Study estimates about 75% of deceased NFL players from 2008-2023 had CTE

Left · 2A study published Wednesday in JAMA Network Open estimated that nearly 75% of former NFL players who died between 2008 and 2023 had chronic traumatic encephalopathy (CTE). 1 2 Left · 2NBC News calls it the highest estimate to date; it follows an August study by the same group that estimated one-quarter of NFL players who died in a five-year span had CTE, while CBS reports that study gave a range of 25% to 98% for players who died between 2016 and 2021. 1 2 Left · 2CTE can only be definitively diagnosed after death, and brain donors are more likely to have had symptoms, a selection bias that has led to criticism of earlier research. 2 1

Left · 2To correct for this, the researchers combined brain-bank data with national death records and factored in that families of players with cognitive symptoms were about five times more likely to donate brains. NBC reports 396 donated brains and 1,966 other deceased players, with about 93% of donated brains showing CTE. CBS reports 362 of 387 deceased ex-players had some form of CTE, a 94% prevalence among donors that was adjusted to an overall estimate of 74.5%. 1 2 Left · 1Of roughly 2,360 players who died in the period, the team estimated about 1,760 had CTE and about 27% had dementia. Study leader Yorghos Tripodis of Boston University said the figure is a best guess because CTE cannot be diagnosed in living people, and that not everyone with CTE signs develops symptoms. 1 Left · 1Lead author Julia Gallini noted CTE is found in less than 1% of donors to community brain banks and said the 75% figure is concerning and suggests a need for more efforts to support families, diagnose CTE in life and treat symptoms. The authors noted the study covers only deceased players and does not predict how many living former or active players have CTE. 2

Left · 1Dr. Jim Kelly, a University of Colorado neurologist not involved in the research, said the numbers are all estimates because there were no autopsies for about five times as many players as there were autopsies, and that some autopsies may have shown only one or a few lesions unlikely to cause symptoms. Dr. Julian Bailes, also not involved, said the findings call for more research into diagnosing CTE in living people. 1 Left · 2The NFL said it "continuously strives to make the game of football safer," pointing to equipment such as Guardian Caps and rule changes such as the dynamic kickoff. The NFL Players Association said the study is one of many that are "critical" to understanding long-term health impacts, and former quarterback Matt Hasselbeck, an ambassador for the study, said the numbers should not be accepted for the next generation. 2 1