(SportsNetwork.com) - San Francisco 49ers linebacker Chris Borland says he's retiring at the age of 24 over concerns about brain trauma.

Borland told ESPN's "Outside the Lines" he was worried about the long-term effects of repetitive head trauma, an issue that's been raised in recent years as studies have linked the sport with neurodegenerative diseases.

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

Borland had 108 tackles, one sack and two interceptions in 14 games as a rookie last season before being placed on season-ending injured reserve in December with an ankle injury.

The third-round draft pick notified the 49ers on Friday that he would retire, according to ESPN, and the team announced his retirement late Monday night.

Borland told ESPN he feels "as sharp as I've ever been" but wanted to be "proactive" in avoiding any potential effects from playing in the league.

"I'm concerned that if you wait till you have symptoms, it's too late," Borland said. "There are a lot of unknowns. I can't claim that X will happen. I just want to live a long healthy life, and I don't want to have any neurological diseases or die younger than I would otherwise."

San Francisco general manager Trent Baalke called the decision "unexpected" but said the 49ers "certainly respect Chris' decision."

"From speaking with Chris, it was evident that he had put a great deal of thought into this decision," Baalke said in a statement. "He was a consummate professional from Day One and a very well-respected member of our team and community.

"Chris is a determined young man that overcame long odds in his journey to the NFL and we are confident he will use the same approach to become very successful in his future endeavors. We will always consider him a 49er and wish him all the best."

The news came six days after 49ers linebacker Patrick Willis announced his retirement at the age of 30 after missing all but six games last season because of a toe injury.

Borland said Willis' retirement had no effect on his decision, according to ESPN. The 5-foot-11, 250-pound linebacker told ESPN there was no chance he would change his mind. He said he's been diagnosed with two concussions in his life, once while playing soccer in eighth grade and the other playing football as a sophomore in high school.