How long does a concussion take to heal?

Quite Variable: Concussions can heal in a few weeks or longer than a year. Many factors affect healing. Factors which lengthen the time of healing are younger age, underlying adhd or learning difficulties, severity of injury, and genetics. If you are re-injured before complete healing, the time also significantly lengthens. To promote faster healing follow your doctor's instructions and rest.

Maybe they don't: Emerging evidence from research in professional sports indicates that they may never heal completely, but may lead to mild traumatic brain injury syndrome. http://neuro.psychiatryonline.org/cgi/content/full/17/3/297.