WEDNESDAY, Sept. 30 (HealthDay News) -- Former professional football players suffer from Alzheimer's disease or other memory-related conditions at rates far higher than the general population, a new study commissioned by the National Football League shows.
And retired players between the ages of 30 and 49 are 19 times more likely to struggle with memory problems than similarly aged men who never played professional football, the study found.
The findings could have implications that reach far beyond the National Football League, which has said in the past that there's no reliable research to establish the proof of cognitive problems among former players.
Head injuries are not uncommon among college and high school players. University of Florida star quarterback Tim Tebow, the best collegiate player in the nation last year, suffered a head injury during a game on Saturday that briefly left him unconscious on the field. He continued to undergo post-concussion tests Tuesday.
And a study published last year in The American Journal of Sports Medicine examined severe head injuries among high school football players between 1989 and 2002. The researchers found that high school players had more than triple the risk of sustaining catastrophic head trauma compared to college players. High school athletes suffered 0.67 such injuries per 100,000 players, compared with 0.21 injuries per 100,000 college players.
The new study of former pro players has not been peer-reviewed, but the results mirror several other recent studies suggesting a link between dementia and head injuries. The results of the study, conducted by the University of Michigan's Institute for Social Research, were first reported Wednesday by The New York Times.
"Single incidents of concussion or head injury with loss of consciousness is a fairly well-established risk factor for subsequent Alzheimer's disease that shows up in big epidemiological projects," said Greg Cole, a professor of medicine and neurology at the University of California, Los Angeles David Geffen School of Medicine.
"Typically, head injury is found to roughly double the risk for developing dementia," added Cole, who's also associate director of the Mary S. Easton Center for Alzheimer's Disease Research. "But if victims also have the most common genetic risk factor [ApoE4], present in about 20 percent of the population and which similarly increases risk by itself, the combined risk is much higher, around tenfold or more. Animal model studies show this relationship is probably causal because head injury can really speed Alzheimer's pathology. All of this makes it pretty clear to experts studying AD [Alzheimer's disease] that in individuals with some preexisting genetic risk for Alzheimer's, repeated head injury should be expected to make dementia much more likely."
For the NFL survey, the Michigan researchers contacted 1,063 retired players by phone late last year. The players, who had to have played at least three seasons to qualify for the survey, were asked a series of questions on a series of topics, including questions on health, financial well-being and satisfaction with life. Most of the questions came from the standard National Health Interview Survey. That way, answers could be compared to previously collected data from the general population. In some cases, a player's wife answered the questions.
The Michigan researchers found that, among players aged 50 and older, 6.1 percent of them said they had received a dementia-related diagnosis -- five times higher than the national average of 1.2 percent.
Players between the ages of 30 and 49 had a dementia-related diagnosis rate of 1.9 percent -- 19 times higher than the national average of 0.1 percent, according to the survey.
The study authors acknowledged that phone surveys aren't a foolproof scientific method to determine rates of diagnosed dementia.
Dr. Daniel P. Perl, director of neuropathology at the Mount Sinai School of Medicine in New York City, told the Times that he considered the new survey significant. "I think this complements what others have found -- there appears to be a problem with cognition in a group of NFL football players at a relatively young age," he said.
Greg Aiello, a spokesman for the National Football League, said the numbers of former players reporting dementia "aren't large in terms of the overall population."
Aiello also said that a phone survey "is not necessarily reliable. It's self-reporting and in the case of some, the wife was answering, because the guy wasn't in great shape."
"It warrants further research, and that's what we are doing and what we will continue to do," he said, adding, "We have done everything to reduce and properly manage concussion with our players, from rule changes to guidelines on how to manage concussions. It's not like we're minimizing anything here."
Sean Morey, an Arizona Cardinals player who has pushed for research into brain injuries, told the Times: "This is about more than us -- it's about the high school kid in 2011 who might not die on the field because he ignored the risks of concussions."
Dr. Halinder S. Mangat, an assistant professor of clinical neurology at the University of Miami's Miller School of Medicine, said: "There are studies in children, which show that at a young age, if you have a concussion or repeated concussion, when they grow up they do have some cognitive impairment."
"This applies to football players," Mangat said, "because the first time they have contact is not when they come into the NFL. It's a career track, so players started playing when they were very young," he said, adding that concussions have a cumulative effect on the brain.
Another expert noted the dangers of concussion might be more marked in younger players.
"One of the concerns is, 'Are concussions in kids that same as they are in adults,' " said Dr. Christopher Giza, an associate professor of pediatric neurology at the University of California, Los Angeles. "It has the potential to be a significant problem. It seems that younger brains might be more sensitive to these kind of injuries."
Giza said it takes a week to 10 days to recover from a concussion. "If you give an appropriate amount of time for the brain to return to normal, there may not be a long-term consequence -- the long-term consequence may be minimized," he said. "But, if you have second or third injuries before the brain is fully recovered, perhaps the risk for a cumulative problem is amplified."
Giza advises parents and coaches that a concussion can occur even if the child did not lose consciousness. Even if there is any temporary clouding of consciousness, there may be a concussion, he said.
"If the individual is still symptomatic, headache, dizziness, confusion, nausea, unsteadiness, they should not return to play," Giza said. When the symptoms disappear they can talk with their coach or trainer about returning to sports, which is not the day the symptoms disappear.
Mangat said that when players reach the NFL -- where safety is taken more seriously because of the money involved -- brain damage may already have occurred. "There should be regular neuropsychological testing prior to joining a college team or a professional team to be able to 'red flag' someone who starts to show some decline," he said.
The University of Michigan study wasn't limited to mental health. According to the authors, the survey found "retired players to be in very good stead, overall. They are satisfied with life and deeply connected within their social networks and communities. Their history of physical fitness [including low rates of smoking and high levels of physical activity] shows up in lower rates of diabetes and cardiovascular disease. On most other health problems, they are similar to or healthier than the general population. However, they do have much higher rates of arthritis and reported pain and mobility problems than the general population."
The NFL released this statement about the survey on Wednesday: "The primary purpose was to get a better look at the overall condition of retired players, and identify specific areas where we can further address their needs. The survey found that playing in the NFL was a very positive experience for most retired players, and that overall they are in very good physical and financial condition."
The statement also responded to the dementia finding: "The survey makes no link between concussions and memory disorders. Concussion as one of many potential factors in memory disorders is being studied throughout the medical community, including our own study on the long-term effects of concussions on retired players. Meanwhile, our focus is also on the proper prevention and treatment of concussions in today's game. We do this through rules changes and enforcement; education of players, their families, coaches and team personnel; and ensuring that our players have the best medical care available. Our medical staffs take a cautious and conservative approach to managing concussions, including expanded use of neuropsychological testing and return-to-play guidelines."
To learn more about concussions, visit the U.S. National Library of Medicine.
SOURCES: Greg Cole, Ph.D., associate director, Mary S. Easton Center for Alzheimer's Disease Research, and professor, medicine and neurology, University of California, Los Angeles, David Geffen School of Medicine; Halinder S. Mangat, M.D., assistant professor, clinical neurology, Miller School of Medicine, University of Miami; Christopher Giza, M.D., associate professor, pediatric neurology, University of California, Los Angeles; Greg Aiello, spokesman, National Football League; Sept. 10, 2009, Study of Retired NFL Players, University of Michigan Institute for Social Research