Study finds brain disease in 110 out of 111 former NFL players

When you sign up to play football, you know there's a chance you might get hurt.  A new study, however, appears to confirm that for players who reach the highest levels of the sport, "chance" might be substantially higher than previously estimated, and the concept of "hurt" might be better understood as "sustaining potentially irreversible brain damage."
A team of Boston University researchers, including Ann McKee, a prominent neuropathologist, examined the brains of 202 former football players for signs of chronic traumatic encephalopathy, or CTE. The degenerative disease is caused by repetitive head trauma from concussive and sub-concussive blows and has been linked to the sport after being discovered in the brains of former players (CTE can only be diagnosed via autopsy).
The study's population included 111 brains of men with NFL experience and researchers found that 110 of them had the disease. It's a small sample size from a very specific population — but the near-ubiquitous presence of CTE makes the study's results troubling for football players and fans alike. 
CTE has been a flashpoint for football over the past few years as the sport debates the treatment of on-field concussions at every level, from the NFL all the way down to local youth tackle leagues. Former football players who were later diagnosed as having CTE exhibited erratic, sometimes violent behavior before they died, as the disease affects the brain's ability to function properly. The most notable case was Junior Seau, a Hall of Fame star who committed suicide in 2012 and was later found to have CTE (his brain was not included in the BU study).
The study found that 177 of the 202 brain samples (87 percent) had CTE, with the disease showing up in 48 of 53 samples (91 percent) of former college players and 3 of 14 (21 percent) samples of former high school players.  The brains of the ex-NFL and college players showed signs of more severe cases of CTE, while the disease's mark on the high school group's brains wasn't as pronounced. However, family interviews showed that members of all three groups exhibited the personality-warping symptoms of the disease before their deaths, which the researchers couldn't explain.
"There’s just no way that would be possible if this disease were truly rare," McKee said in a news release announcing the research. “I think the data are very surprising. We’ve sort of become accustomed to it, but it is very shocking.” 
The results of the study did come with a major caveat: All the examined brains were from former football players. McKee told the New York Times that the samples largely came from former players who were afflicted with CTE's symptoms before their deaths, so their families chose to donate their brains for research, hoping for answers.  The study's limited scope is a concern for Munro Cullum, a University of Texas neuropsychologist who wasn't associated with the research but is considered an expert on concussions