What Are Concussions? The Basics of Brain Structure and Function

Concussions and CTE What You Need to Know 6 Part Series Part 1

The brain is an organ, made up of nervous tissue, contained inside a bony skull. It functions as the coordinating center of sensations and carries out nervous activity. Needless to say, it is one of the most complicated systems in your body and is made up of trillions of cells called ‘neurons’.

A complicated system of nerves also connects your brain to the rest of your body, so that the transmission of signals can occur in split seconds and an intricate coordination can be carried out between your body parts. Think about how fast you pull your hand back from a hot stove! It’s all because your brain is designed so intricately that it functions at the speed of light- literally, it does!

Humans owe their survival to this grand design and consciousness that their brains provide them. To make such complex chain of activity possible at an extraordinary speed, it’s logical to say that each cell of the brain plays its part and at the same time, they coordinate with one another to create synchronized actions. While all the parts of your brain work together, each part is responsible for a specific function – controlling everything from your heart rate to your mood.

Lobes of the Brain

Each area of the brain has a specific type of cells and a designated function. The purpose of exploring these structures is to shed some light on the importance of their functions and emphasize the need of proper nourishment. Because that’s the only way to prevent concussion. If your brain structures are resilient enough to tolerate the abuse, you can survive concussion without complications and even prevent it beforehand.

“The purpose of exploring these structures is to shed some light on the importance of their functions and emphasize the need of proper nourishment.”

These areas have special cells that have varying nourishment needs. If your nutrition lacks those nutrients, these cells become weak and everything starts falling apart. So, even a minor trauma from outside impacts harmfully and sets a stage for complications.

Some important lobes of the brain are as follows:

These lobes play their part and maintain a healthy functioning brain. However, injuries during a head trauma can disrupt their cells and respective functions. There must be some protective mechanism implanted by nature to protect these delicate cells. Their delicacy can be proven by the fact that even a thirty seconds episode of hypoxia (lack of oxygen supply to cells) can cause severe problems. Imagine the magnitude of damage that an external head impact can do to them!

For this purpose, nature has designed protective layer beneath your skull. The brain is surrounded by a layer of tissue called the meninges. These meninges are resilient and extraordinary at what they do! Plus they don’t interfere with your brain’s functioning.

Role of Neurotransmitters

The neurons in your brain have an exhaustive series of connections that help them communicate with each other. The neurons give out projections called axons and dendrites. These axons and dendrites form connections through which a message can travel in the form of nerve impulse and spread in your whole body. The point at which one neuron communicates with the other is called a synapse.

For the passage on nerve impulse through these connections, your body has a neurotransmitter-secreting mechanism. Neurotransmitters are special chemicals that are recognized by the receptors in your body and play an important role in coordination. These neurotransmitters also maintain a chemical balance in your brain that is crucial for proper functioning.

“Neurotransmitters are special chemicals that are recognized by the receptors in your body and play an important role in coordination.”

Think of this complicated arrangement as a relay-race. One athlete has a baton which he passes on to his successor, which he then passes on to the next till they reach the finish line. In a similar fashion, neurotransmitters (baton) carry the information from one neuron to the other till the information reaches the target site. In many injuries, like a concussion, the balance of brain chemicals gets disturbed and causes brain damage.

These neurotransmitters also help your brain in controlling your mood swings. They determine health and overall well-being of the brain and if there’s any disproportion in their quantity or formation, the coordination doesn’t happen.

Your brain needs special nutrition for their formation. These nutritional factors especially include amino acids which act as precursors of many chemicals like serotonin and alanine. In absence of appropriate amino acids, the chemical balance of brain imbalances and makes you prone to injury. A balanced chemical formation is also crucial after the injury because it helps with the recovery process and limiting the inflammation process.

Are there different grades of concussions?

The word concussion comes from a Latin word ‘concutere’, which means to shake violently. That is exactly what happens in concussions. So, what exactly is a concussion?

Let’s start with some basics to have a better understanding of concussions and their grades. Picture a walnut; the nut inside is your brain and the hard, outer shell is the skull. Just like that, your brain is a soft jelly-like structure protected by the hard, outer bone, called the skull. In addition, a fluid between the brain and skull provides additional cushioning. It is called the cerebrospinal fluid (CSF).

Concussions are mainly the result of a direct blow to the head. In addition, a concussion can be the result of when your head accelerates or decelerates too quickly. Normally, the CSF would absorb the impact of the blow, just like an airbag. But, when the blow is a little too hard, it can cause damage to the brain vessels, nerves or the brain itself.

What are the results? It depends on the extent of brain injury and the brain area affected. It can cause temporary loss of consciousness, changes in vision, alterations in taste or auditory sensations and so on. That’s why the cartoon characters often see stars floating in the air when hit on the head!

Based on the severity of trauma and the resulting response of the body, concussions can be divided into different grades. One way to grade concussions is on the basis of loss of consciousness and the extent of loss of memory (amnesia) following concussions. While researchers are still divided on how to grade concussions based on these variables but here is what this system of grading looks like.

What are the initial and long-term symptoms of concussions?

The symptoms following a concussion can be divided into different groups based on different grounds. One way to classify these symptoms is based on their duration of onset. These symptoms can have an acute or a chronic onset. In addition, the symptoms can be classified into physical, mental, and emotional clusters. Here, we describe the symptoms as either acute or chronic.

According to a research conducted at the University of New Jersey, only 47% athletes reported their symptoms following concussions. Those who did not report their symptoms, they either believed that their symptoms were not serious enough (66%) or they held back so that they were not excluded from the sport (41%).

In one research study, 280 patients were enrolled in a study following concussion episodes to determine the nature and duration of symptoms. At the time of presentation, around 85% of the participants complained of a headache, making it the most common symptom following concussions. An additional 64% presented with fatigue and 61% with dizziness. Other symptoms included:
– Cognitive symptoms including poor recalling and taking longer to think- Up to 57%
– Sensitivity to noise and voice- around 41% each
– Nausea- 40%
– Blurring of vision- 32%
– Emotional symptoms of depression, anxiety, and frustration- up to 27%

Upon follow-up, symptoms like nausea, depression, and blurring of vision resolved most quickly. On the other hand, symptoms including a headache, poor concentration, frustration, and sleep disturbance lasted the longest. Finally, more than 20% participants still experienced a headache one month following the initial insult and around 20% took longer to think.

“At the time of presentation, around 85% of the participants complained of a headache, making it the most common symptom following concussions.”

Similar results were observed in an Australian study where researchers at the University of Melbourne studied the pattern of onset and progression of symptoms following head injury in the Australian football players. A headache was the most common symptom (40%) and lasted the longest as well. It was followed by blurred vision, dizziness, confusion, and nausea.

Do the genders vary in their symptoms of brain injury and their progression? Perhaps they do. In one research, funded by the Center for Disease Control (CDC), the sex differences in concussion symptoms of high school athletes were noted. It was noted that the spectrum of acute symptoms did not differ much between the two genders. However, in the first follow-up year, confusion/amnesia/disorientation was more common among males than females. In the second follow-up year, disorientation was more common among males whereas drowsiness and sensitivity to light were more common among females.

Some individuals might develop a Post-Concussion Syndrome (PCS) following a traumatic brain injury. The syndrome is characterized by a constellation of symptoms including depression, impaired cognition, disturbance in sleeping patterns, fatigue, a headache, sensitivity to light and sound, and dizziness. In most of the sufferers, this syndrome resolves on its own within a month. However, in some cases, it may take the sufferers months or even years to fully resurface from the damage done, making it one of the long-term complications of concussion episodes.    In certain cases, repeated concussions may progress to Chronic Traumatic Encephalopathy (CTE), as described in detail later.

What are the factors that make you prone to brain damage following a traumatic insult?

How can you tell if you are prone to brain damage and resultant symptoms following a traumatic insult?

Well, it depends on a number of different variables, which include:

1. Repeated Injury: You are more prone to have brain damage and experience severe concussion symptoms if you’ve undergone repeated blows to the head. This is especially true in the case of contact sports where the athletes experience repeated blows to the head.

For instance, soccer players usually use the technique of heading to pass or deflect the ball. A number of research studies showed a higher incidence of brain injury in older soccer players. In one research study, around 87% of the 31 soccer players showed mild to moderate degree of impairment in the areas of judgment, memory, and attention.
Similarly, boxing is another sport that involves repeated blows to the head. In one study, scientists compared the neurocognitive performance in two groups of boxers. The first group included boxers that received more than 12 high-impact blows to the head while the second group received less than 12 blows to the head. Researchers concluded that the degree of neurocognitive impairment was significantly higher in the former group.

2. Nature of Sport: The degree and chances of brain injury following a concussion episode also depend on the nature of the sport. Although previous research data links players of sports like soccer and ice hockey to have a higher risk of brain damage, but more recent data does not provide any conclusive evidence on these sports being responsible for any significant brain damage. Boxing, on the other hand, is one such sport where research has repeatedly shown a higher incidence of brain damage among the players. Similarly, football players tend to have more aggressive disease compared to other sports.

In other words, whether or not a player is prone to brain damage following multiple concussions depends on the nature of sports. The kind of sports where the impact of a head blow is significantly higher, as in boxing or football, the chances of brain injury are higher too.

3. Age: Although younger athletes are likely to receive more blows to the head… the complications are grave among older adults. The mortality of traumatic brain injury in adults aged 55 or more is 30% to 80% compared to lower incidence of mortality among younger individuals. In another study, researchers found that the mortality rate among traumatic head injury sufferers was twice as high among older adults compared to the younger individuals.

“The mortality of traumatic brain injury in adults aged 55 or more is 30% to 80% compared to lower incidence of mortality among younger individuals.”

4. Sex: Although males are more likely to experience a traumatic brain insult but the overall outcomes are generally poorer among females than males. In one research, both the genders were compared on the basis of outcomes following concussion episodes. On a three month follow-up, females, on an average, had a higher score for Post-Concussion Symptom (PCS) compared to males.

Similarly, research also shows that females are 1.75 times more likely to experience fatal outcomes following traumatic brain injury. Moreover, they are 1.53 times more likely to experience poorer outcomes when compared to males.
Why this discrepancy exists is a matter of on-going debate but researchers speculate that it has something to do with the sex hormones, especially progesterone.

5. The Region of The Brain Affected: Any Traumatic Brain Injury (TBI), including concussions, can damage the brain, the extent of which depends on the region of the brain affected. The chances of permanent and drastic brain damage are more if a TBI affects any of the three main circuits of the brain, which include: dorsolateral prefrontal cortex, orbitofrontal cortex, and anterior cingulate.

Damage to these areas will have following consequences:

What is Chronic Traumatic Encephalopathy (CTE)?

Concussions are frequently the result of contact sports. The average incidence of sports-related concussions in America is 1.6 million to 3.8 million annually.

Scientists have almost always known that repeated head trauma leads to something more sinister than a transient loss of consciousness. While it is true that most of the concussive episodes resolve spontaneously and do not leave behind major side effects. But, there are instances where repeated head traumas lead to rather permanent changes.

Researchers first realized this effect of repeated concussive episodes back in the 1920s. The idea was first coined by Martland in 1928 who observed that multiple sub-lethal blows to the head led to a constellation of behavioral, mental, and physical symptoms. He labeled this condition as ‘punch-drunk’. Later, Millspaugh studied this condition more in detail in boxers and labeled this condition as ‘dementia pugilistica’, which is now known as ‘Chronic Traumatic Encephalopathy (CTE)’.

There is a lot about CTE that we still do not understand. While we understand that CTE is the result of repetitive blows to the head but how many or how severe the blows need to be to elicit CTE symptoms is still a matter of debate.

Based on the features, Corsellis, Bruton, and Freeman-Browne described three stages of CTE.

Demographics of CTE Sufferers

Here are the demographic details of the 51 confirmed cases of CTE.

In addition, one-third of these players developed the features of CTE within the first four years of their retirement.

CTE in Football Players (11% of 51 CTE Cases)

All 5 football players suffering from CTE played in similar positions: 4 played as lineman and 1 as a linebacker. The symptoms of CTE were more aggressive, appeared early, and the footballers died at a younger age compared to boxers. Also, 4 out 5 players died tragic deaths: 2 committed suicide, 1 died after high-speed police chase, and 1 while cleaning his gun.

The predominant symptoms among these footballers were anger, depression, paranoia, agitation, impaired memory, confusion, and impaired concentration.

CTE in Boxers (85% of 51 CTE Cases)

CTE is more frequently associated with boxing. The duration of disease is longest among boxers with instances with boxers living up to 46 years with disease symptoms. Behavioral changes are less common. Most of the boxers with CTE present with dementia and are misdiagnosed as Alzheimer’s disease.

What are the Pathological Events in CTE?

Gross changes

These changes include:
 A generalized reduction in brain weight (brain atrophy).
 Enlargement of the fluid containing compartments of the brain (enlargement of brain ventricles).
 Thinning of the communication between two sides of the brain (corpus callosum).

Microscopic Changes

The microscopic changes include:
 Extensive loss of brain neurons in a number of different areas of the brain.
 Deposition of abnormal proteins (Tau proteins) in different areas of the brain. These proteins compromise the structure and functioning of the brain.
 Loss of axons of the neurons. Axons serve as live wires that serve to interlink the neurons.

Consequences? These macro and microscopic features then present as changes in memory, cognition, behavior changes, and alterations in social interactions.


Is any type of sport making me prone to have this injury?

The one-word answer to this question is YES!

One of the major causes of concussions is aggressive sports. In the past few decades, a significant number of athletes has suffered and even died of head injuries. This fact has raised concerns related to the safety of athletes and various causes of head trauma, concussion being top of them.

The reason of concussion being highly prevalent among sportsmen is the aggressive nature of sports and high level of physical activity involved. Players sustain injuries from either an opponent, by hitting the ground or simply from belligerence of an ongoing game. Another factor that aggravates this problem is the ignorant behavior among coaches and athletes who don’t consider a concussion a serious problem, hence not taking precautionary measures. Resultantly, recent data has suggested a sharp rise in the occurrence of concussion among sportsmen leading to serious brain problems.

A study suggests that minor head injuries like concussion encountered during sports have increased by 62% in the recent years. The situation is alarming, considering that a large number of concussions go unreported as well, owing to their mild intensity and symptoms that don’t render athletes dysfunctional- at least for the time being.

“A study suggests that minor head injuries like concussion encountered during sports have increased by 62% in the recent years.”

If you take part in any sports, there are healthy chances of you encountering a concussion, and if you aren’t careful, multiple times in your life. Any sport makes you prone to a concussion but there are some notorious for it. They include the following sports:

1. Soccer

Soccer is among the games with the highest rate of concussions. Research shows that 3 to 30% of active as well as retired players sustain head injuries during soccer games.

Although a soccer ball can achieve a speed of 100km/hour and chances of it hitting the head are fairly high, the most concussions occur due to head-to-head collision among players. The number of women affected during soccer is comparatively higher than men and experts associate this difference to the lack of practice, expertise, and precautionary measures.

2. Football (Rugby)

Rugby demands violently active levels of physical activity. So, playing rugby makes you prone to concussion by hitting other players or the ground.

3. Basketball

In basketball, women are more likely to get a concussion. The chances become fairly high for the person defending the pole because he has to resist the ball and face the heat of the ongoing game. According to collected data, 3.6% injuries per year in basketball constitute concussion.

4. Ice hockey

Ice hockey is also considered risky in case of concussion with hundreds of players suffering from concussion every year. With landing and flipping, the risk of head injury becomes greater.

5. Boxing

Despite the head-on fighting nature of boxing, concussion rate is fairly lower than soccer and basketball. However, most concussions are caused by the opponent’s bluffing.

Other less common sports include baseball, softball, auto racing etc.

What other factors may contribute to this type of injury?

Besides sports, there are multiple factors involved in aggravating this type of injury. Some of these are:

Part 2 of this 6 part series will cover what to do if you have suffered a concussion.


Dr. DeWitt is a Vanderbilt University graduate who earned a full athletic scholarship after his first semester. He went on to become the starting defensive end for the next four years and was awarded The Wade Looney Award for outstanding work ethic. He continued his football career with the NFL Houston Oilers, NFL Europe Champion Scottish Claymores, Montreal Alouettes of the CFL, San Francisco Demons of the XFL, and several teams in the AFL including three seasons with the LA Avengers. After retiring from football, Dr. DeWitt earned his Doctor of Chiropractic degree from Los Angeles Chiropractic College. He is practicing in Orange County, at Bergman Family Chiropractic, specializing in concussion assessment, advanced sports nutrition, natural vision correction techniques and more. Dr. DeWitt can be heard on several radio shows from LA Talk Radio to ABC News Radio. He speaks on the future of sports as well as other natural ways to optimize brain function, eyesight and overall productivity. He has authored several, best-selling books on a variety of topics including Goal Setting, Golf, Concussions and CTE and a three-part series on Natural Vision Correction. He has been happily married to Cathy DeWitt for over nineteen years. They live in Huntington Beach, CA with their two adorable dogs, Ricky and Lucy.

22. May 2018
22. May 2018
This is a fab article and I would have liked to cite it in my dissertation on Concussion but there are no references for the figures/research. It would have been really useful to know the sources.


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