A new study published Wednesday in Jama Network Open estimates that approximately 75% of former National Football League players who died between 2008 and 2023 showed evidence of chronic traumatic encephalopathy. The research, conducted by a team based in Boston, represents the first attempt to estimate the prevalence of the degenerative brain disease across a broad group of deceased athletes rather than limiting the analysis to those who donated their brains for scientific study.
Prevalence Among Deceased Ex-NFL Players
The analysis included records from 2,362 deceased former players who spent an average of five years in the league. Among the nearly 400 players whose brains were donated for examination, 93.5% showed evidence of the condition. This figure stands in stark contrast to data from community-based brain banks, where less than 1% of samples from the general population contain evidence of the disease.
Physical changes associated with the condition include brain atrophy, which involves the loss of brain tissue, and accumulations of tau protein. These accumulations are also a characteristic feature of Alzheimer’s disease. The study found that approximately 27% of the former players included in the analysis had dementia.
Symptoms and Clinical Impact
CTE can damage areas of the brain responsible for emotional control and behavior. Potential symptoms include depression, memory problems, severe mood changes, and other behavioral difficulties. However, researchers noted that the presence of CTE-related changes in the brain does not necessarily mean a person will develop dementia or experience declining cognitive abilities. Some individuals with the condition may never develop noticeable symptoms.
Yorghos Tripodis, the study’s senior author, acknowledged the potential impact of these findings on current athletes and their families. “We recognize these findings may cause concern for the community of living players and their families,” Tripodis said in a statement released by Mass General Brigham. “We want them to know that we and others are standing by to provide support, and that we have hope for those living with CTE.”

Tripodis added that discoveries from the brain bank have already brought researchers significantly closer to a diagnosis during life. He stated that the most important goal at that point will be to develop effective treatments for the condition.
League Response and Previous Research
The findings follow another study released in August, which determined that at least one in four former NFL players who died between 2016 and 2021 had CTE. The NFL addressed its efforts to improve player safety in a statement following the publication of that earlier study. The league stated it continuously strives to make the game of football safer, including by implementing strategies to reduce concussions and head impacts.
A number of high-profile NFL players who took their own lives were found to have had CTE when their brains were analyzed after their deaths. These players include Junior Seau, Dave Duerson, and Aaron Hernandez. The new data provides a broader statistical context for the individual cases that have previously drawn public attention to the health risks associated with professional football.
Source: The Guardian

