Boston Study Puts CTE Rate at 75% Among Deceased Ex-NFL Players

Researchers based in Boston estimate that approximately 75% of former National Football League players who died between 2008 and 2023 showed signs of chronic traumatic encephalopathy. The study, published in Jama Network Open on Wednesday, represents the first effort to project CTE prevalence across all deceased former players during that period, rather than limiting the analysis to those who donated their brains for examination.

The team analyzed records for 2,362 former players, who averaged five years in the league. Of that group, nearly 400 had their brains donated for study. Examination of those donated brains revealed CTE evidence in 93.5% of cases. The researchers noted that this rate stands in sharp contrast to the general population, where fewer than 1% of brain samples held by community-based brain banks show signs of the condition.

Yorghos Tripodis, the study’s senior author, said in a statement issued by Mass General Brigham that the findings may cause concern for living players and their families. He stated that researchers are standing by to provide support and expressed hope for those living with the disease. Tripodis added that discoveries from the brain bank have moved researchers closer to achieving a diagnosis during a patient’s lifetime, with the next major goal being the development of effective treatments.

The study authors clarified that the physical hallmarks of CTE, which include brain atrophy and buildups of tau protein, do not automatically result in dementia. While the condition can impact areas of the brain governing emotional control and behavior, some individuals never develop noticeable symptoms. The researchers estimated that about 27% of the former players in the analysis had dementia. Common symptoms associated with the disease include depression, memory problems, and severe mood changes.

This analysis follows a report released in August that found at least one in four former NFL players who died between 2016 and 2021 had CTE. Following that earlier report, the NFL said it continuously strives to make the game safer by implementing strategies to reduce concussions and head impacts.

The condition has been identified in the post-mortem examinations of several prominent former players who died by suicide, including Junior Seau, Dave Duerson, and Aaron Hernandez.