Chronic traumatic encephalopathy neuropathological change (CTE-NC) is a neurodegenerative pathology associated with a history of repeated head trauma. CTE-NC can only be diagnosed by post-mortem histopathological examination.

There are a growing number of case studies and case series which document change (CTE-NC) in retired athletes with a history of RHT. There remain many uncertainties about the strength of the association between RHT, concussion, and CTE-NC.

CTE-NC is not an inevitable consequence of exposure to repeated head trauma. Further research is required to understand the prevalence of CTE-NC in athletic cohorts and the factors that predispose some athletes to the development of CTE-NC following exposure to RHT. Properly designed prospective studies, which control for potential confounding variables, are required to improve our understanding of CTE-NC and why some individuals are susceptible

CTE-NC is characterized by the build-up of hyperphosphorylated tau (p-tau) in neurofibrillary tangles (NFTs), neurites, and, sometimes, astrocytes, surrounding small blood vessels in a patchy distribution at the sulcal depths of the cerebral cortex.

Most of the reported cases of CTE-NC have been detected in sport brain banks. There are issues with significant selection bias in these studies. Research using non-sport brain banks in Australia, the US and Europe show rates of CTE-NC of less than 1%.

The potential contribution of confounders, such as genetic predisposition, psychiatric illness, alcohol and drug use or co-existing dementia, is not adequately accounted for in the current literature.