No one seems to know exactly how forceful or frequent head trauma has to be to result in long-term brain damage, but researchers are accumulating grim evidence that it may not take all that much.
The latest study by investigators from Boston University's Center for the Study of Traumatic Encephalopathy and the U.S. Department of Veterans Affairs' Boston Healthcare System showed evidence of degenerative brain disease similar to Alzheimer's in the tissue of 68 out of 85 deceased male subjects ages 17 to 98.
Autopsies showed those men had extensive protein tangles clogging their brains and destroying brain cells. The study group included football players, wrestlers, hockey players, boxers and military veterans who served in combat zones from World War II onward.
Brains of 18 other males covering a similar age range, but who had never experienced concussions or other brain injuries, showed no signs of the deterioration.
Among the group found to have degenerative injury, 50 were football players: 33 played in the NFL, nine played college football and six played only in high school. Twenty-one veterans, most of whom were also athletes, also had signs of CTE in their brains.
The findings were released even as the NFL absorbed another violent death of a player, Kansas City's Jovan Belcher, who shot himself outside the Chiefs' training facility shortly after fatally shooting his girlfriend. No one knows if head trauma played a role in this tragedy. Team officials said he was not known to have had many concussions during his four years in the NFL, but some friends said he'd experienced short-term memory loss since taking a hit Nov. 18 against Cincinnati. A pending autopsy may reveal more.
The Boston study and a lot of other recent concussion research show that the total number and frequency of head injuries may matter as much or more than a few major concussions.
"Not all concussions are created equal,'' said Dr. Robert Cantu, a neurosurgeon and co-author of the study, adding that total head traumas may be the "dots" that need to be connected.
Age, genetics and a host of other factors, including medical care, may be key in determining whether one individual sustains long-term brain injury and another does not.
Researchers are scrambling to find ways to measure the extent of degenerative brain damage in the living through various scanning techniques and other tests. Only when doctors, coaches and athletes can see and understand the injuries in real time can the toll on athletes, soldiers and others really be addressed.