Strong correlations suggest the far-reaching detriments of repetitive head trauma may underlie many neurologic conditions


Ray Stubblebine/Reuters

PROBLEM: It's becoming well-known that brain injuries, and the resultant neuron death, can cause serious problems for football players. Does this extend to them having a higher rate of mortality from neurodegenerative diseases?

METHODOLOGY: From a previously gathered cohort of former professional football players who played at least five seasons from 1959 to 1988, researchers examined the death certificates and National Death Index data for the 334 that are now deceased. They divided the old pros into a "speed group" (everyone but linemen) and a "non-speed group" (linemen), leaving out punters and kickers. Deaths where Alzheimer's, Parkinson's, or ALS, also known as Lou Gehrig's Disease, were listed as a primary or contributing cause were compared to the general U.S. population. Since relatively recent research suggests that chronic traumatic encephalopathy (CTE), which can only be diagnosed via brain autopsy, may have been the actual cause of death of some of the players, the researchers also looked at overall neurodegenerative death rates.

RESULTS: While this cohort had less overall mortality than U.S. male population, its risk of death by neurodegenerative disease was three times as great. Worst among them were ALS and Alzheimers, in which related death was four times higher than the general population. (These diseases are listed as contributing rather than underlying causes of death). There was however no significant increase in their rate of Parkinson's-related deaths. In addition, the speed group was over three times more likely than the linemen to die from a neurodegenerative cause.

CONCLUSION/IMPLICATIONS: This data supports other findings that football players are at an increased risk of neurodegenerative disease. The implication is that repetitive head trauma is the cause, though other variables do exist. 

LIMITATIONS: Although the authors started out with a large cohort of 3,439 NFL players, only 10 percent had passed away at the time of the study, leaving them with a small data set. They also were unable to obtain specific data on the rates or severity of injuries sustained by the players, which could have helped to elucidate their findings.

The full study, "The Neurodegenerative causes of death among retired National Football League players," was published in the journal Neurology.