Evidence that soccer heading -- where players use their heads to strike a ball -- is dangerous continues to mount.
Research to be presented at the Radiological Society of North America (RSNA) annual meeting in Chicago on Tuesday points to a measurable decline in brain structure and function as a result of the practice.
"There is enormous worldwide concern for brain injury in general and in the potential for soccer heading to cause long-term adverse brain effects in particular," said senior study author Dr. Michael Lipton, a professor of radiology and an affiliate professor of biomedical engineering at Columbia University in New York City. "A large part of this concern relates to the potential for changes in young adulthood to confer risk for neuro-degeneration and dementia later in life."
Unlike other studies that have examined adverse effects at one point in time, Lipton's team looked at brain changes over two years.
They asked 148 amateur players (average age: 27) how often they play, practice and head the ball -- and in what situations. Their exposure was ranked low, moderate or high. Just over a quarter of participants were women.
Players' verbal learning and memory were assessed and each had a specialized head scan known as diffusion tensor imaging (DTI). These advanced MRI techniques track the movement of water through brain tissue.
The images were telling.
Compared to baseline tests, participants who reported more than 1,500 headers over two years showed significant brain changes.
"Our analysis found that high levels of heading over the two-year period were associated with changes in brain microstructure similar to findings seen in mild traumatic brain injuries," Lipton said in a university news release. "High levels of heading were also associated with a decline in verbal learning performance. This is the first study to show a change of brain structure over the long term related to sub-concussive head impacts in soccer."
Lipton and his colleagues also plan to report findings from a second study that used DTI to examine links between repetitive head impacts from soccer heading and verbal learning performance.
That study included 353 amateur players between 18 and 53 years of age, 27% female. It used DTI to examine the interface between the brain's white and gray matter closer to the skull.
That's a brain region at risk of damage but one that has been overlooked due to limitations of existing methods, Lipton said. Using DTI has the potential to disclose the extent of injury not only from repetitive heading, he said, but also from concussion and traumatic brain injury to an extent not previously possible.
The DTI showed that the normally sharp gray matter-white matter interface was blunted with repetitive head impacts.
"In various brain disorders, what is typically a sharp distinction between these two brain tissues becomes a more gradual or fuzzier transition," Lipton said, adding that integrity of the gray-white matter interface may be a cause of the link between repetitive head impacts and thinking declines.
"These findings add to the ongoing conversation and contentious debate as to whether soccer heading is benign or confers significant risk," he said.
Research presented at meetings is typically considered preliminary until published in a peer-reviewed journal.
More information
The Mayo Clinic has more about traumatic brain injury.
SOURCE: Radiological Society of North America, news release, Nov. 28, 2023