Heading for trouble?
Soccer is the most popular sport in the world. It is also the only game in which the participants’ head regularly comes into contact with the ball – and players do not wear protective headgear. In other ball games, such as American Football, convincing evidence is now available which shows that repeated head-to-head contacts between (helmeted) players have a deleterious impact on the brain. Evidence that heading the ball in soccer may also damage the brain, even when there are no obvious signs of concussion, has so far been less compelling.
Researchers at LMU and Harvard Medical School in Boston have now detected clear signs of tissue alterations in the brains of professional soccer players. “The changes we see resemble those observed in patients suffering from concussion, except that they are less pronounced,” says Dr. Inga Katharina Koerte, who is first author on the new study. “The lesions are found in the white matter – areas of the brain that are characterized by high concentrations of the projecting fibers which transmit signals between nerve cells – and particularly in regions that are involved in attention, visual processing, complex thought processes and memory.
Soccer players vs. swimmers
Among the subjects investigated during the study were a dozen male professional footballers drawn from German clubs, who had never shown symptoms of concussion. An age-matched group of eight professional swimmers served as controls. “Swimmers do not normally encounter repeated physical shocks that result in brain trauma,” says Koerte, who holds research positions both at Munich University Hospital – where the data were obtained – and at Brigham and Women’s Hospital, which is affiliated with Harvard Medical School.
Conventional magnetic resonance procedures that are used routinely clinically did not detect brain abnormalities in either group. The researchers also employed diffusion tensor magnetic resonance tomography, a much more sensitive method. This technique is capable of imaging tissue architecture in microscopic detail, enabling the investigators to study the structure, organization and density of the white matter. These scans revealed extensive alterations in the brains of the soccer players relative to those of the swimmers.
“It is not clear how this damage arises,” says co-author Dr. Martha Shenton of Brigham and Women’s Hospital. “Recurrent minor shocks, like those that a player experiences when heading the ball, are one possible cause. More work will be needed to clarify the effects of these brain lesions on cognitive performance.” The consequences could be far-reaching, since the white matter is largely composed of the data transmission lines that make neuronal communication in the brain possible in the first place. (Brigham and Women´s Hospital/LMU)
The study was made possible by the Else Kröner-Fresenius Foundation and the German Academic Exchange Service (DAAD), and supported by US government funding made available to the National Institutes of Health and INTRuST. (JAMA, 14. November 2012)
Dr. Inga Katharina Koerte
Munich University Hospitals and Harvard University