The headbanging collisions that thrill sports fans have lifelong effects on the athletes, with impairments in movement and thinking skills showing up 30 years or more after the concussions, researchers reported Tuesday.
The slight deficits resulting from one or two concussions were similar to problems found in patients with the early stages of dementia, although they did not interfere with the daily life of the otherwise healthy men, researchers reported in the journal Brain.
"They were all very functional, working, still playing sports, and really in good health," said senior author Dr. Maryse Lassonde of the University of Montreal. "It is only when we compare them to people who did not have concussions that the problems come up."
For those who have more concussions, however, the results are far more severe, according to a separate study released Tuesday at a news conference in Tampa, timed to coincide with Sunday's Super Bowl in that city.
Researchers said a biopsy of the brain of nine-year NFL veteran Tom McHale, who died last May of a drug overdose at age 45, showed that he suffered from a severe degenerative brain disease called chronic traumatic encephalopathy. It was caused by repeated concussions.
The biopsy was the sixth out of six performed on deceased NFL players between the ages of 25 and 50 that showed evidence of such severe damage. All six men suffered emotional and behavioral problems after their playing days were over, often culminating in erratic behavior, drug abuse and suicide or overdose.
Dr. Ann C. McKee of Boston University's Center for the Study of Traumatic Encephalopathy, who performed the biopsy on McHale, said she had found similar damage in the brain of a recently deceased 18-year-old who had suffered multiple concussions playing high school football -- the youngest age at which it had ever been observed.
The damages in both cases were similar to those observed in boxers who have taken severe beatings to the head, McKee said. Although they are also similar to the changes seen in Alzheimer's disease, she added, "they represent a distinct disease with a distinct cause, namely repetitive head trauma."
The results from the two studies indicate that increasingly severe restrictions aimed at limiting concussions in professional athletes "need to be implemented at lower levels" of athletics, Lassonde said.
The problem is also of concern outside the sports community because of the rising incidence of concussions and traumatic brain injury suffered by soldiers serving in Iraq and Afghanistan.
To outside observers, the Lassonde study was more surprising because researchers were already familiar with the problems in some NFL players.
There still is disagreement within the NFL about how to react to concussions. One of the starting quarterbacks in Sunday's game, Pittsburgh's Ben Roethlisberger, suffered a concussion in the final regular-season game. There was some concern he might not be able to play two weeks later in the Steelers' first playoff game, but he started and showed no visible effects from the injury.
"The evidence in the literature has been building that repeated mild [brain] injuries in children and adults has the potential for long-term, cumulative effect," said Dr. Christopher C. Giza, a neurosurgeon and pediatric neurologist at UCLA's Brain Injury Research Center. Lassonde's results "open the door" to the possibility that "it may not require that many events to lead to a long-term problem."
Lassonde, who is the neuropsychologist for the National Hockey League's Montreal Canadiens, has been studying concussions for nearly a dozen years. Her group has published a variety of studies documenting the problem and showing continued deficits three years after the injury.
In the current study, Lassonde and her co-workers examined 19 former university hockey and football players with a mean age of 60 who had suffered between one and five concussions in college and compared them to 21 carefully matched former athletes who had not suffered concussions. All 19 showed minor impairments in thinking and motor skills compared with the non-concussion group.
The deficits were similar to those observed previously in concussion victims three years after their injury.
The changes were relatively small, but they appeared on a variety of different tests, "and that adds strength to their conclusions," Giza said. "It's a pattern of things that actually makes some sense."
Lassonde said she plans to continue studying the 19 men to determine whether the damage she observed is associated with an earlier-than-normal onset of more severe mental problems.
McKee's findings have not been published yet, but she said she thinks they will appear in a journal by May.