A very large and well designed study from Glasgow strongly supports an association in professional football players between heading the ball and, later in life, ‘neurodegenerative disease’ (dementia, Alzheimer’s disease, non-Alzheimer dementia, motor neuron disease, and Parkinson’s disease). Five percent of the former soccer players were identified with a neurodegenerative disease diagnosis compared with a neurodegenerative disease diagnosis compared with 1.6 percent of matched population control people. Risk of neurodegenerative disease was highest for defenders and lowest for goalkeepers. Defenders head the ball much more than goalkeepers do. The risk of neurodegenerative disease was highest among former soccer players with professional career lengths longer than 15 years. Risk remained similar for all players born between 1910 and 1969. This last finding suggests that changes in the way balls are made (largely leather to synthetic) did not alter risk.
This study builds on a large body of evidence beginning with ‘punch drunk syndrome’ in boxing and going on to include professional contact sports (American Football and the Rugbys). This evidence reflects late outcomes from traumatic brain injury or repetitive ‘subconcussive’ head impacts not necessarily causing concussion. Less is known about risks in amateur and youth soccer.
The authors also note that former soccer players, compared to the general population appear to have lower rates of cardiovascular deaths, lower hospitalisation rates for common mental health disorders – including drug and alcohol disorders.
JAMA Neurology, August 2021: Association of Field Position and Career Length With Risk of Neurodegenerative Disease in Male Former Professional Soccer Players