Chris Borland, a standout NFL player, has retired at age 24 due to concussion concerns

A standout NFL player has retired after just one year in the league due to concerns about concussions and long-term brain damage.

The 49ers' Chris Borland, a 24-year-old linebacker who had a very successful rookie season, told ESPN's Outside the Lines on Monday that he was retiring.

"I just honestly want to do what's best for my health," he said. "From what I've researched and what I've experienced, I don't think it's worth the risk."

What's most striking about this is Borland is a young star, retiring while on the verge of a seemingly lucrative career. To fans, this is very different from the many older, long-retired players quietly suffering from dementia out of the spotlight.

Borland has experienced two diagnosed concussions during his lifetime (both before college), but may have suffered more undiagnosed ones. He said that after speaking with concussion experts and reading about the link between head trauma and the long-term neurodegenerative disease chronic traumatic encephalopathy (CTE), he decided it wasn't worth it to keep playing.

"I'm concerned that if you wait till you have symptoms, it's too late," he told ESPN. Borland is one of the first NFL players to retire at such an early age because of worries about head trauma in particular.

In recent years, researchers have determined there's a link between repeated concussions and the development of symptoms like depression and dementia down the road as part of CTE. But it's unclear how exactly CTE develops and what level of head trauma is necessary to lead to it.

The NFL, meanwhile, has been trying to limit concussions by outlawing certain kinds of particularly vicious hits, and has put new protocols in place to properly diagnose concussed players. But while these strategies can help cut down on concussions, they certainly can't eliminate them entirely.

Borland is the fourth NFL player under 30 to surprisingly retire due this offseason, although none of the others cited head injury concerns in their decisions. Still, some experts are already saying his retirement could be the start of a trend — one that should worry the NFL.

Read more:

• We lost our son to football and brain disease. This is our story.
• Here's what we know about football, concussions, and the brain.
• League of Denial, Frontline's excellent documentary on the NFL's concussion crisis

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