Chris Borland, retiring from the NFL at the age of 24, could mean some changes for the future of football.

By Sam Laird, Mashable

Rookie linebacker Chris Borland filled in admirably for the San Francisco 49ers this past season as star Patrick Willis sat out with a toe injury. He earned acclaim and was seen as a rising star who could help anchor the team’s defense for years to come.

Then Borland called it quits, retiring at age 24, leaving millions of dollars and several promising seasons on the table after playing just one year in the league. Borland left no question about why he decided to retire: His fear that a career’s worth of head trauma wasn’t worth NFL glory and money.

The longterm effects of playing a game built around repeated violent collisions have long been a concern. But as recently as just a few years ago, these issues were confined to the sidelines of the mainstream sports conversation, mostly ignored by fans, players and media alike.

Then, legendary San Diego Chargers linebacker Junior Seau killed himself with a gunshot wound to the chest in May 2012 and was posthumously diagnosed with CTE (chronic traumatic encephalopathy), a disease caused by brain trauma. The year after that came League of Denial, an acclaimed investigative book about research on the debilitating long-term effects of concussions — and the NFL’s long quest to obfuscate those findings.

Read more: Mashable