues to grow.

• The English Football Association (FA), which has banned headers in soccer practice for children under 12 since 2020, announced a trial on Monday to extend that ban to games.
• Nearly 200 rugby players plan to sue the sport's governing bodies for failing to protect them from permanent brain injury caused by repeated concussions.
• Two American athletes, Demaryius Thomas (NFL) and Scott Vermillion (MLS), were posthumously diagnosed with CTE in the past month. That remains the only way to diagnose the disease — for now.

What we're watching: CTE is most often linked with hard-hitting sports like football and rugby. Now it's soccer — which doesn't have constant collisions but does have headers — that's facing a reckoning.

• The FA already recommends that pros limit headers, which have been linked to dementia, in training. If they completely ban them for kids, we could see the skill gradually fade from the game.
• That would, of course, fundamentally alter the world's most popular sport. "The threat [of a header] itself has value," writes NYT's Rory Smith. "Soccer is defined, still, by all the crosses that do not come."