1. The study used diffusion tensor imaging (DTI) to examine white matter abnormalities in the brains of high school football players who experienced repetitive head impacts over a season compared to non-contact athletes and individuals with diagnosed concussions. 2. DTI detected changes in fractional anisotropy (FA) values in football players compared to controls, suggesting asymptomatic white matter damage from repeated subconcussive blows. Players showed higher FA values chronically while concussed individuals showed lower FA values. 3. The analysis demonstrates DTI's ability to detect pre-symptomatic white matter changes associated with repetitive head impacts, which has implications for preventing neurodegenerative conditions like chronic traumatic encephalopathy.