Around 3.8 million concussions occur each year and that’s only from sport-related injuries. Quite a lot right? If it is such a common injury, is there even anything to worry about? In this article, we are going to explore the science behind concussion and will decide whether concussion is actually more serious than just a hit on the head.
WHAT DO WE MEAN BY ‘CONCUSSION’ AND HOW DOES IT OCCUR?
Let’s start with defining what exactly a concussion is; it is commonly understood “as a rapid onset of short-lived impairment of neurologic functions resolving spontaneously”. Such an impairment can be caused by 3 different mechanisms which present themselves commonly in sports but could also occur in other situations such as falls or car accidents. These mechanisms are as follows:
Direct impact: result of a direct hit in the head, for example with a ball
Sudden acceleration or deceleration: also known as whiplash injury. There is no direct contact of head with a surface but instead it is the head movement that causes the concussion. An example of when this might happen is when the head is strongly shaken.
Blast injury: caused by a sudden change in pressure, among other causes, it could be the result of an explosion.
Now we understand how a concussion can occur, but to fully understand this injury we need to look at what happens at a molecular level.
THE DISRUPTED WORLD OF MOLECULES
There is a lot to unpack in terms of changes on a microscopic level during concussion. To understand them better, we should first look at the anatomy and functioning of a normal brain.
The brain is composed of around 86 billion neurons. Each neuron has a body, axon and many dendrites with which it connects to other neurons. Normally, when an electrical signal is passed from one neuron to the other, there is a change in an action potential within that neuron caused by the exchange of ions between the inside and outside of the cell. After the signal is passed on to the next neuron, the cell comes back to its resting stage in which the ion concentrations are back to normal.
What happens to this process during concussion? First of all, the difference in density of body and axon causes stretching and sometimes even breaking of neurons due to the forces impacting the brain. As you can imagine, this disrupts the action potential and signal transduction in the brain because the ions start leaking from the neurons. All of the sudden there is a ‘flood’ of signals received by neurons which begin to fire rapidly exhausting the energy resources in the form of ATP. Those ATP molecules which are now scarce are now needed more than ever to remove excess calcium which has found its way into the neurons during concussion. This is important because it balances proper neuron functioning. Why do neutrons struggle to get rid of calcium and why does it take such a long time? That’s because the necessary ATP molecules are formed from nutrients in food, more specifically glucose. Glucose then need to travel to the brain via the bloodstream and enter mitochondria where ATP is released. However, during concussion blood flow to the brain is restricted and the release of calcium disrupts the process of ATP production. Therefore, people suffering from this type of injury may feel very tired for the first few weeks and need to wait a long time until those changes in the brain are fixed.
LONG TERM IMPLICATIONS OF A CONCUSSION?
Knowing the science behind a concussion, we can now talk about the long-term consequences of this injury. These will depend on the severity of concussion, the immediate and later actions taken after the incident, biological differences between each of us, and many more factors. Some people will forget about the concussion after a few months, but for the less fortunate among us, repeated concussion might turn into Post-concussion syndrome or severe Traumatic Brain Injury. After all, there is a limit to how much we can expose our brains to energy deprivation, neuron breakage, and ion ‘storms’.
As illustrated throughout the article, a concussion is much more than just a hit on the head. The drastic and sudden changes resulting from a concussion require time to heal and in some cases, the brain might never be quite the same again. So what do you think? Should more attention be paid to concussion awareness?
Concussion Alliance. (n.d.). What happens to your brain when you get a concussion: a deeper dive. [online] Available at: https://www.concussionalliance.org/what-happens-to-your-brain-deeper-dive.Linder, C. (2022). Your Brain Can’t Handle More Than One Thought at a Time. [online] Popular Mechanics. Available at: https://www.popularmechanics.com/science/a38349973/conscious-brain-multitasking/.www.cemm.af.mil. (n.d.). CEMM > Programs > Traumatic Brain Injury > Mild TBI/Concussion > Mechanisms of TBI. [online] Available at: https://www.cemm.af.mil/Programs/Traumatic-Brain-Injury/Mild-TBI-Concussion/Mechanisms-of-TBI/.