Chris Borland, who retired from the 49ers after one season because of concerns about the long-term effects of repeated head trauma, said Thursday he has been heartened by the mostly positive response to his decision from teammates and former NFL players.
"It was difficult, and I think [49ers teammates] wish I was playing, but they understand where I'm coming from," Borland said on "CBS This Morning". "They know what type of guy I am, that it's well researched and I'm passionate about it, so I have their support -- guys I've played with, guys I've looked up to who played before me.
"The most meaningful thing is the former players who have struggled who've reached out. That's been really touching."
Borland, 24, is the fourth NFL player 30 or under to retire recently, but the only one to cite the potential dangers of head trauma as the reason. He told CBS he had planned a longer NFL career, but that changed after he suffered a head injury in training camp.
"I've always been aware of the dangers, or I thought I was," he said. "In camp last year, I sustained a hit, and it was nothing out of the ordinary for a linebacker, and just thought to myself after that, 'Is this the route I'm going to go? How many times am I going to do this, for how long, and what are the real consequences?'
"So it triggered a change in thought for me and subsequently I did a lot of research and ultimately came to the conclusion that it wasn't worth it for me personally."
Asked if he feared permanent brain damage if he kept playing, Borland said: "That was my conclusion. People talk about knowing the risk going in and I think guys understand it's not good for you. But I don't think even the top neurologists truly understand the risks, the connection. That's what I found in my research.
"There's just too much unknown for me and there's been too many tragedies for me to be comfortable playing."
He has cited the suicides of Junior Seau and Dave Duerson as factors. Both players' brains were diagnosed with chronic traumatic encephalopathy, a degenerative disease linked to repeated head trauma.
"I could be wrong, and I hope I am," Borland said of his decision to retire and the subsequent loss of income. "However, it's a difficult conversation to have with families who have lost loved ones, about how important it is to make a lot of money playing football."
Borland also disputed the notion put forth Wednesday by Steelers neurosurgeon Joseph Maroon, who advises the NFL on head, neck and spinal injuries. Maroon told the NFL Network that football "has never been safer'' and that youth football is safer than riding a bicycle or a scooter or using playground equipment.
"The act of riding a bicycle isn't causing brain trauma," Borland said. "Yeah, you could fall, but that's if something goes wrong. Everything could go right in football, and it's still dangerous."
Borland said his decision to retire "isn't an indictment of the game. If you love it, if you think it's worth it, you should play. The important factor is that it's an informed individual choice."
Borland, who has a degree in history from Wisconsin, said he plans to go back to school.
"I have some interesting opportunities," he said. "There are some things I can do in academics or business. I need to learn more, but there's a lot on the table. A lot could happen."