(NEW YORK) -- For almost a decade, Jacob Bell was living his dream: making millions playing professional football, starting 100 games for the Tennessee Titans and the St. Louis Rams.
But every season, he took thousands of hits to the head, and he worried about the toll it might be taking on his brain health. Then came a moment of truth: the suicide of longtime NFL player Junior Seau.
"Seau's death rocked everybody. It rocked me a lot," Bell said. "The fact that there is a chance it was football-related and the fact that I was a football player, it hit home with me."
And so he quit the NFL, walking away from a free-agent contract with the Cincinnati Bengals earlier this month.
Bell said his plan now is to act as an advocate for players, alerting them to the dangers of chronic traumatic encephalopathy, or CTE. First discovered about a decade ago in the brains of former football players, it's a degenerative disease linked to symptoms like dementia, erratic behavior, and suicide. The small cadre of doctors who study CTE have diagnosed it in dozens of now-dead NFL players.
The NFL released a statement in February, saying that the league "has long made player safety a priority and continues to take steps to protect players and advance the science and medical understanding of the management and treatment of concussions." In 2010, the league donated a $1 million grant, no strings attached, to Boston University School of Medicine's Center for the Study of Traumatic Encephalopathy (CSTE), which researches brain disease in retired football players.
But there is increasing evidence that the way the game is played is leaving a trail of invisible injuries, even among amateur athletes who have never sustained the kind of knock-out concussions often seen on the NFL gridiron.
According to research published in this month's issue of Neurology, a football player could sustain 8,000 hits over the course of a four-year high school and a four-year college career combined.
Owen Thomas is one of the youngest players ever diagnosed with CTE. It was discovered in his brain after he committed suicide during his senior year at the University of Pennsylvania, where he was the captain of the football team. He was 21.
Doctors are now on the leading edge of discovering how young players like Thomas -- with no documented history of concussions -- might have damaged their brains.
Researchers call these hits "subconcussive blows" -- moments at which the brain hits the inside of the skull, but not hard enough to sustain what a doctor would diagnose as concussion.
The question now is whether an accumulation of these lesser blows over time could cause brain damage powerful enough to lead to CTE, which has thus far mostly been documented in professional players with a history of concussions.
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