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

Approximately 75% of former National Football League players who died between 2008 and 2023 likely suffered from chronic traumatic encephalopathy. The new estimate appears in a study published Wednesday in JAMA Network Open. The research team, based in Boston, sought to determine how widespread the degenerative brain disease was among all deceased players during that 15-year window, rather than only among those whose brains were donated for scientific examination.

The analysis included records for 2,362 former players. These individuals spent an average of five years in the league. Close to 400 of them had their brains donated for post-mortem examination. Researchers found evidence of CTE in 93.5% of those donated brains. This high rate in the donor group served as a key data point for the broader statistical estimate.

The findings stand in sharp contrast to rates in the general public. The study authors noted that fewer than 1% of brain samples in community-based brain banks show signs of CTE. The physical markers of the condition include brain atrophy and the accumulation of tau protein, a substance also associated with Alzheimer's disease.

Senior author Yorghos Tripodis addressed the potential impact of these numbers on the football community. In a statement issued by Mass General Brigham, he acknowledged that the findings may cause concern for living players and their families. Tripodis stated that researchers are standing by to provide support. He also noted that recent discoveries from brain bank data have moved the field significantly closer to diagnosing the disease while patients are still alive.

The researchers clarified that the presence of CTE-related changes in the brain does not automatically result in dementia or cognitive decline. Some individuals with the condition never develop noticeable symptoms. However, the study estimated that about 27% of the former players in the analysis had dementia. CTE can also impact emotional control and behavior, leading to symptoms such as depression, memory issues, and severe mood shifts.

This report follows an earlier study from August that found at least one in four former players who died between 2016 and 2021 had CTE. Following that initial report, the NFL said it continuously strives to make the game safer by implementing strategies to reduce concussions and head impacts. Several prominent former players who died by suicide, including Junior Seau, Dave Duerson, and Aaron Hernandez, were found to have had CTE upon examination of their brains after death.