A study published in the latest issue of Nature magazine shows that repeated brain impacts on young athletes can cause neuronal loss long before signs of neurodegenerative disease appear. The research results can help explain the early symptoms of individuals exposed to contact sports and guide related studies on early identification and treatment of brain injuries. Chronic traumatic encephalopathy (CTE) is a neurodegenerative disease associated with repetitive brain impacts, commonly found in contact sports such as American football. At present, the disease can only be diagnosed by detecting abnormal accumulation of tau protein in specific brain regions after death. However, many young athletes experience symptoms before the protein appears, indicating the need for a deeper understanding of early brain changes. The Boston University team analyzed post-mortem brain tissue from 28 individuals under the age of 51, including 8 individuals without a history of traumatic brain injury, 9 contact athletes without signs of tau protein accumulation, and 11 contact athletes diagnosed with early-stage CTE. The team found that regardless of CTE status, all contact athletes had higher levels of neuroinflammation, vascular damage, and neuronal loss than the non athlete control group. In particular, they found that the surface cortex neurons of contact athletes were 56% fewer than those of age-matched individuals without traumatic brain injury, which is a critical brain region involved in thinking and emotions. This neuronal loss is not related to tau protein accumulation, indicating that it occurs earlier and is independent of the typical pathological features of CTE. This study highlights the importance of protecting young athletes and proposes new directions for potential diagnostic and therapeutic targets for brain changes caused by repetitive brain impacts. (New Society)