Head injuries, including concussions, particularly in the game of American football, have become a subject of deep concern, much study and even Congressional hearings in the United States.
Contrary to popular belief, a concussion is not a bruise to the brain caused by hitting a hard surface. Indeed, no physical swelling or bleeding is usually seen on radiological scans. The injury generally occurs when the head either accelerates rapidly and then is stopped, or is spun rapidly.
This violent shaking causes the brain cells to become depolarized and fire all their neurotransmitters at once in an unhealthy cascade, flooding the brain with chemicals and deadening certain receptors linked to learning and memory. The results often include confusion, blurred vision, memory loss, nausea and, sometimes, unconsciousness.
Neurologists say once a person suffers a concussion, he is as much as four times more likely to sustain a second one. Moreover, after several concussions, it takes less of a blow to cause the injury and requires more time to recover.
Studies on Head Injuries
A 2000 study surveyed 1,090 former N.F.L. players and found more than 60 percent had suffered at least one concussion in their careers and 26 percent had had three or more. Those who had had concussions reported more problems with memory, concentration, speech impediments, headaches and other neurological problems than those who had not, the survey found.
A 2007 study conducted by the University of North Carolina’s Center for the Study of Retired Athletes found that of the 595 retired N.F.L. players who recalled sustaining three or more concussions on the football field, 20.2 percent said they had been found to have depression. That is three times the rate of players who have not sustained concussions.
SOURCE: NEW YORK TIMES ONLINE