The world's most popular sport, soccer, is facing significant health concerns as new research reveals the detrimental effects of repetitively heading a soccer ball on brain health. The largest study of its kind has shown that this common action can negatively impact the brain, particularly among amateur players who do not report experiencing concussions. This groundbreaking study involved 352 amateur adult soccer players and revealed that those who executed more than a thousand headers annually displayed microscopic changes in the brain's outer structure, specifically the area located just behind the eyes, irrespective of their age or sex.
The study's results indicate that these players performed slightly yet significantly worse on tests measuring memory and learning capabilities. Neuroscientist Michael Lipton from Columbia University, who has been at the forefront of research on the effects of soccer heading on brain health for over a decade, explains the importance of these findings. "Our study shows for the first time that exposure to repeated head impacts leads to specific changes in the brain, which subsequently impair cognitive function," he states.
While contact sports such as American football, Australian rules football, and rugby have been grappling with the repercussions of repetitive head trauma, the discourse surrounding these issues often centers on a concussion crisis among professional athletes. However, Lipton's research suggests that even minor head impacts can accumulate over time, affecting not just professional players but also those who engage in the sport recreationally.
Earlier studies conducted by Lipton uncovered alterations in white matter among amateur soccer players when compared to swimmers, indicating that brain changes could occur even without a history of concussions. However, establishing a direct link between these brain changes and clear cognitive alterations has proven challenging. Lipton and his team have developed a novel method for identifying damage in the outermost wrinkles of the brain, an area previously difficult to study using diffusion magnetic resonance imaging (dMRI).
This specific layer, known as the cortical gray matter–white matter interface (GWI), has only recently garnered attention. Utilizing their advanced imaging technique, Lipton's team scanned the brains of amateur soccer players with at least five years of experience who had participated in the sport within the last six months. Players who reported taking more headers exhibited significant changes in the GWI, particularly in the front part of the brain—an area aligned with the trajectory of a soccer ball during headers.
The researchers suspect that the changes observed at this injury site are indicative of a contrecoup force, resembling a bruise on the brain that occurs on the opposite side of the skull from the initial impact. It's possible that injuries to the GWI have been overlooked or underestimated in previous imaging studies, which may explain the conflicting findings regarding the neurological consequences of heading a soccer ball.
Joan Song, a graduate student in Lipton's lab, has made significant strides in characterizing the MRI scans. "In healthy individuals, there's a sharp transition between these tissues," she explains. "We studied whether an attenuation of this transition might occur due to minor impacts from heading." The results were telling: the boundary between white and gray matter was less distinct in players who took more headers, presenting strong evidence that these microstructural changes may contribute to cognitive deficits.
While further investigation is necessary, the findings suggest that the GWI could be a critical area for imaging in future studies examining the impacts of soccer heading. Additionally, these changes may be linked to conditions such as chronic traumatic encephalopathy (CTE), highlighting the urgent need for awareness and further research into the long-term effects of heading in soccer.
