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NFL players at higher risk of degenerative brain disorders, especially Alzheimer’s and ALS, CDC finds

REUTERS/Ray Stubblebine
Dallas Cowboys quarterback Tony Romo sacked by New York Giants linebacker Keith Rivers and Jacquian Williams during Wednesday night's NFL opening game.

Just hours before the National Football League’s regular-season opening game yesterday, the sport was hit with the latest in a string of bad news about the potential danger it poses for its players’ brains.

A sobering new study from the Centers for Disease Control and Prevention (CDC) reported that professional football players are three times more likely to die from neurodegenerative brain disorders (ones involving damaged brain cells) than the general U.S. population.

For two particular neurodegenerative disorders, amyotrophic lateral sclerosis (ALS) and Alzheimer’s disease, the risk was even higher.

“These results are consistent with recent studies that suggest an increased risk of neurodegenerative disease among football players,” the study’s authors concluded.

The study was published online Wednesday in the journal Neurology, which is the official publication of the Minneapolis-based American Academy of Neurology.

Study’s details

Previous research has identified an association between contact sports and a progressive neurodegenerative disease called chronic traumatic encephalopathy (CTE), which occurs in people with a history of repeated head injuries, including concussions. CTE can cause a range of physical and psychological symptoms, including tremors, memory loss and severe depression.

CTE is a relatively new diagnosis, however, and can be confirmed only with a brain autopsy. For the current study, therefore, CDC researchers took a different approach to determining the rate of neurodegenerative diseases among contact-sports atheletes. They looked through the death certificates of former football players to see if the cause of death was listed as Alzheimer’s disease, ALS or Parkinson’s disease. Scientists now believe that many athletes previously diagnosed with one of those neurological conditions may actually have had CTE. The symptoms can be similar.

The CDC researchers began with a database of 3,439 retired NFL players who had played professional football for at least five seasons between 1959 and 1988. They then searched national death registries and found that 334 of those players had died by 2007. In 27 of those deaths, a neurodegenerative disease was cited as either the prime or contributing cause. Thirteen deaths were attributed to ALS, nine to Alzheimer’s disease, and five to Parkinson’s disease.

Those numbers, although small, suggested the players were dying from Alzheimer’s disease and ALS at a rate that was almost four times greater than that of other people (matched for age and ethnicity) who hadn’t played professional football. The death rate from Parkinson’s disease was also higher, but not high enough to be considered statistically significant.

An analysis of the data also found that quarterbacks, running backs, wide receivers and other players in “speed” positions — ones in which the players tend to build up considerable momentum before being tackled or tackling another player — were three times more likely than “non-speed” defense and offense linemen to die from a neurodegenerative disease.

Study’s limitations

The CDC researchers point out that their study involved only professional football players with at least five seasons behind them. “Our findings may not be applicable to other professional or nonprofessional football players, they write. “However, recent autopsy studies have reported pathologic findings of CTE in college-age and professional football players with relatively short playing careers.” 

The study has many limitations, as its authors point out. The number of people in the study who died of neurodegenerative diseases was small, a factor that makes the findings less reliable. In addition, the researchers had no data on player injuries or concussions. Nor did they have any medical information about the players’ genetic or environmental risk factors for neurological disorders. The study, therefore, establishes only an association between football and an increased risk of life-threatening degenerative brain diseases. It could be that some other, yet-to-be-identified factor was behind the increased risk.

“Although the results of our study do not establish a cause-effect relationship between football-related concussion and death from neurodegenerative disorders,” write the CDC researchers, “they do provide additional support for the finding that professional football players are at an increased risk of death from neurodegenerative causes.”

NFL pledges research money

The researchers also called for more research. They’ll soon have more funding for it. On Wednesday, the NFL announced it was pledging $30 million to the Foundation for the National Institutes of Health to study athletic-related medical conditions, including head trauma and its relationship to the development of neurodegenerative disorders later in life.

“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,” NFL Commissioner Roger Goodell said in a statement.

Perhaps they’re also hoping it will slow down the legal action being taken against them. Last June, more than 2,000 NFL players filed a lawsuit against the league, alleging, as CNN reported, “that the NFL failed to acknowledge and address neurological risks associated with the sport and then deliberately failed to tell players about the risks they faced.”

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