Former Professional Athletes Prone to Neurodegenerative Disease

by | Nov 12, 2019 | 2019, Brain Health

Written by Joyce Smith, BS. Former Scottish professional soccer players used more dementia-related medications and had more than three times greater risk of death from neurodegenerative disease than the study controls from the Scottish population.

The increasingly popular game of soccer is prevalent in over 200 countries and has over a quarter billion participating players 1. There is growing concern for the neurocognitive consequences of contact sports 2. While participation in professional sports is associated with reductions in all-cause mortality and the risk of cardiovascular disease 3, contact and collision sports have been linked to cognitive and neuropsychiatric impairment later in life as well as neurodegenerative diseases and chronic  traumatic encephalopathy from repetitive brain trauma 1,4,5.

In a current study 6, Mackay and colleagues conducted a retrospective study to compare mortality from neurodegenerative diseases in 7,676 former professional soccer players born before 1977 to that of 23,028 controls from the general Scottish population. Participants were matched on sex, age, and degree of social status, causes of death via death certificates, and finally medication dispensing for dementia treatment based on national prescribing data.

Over an 18 year follow-up, 1,180 soccer players and 3,807 controls died (mean death age of 68 for former soccer players and 65 for controls.)  Until age 70, all-cause mortality was lower among former players, and thereafter became higher.  Mortality from ischemic heart disease and lung cancer was lower (P=0.02 and  P<0.001 respectively) compared to  controls; however, after adjusting for heart disease and cancer deaths, mortality from neurodegenerative disease was listed as the primary cause of death among 1.7% of former  soccer players and 0.5% among controls. Compared to controls, Alzheimer’s disease mortality was five times higher (P<0.001), amyotrophic lateral sclerosis (ALS) was four times higher and Parkinson’s disease was twice as high (p<0.01) in former soccer players. In addition, dementia-related medications were prescribed more frequently to players than to controls (p<0.001).

These results are similar to those reported in a study of former National Football League (NFL) players where all-cause mortality was lower in former NFL players than in the general population, but neurodegenerative mortality was higher 7.

An additional recent study, comparing former NFL players to former Major League Baseball players, found that all-cause mortality, cardiovascular mortality, and neurodegenerative mortality were all higher among the former NFL players 8 which may been due to certain aspects of playing in professional American-style football such as body habitus and exposure to repetitive head impacts, rather than common factors such as overall physical activity.

A study strength was the fact that this study design gave the researchers a detailed look at the rate of occurrence of different neurodegenerative disease subtypes; however, death certificates may contain reporting errors, and this analysis was unable to include chronic traumatic injury as a possible cause of death. The study could not determine what caused increased neurodegenerative disease, nor could the results be extrapolated directly to collegiate, recreational, and amateur players. The authors recommend additional research concerning the neurologic consequences of soccer heading, including studies of female former pro players and amateur players of both sexes, as well as prospective longitudinal studies to confirm or refute the existing evidence that repeated blows to the brain from heading in professional soccer is an occupational risk that needs to be addressed.

Source: Mackay, Daniel F., Emma R. Russell, Katy Stewart, John A. MacLean, Jill P. Pell, and William Stewart. “Neurodegenerative disease mortality among former professional soccer players.” New England Journal of Medicine (2019).

 © 2019 Massachusetts Medical Society.

Posted November 12, 2019.

Joyce Smith, BS, is a degreed laboratory technologist. She received her bachelor of arts with a major in Chemistry and a minor in Biology from  the University of Saskatchewan and her internship through the University of Saskatchewan College of Medicine and the Royal University Hospital in Saskatoon, Saskatchewan. She currently resides in Bloomingdale, IL.

References:

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  6. Mackay DF, Russell ER, Stewart K, MacLean JA, Pell JP, Stewart W. Neurodegenerative Disease Mortality among Former Professional Soccer Players. New England Journal of Medicine. 2019.
  7. Lehman EJ, Hein MJ, Baron SL, Gersic CM. Neurodegenerative causes of death among retired National Football League players. Neurology. 2012;79(19):1970-1974.
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