NFL players are three times as likely as the general population to die from a neurodegenerative disease such as Alzheimer's disease or Parkinson's disease, according to a new Centers for Disease Control study of retired NFL players.
The study looked at nearly 3,500 retirees who played for at least five seasons between 1959 and 1988. Of the 334 former players in that cohort who have died, neurodegenerative disease caused or contributed to 17 deaths.
Although the research suggests that concussions and repeated blows to the head are likely to blame for the increased risk, researcher Everett Lehman says multiple studies are needed to definitively blame concussions.
"There's no one study that's going to make that determination," Lehman says. The league has been plagued by a series of high-profile suicides that many have attributed to chronic traumatic encephalopathy, which can be diagnosed only after death.
"Recent research now suggests that CTE may have been the true primary or secondary factor in some of these [Alzheimer's or Parkinson's] deaths," the report, which was released in Neurology journal, says.
No matter which neurological disease players are dying from, Lehman says it's important to understand why players are getting these diseases at an increasingly high rate and for the league to stop it. Once an Alzheimer's or Parkinson's diagnosis is made, it's already too late, he says.
"Right now, we need to be able to test for neurological problems and treat them—once you get to the point of having a full-blown disease, there's not a whole lot we can do," Lehman says. "The idea is to intervene much earlier on."
The NFL announced Wednesday that it will make a $30 million donation to the Foundation for the National Institutes of Health for brain injury research, the single largest donation the NFL has made in its 92-year history.
A spokesperson for the league responded in an E-mail that the study proves recent rules changes to reduce concussions were necessary, and that the league was taking action to make the game safer "well before this study was released."
"The study underscores the continuing need to invest in research, education, and advocacy, strengthen and enforce our rules on player safety, and do all we can to make our game safer," the league said. "We remain committed to doing all that we can to promote player health and safety."
According to a study released last month, some of the rules changes, including moving kickoffs up to the 35 yard line, decreased the number of overall concussions last season. The league kicks off its second season with new rules on Wednesday.
"We hope this grant will help accelerate the medical community's pursuit of pioneering research to enhance the health of athletes past, present, and future," Roger Goodell, commissioner of the league, said in a statement. "This research will extend beyond the NFL playing field and benefit athletes at all levels and others, including members of our military."
In July, more than 3,000 former NFL players sued the league over the way it has handled concussions. Request for comment from the NFL Alumni Association and the NFL Players Association were not immediately returned.
Jason Koebler is a science and technology reporter for U.S. News & World Report. You can follow him on Twitter or reach him at firstname.lastname@example.org
Corrected 9/5/12: The number of deaths caused by neurodegenerative diseases has been corrected to 17.