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Heading a football and brain damage: Is there really a problem?
In recent years there have been claims that repeatedly heading a football can cause cumulative damage to the brain that eventually manifests in neuropsychological and other impairments. A coroner has even attributed the death of a former international to an illness brought on by heading. But how strong is the evidence for these claims?
Dr Andrew Rutherford from the School of Psychology at Keele University has been researching the possible damage caused by heading for several years and has published a number of articles on this subject.
He says: “There have long been suggestions that heading the ball in football could have detrimental effects on the brain. The old-fashioned footballs that became heavier as they absorbed water certainly made this an issue of concern. However, the quality of many of the initial studies claiming to have identified ‘neuropsychological decrements’ related to football heading is poor.
The initial studies also ignored the important point that footballers who head the ball frequently also compete to head the ball, and most head trauma observed in football is associated with head-to-head, or elbow-to-head contacts arising from this competition. Generally, earlier studies failed to separate any psychological consequences of these clashes from any psychological consequences due to just heading the ball. While the head injury rate in football is significant, it also should be appreciated that it is far less than is observed in other contact sports, especially rugby.
Recent biomechanical studies investigating the forces involved in heading modern footballs also have indicated that the forces acting on the adult brain are insufficient to warrant serious concern. However, players’ heading technique, which has a large bearing on the forces experienced, varies widely and still has to be taken into account.
Dr Rutherford believes sport related concussion is an important subject for research. And as football is the most popular participatory (and spectator) sport in the world, football related concussion is a particularly important subject for research.
Football provides opportunities for maintaining fitness and building social networks that benefit participants’ physical and mental health. However, Dr Rutherford says these benefits must be weighed against any costs and footballers should be able to make informed decisions about the risks of participating in their sport. The information footballers require about head injury, as well as the more typical leg and knee injuries, can be provided only by research carried out to the highest standards.
Dr Rutherford explains that so far studies have tended to use a cross-sectional or ‘snapshot’ designs, where groups of footballers are compared with other (control) groups. But apart from some poor choices as controls and the failure to accommodate head trauma attributable to competing to head the ball, as well as a casual disregard for Type 1 error inflation when multiple hypotheses are tested, some studies even have ignored the fact that heading frequency varies greatly across the players in the same team.
He says: “It is not clear what hypothesis is tested when an amorphous group of footballers is compared with a dubious control group.”
One way of increasing the value of research into the effects of heading would be to carry out more ‘longitudinal’ studies – studies which follow the same group of people over a number of years.
Dr Rutherford says: “Although longitudinal studies tend to be more expensive than cross-sectional studies, they would provide far better opportunity to collect accurate data on how often those taking part play football, head the ball and sustain football related head injury. The studies so far have relied on people making retrospective estimates, but our research indicates that these estimates are not particularly accurate.”
Dr Rutherford says that he is aware of no study that has examined the relationship between the sort of head injuries players receive in football – either concussions or the hypothesized cumulative trauma due to football heading – and the development of dementias, such as Alzheimer's disease, although he is involved in research on this topic currently.
Although multiple concussions are known to impair neuropsychological performance, the good news is that no neuropsychological effects of football heading have been detected by those studies applying the superior methods and data analyses Dr Rutherford and colleagues have advocated.
If you are interested in the issues raised in this article, please contact Andrew Rutherford.