(CNN)—You're a 24-year-old professional football player. You signed a nearly $3 million contract with the San Francisco 49ers and banked a $600,000 bonus. You're looking real pretty after a stellar rookie season. But there's something seriously bothering you. You keep thinking, what if, one day, all those hits, those concussions, add up? Is your health really worth the risk?
Chris Borland said Tuesday night that it just wasn't, and he has chosen to retire from the NFL to avoid long-term injuries he could suffer from head injuries.
"I just honestly want to do what's best for my health," he told ESPN. "From what I've researched and what I've experienced, I don't think it's worth the risk. ... I'm concerned that if you wait (until) you have symptoms, it's too late."
Borland may be the first to retire for this reason. But he's part of a shift in thinking about what repeated head injuries can do to an athlete. Reports show an increasing number of retired NFL players who have suffered concussions developed memory and cognitive issues such as dementia, Alzheimer's disease, depression and chronic traumatic encephalopathy, or CTE.
"For me, it's wanting to be proactive," Borland said. "I'm concerned that if you wait (until) you have symptoms, it's too late. 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."
Passionate reactions to his decision came quickly, with many supporting him.
Others say that while the move might be smart for Borland, and even encourage other players to speak out and stand up for their health, there will always be plenty of guys eager to replace players like him.
'Risks ... I don't want to take on'
Last August, thousands of former football players and their families reached a deal in a class-action suit that called for the NFL to cover the cost of concussion-related compensation, medical exams and medical research for retired players and their families.
The suit alleged that the NFL deliberately misled players about scientific data that the medical community had found about the risks associated with concussions. A federal judge needed to approve that. In July 2014, a federal judge granted preliminary approval to the landmark deal.
Chris Dronett was one of the plaintiffs. Her husband, former Denver Bronco Shane Dronett, committed suicide in 2009 when he was 38. After his death, scientists found evidence of CTE in his brain.
Borland named three players specifically that he said made him rethink a life in the NFL.
"I've thought about what I could accomplish in football, but for me personally, when you read about Mike Webster and Dave Duerson and Ray Easterling, you read all these stories. And to be the type of player I want to be in football, I think I'd have to take on some risks that as a person I don't want to take on," he said.
Kansas City Chiefs linebacker Jovan Belcher shot and killed his girlfriend before killing himself two years ago. Pathology reports show he likely had chronic traumatic encephalopathy, or CTE, doctors say. Scientists believe repeated head trauma can cause CTE, a progressive degenerative disease of the brain. Symptoms include depression, aggression, and disorientation, but so far scientists can only definitively diagnose it after death. Here are a few of the former athletes who have been diagnosed with CTE.
Photos: Athletes and CTE 17 photos
Kansas City Chiefs linebacker Jovan Belcher shot and killed his girlfriend before killing himself two years ago. Pathology reports show he likely had chronic traumatic encephalopathy, or CTE, doctors say. Scientists believe repeated head trauma can cause CTE, a progressive degenerative disease of the brain. Symptoms include depression, aggression, and disorientation, but so far scientists can only definitively diagnose it after death. Here are a few of the former athletes who have been diagnosed with CTE.
Hall of Famer Mike Webster was the first former NFL player to be diagnosed with CTE. After his retirement, Webster suffered from amnesia, dementia, depression, and bone and muscle pain.
The death of 36-year-old Pittsburgh Steelers offensive lineman Justin Strzelczyk put the link between playing football and CTE in the national spotlight. Strzelczyk was <a href="
http://www.nytimes.com/2007/06/15/sport ... brain.html" target="_blank">killed in 2004</a> in a car crash after a 40-mile high-speed chase with police in New York.
Evidence of CTE was found in the brain of football player Lew Carpenter after his death in 2010 at the age of 78.
Pro Football Hall of Famer Louis Creekmur, who played for the Detroit Lions from 1950 to 1959, suffered decades of cognitive decline before his death.
Linebacker John Grimsley of the Houston Oilers died of an accidental gunshot wound to the chest. Analysis of his brain tissue confirmed damage to the neurofibrillary tangles that had begun to affect his behavior and memory.
Chris Henry played five seasons for the the Cincinnati Bengals before dying at the age of 26. <a href="
http://www.cnn.com/2010/HEALTH/07/02/br ... x.html">He died after falling from the bed of a moving pickup</a> during a fight with his fiancée, ending a life plagued by behavioral problems. His young age prompted concern over how quickly athletes start to suffer from CTE.
Offensive lineman Terry Long of the Pittsburgh Steelers commited suicide by drinking antifreeze. Although the antifreeze caused swelling of the brain, football-related brain injuries were a contributing factor to his death.
Pro Football Hall of Famer John Mackey suffered from dementia for years before dying at the age of 69.
Ollie Matson played 14 NFL seasons starting in the 1950s and suffered from dementia until his death in 2011.
Tom McHale of the Tampa Bay Buccaneers, right, died in 2008 <a href="
http://www.cnn.com/2009/HEALTH/01/26/at ... x.html">of an apparent drug overdose</a> at the age of 45.
Junior Seau <a href="
http://www.cnn.com/2013/01/10/health/se ... ease">took his own life</a> in 2012 at the age of 43. The question of CTE came up immediately after his death; scientists at the National Institutes of Health confirmed the diagnosis in January 2013.
Wrestler Chris Benoit was found dead at his suburban Atlanta home along with his wife, Nancy, and son in an apparent murder-suicide. Later testing found that the damage to his brain was similar to that of an elderly Alzheimer's patient.
Reggie Fleming, who played for six NHL teams, mainly in the 1960s, was the first hockey player to be diagnosed with CTE.
Hockey player Bob Probert was found to have CTE after suffering from heart failure at the age of 45.
<a href="
http://www.cnn.com/2013/12/15/health/ba ... ide/">Ryan Freel </a>became the first MLB player to be diagnosed with CTE nearly a year after he committed suicide at age 36.
Webster had a career with the Pittsburgh Steelers and Kansas City Chiefs that spanned from 1974 to 1990. He was the first former NFL player to be diagnosed with CTE. After he retired, he was diagnosed with amnesia, dementia, depression, and bone and muscle pain.
Duerson killed himself with a gunshot to the chest. He had sent a text to his family asking that his brain be sent to Boston University School of Medicine, which was researching CTE. BU neurologists confirmed the NFL veteran had the disease.
Easterling, who played eight seasons with the Atlanta Falcons, committed suicide in 2012. He apparently suffered dementia. An autopsy revealed he had CTE.
Some on social media said that Borland's decision made them think about former NFL linebacker Junior Seau. He was 43 when he was found dead with a gunshot wound to the chest. Friends and family members say multiple concussions were to blame for the suicide, but an initial autopsy report found no apparent brain damage.
Portions of Seau's brain were sent to the National Institutes of Health, which found "abnormalities ... that are consistent with a form" of CTE.
The NFL has reported that in 2013, 228 concussions were diagnosed from practices and games. At least 261 were diagnosed the previous year, the league said.
And complaints keep coming. In July of last year, ex-NFL players Christian Ballard and Gregory Westbrooks filed suit against the NFL Players Association, alleging the union withheld information about head injuries.