Playing soccer is associated with a significant deterioration in brain function, the problem is touching the ball with your head, according to a new study
New research presented this week at the annual meeting of the Radiological Society of North America (RSNA) links soccer headers – where players hit the ball with their head – to measurable deterioration in brain microstructure and function over a two-year period in connection years.
“There is enormous concern worldwide about brain injuries in general and in particular about the possibility that headers in football have long-term harmful effects on the brain,” said the study’s lead author, Professor of Radiology, Dr. Michael L. Lipton at Columbia University Vagelos College of Physicians and Surgeons and associate professor of biomedical engineering at the same university. “Much of this concern relates to the possibility that changes in early adulthood confer risk for neurodegeneration and dementia later in life.”
While previous research looked at the negative effects of playing football on the brain at one point in time, this new study looked at brain changes over a two-year period.
The headbutt, a mild traumatic injury that repeats itself
148 young adult amateur soccer players (average age 27 years, 26% women) took part in the study. The research team developed a special questionnaire for players to determine how often they hit the soccer ball with their head.
“When we started, there was no method to assess the number of head impacts a player had sustained,” explained Dr. Lipton. “That’s why we developed a structured epidemiological questionnaire that has been validated in several studies.”
The questionnaire consists of a series of questions about how often a person plays, practices and heads the ball and in what situations. Exposure to pitching over a two-year period was classified as low, moderate, or high.
Players were tested for verbal learning ability 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 tracking the microscopic movement of water molecules through the tissue.
Compared to baseline test results, the high head exposure group (more than 1,500 heads over two years) showed increased diffusivity in frontal white matter regions and reduced orientation scattering index (a measure of brain organization) in certain brain regions after two years of exposure to the Head. The analysis adjusted for variables such as age, gender, 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 those seen in mild traumatic brain injury,” said Dr. Lipton. “A high level of pitching was also associated with a decline in verbal learning performance.” “This is the first study to show a long-term change in brain structure associated with sub-concussive head impacts in football.”
Dr. Lipton and colleagues also presented another study today in which they used DTI to examine the relationship between repeated head impacts during soccer heading and verbal learning performance.
Less communication between the gray and white matter of the brain
For the second study, researchers analyzed pre-DTI headers and verbal learning performance of 353 amateur soccer players (aged 18 to 53, 27% female) for 12 months. Unlike previous research that focused on deep regions of white matter, this study used a new technique that used DTI parameters to assess the integrity of the interface between the brain’s gray and white matter closest to the skull lies to judge.
“Importantly, our new approach targets a region of the brain that is vulnerable to injury but has been neglected due to the limitations of existing methods,” said Dr. Lipton. “The use of this technique has the potential to reveal the extent of injuries from repetitive head impacts, as well as concussions and traumatic brain injuries, on a scale not previously possible.”
The researchers found that the normally sharp interface between gray and white matter became weaker in proportion to exposure to repeated impacts to the head.
“We use DTI to assess the sharpness of the transition from gray matter to white matter,” explains Dr. Lipton. “In various brain diseases, the normally sharp difference between these two brain tissues becomes a more gradual or diffuse transition.”
He added that the integrity of the interface between gray and white matter may play a causal role in the negative association between repeated head impacts and cognitive performance.
“These findings contribute to ongoing conversations and contentious debates about whether heading the ball in football is harmless or poses significant risk,” he said.