Leading researcher seeks to uncover consequences of repetitive head impacts in soccer

Anyone who’s paid attention to sports over the past two decades has heard of CTE. Chronic Traumatic Encephalopathy has dominated headlines ever since the tragic deaths of numerous former athletes, mostly football and hockey players, whose lives were affected by brain injuries sustained over a lifetime of sports. Research in the causes of CTE has led to multi-million dollar lawsuits, rules changes, and a greater emphasis on player safety from grassroots levels to the professional ranks.

The existence of concussion and head injury protocols have mostly come from studies on American football, hockey, and professional wrestling, sports known for the high impact collisions, the tough guys who drop the gloves, or the thrilling suplex off the top rope. And during the time since CTE has become a mainstream warning system for contact sports, off in the distance, in whispers and murmurs, corner conversations and background fodder, voices asked “What about soccer?”

In June 2021, Scott Vermillion became the first former MLS player diagnosed with CTE. The four-year MLS veteran and U.S. Youth National Team member lost his life after a battle with addiction. The story caused a nationwide buzz. Players and coaches offered their perspectives, most notably TV analyst Taylor Twellman, whose career was shortened by concussions and has been an advocate for concussion awareness and player safety in the game.

Since then, coaches renewed their Safe Sport training, the annual concussion awareness program required by anyone involved in a U.S. Soccer program. Seasons began with a renewed sense of limiting head impacts and following concussion protocols. Next, we experienced the World Cup, where players clashed heads, whiplashed headers off corners, and fell to the ground, heads snapping back or bouncing off the pitch, returning to action without missing a step. Then we witnessed Iran keeper Alireza Beiranvand collide with a teammate in the group stage match vs England, only to remain in the game after receiving medical treatment for obvious signs of a concussion. The moment came and went because Messi was on the verge of winning his first trophy and we could enjoy soccer over Thanksgiving dinner or meet with friends and colleagues over drinks in crowded pubs decorated for the holiday season while the world’s greatest game played on every screen. We want the game to be safer, but we have so many questions.

For over a decade, the search for answers has been ongoing in a Boston research center where a team of doctors has tried to uncover what happens to our brains when they’re subjected to a lifetime of repetitive brain trauma. CTE is a progressive degenerative disease in the brain found in people with a history of repetitive head impacts often found during contact sport play, military, and other activities that involve repeated blows to the head. The disease resembles dementia pugilistica, or punch drunk syndrome, a condition found in boxers during the late 1920s. Unfortunately, CTE can only be clinically diagnosed by observing the brain tissue of a deceased subject, so researchers are in the process of identifying causes and symptoms that lead to the disease while individuals are still alive.

Dr. Robert Stern is one of the leading figures studying how sports contribute to the neurodegenerative diseases found later in an athlete’s life. Stern, Co-Founder and Director of Clinical Research for Boston University’s CTE Center, is a Professor of Neurology, Neurosurgery, and Anatomy & Neurobiology. After years studying Alzheimer’s, his primary interest has shifted toward developing methods of detecting and diagnosing CTE during life as well as understanding the consequences of repetitive mild brain impacts. His latest study, the Head Impact & Trauma Surveillance Study, or HITSS, will try to understand what happens to the brains of soccer players over time. The study, funded by the National Institute of Health and the first of its kind, will investigate the lives of 4800 former soccer and American football players, including 1200 women former soccer players, all over 40 years of age.

During an interview at the United Soccer Coaches Convention in Philadelphia, Dr. Stern discussed his motivation for focusing on soccer players and potential CTE connections.

“The problems in the brain with Alzheimer’s disease begin ten to twenty-five years before there’s any problems at all,” he said about the most common form of neurodegenerative brain disease.

As problems worsen, eventually the subject’s condition can lead to dementia, or severe cognitive impairment, such as loss of memory, language, problem solving, or thinking abilities.

“Alzheimer’s is one of the leading causes of dementia. CTE is another one of those diseases that starts early and eventually destroys enough brain tissue and spreads and destroys more tissue and gets in the way of daily functioning. That’s when we look
for dementia.”

Throughout previous studies of the lives of individuals with CTE, commonalities emerged. “CTE is a very unique neurodegenerative disease because we now know what the necessary ingredient is to start it—exposure to repetitive head impacts.” Some head impacts may appear more obvious because they lead to concussion symptoms, such as the Beiranvand example, but research shows that most repetitive impacts cause sub-concussive trauma, the type of impacts that damage the brain but without the typical concussion symptoms. In American football, players sustain sub-concussive hits on nearly every play.

“But all throughout this research over the last twelve, fourteen years,” Stern said, “I’ve had a big concern that we’ve been focusing almost exclusively on men and almost exclusively on American football and with American football almost exclusively on professionals.”

Dr. Stern says the focus on repetitive trauma in soccer has led to research on heading. “We don’t know for sure whether heading is a definite cause for CTE, and we don’t know if there are other parts of the game that might increase someone’s risk for it. We don’t know how common it is. We don’t know if it’s just professional soccer players who might be at an increased risk for CTE. We have so many questions that we have to come up with some answers soon.”

Stern referenced a recent study which analyzed the mortality rates of 7,676 professional Scottish soccer players who played between 1930 and 1998. “What they found was interesting,” he said. “Up until the age of 70, the former soccer players had a lower mortality rate. Then after age 70, they didn’t have a lower mortality rate and they had a tremendously increased risk of dying from neurodegenerative disease on their death certificates as well as having more prescriptions in their medical records for dementia type of communications.”

Stern said though we can’t tell from death certificates what type of neurodegenerative diseases the players suffered from because of the wide variety (Alzheimer’s and ALS as the leading examples), the findings are almost identical to mortality rates of American football players.

“We’re talking about a three to tenfold increased risk for neurodegenerative disease.” The study also found differences by length of career as well as by position. Players in the game over 15 years had a greater risk. Goalies showed similar risks as the average person, but defenders showed the greatest risk.

There have been several recent cases of former soccer players who had diagnosed symptoms of dementia before they died and whose brains showed evidence of CTE, which has led Dr. Stern to focus on soccer’s most common form of repetitive head impacts. There has been an increase in studies on heading over the last five years on players, especially former players. Studies looked at changes in the brain due to heading, which are not due to concussions.

“Study after study, with a few exceptions,” he said, “have shown that after a season of routine heading, at different levels of play, high school, college, elite, there are changes to the structural integrity to the brain, changes to both functioning of the brain, changes to cognitive functioning directly related to the amount of heading by the individual in that study.”

So does this mean, we can link the two together? “Not quite,” Stern said.

Which leads us to the HITSS Study, the largest of its kind to include American soccer players in an attempt to try to answer later risks for different types of head and brain health problems. Dr. Stern and his colleagues are not looking at CTE yet. It’s not a biological test but an online study, ground-floor research per se, involving players of different levels, backgrounds, and playing experiences.

Perhaps the most important aspect of the study is the hope it will lead research toward specific directions in soccer, for example quantifying headers, like what has been done in American football studies, where researchers place accelerometers inside helmets and track linear and rotational hits, accurately projecting the force and number of repetitive head trauma. Dr Stern said soccer doesn’t have the technology to quantify headers due to the difficulty placing the sensors, though the HITSS study plans to find ways to estimate the amount of heading done through one’s career.’

For years, the diagnosis of CTE in a player’s life post-mortem has led to the search for breadcrumbs, which is what Dr. Stern and his team hopes to uncover. Collaborative research has led to establishing consensus diagnostic criteria for Traumatic Encephalopathy Syndrome, a term researchers use to describe what they think is the clinical syndrome associated with outerlying CTE occurrence.

That data has changed since 2014, but research has found several relationships between CTE and symptoms associated with the deceased athlete’s life. Dr. Stern says so far they’ve identified three: problems with memory (ability to learn and store new information), executive function (planning, organization, multi-tasking, control impulsive thinking), and a lot of exposure to repetitive blows to the head (like 11 years of American football). There also may be a connection between CTE and neurobehavioral dysregulation, which is the difficulty controlling emotions and behaviors (short fuse, rage). There are other problems and potential symptoms being researched that could provide potential links.

At the United Soccer Coaches Convention, Dr. Stern joined Gina Lewandowski, 15-year pro and current assistant coach at Lehigh University as well as Bruce Murray, former U.S. Men’s National Team player and member of the U.S. Soccer Hall of Fame in discussing the goals of the HITSS study and repetitive impacts in soccer. Lewandowski and Murray are two of the study’s many ambassadors, which include Twellman, Gotham FC GM Yael Averbuch, U.S. Hall of Famer Brandi Chastain, and broadcaster Bob Costas, to name a few.

Lewandowski opened up about her interest in the study, which included her background in science and her lengthy career as well revealing a family history of dementia and witnessing a good friend and teammate’s career ending due to a concussion. “I just want to be an advocate to help spread awareness of the research,” she said, “and hopefully get more individuals, female athletes to participate and allow the younger generations to play the sport free of any implications or having the transparent understanding of knowing if there could be potential damage.”

Lewandowski was a midfielder before switching to defense early in her pro career. She went on to win the UEFA Women’s Cup with Frankfurt as well as multiple German Cups and Bundesliga titles before returning to the US with Gotham FC in 2020, retiring last summer.

Murray, who’s publicly revealed his struggles with a number of cognitive issues, relayed his history of “being a punching bag for 12 years” as a striker on the national team. As a target forward, Murray revealed the countless number of headers in which he felt affected, going as far as sharing a story about his time as a pro in Switzerland when a heading session was used as punishment. “We had a bad game and the coach sent two assistants out and punted balls, and we had to run up and head them as high and as far as we could. And all you would do was stagger back, you know, and just pray.”

Murray compared his training as a striker, with repetitive crosses and finishes with the head, as examples of where training methods and safety need to be considered more closely. He also spoke about the safety of the game, asking if rule changes involving heading need to go up to the professional level. Currently, heading is banned up until age 13.

The goal of finding subjects over the age of 40 is an integral part of the study because athletes at this stage have likely concluded their playing careers and may start developing symptoms. Another connection with the age comes from the evolution of the soccer ball, which went from heavy leather to the current synthetic version around the early 2000s. Those of us who
remember heading the waterlogged soccer balls may have found the new ball comforting, but Dr. Stern suggests the lighter ball has actually increased the number of headers due the reduction of pain it causes, similar to the helmet in football or the padded glove in boxing.

With so many questions about repetitive head impacts in soccer and the possibilities of a connection to CTE, the game is entering an important stage where player safety becomes paramount to its future. Findings from American football and hockey studies have led to positive changes without a dramatic reduction in quality, so only time will tell how research on soccer players will change the game. The upside to the conversation is that leaders like Dr. Robert Stern, Gina Lewandowski, and Bruce Murray are taking the initiative to find out what happens to our brains when we’re exposed to repetitive head impacts in soccer, and all of us can play a role.

The beautiful game, our health, and the health of our next generation of soccer players demands our attention.

More information about the HITSS study can be found at www.hitss.org.