Study finds three of four deceased ex-NFL players likely had CTE

Three out of every four former NFL players who died between 2008 and 2023 likely suffered from chronic traumatic encephalopathy, according to a new study published Wednesday in JAMA Network Open. The research team from Boston University calculated that 74.5% of the 2,362 deceased players had some stage of the degenerative brain disease.

The study addresses a known flaw in previous research that relied solely on donated brains. Families were far more likely to donate a brain if the player exhibited memory loss or behavioral changes. In the current dataset, 396 players donated their brains to the Boston University brain bank. Of those examined, 93.5% showed signs of CTE. Players with cognitive symptoms were roughly five times more likely to be included in that sample.

To correct for this bias, the researchers used federal death records for all former players who passed away during the study period. They applied statistical adjustments to estimate the prevalence of the disease across the entire group. The most conservative estimate in the report places the rate at 63.7%.

Yorghos Tripodis, a biostatistician at the Boston University School of Public Health and one of the lead researchers, noted that CTE appears in less than 1% of the general population that does not experience repetitive head impacts. He stated that the 75% rate among players with the longest careers underscores the specific risk of the sport.

The authors cautioned that many of the cases identified may have been early-stage and asymptomatic. The findings do not apply to players currently active in the league or to those who played only in high school or college. Tripodis explained that the goal is to make the game safer, not to end it.

The NFL acknowledged the link between football and CTE in 2016. Since then, the league has modified rules and equipment standards. These changes include allowing the use of padded Guardian Caps worn over standard helmets. Tripodis argued that such equipment protects the skull but does not stop the rotational movement of the brain inside the skull, which he identified as a primary cause of the disease.

New England Patriots head coach Mike Vrabel, a former linebacker, said he supports the league's safety initiatives. He noted that players accept the risks to stay on the field. The NFL Players Association said the study helps improve understanding of the sport's long-term impacts. The union stated it will continue to support players through programs like the Football Players Health Study at Harvard University.