A new imaging technique has allowed the detection of protein abnormalities in the concussed brains of living retired football players that are identical to the autopsy findings of chronic traumatic encephalopathy (CTE) in deceased athletes, researchers reported.
Positron emission tomography (PET) scanning using a tracer for tau protein known as FDDNP found significantly higher binding values among retired players than in controls in several regions of the brain, including the amygdala and caudate, according to Dr. Gary Small of the University of California Los Angeles and colleagues.
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In addition, the tau binding values were highest in the players who had experienced the most concussions during their careers, which "suggests a link between the players' history of head injury and FDDNP binding," the researchers wrote in the February American Journal of Geriatric Psychiatry.
"If this research continues in the direction we expect, it would have a big impact on the early detection of this condition, helping us to develop interventions that could delay the onset of symptoms," Small told MedPage Today.
But it will be important to replicate these findings in larger studies, experts cautioned.
"If indeed it is sensitive and specific enough for tau, it would be extremely exciting and hugely important, but this was only five players," said Dr. Robert Cantu of Emerson Hospital in Concord, Mass., and co-director of Boston University's Center for the Study of Traumatic Encephalopathy.
The list of athletes who experience multiple concussions during routine play and then develop cognitive, behavioral, and mood disturbances, which in some cases lead to suicide, continues to grow, and some 4,000 former National Football League players are suing the league, claiming that the risks of repetitive head injury were long downplayed.
Autopsy findings in players who died have included deposits of phosphorylated tau in neurofibrillary tangles, as well as diffuse injury to axons and abnormalities of white matter.
Despite the increasingly widespread recognition that players with multiple concussions are experiencing severe consequences, research into the resulting condition has been hindered by the fact that no diagnostic test has been available that could identify changes before death.
Small and his colleagues developed the tau tracer FDDNP with the goal of detecting the presence of tau tangles and amyloid plaque in the living brains of Alzheimer's disease patients.
They found that with this PET technique they could differentiate Alzheimer's patients from those with milder forms of cognitive impairment or normal changes of aging.
In the current study, they performed neuropsychiatric evaluations of five former players who exhibited mood or cognitive symptoms clinically, and then used PET scanning with FDDNP to examine their brains.
The players had played various positions, including quarterback, center, and defensive lineman, with careers ranging from 10 to 16 years.
The researchers also assessed five controls who were matched for age, body mass index, family history of dementia, and educational attainment.