Causes
Some experts believe post-concussion symptoms are caused by structural damage to the brain or disruption of the messaging system within the nerves, caused by the impact that caused the concussion.
Others believe post-concussion symptoms are related to psychological factors, especially since the most common symptoms â headache, dizziness and sleep problems â are similar to those often experienced by people diagnosed with depression, anxiety or post-traumatic stress disorder.
In many cases, both physiological effects of brain trauma and emotional reactions to these effects play a role in the development of symptoms.
Researchers haven't determined why some people who've had concussions develop persistent post-concussion symptoms while others do not. There's no proven connection between the severity of the injury and the likelihood of developing persistent post-concussion symptoms.
However, some research shows that certain factors are more common in people who develop post-concussion syndrome compared with those who don't develop the syndrome. These factors include a history of depression, anxiety, post-traumatic stress disorder, significant life stressors, a poor social support system and lack of coping skills.
More research is still needed to better understand how and why post-concussion syndrome happens after some injuries and not others.
Source: http://www.mayoclinic.com