In 2009, a team of researchers looked up every confirmed case of chronic traumatic encephalopathy (CTE) they could find in the scientific literature. They discovered 48. Today, a new study adds 177 more cases, all in former football players, to science's understanding of the brain disease that can strike those who suffer repeated hits to the head over many years, and can end in dementia and suicide.
"In just eight years, we were able to amass 177 cases of CTE," says Dan Daneshvar, a doctor and scientist who worked on the new study while he was at Boston University's CTE Center; he's now a resident at Stanford University. "The fact that so many of them had evidence of CTE indicates that CTE is maybe related to prior participation in football and is certainly not a rare disease in individuals with exposure to repetitive brain trauma."
Chronic traumatic encephalopathy has garnered a lot of attention in the past several years, as autopsies have revealed it affected NFL stars such as Frank Gifford, whose family said in a statement that he suffered from "cognitive and behavioral symptoms" before dying of natural causes, and Junior Seau, who committed suicide in 2012.
In 2015, a United States district judge approved a settlement between the NFL and a group of former players who have long-term brain diseases, which the Associated Press reports could reach $1 billion or more. Yet a lot of questions remain about CTE, including which symptoms are caused by the condition and which may be the result of other, non-football-related mental disorders. Daneshvar and his colleagues' study offers some answers.
The research team studied 202 brains, belonging to male former football players, that the men or their families had donated to the VA-BU-CLF Brain Bank after their deaths. Among those, 177, or 87 percent, had diagnosable CTE. Fourteen of the donated brains came from men who had played football in high school; three of them had CTE. Fifty-three of the brains came from former college players; 48 of those had CTE. And 111 former NFL players had donated to the Brain Bank. All but one had CTE.
"CTE is certainly not a rare disease in individuals with exposure to repetitive brain trauma."
These numbers don't reflect the rates of CTE among football players of different levels. Because families are probably more likely to donate to the Brain Bank when they're worried about CTE, the real rates of CTE among football players in general are much lower. But the data is an indication CTE can develop among folks who play football at those levels.
Among the men whose brains showed signs of the severest CTE, nearly all had problems with their memory and problem-solving. Many had memory problems so severe they were diagnosed with dementia while they were alive, and dementia-related causes were their most common reason for death. The majority in this category also exhibited mood disorders, such as depression.
The men who had less-severe CTE tended not to have as bad of cognitive problems as their counterparts with worse CTE. But their families told researchers they tended to have behavioral and mood problems, including a lack of impulse control and feelings of hopelessness. The most common cause of death among the donors with mild CTE was suicide.
During the study, the scientists who worked on diagnosing CTE in the brain samples and the scientists who worked on gathering medical histories from family members didn't consult one another, so they wouldn't be influenced by the other team's diagnosis for any one donor. All of the men who had CTE features in their brains turned out to have CTE-like symptoms in life too.
Studies like this start scientists on the path toward figuring out what puts people at risk for CTE, Daneshvar says. Does it matter how old you are when you start playing high-impact sports, for example? Are there certain genetics that make CTE more likely? Daneshvar also hopes his work will help doctors figure out how to diagnose CTE while people are still alive. For now, families can only get a definite diagnosis after death and an autopsy. "Diagnosing in life is really the first step toward developing potential treatments," he says.
There's a lot more to learn, but there's also a lot of material left to learn from. Daneshvar's team is working on a study comparing football players of various levels, he says, and the VA-BU-CLF Brain Bank now has nearly 500 brains, donated by victims and their loved ones, searching for answers.