Retired pro football players seem to have higher-than-average risks of dying from Alzheimer's or Lou Gehrig's disease, U.S. government researchers reported Wednesday.
In a study of more than 3,400 retired National Football League (NFL) players, the researchers found that death rates from the two brain diseases were four times higher than those in the general U.S. population. The researchers, from the National Institute for Occupational Safety and Health (NIOSH), cannot be sure of the reasons.
But they suspect they could be looking at the long-term consequences of repeat concussions during players' careers. "This study cannot establish cause-and-effect," said lead researcher Everett J. Lehman.
"We did not have data on concussions." But, Lehman said, other studies have found links between repeat concussion and an increased risk of neurological disorders, including memory impairment.
Lab research has specifically linked concussions in athletes to a distinct disorder known as chronic traumatic encephalopathy (CTE) -- a progressive decline in brain cell function that eventually causes problems with memory, movement and balance.
Dr. Ann C. McKee, co-director of Boston University's Center for the Study of Traumatic Encephalopathy, has analyzed autopsied brain tissue from athletes, including football players, to find the damage that marks CTE.
The new study expands those lab findings, by uncovering higher risks of being diagnosed with Alzheimer's or ALS, according to McKee. (Right now, CTE can be pinpointed only after a brain autopsy.) "This is an important paper representing a significant advance that ties clinical findings to our neuropathological data," McKee said in an email.
The findings, reported in the journal Neurology, come at a time of rising concern over former football players' risk of degenerative brain diseases.
In May, retired NFL great Junior Seau killed himself, heightening concerns about the potential long-term effects of repeated blows to the head and concussions among pro players.
Seau's suicide came on the heels of two others. Last year, Dave Duerson, a former Chicago Bears player, killed himself and left a note asking for a postmortem brain exam.
That later turned up signs of CTE. And earlier this year, former Atlanta Falcons safety Ray Easterling, who'd been diagnosed with dementia, shot himself at the age of 62.
More than 2,000 former NFL players have now joined a lawsuit, alleging the league historically concealed brain injury risks from players.
And this morning, the NFL announced a $30-million donation to the Foundation for the National Institutes of Health for research into conditions including CTE, concussions, and Alzheimer's.
This latest study, Lehman said, helps "quantify" the risk of degenerative brain disease among former NFL players.
The researchers had data on 3,439 players who spent at least five seasons in the NFL between 1959 and 1988.
By the end of 2007, 10 per cent of those men had died -- only about half the rate that would be expected among U.S. men their age.
"So overall, this cohort is very healthy," Lehman said. "It's only deaths from neurodegenerative causes where we see a higher risk."
Seven players had Alzheimer's listed on their death certificate, and the same number had amyotrophic lateral sclerosis (ALS) -- commonly known as Lou Gehrig's disease.
Those are small numbers, Lehman said, but the rate of each disease was about four times higher than would be expected in the general population.
ALS is an invariably fatal neurological disease in which the nerve cells that control movement progressively degenerate, leading to paralysis and death from respiratory failure.
It's diagnosed in about 5,000 Americans each year. Alzheimer's disease is the most common form of dementia, affecting more than 5 million Americans, according to the Alzheimer's Association.
In this study, NFL players in "speed" positions - like wide receiver, running back and quarterback - accounted for most of the deaths from Alzheimer's or ALS.
That makes sense, according to Lehman, because they are probably involved in more "high-speed collisions" than non-speed players, like linemen. If it is, in fact, repeat concussions that explain the Alzheimer's and ALS risks, that raises the question of whether preventing head injuries will cut those disease risks.
Lehman said the "jury is still out" on the benefits of helmet alterations, for instance. But there is much more awareness of the concussion issue now than there was back when the players in this study were on the field.
Lehman noted that the NFL has taken steps to prevent more concussions, like fining players for dangerous hits - including helmet-to-helmet crashes. The treatment of athletes' concussions - whether pro or high school - has also changed.
"The medical management is much better now," Lehman said. "They're not just 'shaking it off' and getting back on the field anymore." Experts now recommend that an athlete with a concussion rest, physically and mentally, and not get back in the game until all symptoms have passed and they have a doctor's OK.
Those symptoms can include headache, dizziness, nausea, ringing in the ears, fatigue and confusion. Contrary to popular belief, a concussion does not usually knock a person unconscious.
These latest findings may leave parents wondering whether kids who play football could face similar risks later in life. "Direct extrapolation is difficult," Lehman said.
The men in the current study spent years in the NFL, and, Lehman noted, pro players are a "very different group" from men whose football years were limited to high school.
The possible risks to former student-athletes should continue to be studied, according to Lehman. "But I don't think there's cause for alarm, based on these findings," he said.