Brain Injury in the NFL
Categories: Sports and entertainment
September 6th, 2012 10:58 am ET - Everett Lehman, MS
The paper, “Neurodegenerative causes of death among retired National Football League players
In addition to the overall comparison with the general population, the study also compared the deaths of players associated with neurodegenerative disorders based on playing positions. More neurodegenerative deaths were observed among players in “speed” positions (quarterback, running back, halfback, fullback, wide receiver, tight end, defensive back, safety, and linebacker) compared with players in “non-speed” positions (all defensive and offensive linemen). Other research studies have shown that speed players may be at higher risk of concussion since they can build considerable momentum prior to the point of being tackled or tackling another player. Offensive and defensive linemen usually engage other players soon after the football is snapped, mitigating the potential to build up momentum to a tackle or a block.
Study limitations
While our study is consistent with other recent studies that have found increased risk of neurodegeneration among NFL football players, our research has several limitations. Some of the limitations are listed below.- It is not possible to determine from our study the cause of the increased risk of death from neurodegenerative disorders. Research suggests that football players who have experienced one or more concussive blows to the head are at increased risk of neurologic disorders but our study does not establish a cause-effect relationship between football-related concussions and death from neurodegenerative disorders.
- Since our cohort was limited to longer-term professional players, our findings may not be applicable to those who play for a shorter term or high school and college football players. The magnitude of risk may depend on the intensity and frequency of brain injuries incurred over a number of years.
- The study relied on death certificate information for causes of death; at the time of analysis only 10 percent of the participants had died. Of the 334 players who had died, Alzheimer’s, ALS, and Parkinson’s Disease were listed for 17 of them. The small number of deaths used in the study only allowed us to place players into two broad position categories. We were not able to identify potentially important differences in neurodegenerative mortality risk across the various positions included within the speed position group.
- Other studies have suggested that Chronic Traumatic Encephalopathy (CTE), which can exhibit symptoms similar to Alzheimer’s disease and ALS, may occur years after sustaining football-related concussions. Since CTE is a newly confirmed diagnosis, it is possible that some deaths attributed to Alzheimer’s or ALS on death certificates may actually have been related to CTE. A brain autopsy is necessary to diagnose CTE and distinguish it from Alzheimer’s or ALS; no death certificate would have listed CTE as a cause.
- We did not have information on environmental, genetic or other risk factors for neurologic disorders.
Everett Lehman, MS
Mr. Lehman is an occupational epidemiologist and deputy division director in NIOSH’s Division of Surveillance, Hazard Evaluations & Field Studies.
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