New Study Finds CTE in at Least 25% of NFL Players

A Quarter of NFL Players Studied Had CTE, Study Finds

A new study from researchers at Mass General Brigham, published in the British Medical Journal (BMJ) in August 2026, found that at least 25% of NFL football players had chronic traumatic encephalopathy (CTE).

This neurodegenerative brain disease occurs in people with a history of head trauma, such as football players, hockey players, and boxers.

Several prominent studies over the decades have shown a high correlation between football players and CTE. Still, unlike most brain disorders, CTE can only be diagnosed on autopsy after death, meaning that retired NFL players with repetitive head trauma and symptoms associated with CTE never receive a diagnosis or any potential treatment while alive.

Because CTE is diagnosed post-mortem, people must donate their brains to science so a brain dissection can be performed to determine if CTE is present. This can make studying CTE tricky.

However, since research has shed light on this brain disease among professional athletes, there has been an increase in NFL players donating their brains to help collect data.

The BMJ Study Results

To start, study researchers cataloged every NFL player who died after 1949, when hard-shell helmets were introduced, by obtaining death certificates and demographic data from the Centers for Disease Control and Prevention.

They then pulled data from 2008-2021 because there was an increase in NFL players donating their brains for post-mortem dissection for CTE diagnosis beginning in 2008.

Among all 1,712 NFL players who died, the possible CTE prevalence at death ranged between 18.5% and 98.7%. The possible prevalence at death during 2016 to 2021, when brain donation was most frequent, ranged between 24.5% and 97.7%. Hence, the study results showed a prevalence of at least 25% of NFL players having a diagnosis of CTE, which is the most conservative estimate.

From these results, the study authors concluded that, “At minimum, nearly a quarter of all former NFL players who died during 2016-21 had CTE neuropathology at death. Among NFL player brain donors, dementia diagnosed based on records before death was common and associated with stage IV CTE.”

History of CTE

CTE was first studied by Dr. Harrison Martland in 1928 in a paper published in the Journal of the American Medical Association. Before it was called CTE, chronic head trauma that was associated with neurological symptoms such as confusion, tremors, and gait abnormalities was originally called “punch drunk.”

Dr. Martland coined the term “punch drunk” because he observed these symptoms in professional boxers with repetitive head trauma. This term evolved over decades of research into chronic traumatic encephalopathy.

Due to advanced medical techniques, late manifestations of CTE are known to be linked to the formation of neurofibrillary tangles, which are associated with tau proteins, a primary marker for Alzheimer’s disease. Research suggests that these tau protein aggregates can occur years or decades following recovery from head trauma, specifically when axonal shearing occurs due to severe hits to the head.

The correlation between American football players and CTE has been extensively studied over the last decade due to the rising awareness of CTE in NFL players. Because of this awareness, a growing number of NFL athletes are donating their brains to science after they die. These NFL athletes are experiencing mental health symptoms and impairments in memory and thinking that are affecting their daily lives, especially during retirement. Many believe this is due to CTE.

A study in JAMA Neurology in 2024 surveyed 1,980 former NFL players and found that 1 out of every 3 of these players believes they have CTE due to symptoms associated with CTE. The study also examined mental well-being and found that suicidality was reported by 25% of players who believed they had CTE, compared to 5% in those who did not believe they had CTE.

The study also showed that the NFL players who believed they had CTE reported more cognitive difficulties and had higher rates of chronic pain, low testosterone, and headaches than former players who did not believe they had CTE.

Because CTE cannot be diagnosed until after death, it is unknown whether these players actually had CTE. Still, this study highlights the urgent need for accurate diagnostic tools and mental health support for NFL players.

Mental Health Impacts Associated with CTE

The importance of this research stems from the mental health and cognitive impacts associated with CTE. Research suggests that CTE is linked to cognitive decline and memory loss, as well as:

• Depression
• Insomnia
• Poor impulse control
• Aggressive behavior
• Suicide

Research has also shown that people with CTE who have a family history of mental illness face a much higher risk of developing aggressive and violent behaviors.

Because CTE cannot be diagnosed in living persons, NFL players who experience these symptoms often believe they have CTE due to the correlation of symptoms associated with this disease.

Mental Health Support for CTE Symptoms

Although there may not be treatment for CTE, it is important to treat mental health symptoms associated with repetitive head injuries in NFL players with both medications and psychotherapy.

There is a large amount of research on effective treatments for behavioral problems in people with head injuries, such as traumatic brain injury, which may help guide treatment interventions for NFL athletes experiencing these behavioral symptoms who are at risk of CTE.

Taking care of your mind and body throughout life is crucial. Whether it is seeking therapy from a professional or taking medications for depression, many treatment options can greatly reduce mental health symptoms.