Repetitive head impacts cause white matter disruptions in adult amateur soccer players
By Anni Yurcisin. This article was initially published in the 10/9/25 edition of our Concussion Update newsletter; please consider subscribing.
A recent study in Neurology examined the impact of repetitive head injuries (RHI) in soccer players and their effect on the brain. Bluye DeMessie et al. examined adult amateur soccer players and adult non-collision sport athletes with diffusion MRI, looking at microstructural disruptions in white matter. They found that at the depths of sulci – the grooves or indentations in a brain’s outer layer – there were significantly more white matter disruptions in soccer players with high RHI exposure than players with lower exposure or non-collision sport athletes. The study also assessed verbal learning and verbal memory through a validated series of cognitive tests and found that the disruptions were correlated with worse performance on these tests. This study particularly emphasizes the importance of continuing to examine non-concussive head impacts when looking at long-term brain health. Raffaele Cacciaglia, author of an editorial published soon after the study, says “[The study] suggests that white matter microstructure is not merely a biomarker of exposure, but a mediating mechanism linking repetitive impacts to cognitive decline”.
The study specifically looked at fractional anisotropy and orientation dispersion index as the areas of interest. Fractional anisotropy (FA) is a quantitative measure that indicates the degree of water diffusion within a unit of brain tissue. The higher an FA value, the more organized, densely packed, and healthier the white matter is in that unit. Orientation dispersion index (ODI) is similar in that it indicates the extent to which the neurons are tightly packed and organized. The lower the ODI value, the tighter and healthier the white matter is. The authors found that both FA and ODI showed significant correlations with verbal learning and verbal memory. Healthier imaging values (lower ODI and higher FA) were correlated with better performance on the cognitive tests. The soccer players with higher RHI exposure had higher ODI values and lower FA values, demonstrating the microstructural damage done to their white matter. This study provides insight into how even subconcussive exposure can affect the brain and, according to Cacciaglia, “highlights the potential of depth-of-sulcus white matter as a sensitive biomarker of RHI, reveals exposure-related cognitive effects even in amateur players, not just in professionals, and offers a novel methodological approach that may improve detection and monitoring of sports- related brain injury.”
