A research study of the brains of 202 former football players who had donated their brains to science found that 177 -- almost 90 percent -- showed signs of chronic traumatic encephalopathy. The brains came from deceased athletes who played in the NFL, during college and even in high school.
Chronic traumatic encephalopathy, or CTE, is thought to be caused by repeated blows to the head, which are extremely common in American football. The disease begins subtly but can be extremely debilitating, with symptoms including memory loss, confusion, behavioral changes and others. Currently, it can only be diagnosed post-mortem and there is no known treatment.
The high percentage of former players with CTE in the study may not reflect the actual percentage of CTE sufferers living today. Some families may have been motivated to donate their loved ones' brains after observing troubling symptoms while they were alive. It's also possible that the players' lifestyles, including any drug and alcohol use, steroid use or poor diet may have contributed. Therefore, it's hard to say how many CTE sufferers there may be among today's players.
"There are many questions that remain unanswered," said the study's lead author, including how many years of football may be too many. Also unanswered is whether there is a genetic risk for the disease, along with why a minority of players showed no signs despite playing for many years.
CTE is believed to develop when repeated blows to the head create a progressive loss of normal brain tissue while an abnormal protein called tau builds up. Not only football players are at risk -- military veterans and players in any rough contact sport such as boxing or hockey can also develop the condition.
Among the former players represented in the Boston "brain bank" that has collected the samples, here are the numbers who were diagnosed with the disease:
- 110 of 111 former NFL players
- 48 of 53 college players
- 9of 14 semi-professional players
- 7 of 8 Canadian Football league players
- 3 of 14 high school players
- 0 of 2 younger players
After years of denying any connection between aggressive play involving head blows and brain injury, the NFL finally acknowledged the link and agreed to a $1 billion settlement with former players. Regarding this new study, the NFL issued a statement saying the report is important for the advancement of science as it relates to head trauma. It also said it would "continue to work with a wide range of experts to improve the health of current and former NFL athletes."
The report was published July 25 in the Journal of the American Medical Association.