Football is a dangerous sport. What makes it particularly concerning is its physical nature and the toll it takes on players' bodies. Repeated head impacts in football are associated with long-term neurological risks, including CTE, a neurodegenerative disease that currently can be definitively diagnosed only after death.
A recent study has highlighted just how serious the issue is. A recent study estimated that 74.5% of former NFL players who died between 2008 and 2023 had CTE neuropathology.
CTE stands for Chronic Traumatic Encephalopathy, a progressive degenerative brain disease found in people with a history of repeated head impacts. What's particularly concerning about the condition is that it can only be diagnosed after death.
Former Eagles linebacker Emmanuel Acho believes the report should not be trusted blindly, arguing that there could be significant selection bias in the study sample.
The report was released by researchers at Boston University, Mass General Brigham, and the Concussion & CTE Foundation.
It was based on a sample of 2,362 deceased former NFL players who died over a 16-year period, from 2008 through 2023. Of these, 396 players had donated their brains for research, while data on the remaining non-donors was collected from national death records.
"A helmet was never meant to cure concussions nor cure CTE. It is a very real thing. However, you have to put in context that studies like this often have a selection bias," Acho said during Thursday night's episode of the "Speakeasy" podcast.
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"When God calls me home, I'm not going to donate my brain to a CTE study because I don't have CTE. But if I were to struggle with CTE or struggle with suicidal ideation and struggle with all of these other mental health thoughts, then I would likely donate my brain when I die to be researched because I assume something is there. Hence, why I'm going to donate my brain for it," he added.
Acho used a similar analogy, suggesting that someone who isn't sneezing or sniffling is unlikely to visit a doctor. In his view, this creates a significant bias in the collected sample.
After finding CTE in 93.5% of evaluated brain donors, researchers modeled the selection bias associated with brain donation and estimated a prevalence of 74.5% across the full cohort.
Similarly, an August paper by several of the same researchers found that at least about one in four former NFL players who died between 2016 and 2021 had CTE, while noting that the true prevalence could have been considerably higher.
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Some of the most prominent CTE cases in NFL history include Steelers legend Mike Webster, Eagles safety Andre Waters, Chargers linebacker Junior Seau, Raiders player Ken Stabler, and several others.
The NFL has adopted rules intended to reduce dangerous head contact, while its 2026 accountability system allows suspensions for repeated violations of certain player-safety rules.
However, player safety remains a subject of debate, particularly regarding the continued use of artificial turf in some NFL stadiums instead of natural grass.
The NFL Players Association said studies like this are critical to understanding football's long-term health impacts and reiterated its commitment to supporting research, player well-being resources, and expanded access to care.
This article originally appeared on Pro Football Network .
