Concussions, as defined by the Centers for Disease Control and Prevention (CDC), are a form of traumatic brain injury that is caused by a bump, blow, or jolt to the head or by a hit to the body, which causes the head and brain to move rapidly back and forth. This sudden movement can cause the brain to bounce around or twist in the skull, creating chemical changes in the brain and sometimes stretching and damaging brain cells. Concussions are often referred to as mild traumatic brain injuries because in most cases they do not directly lead to death; however, mild traumatic brain injuries may lead to severe long-term effects.
The Brain Injury Association of America defines the three main symptoms of mild traumatic brain injuries as the following:
- Physical symptoms, including changes in vision, headaches, sensitivity to sound, feeling dizzy/unbalanced, and nausea;
- Cognitive symptoms, including trouble with thinking through problems, a slow-moving feeling, feeling foggy or confused while concentrating, and having difficulty remembering; and
- Behavioral symptoms, including irritability, impulsiveness, lack of emotional responsiveness, depression, anxiety, and an overall change in sleeping patterns.
A person suffering from a severe mild traumatic brain injury can experience long-term effects such as defects in memory, speech, hearing, vision, balance, and emotions; the likelihood of developing these symptoms will increase if appropriate measures are not taken immediately post-injury.
In recent years, traumatic brain injuries have been a principal focus of medical research. A study published in the Journal of American Medical Association found that concussion rates for high school athletes increased 16% every year between 1997 and 2008. Additionally, other groups have shown that the number of sports-related concussions that occur each year in adolescent athletes is often underreported due to limited efforts to detect and monitor concussions in this age demographic.
Notably, researchers from two groups have identified adolescent athletes as particularly more susceptible to working memory impairments and development of second impact syndrome (SIS) compared to all other age groups. SIS refers to a second concussion that is endured before the first concussion is fully healed. This second concussion can lead to rapid and severe swelling of the brain. Increased risk for developing SIS is explained by the ongoing development of the frontal lobe of the brain in adolescents. The frontal lobe, the foremost area of the brain in the front of the skull, is the area of the brain where cognition and memory learning take place. Damage to this area of the brain during development could permanently change the architecture and functionality of this lobe and lead to permanent, long-term, adverse effects.