A study published Tuesday in The BMJ reports that at least one in four former NFL players may develop chronic traumatic encephalopathy (CTE). Researchers from Massachusetts conducted a postmortem analysis of 338 brains from former players who died between 2008 and 2021. The study found that 315 of those donors, or approximately 93%, were diagnosed with the degenerative brain disease.
CTE is a condition currently only diagnosable after death through brain tissue analysis. The Centers for Disease Control and Prevention (CDC) describes the disease as a buildup of abnormal proteins that damage brain tissue and lead to cell death. While frequently associated with football due to repeated head impacts, the Boston University CTE Center notes the condition has also been found in boxers, soccer and hockey players, military veterans, and first responders.
The study highlighted a higher prevalence among recent donors; of 235 players who died in the last six years, more than 210 had CTE. Furthermore, donors who had been diagnosed with dementia during their lives were found to have more severe cases, with 94 individuals identified as having Stage 4 CTE. Researchers noted that symptoms such as mood swings, memory loss, and suicidal thoughts can take decades to develop, though these symptoms do not always indicate the presence of the disease.
For an individual player or their family, this means a shift in how they monitor long-term health, as symptoms may not appear for years or decades after their career ends. The study indicates that players with dementia are particularly susceptible to the most severe forms of the disease, Stage 4 CTE, which can interfere with daily activities and mood regulation. These neurological changes can lead to severe behavioral shifts, as seen in reported cases involving former players like Irv Cross and Aaron Hernandez, affecting their ability to work or maintain social connections.
The findings set a precedent for ongoing medical research into earlier diagnostic tools, as the disease currently requires postmortem analysis. As researchers at Boston University continue to look for risk factors and earlier detection methods, the sports industry and military institutions face continued scrutiny regarding safety protocols and long-term care for participants. While the study provides a specific look at deaths through 2021, the exact timing for when new diagnostic methods might become available for living patients remains not reported.
The study included several specific cases of former players diagnosed after death. Marshawn Kneeland, who died in November, was found to have Stage 1 CTE. Other players diagnosed with later stages included Frank Wycheck and Aaron Hernandez at Stage 3, and Irv Cross at Stage 4. The researchers noted that while brain donation has become more frequent in recent years, allowing for more data, the condition remains incurable.
Research into CTE is ongoing, with organizations like Boston University focusing on how the disease develops and potential risk factors. The CDC maintains that while there is no cure, treatments are available to manage the symptoms associated with the condition. The study did not provide a specific date for when the next phase of research would be published.