Causes and Risk Factors of Concussions

Causes of Sports and Non-Sports Concussions

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There is plenty we don't know about what happens to cause a concussion, however, it is generally thought of as a type of traumatic brain injury that results in a temporary change in brain functioning. It is usually caused by a blow to the head.

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Common Causes

Damage to the brain from direct forces, twisting, and the brain striking the inside of the skull during acceleration or deceleration are actual causes of concussions. Certain types of activities are known to have a higher incidence of this.

Concussion causes can be divided into two categories: sports-related concussions and non-sports concussions. Between the two, there is little difference in the actual damage to the brain, but focused medical care and concussion detection in sports does change the reporting—and therefore the incidence rates—on and off the field.

Sports-Related Causes

Of all sports, boxing is the king of concussions. Indeed, the only guaranteed way to win a bout is to cause a concussion in your opponent (knock him out).

Research on amateur boxers shows that a knockout isn't the only way to cause a concussion though. Repetitive blows to the head—even though they don't result in an acute loss of consciousness—may cause concussions. It takes nearly as long for a boxer to fully recover after a bout, whether he is knocked out or not. In fact, if a boxer is not knocked out, it just means he spent more time getting pummeled.

According to most reports, football and ice hockey have the largest incidence of concussions in youth sports. Football has the largest overall participation in a single sport.

Knowing that football causes concussions has led to much more medical support for players on the field and in the doctor's office. All the attention might have increased the detection and reporting of concussions, which in turn adds to the statistics.

Women's soccer is the female team sport with the highest rate of concussion, typically due to head-to-head collisions while heading the ball.

Virtually every scholastic team sport causes concussions in some way. Volleyball, cheerleading, softball, baseball, basketball, and lacrosse are all responsible for concussions to players in increasing numbers since the late 20th century.

In scholastic competition, wrestling is the individual (non-team) sport with the highest rate of concussions. Takedowns cause the most concussions.

Non-Sports Concussion Causes

Outside of the gridiron or the ring, the most common causes of concussion happen on the battlefield. Military or combat-related concussions aren't reported quite the same way as sports-related concussions are, so there is no way to do a direct comparison. However, the concussion causes in combat are well documented and tend to be most often related to explosions.

As in sports-related concussions, combatants often have access to medical personnel before and after ​a concussion, which allows for more in-depth assessments as well as pre-concussion baseline assessments. Those assessments help with concussion detection after an injury.

Treating a Concussion

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Other than explosions, other concussion causes in military duty are similar to occupational injuries in non-military industries: vehicle collisions, falls, accidental head strikes, etc.


Concussion was long thought to be a relatively minor medical condition—or not a condition at all. Only since the turn of the 21st Century has the seriousness of concussion really come to light and research is still catching up.

Women seem to have a lower threshold for concussion injury than men in both sports and military data. Research also suggests there is some genetic variability influencing susceptibility to concussions and differences in recovery.

Risk Factors

The biggest risk factor for concussion is a previous concussion or repetitive blows to the head. Boxing, for example, is associated with much higher risk of long-term concussive damage due to direct head strikes.

Avoiding direct, repetitive injury is the single most important factor in lowering personal risk for complications of concussion.

That being said, sometimes it isn't possible to completely avoid the behavior. A football player or career soldier is going to be exposed to potential injury. One study identified that there are potentially ways to mitigate the damage potential incurred during a blow to the head. For example, increasing neck muscle strength showed a statistically significant reduction in damage, especially when coupled with anticipating and bracing for impact. When possible, wearing well-constructed safety helmets also reduces risk, as well as replacing helmets when needed.

Frequently Asked Questions

How hard do you need to hit your head to get a concussion?

Not very hard. In fact, you can get a concussion without a blow to the head at all. This is because the damage done to the brain occurs when the head is jarred enough to cause the brain to bang against the hard shell of the skull. In fact, any sudden movement of the head can cause this acceleration of the brain, which can even happen when, say, an athlete takes a blow to the chest or a face mask.

What happens to the brain in a concussion?

When the brain jerks around inside the skull, a collection of things happen that temporarily affect how the brain functions and lead to concussion symptoms:

  • Depolarization of neurons (nerve cells) known as ionic flux, which is largely responsible for severe, migraine-like head pain
  • Changes in how glucose (the main source of fuel for the brain) is metabolized, which increases vulnerability to future concussions
  • Stretching and damage to nerve cells, which causes cognitive deficiencies
  • Impairment of transmission of brain chemicals, which also slows thinking as well as reaction time
  • Changes in certain enzymes and proteins, which can result in cell death

What is post-concussion syndrome?

Post-concussion syndrome (PCS) refers to concussion symptoms that persist for longer than normal. It typically is diagnosed when symptoms linger beyond a month or two. PCS symptoms tend to occur in response to physical or mental activity but can also occur when someone is resting. The syndrome can interfere with a person's relationships, work, and overall quality of life.

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