January 7th, 2013
04:51 PM ET
A marker for later cognitive problems may be starting to show up in the brain tissue of former National Football League players.
According to a study published Monday in JAMA Neurology, researchers found that cognitive problems and depression are more common among aging NFL players with a history of concussion. But brain damage and mood problems among some segments of the NFL population is not stunning news anymore.
What has got scientists slightly giddy are those markers: Poor performance on cognitive tests also showing up on sophisticated brain scans. It suggests that damage post-concussion could some day be detectable by scanning the brain.
"We found some interesting markers that may help explain what is going on in the brain when people start developing (long-term) problems," said Dr. John Hart, medical science director of the BrainHealth Institute for Athletes at the University of Texas at Dallas and lead author of the study.
Hart and colleagues studied 34 former NFL players, and were able to do brain scans on 26 of them; they measured blood flow and white matter changes in their brain tissue.
White matter is brain tissue that acts as a sort of conveyor belt for signals traveling to different brain regions. When white matter is damaged - think about that conveyor belt veering off-course or stopping altogether - problems crop up with cognition, or thinking ability.
It was problems with white matter among players that caught study authors' interest.
For example, a player who performed poorly on a test of word choice on a later brain scan might also have subtle damage in areas governing language. Players who struggled on tests of memory might be found to have abnormalities or damage to areas of the brain associated with memory.
Those subtle problems were found in some players, but since the study group was so small, the association is still pretty thin.
Also, white matter problems tend to be "subtle and not specific," according to an editorial by Dr. Roman Diaz-Arrastia and Dr. Daniel Perl, both with the Center for Neuroscience and Regenerative Medicine at the Uniformed Services University of the Health Sciences.
Another issue: The average age of players found to have cognitive problems in the study was 66, an age when cognitive problems are typical - "common in normal aging, Alzheimer's disease, and other neurologic disorders," said Diaz-Arrastia and Perl.
"Ideally, they would be taking these scans in a younger group, say 45, 50, 55 years old," said Kevin Guskiewicz, director of the Center for the Study of Retired Athletes at The University of North Carolina at Chapel Hill. "You don't need a marker to find cognitive impairment in a 66-year-old."
Ideally, the brain scan should be a way to predict disease, not just confirm it.
Still, Guskiewicz, who was not involved with this research, agrees that even a possible glimpse into the progression of brain diseases thought to be associated with concussion - early dementia and chronic traumatic encephalopathy - is a step in a positive direction for researchers.
"We may be working closer to an imaging marker for concussion, but it will require more longitudinal studies," he said.
"The main value of the study is that it potentially identifies a novel target for measuring disease progression and developing therapies," added Diaz-Arrastia and Perl.
But it will likely take years before the target materializes.
Hart agrees that further study should be done, and he plans to continue following the current crop of players he has scanned, and add more. While he is hopeful that he and colleagues will hone in on a marker, in the meantime he is stressing depression screening for former NFL players.
"We saw a lot of depression that was not diagnosed, and we were surprised by that," said Hart.
Another finding of the study is that not everyone who plays football will suffer cognitive problems: 20 of the 34 former players studied were cognitively normal.
"The fact is, if you look at all these studies overall, a lot of individuals don't have problems," said Hart. "It is not a fait accompli that everyone is going to have a problem."
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