Jan. 7, 2013 -- Problems in thinking skills and depression may be more common in former National Football League players compared with other people as they age, according to a new study.
The research suggests the problems may be linked with a history of concussions.
"It's clear that concussions can pose an increased risk of developing cognitive problems and mood problems later in life," says researcher John Hart Jr., MD, medical science director at the Center for Brain Health and director of the Brain Health Institute for Athletes at the University of Texas at Dallas.
However, he says, many players in his small study of 34 former NFL players had no such problems, despite a history of concussion. He can't explain which people might be most vulnerable.
"Half the players we studied had nothing wrong whatsoever," Hart says, "and they had a bunch of concussions."
A concussion is a brain injury that can change a person's behavior, thinking, or functioning for a period of time. In contact sports such as football, it's usually caused by a forceful blow.
Thousands of former NFL players are suing the league, accusing it of concealing information that links football-related injuries to brain damage over the long-term.
Previous studies have also found a link (but not cause and effect) between head trauma in retired football players and thinking and memory problems later.
Guidelines about how to handle concussions in players are now in place for pro, collegiate, and high school athletics.
Aging Football Players & Health Status
Hart and his team studied 34 former NFL players, on average age 62. They self-reported concussions. (All but two had a history of concussions.) On average, they reported four.
Hart's team gave the players neurological and neuropsychological assessments. Twenty-six players also had neurological imaging tests.
These images were compared with images in 26 healthy men from a comparison group matched for age and other features.
Of the 34 former players, Hart found 20 had normal mental skills. Eight of the 34 had depression. Most had not been treated for depression or been diagnosed with it previously.
That rate of depression is about double that expected in the general population of the same age, the researchers say.
Fourteen players had either a mild problem with thinking skills or full-blown dementia.
Those with thinking problems had trouble with findings words. They had memory problems and trouble with naming things.
They also had disruptions in the white matter of the brain, Hart found. He says it is the first time such a link has been found.
This white matter is crucial to allowing information to travel between brain cells.
Hart also found blood flow differences to brain regions linked with skills such as memory or finding words in those who had thinking problems.
Aging Football Players & Brain Health: Explaining
Hart says he can only speculate as to why some players appear more vulnerable to problems with depression and cognitive skills.
It may have to do with the type of concussion, he says. "I don't think there is one clear kind of head injury that leads to problems."
The health problems later may be linked, he speculates, not only to the concussions but also to the continual and repeated shaking of the head that happens during play.
"I think genetics probably can play a complicated but important role," Hart says.
Football Players & Brain Health: Perspective
Eventually, the finding about disruptions in the brain's white matter may help experts measure the effects of concussions, says Daniel Perl, MD, professor of pathology at the Uniformed Services University of the Health Sciences in Bethesda, Md.
He co-wrote an editorial to accompany the study.
The findings reflect a need for more research, Perl says. "This paper is describing abnormalities in the white matter," he says. "The nature is unclear. We need to know what they are on a cellular level."
While the study focused only on former NFL players, Perl writes that it is possible the problems later on in life ''are not limited to professional football players but may also occur in amateur collegiate athletes and even adolescent and younger players."
"I think we have to be concerned about concussions in anyone," he says, "and we have to be even more concerned about repeated concussions in anyone. These are not trivial events and require proper evaluation and concern."
The study was supported by the Brain Health Institute for Athletes and a grant from the National Institute on Aging.
It is published online in JAMA Neurology.