From a story on futurity.org by Andrew Thurston headlined “Even Young Athletes Are at Risk for CTE”:

In a new study, more than 40% of football, soccer, ice hockey, and other contact sport athletes under the age of 30 had signs of CTE, a degenerative brain disease.

So it’s not surprising that after enduring decades of head-thumping collisions on the football field, many NFL veterans spend their retirements grappling with declining brain health. Almost all—92%—of ex-NFL players studied have been diagnosed with chronic traumatic encephalopathy (CTE).