Jornal Do Brasilia - At least a quarter of NFL players may get brain disease: study

Chronic traumatic encephalopathy (CTE) is caused by repeated head impacts and its symptoms include trouble with thinking and memory loss, difficulty walking, emotional instability and suicidal thoughts.

It has previously been linked to contact sports including American football and boxing, and found in military members exposed to explosive blasts.

But since CTE can only be confirmed in a post-mortem brain exam, the true extent of CTE among NFL players has remained unclear.

In the new study, led by Daniel Daneshvar, a professor at Harvard Medical School, and published in the British Medical Journal, researchers looked at the brains of dead players who had played at least one NFL game in the mandatory plastic helmet era that began in 1949.

The main finding comes from people who died between 2016-2021, when brain donations were most frequent. Of the 878 deaths during this period, 235 had their brains donated and examined, and 215 had confirmed CTE.

That means, at minimum, the rate of CTE was 24.5 percent if none of the brains that weren't examined would have shown CTE. The maximum estimate was 97.7 percent, and the true figure likely lies somewhere in the middle.

The researchers also assessed severity of CTE and found a connection between high grade CTE and dementia before death, with the latter ascertained by the players' medical notes and interviews with family members.

"Together, these findings indicate that NFL players have a higher prevalence of CTE at death than has been previously shown in multiple community based studies," wrote the authors.

"These data indicate that CTE severity at death is significantly associated with dementia in NFL player brain donors, and that dementia is common in these donors."

But they also acknowledge several limitations, including that not all former NFL players who died during the study window were included, and that some family members may have inaccurately recalled or over-stated symptoms.

Writing in a related editorial, professors Tobias Kurth of the University Medical Center Berlin and Richard Riley of the National Institute for Health and Care Research in Birmingham praised the study design.

No single study can fully define the rate of CTE among NFL players, but "Daneshvar and colleagues provide one of the most informative estimates to date," they said.

Above all, they argued, it is essential to regularly communicate the scientific evidence to past, present and prospective NFL players.

M. Oliveira--JDB