Even without a concussion, repetitive impacts experienced by those who play contact sports have clear effects on the brain. Rugby players who reported no concussions had alterations in the microstructure of the brain, specifically in the brain stem. Alterations in the functional organization of the brain were also discovered in MRI images of those who played contact sports.
Researchers also found that for rugby players only, the microstructure of the brain changed between in- and off-seasons, specifically in the brain stem, which controls the flow of messages between the brain and body. Researchers found differences in the functional organization of the brain too. When compared to swimmers and rowers, rugby players had changes in connectivity–how the brain communicates–between the areas of the brain that control memory retrieval and visual processing.