A single incidence of traumatic brain injury (TBI) can lead to long-lasting neurodegeneration, according to a study of 32 individuals. In addition to clarifying the little-understood chronic effects of TBI, the study's methods could improve the diagnosis and monitoring of brain damage in patients who have suffered an injury. Research has shown that TBI can trigger progressive accumulation of tau, a protein associated with neurodegeneration that plays a major role in Alzheimer's disease. Scientists have studied the effects of TBI by combining PET imaging with flortaucipir, an imaging agent that binds to tau. Most imaging studies have been performed in athletes who have experienced multiple injuries, but it is less clear how the brain changes in survivors who experienced a single TBI. Nikos Gorgoraptis and colleagues performed flortaucipir PET scans to study the distribution of tau in 21 participants who experienced a TBI at least 18 years prior, due to either traffic accidents or assault. The experiment revealed that collectively, the TBI cohort showed more deposition of tau (as indicated by higher flortaucipir binding) compared to 11 healthy controls and performed more poorly on tests of memory and cognitive performance. Furthermore, TBI subjects with higher tau deposition showed more severe neurodegeneration, and tau deposition was also linked to damage to the brain's white matter - the tissue that insulates and nurtures neurons. The ability to detect tau in patients after TBI could help in the design of future trials of tau-targeting therapies, the authors add.