Football players may risk more than bruises and broken bones. Evidence is mounting that repeated concussions many pro athletes suffer can cause chronic traumatic encephalopathy (CTE), a degenerative brain disease marked by depression, dementia, and other Alzheimer's-like symptoms. But to find out the exact cause of CTE, researchers need to be able to study athletes' brains.
That's where NFL players come in. Keep clicking to meet players - some living and some deceased - who are in the vanguard of pro athletes to have donated or announced their intention to donate their brains to science.
"Iron Mike" Webster helped the Steelers win four Super Bowls in the 70's. After leaving the game, he suffered depression and dementia, dying in 2002 at the age of 50. He became the first apparent case of "footballer's dementia" for Brain Injury Research Institute (BIRI) pathologist Dr. Bennett Omalu. Webster's brain was said to have been through the equivalent of "25,000 car crashes" over his 25 years of playing football in high school, college, and the NFL.
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Safety Dave Duerson won a Super Bowl as a cog in the 1985 Bears defense. In February 2011, Duerson, 50, texted to his ex-wife Alicia an odd request: "Please, see that my brain is given to the N.F.L.'s brain bank." When Duerson's body was found, there was a handwritten suicide note repeating the request. "I think David knew that inside of him there was something wrong," Alicia told the New York Times.
Bengals wide receiver Chris Henry's death - after falling from a truck during a domestic dispute in 2009 - shocked football fans. An autopsy by the BIRI found that the 26-year-old had chronic traumatic encephalopathy.
"I was surprised in a way because of his age and because he was not known as a concussion sufferer or a big hitter. Is there some lower threshold when you become at risk for this disease? I'm struggling to see if something can come out positive out of this," Dr. Julian Bailes of the BIRI grimly told the New York Times.
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Strzelczyk was an offensive lineman with the Steelers for eight seasons. In 2004, he died in a car crash after taking police on a high-speed chase, the Pittsburgh Post-Gazette reported. Toxicology reports showed no evidence of drugs or alcohol in the 36-year-old's body. So what caused his erratic behavior?
Strzelczyk's family donated his brain to the Brain Injury Research Institute. Dr. Ronald Hamilton of the University of Pittsburgh told the New York Times, "If I didn't know anything about this case and I looked at the slides, I would have asked, 'Was this patient a boxer?'"
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Long played right guard for Steelers from 1984 to 1991. In 2005, when he was 45, he killed himself by drinking antifreeze, the Pittsburgh Post Gazette reported. The Brain Injury Research Institute examined his brain and saw evidence of damage that might well have contributed to his suicide.
"Terry Long committed suicide due to the chronic traumatic encephalopathy due to his long-term play." Dr. Omalu told the newspaper.
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Waters was regarded as one of the league's hardest-hitting defensive backs during his career with the Philadelphia Eagles. But he committed suicide in 2006, at the age of 44. An autopsy showed that his brain tissue to be similar to that of an 85-year-old's Alzheimer's patient, Dr. Omalu told the New York Times. "If Waters had lived another 10 to 15 years, he would have been "fully incapacitated," Dr. Omalu told the newspaper.
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When former Houston Oilers linebacker John Grimsley died in 2008 at the age of 45, his wife donated his brain to the Center for the Study of Traumatic Encephalopathy. An autopsy revealed brain abnormalities typically seen in elderly Alzheimer's patients. The site compares slides of Grimsley's brain tissue to those of a 73-year-old ex-boxer.
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Since his football career ended, CNN says, former Patriots linebacker and three-time Super Bowl winner Ted Johnson, 38, has battled anger, depression and Alzheimer's like symptoms - symptoms he blames on football. He decided he would donate his brain to the CSTE once he died.
"I'm not trying to reach up from the grave and get the N.F.L. But any doctor who doesn't connect concussions with long-term effects should be ashamed of themselves." Johnson told the New York Times.
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Matt Birk, 34, is a six-time Pro Bowler for the Vikings who now plays for the Baltimore Ravens. His greatest contribution to the game might not fill a stat sheet, though. After being asked, he agreed to donate his brain after death, telling the Associated Press, "The decision to do this brain donation, if it can help make the game safer for future generations, than why not?"
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When Brent Boyd was playing the 1980's as an offensive guard for the Vikings, brain injury awareness was an afterthought. "We didn't even know what a concussion was...you got your bell rung, you got dinged," Boyd told CBS News.
After hearing of other players' deaths following apparent neurological problems, Boyd, 53, realized where his depression, dizziness, and headaches might be coming from. His struggle led him to find a retired player's advocacy group called Dignity After Football. He also agreed to donate his brain to the CSTE.
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Sean Morey's 10-year career as a special teams ace came to an abrupt halt in 2010 when "post-concussion syndrome" forced his retirement. Even though he was no longer playing, he told Sports Illustrated that he felt like he had just "made six or seven tackles." His experience led him to donate his brain to the CSTE.
"One of the most profound actions I can take personally is to donate my brain to help ensure the safety and welfare of active, retired, and future athletes for decades to come." Morey, 35, said in a written statement.
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Former player Zach Thomas, 37, was a Pro-Bowl linebacker for the Miami Dolphins. In 2010 he joined several others on the CSTE's living donor registry. "I want to do my part to help the researchers understand this disease and to discover treatments and an eventual cure," he said in a written statement.
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Turley, 35, played offensive tackle for the Saints, Rams, and Chiefs during his NFL career. Recently, he's been in the spotlight talking about the debilitating effects the hits he took as a player have had on his body, and his decision to support this cause. "If I can donate my brain to this situation, this cause, I'm helping my boy out. I want him to be able to grow up and at least have a chance, you know, not be facing these things that I've been facing" Turley said in a 2010 interview with Arrowhead Addict, a Chiefs fan blog.
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Junior Seau, one of the NFL's best and fiercest players for nearly two decades, had a degenerative brain disease when he committed suicide last May, the National Institutes of Health revealed on Jan. 10, 2013. Results of an NIH study of Seau's brain revealed abnormalities consistent with chronic traumatic encephalopathy (CTE). The NIH, based in Bethesda, Md., conducted a study of three unidentified brains, one of which was Seau's. It said the findings on Seau were similar to autopsies of people "with exposure to repetitive head injuries."
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In this July, 1975, file photo, Atlanta Falcons safety Ray Easterling is shown. Easterling, who helped lead the team's vaunted defense in the 1970s and later filed a high-profile lawsuit against the NFL targeting the league's handling of concussion-related injuries, committed suicide on April 19, 2012, in Richmond, Va. He was 62. After his career, he suffered from dementia, depression and insomnia, according to his wife, Mary Ann. Tests revealed that Easterling suffered from CTE.
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Ralph Wenzel, who played guard for the Steelers and Chargers for seven seasons in the 60s and 70s, died in June 2012 from complications of dementia, according to his wife, Eleanor Perfetto. He was 69. Wenzel's brain is among more than 100 that have been donated to the Boston University brain bank.