Scientific evidence is mounting that repetitive hits to the head—not just concussions—can lead to a devastating neurodegenerative disease called chronic traumatic encephalopathy (CTE). But so far, all the current data about CTE come from studying groups of males. Despite the fact that Boston University researchers have diagnosed CTE in the brains of hundreds of deceased men—most former pro-football players and some military veterans—only two women have ever, anywhere, been diagnosed with CTE.
To bridge the gaping hole in understanding how CTE affects women, researchers at the BU CTE Center are launching a first-of-its-kind study, funded by the National Institute on Aging and the Concussion Legacy Foundation, that will analyze the brains of female former professional soccer players. (This news comes as the Fédération Internationale de Football Association, aka FIFA, Women’s World Cup is underway in France, and the United States is considered a favorite to win it.)
The study, called the Soccer, Head Impacts and Neurological Effects Study (SHINE) is recruiting a total of 20 former soccer players and will create the first all-female study cohort dedicated to understanding CTE. Former US soccer stars Brandi Chastain and Michelle Akers have recently made waves in the media by going public with their decision to take part in the study and to donate their brains to the CTE Center brain bank after their death.
For soccer players, the study couldn’t come sooner. FIFA currently estimates that 265 million people around the world play soccer, a game that often relies on headers—hitting the ball directly with the head—as part of both defensive and offensive play. More data on a link between headers and CTE are desperately needed.
The Brink spoke with the CTE Center’s director of clinical research, Robert Stern, a School of Medicine professor of neurology and the lead investigator on the new SHINE study, to learn more about what the SHINE team hopes to accomplish.
The Brink: Is there any known connection between soccer players and CTE?
Stern: Yes, there have been a handful of postmortem cases of CTE found in former soccer players—all men. One of the most important studies took place in the UK, where researchers found four cases of CTE among six former soccer players whose brains were being examined as part of a study on dementia. They concluded that it was related to the soccer players’ exposure to repetitive hits from heading soccer balls thousands of times over the course of their careers. Of the four players diagnosed with CTE, there were very few concussions, maybe one or two in total, reported throughout their careers.
Now, one thing to consider is that these folks played the game earlier in their lives, when soccer balls were much bigger and heavier than today’s regulation soccer balls. Soccer balls used to be made of leather. If it was raining and they got wet, they could get quite waterlogged and become even heavier. These four men who were diagnosed with CTE were somewhat unique in the fact that they would head the ball. It wasn’t that common back then, because as heavy as that soccer ball was, heading it would hurt quite a bit.
One could ask if because it was so heavy and big, it resulted in more problems for them. But in the last few decades, as the soccer ball has changed, the amount of heading that happens during play has dramatically increased.
What about the two women who were diagnosed with CTE—if they weren’t soccer players, how did they develop CTE?
Of the two known women who were diagnosed with CTE, one was a victim of domestic violence, and the other was a developmentally disordered individual who was a habitual headbanger. Both women were exposed, repeatedly, to hits to the head.
By looking at the brains of those two women, is there anything that suggests there are differences between men and women in the prevalence and development of CTE?
We have no idea at all about whether there are sex-based differences in CTE, or about how prevalent CTE is among men vs. women, because we haven’t seen any women’s brains that have shown signs of it after athletic exposure. Most cases of CTE come from men who formerly played football, and so we need to compare that data with that from women who similarly were exposed to head impacts through athletics. College and professional soccer didn’t become mainstream for women until the 1970s, after Title IX, so the first population of female professional soccer players is now reaching an age, in their late 40s and early 50s, where CTE symptoms could be popping up.
Will the women in the SHINE study donate their brains after they die?
It’s not mandatory to donate their brains, although Brandi Chastain and Michelle Akers have decided they will donate.
If participants choose not to donate their brains, what tests will you do to detect signs of CTE?
For all women in the study, whether they plan to donate their brain or not, there will be cognitive and neurological assessments, extensive MRI scans, blood draws so that we can look for biomarkers and genes related to neurodegeneration and CTE, and also an optional lumbar puncture so that we can look at their spinal fluid. All of these same tests are also being done in our research looking at men and women in our BU Alzheimer’s Disease Center studies. We’re also doing studies with local people who have played various contact and collision sports, like ice hockey, soccer, martial arts, boxing, and football. The whole idea is to compare and contrast these different data sets. The SHINE study will give us the first look at how repetitive head impacts affect female athletes, a critical aspect of taking a comprehensive look at how CTE develops in humans.
What would you like to say to soccer coaches working with high-school-age and younger players? Can you give us a sense of how dangerous headers are for young men and women playing soccer?
There is enough evidence out there that heading the ball can shake up the developing brain and that older kids should learn how to responsibly head the ball at an age when their necks have gotten stronger. US Soccer, the organization that oversees youth soccer programs in America, has already made a major policy change regarding headers. Kids under 10 are no longer allowed to head the ball during practice or games; 11-to-12-year-olds are allowed to take part in specific practice drills that teach them to head the ball safely and to head the ball a limited number of times during games. Players aged 13 and up are allowed to head the ball without restriction.
When will we get to a point when it’s possible to say without doubt, scientifically, that head impacts, even if they aren’t hard enough to cause concussions, are detrimental to brain health?
We can’t wait until adequate data are compiled 30 to 60 years from now, when we’ve been able to follow a group of people throughout their entire lives, to prove that head impacts can cause CTE. We need to combine common sense with the growing body of evidence. Sometimes it’s helpful to step back and consider, as a baseline, if it’s appropriate for kids to be heading a soccer ball in a fashion that may put them at short-term and long-term risk. For me, it is better to err on the side of caution.
I want to read you an anonymous email I received from someone recently: “I had a coach during high school who used to line all of the players up on center field and use a modified pitching machine to send soccer balls, at high velocity, for us to hit with our heads—to make us more fearless about headers on the game field.”
That’s definitely not the first time I’ve heard a story like that from a former soccer player.
Robert Stern is also the director of the BU Alzheimer’s Disease Center Clinical Core.