Maybe you have heard of Muhammed Ali, also named as “The Greatest”. Muhammed Ali, born in Louisville, is considered the best heavyweight boxer of all time among the boxing community. Unfortunately, after his last game in 1981, his boxing career came to an end. Up until that point, he had absorbed 200.000 hits on his whole body during his whole career. In 1984, Muhammed was diagnosed with Parkinson’s disease, a progressive condition in which specific nerve cells from the substantia nigra gradually break down which results in loss of motor control.
You might wonder, why is this case brought up? Up to this date, the reason why Muhammed suffered from Parkinson’s disease is still not completely clear. However, medical experts explained that his condition could be due to the repeated blows to the head that he received during his boxing career. According to a study by Meehan and colleagues in 2013, Muhammed is not the only athlete experiencing this type of traumatic brain injury. Strikingly, the study showed that nearly one third of various athletes attending clinics in Pittsburgh or Boston who had a blow to the head during their career that resulted in signs and symptoms of a concussion, went unnoticed and did not receive the diagnosis “concussion”. This can have devastating consequences, since this means that the risk for developing debilitating consequences over the lifespan due to having this Traumatic Brain Injury (TBI), like Muhammed Ali, increases proportionally with the amount of blows to the head.
The second question you might have, is how is it possible that a blow to the head can result in for example a neurological disorder like Parkinson’s disease? To explain this, I would like to introduce two terms to you, namely; coup and contrecoup. By taking a punch straight against the forehead of Muhammed Ali as an example, the coup injury occurs at the point of impact, in this case the frontal lobe. However, since our brain is not attached to our skull, it lays loose in this hard skeleton. Consequently, with the force that is being applied to Muhammed’s forehead, the brain is pushed backwards, and meets the back part of the brain by crashing against the brain’s skull. This is what we call the contrecoup; when the brain rebounds, the contrecoup injury typically occurs on the opposite side of the impact, in this case the occipital lobe.
However, there is more to the story. With the movement of the brain within the skull, important white matter connections, which form the highways between brain areas necessary for communication, become twisted and turned as well. Therefore, in addition to the frontal and occipital lobe that may become damaged by the blow to Muhammed’s forehead, these important highways can be broken up as well, therefore interfering with signal transfer between brain areas. This is also the case for Muhammed which is maybe one of the explanations for why he suffered from Parkinson’s disease after his boxing career. Indeed, something called chronic traumatic encephalopathy, a condition of brain damage which is linked to repeated head trauma and concussion typically present among athletes, is now recognized among medical experts. However, important to point out is that there will always be more to the story explaining Muhammed’s condition, but that will always stay the beauty of neuroscience in my opinion.
Author: Joyce Burger
Image: Joyce Burger
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