Highlights
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New research presented at the annual meeting of the Radiological Society of North America (RSNA) links heading in soccer with a measurable decline in brain microstructure and function over a two-year period.
"There is enormous global concern about brain injuries in general and the potential for headers in soccer to cause long-term adverse brain effects in particular," said lead author Michael L. Lipton, M.D., Ph.D., professor of radiology at Columbia University’s Vagelos College of Physicians and Surgeons and affiliate professor of biomedical engineering at Columbia University. "A large part of this concern relates to the possibility that changes in young adulthood confer risk for neurodegeneration and dementia later in life."
While previous research has examined the adverse effects on the brain related to heading in soccer at a single time point, this new study looked at brain changes over two years.
The study included 148 young adult amateur soccer players (mean age 27 years, 26% female). The research team developed a specialized questionnaire for players to determine how often they hit the soccer ball with their heads.
"When we started, there was no method to assess the number of head impacts a player experienced," Dr. Lipton said. "So, we developed a structured epidemiological questionnaire that has been validated in multiple studies."
The questionnaire consists of a series of questions about how often an individual plays, practices and heads the ball, and in what types of situations. Two-year course exposure was classified as low, moderate, or high.
Players were assessed for verbal learning and memory and underwent diffusion tensor imaging (DTI), an MRI technique, at enrollment and two years later. DTI characterizes the microstructure of the brain by following the microscopic movement of water molecules through tissue.
Compared to the initial test results, the high-heading group (more than 1,500 headings over two years) demonstrated increased diffusivity in frontal white matter regions and a decreased orientation dispersion index (a measure of brain organization) in certain brain regions after two years of exposure to the title. The analysis was adjusted for variables including age, sex, education, and concussion history.
"Our analysis found that high levels of pitching over the two-year period were associated with changes in brain microstructure similar to findings seen in mild traumatic brain injuries ," Dr. Lipton said. “High levels of pitching were also associated with a decrease in verbal learning performance. “This is the first study to show a long-term change in brain structure related to non-concussive head impacts in football.”
Dr. Lipton and colleagues also presented today another study in which they used DTI to investigate the association between repetitive head impacts caused by heading in soccer and verbal learning performance.
For the second study, researchers analyzed heading for 12 months before DTI and verbal learning performance tests in 353 amateur soccer players (aged 18 to 53, 27% female). Unlike previous research that focused on deep white matter regions, this study employed a new technique, using DTI parameters to assess the integrity of the interface between the gray and white matter of the brain closest to the skull.
"Importantly, our new approach addresses a region of the brain that is susceptible to injury but has been neglected due to the limitations of existing methods," Dr. Lipton said. "Applying this technique has the potential to reveal the extent of injury from repetitive pitching, but also from concussion and traumatic brain injury to a degree that was not possible before."
The researchers found that the normally clear interface between gray matter and white matter weakened in proportion to high repetitive exposure to head impacts.
"We used diffusion tensor imaging (DTI) to assess the sharpness of the transition from gray matter to white matter," Dr. Lipton said. "In various brain disorders, what is normally a clear distinction between these two brain tissues becomes a more gradual or blurred transition."
He added that the integrity of the interface between gray matter and white matter may play a causal role in the adverse association between repetitive head impacts and cognitive performance.
"These findings add to the ongoing conversation and contentious debate about whether heading in soccer is benign or confers significant risk," he said.
The authors of the first study are Molly F. Charney, MD, Kenny Ye, Ph.D., Roman Fleysher, Ph.D., Liane E. Hunter, MD, Ph.D., Shimon Garrel, BS, Bluyé Demessie, AB , M.S., Joan Y. Song, BSE, M.S., Molly E. Zimmerman, Ph.D., Walter F. Stewart, Ph.D., Mimi Kim, Sc.D. and Richard B. Lipton, M.D.
Co-authors of the second study are Joan Y. Song, BSE, MS, and Roman Fleysher, Ph.D.
