Christine Coffey takes a look at the brain disease that can result from years of playing contact sports.
More than one in four professional American football players suffer from serious cognitive impairment. This does not just result in slightly lower school exam scores than the average American, nor does it simply lead to a shorter attention span or greater susceptibility to the odd migraine. It affects their ability to walk, to use their hands, and in some cases, to recognise their loved ones.
Head trauma which can be caused by collisions in contact sports can result in chronic traumatic encephalopathy (CTE). The symptoms typically appear in a patient’s late 20s or 30s, and can affect a patient’s mood and behavior. Common problems include poor impulse control, aggression, depression, and paranoia. Cognitive problems usually appear in a person’s 40s and 50s. Sufferers are more likely to experience neurodegenerative diseases like Parkinson’s and Alzheimer’s in later life. The exact progression of brain damage due to repeated blows to the head is still unknown, but the growing body of evidence from international research suggests that there is a clear association between concussive and sub-concussive blows, and cognitive impairment.
“Players of [American football] are more likely to suffer neurodegenerative diseases like Parkinson’s and Alzheimer’s.”
Boxing was the sport that originally received the most attention for its debilitating long term effects on the brain, with “punch drunk syndome” being one of the first terms used to describe the effects on boxers that had suffered severe blows to the head. However, by the turn of the century it was American football which came under scrutiny. Research by Dr. Bennet Omalu and his colleagues at the University of Pittsburgh on a group of former NFL players found evidence for the progressive degenerative disease CTE. Every person who has been diagnosed with CTE so far has a history of repetitive hits to the head. This stretches across many contact sports, including soccer, rugby, ice hockey, cycling, lacrosse, and MMA.
Most of the research on this topic has been conducted in Boston University’s CTE centre and the VA-BU-CLF Brain Bank. As a consequence of this, the vast majority of information currently available on CTE is from research on American football players. In a study of 80 former professional NFL players’ brains, 77 had developed CTE. There are over 200 confirmed cases from American football across all levels, over 20 from ice hockey players, 50 from boxing, 5 from rugby and professional wrestling each, and 10 from soccer.
For rugby players, scrumcaps protect against concussions about as well as they protect against the development of cauliflower ears, and as players are getting bigger, tackles are becoming more dangerous. In Ireland there is virtually no information on our native games as we are only really beginning to research CTE domestically. However, we do know that increases in the physicality of the sports, particularly in Gaelic football, lead to more and more dangerous collisions. Furthermore, this physicality has shown to be on the increase in younger age groups. This is worrying given research from the USA which suggests that athletes who begin playing contact sports at a younger age are more likely to accrue brain damage.
A brain imaging technique called “diffusion tensor imaging” has been used to monitor large groups of nerve cell bundles in the brains of soccer players. Several images over a period of time have shown changes in these bundles. The imaging revealed that the number of times a player heads the ball is directly associated with the structural integrity of these nerve bundles. The more a player heads the ball, the poorer the structural integrity of these bundles.
“It is estimated that some 50-80% of concussions go unreported and untreated in the USA.”
Perhaps the most disturbing thing about CTE is that it may occur even when a person has never been concussed. Autopsies have revealed that in some people suffering from the disease, there were no reported concussions. That said, it is estimated that some 50-80% of concussions go unreported and untreated in the USA. Thus, it is not clear if this is because of a lack of reporting, or the absence of concussions. Another problem is that CTE cannot be fully confirmed until autopsy. Nevertheless, there is sufficient evidence to suggest that repeated concussive or sub-concussive hits have a detrimental effect on the cognitive well-being of athletes in the long term.
“Perhaps the most disturbing thing about CTE is that it may be caused even when a person has never been concussed.”
Sub-concussive hits are the Achilles’ heel of brain recovery, as the damage is not severe enough to cause symptoms which would force the player into recovery. This means that minor damage does not get time to be repaired, and worsens as the contact sport is continued. Counterintuitively, it is not the movement caused by head-on collisions that cause the most damage, but rather the rolling of the head in side-on collisions.
Many more studies will need to be carried out to better determine the incidence and prevalence of the disease. Animal models could be used to understand the exact mechanism of the degeneration, because we can’t keep waiting until we’re looking under the microscope at the brain tissue of former athletes to make the diagnosis. We need to fully understand the effects of repeated blows to the brain and start adjusting contact sports accordingly, or else start playing golf.