A new study has reported a higher burden of degenerative brain disease among deceased former NFL players than had previously been demonstrated. According to the BBC’s account, at least one in four former players who died during the six-year period from 2016 to 2021 had such a disease.
The study also indicates that the true figure could be much higher. The evidence supplied does not explain why the confirmed proportion may be an underestimate, and it does not provide a higher projected rate. It therefore remains unclear how far the actual prevalence could exceed the reported minimum of 25%.
Important details about the research are not included in the available account. The name of the degenerative disease or diseases, the total number of former players covered, the method used to identify cases and whether every player who died during the period was assessed are not stated.
The finding applies specifically to former NFL players who died between 2016 and 2021. On the evidence available, it should not be treated as an estimate for living former players, active NFL players or people who did not play in the league.
Even with those limitations, the study adds evidence that brain disease among deceased former professional American football players may have been undercounted in earlier findings. Further information about the study’s sample and methods would be needed to judge the scale of the difference and the strength of its estimate.