By Dr Davide Bruno, PhD, LJM University, and Dr Andrew Rutherford, PhD, University of Keele — The Conversation, 2 November 2021
The potential long-term neurological effects of concussions and other knocks to the head in professional sport have attracted significant attention and research interest over recent years. Confirmation in 2014 that former England footballer Jeff Astle died as a result of chronic traumatic encephalopathy (a form of dementia) — and that it was caused by regularly heading the ball — ignited a furore on the risks of this practice in particular.
New guidelines introduced this year limit the number of “higher force headers” professional English footballers are allowed to make each week in training to ten. These are usually headers following a long pass (more than 35 metres) or from crosses, corners or free kicks. Similar guidelines had already been adopted across all children’s football leagues in The UK.
Recent work carried out at The University of Glasgow by neuropathologist William Stewart and his team analysed the death certificates of Scottish men. They found higher rates of dementia among former professional footballers compared to the general population, with ex-footballers about 3.5 times more likely to die from a neurodegenerative disease than men who didn’t play football professionally. Stewart’s group also showed that dementia deaths in former professional footballers were greater among those who had played in positions where heading tended to be more frequent, like central defenders.
In our study of former professional footballers, recently published in the Journal of Neuropsychology, we collaborated with two former professional footballers’ associations in England to recruit a total of 60 former male footballers, whose average age was about 68. We found strong evidence that the more heading a participant had done over their professional football careers, the lower their scores on the Test Your Memory cognitive assessment.
We estimated that, on average, former professional footballers lost about three points off the Test Your Memory score for each 100,000 career headers reported — a drop that can be the difference between being classified as normal or as having memory problems. A professional footballer can make hundreds of thousands of headers over a career. Our participants averaged around 50,000 career headers each.
To our knowledge, this is the first study to provide direct evidence supporting an association between heading the ball and cognitive impairment in retired professional football players. Evidence of cognitive impairment is the first step towards a diagnosis of dementia, so our results suggest there may be a link between heading the ball often and developing a neurodegenerative disease. The decision to reduce headers in training is probably the right call, though more research is needed to establish what might be a safe number.