BU Says Three in Four NFL Players Who Died Since 2008 Likely Had CTE. Vrabel: Players Know the Risk

A Boston University study published Wednesday in JAMA Network Open estimates that three out of four former NFL players who died between 2008 and 2023 likely had chronic traumatic encephalopathy, the degenerative brain disease linked to repeated hits to the head, NBC10 Boston reported.

The method is the news here. CTE can only be diagnosed after death, and most research relies on donated brains, which skews the results because families are more likely to donate when a player had memory or behavior problems. So the BU team started with federal death records for all 2,362 former NFL players who died in the period. Of those, 396 donated their brains to BU's brain bank, and 93.5 percent of the brains examined had CTE. Players with cognitive symptoms were about five times more likely to be donated.

After adjusting for that bias, researchers estimated 74.5 percent of all the players had some stage of CTE. Their most conservative estimate was 63.7 percent. The authors cautioned that many cases may have been early-stage with no symptoms, and the findings don't apply to living players or people who only played in high school or college.

"Among those who are not exposed to repetitive head impacts, we see CTE in less than 1%," said Yorghos Tripodis, a BU School of Public Health biostatistician and one of the lead researchers. "Now, we see among those who played (football) the longest, the prevalence of CTE is 75%." He added: "It's not that we are anti-football. We would like to understand what the risks are so we can make the game safer."

Tripodis was critical of the padded Guardian Caps the NFL now allows over helmets. "It doesn't do enough to protect you from these rotational movements that happen in your brain within the skull," he said, and argued for reducing tackle football before high school and limiting tackling in practice at all levels.

Patriots coach Mike Vrabel, a former linebacker, said he supports the league's safety efforts but that players understand what they're signing up for. "You love the game so much that you know you're going to do whatever you can to play the game," he said. The NFL Players Association called studies like this "critical to improving our understanding of football's long-term impacts" and pointed to programs including the Football Players Health Study at Harvard. The NFL acknowledged a link between football and CTE in 2016.

WBUR noted the study landed alongside a separate Harvard study that NFL widows say minimizes their experience, so the research fight isn't over.

Dez's take: Boston keeps being the place where football's bill comes due, and BU just made the donation-bias argument a lot harder to lean on. Vrabel's answer is honest, and it's also the answer a 30-year-old gives. The interesting question is what parents of 9-year-olds in Brockton and Quincy do with that 74.5 percent.

What we still don't know: how many of those CTE cases caused symptoms in life, which this study can't answer.