It’s called “chronic traumatic encephalopathy,” or CTE, and has been associated with the kind of physical contact that takes place most commonly in tackle football and ice hockey. It is a degenerative Alzheimer’s-like disease brought on through blows to the brain, which is a soft tissue that can easily be bruised and torn by being slammed into a very hard skull.

CTE cannot be diagnosed in any living person, but only by examining the brain of a deceased one. Former football players like Junior Seau, who committed suicide in his early 40s, have been examined and determined to have CTE. The youngest case diagnosed so far was a high school football player aged 17.

There is simply too little known about what kinds of blows to the head can result in CTE, which results in dementia, memory loss, confusion, aggression and death, and can take decades to manifest itself. It has drawn more attention recently because of a growing number of suicides of former professional football players who were diagnosed postmortem with CTE.

It is not known whether major blows causing concussions are more likely to cause it, or repetitive sub-concussive impacts. A football lineman, between practices and games, can experience up to 1,000 sub-concussive impacts in a single season.

Best selling author Malcolm Gladwell, author of Outliers, The Tipping Point, Blink and others, delivered a powerful address at the University of Pennsylvania on February 14, 2013 on the dangers of CTE in football that was a particularly provocative challenge to the students. It can be viewed on YouTube.

He said that sometimes a society needs too much proof before taking action against something that poses a threat. He cited the case of black lung disease in coal miners, noting that the correlation between coal mining and “miner’s asthma” was conclusively established in 1918, but those insisting the report did not include enough “proof” prevented any action from being taken until 1975. “The need for too much proof can be an excuse not to do anything,” he said.

“The benefits of sports,” he said, including discipline, teamwork and competitiveness, “can be found in sports where chances of incurring hidden injury is not nearly so great as in football.”

Gladwell also spoke to the legal liability issues of programs that continue to encourage young men to engage in an activity presenting an unknown level of risk. The reason that some predict professional football is doomed to extinction is the level of lawsuits may be coming to rip it asunder, because the numbers of collisions on a football field has escalated so dramatically in recent years.

Players are far bigger and faster than they used to be, and therefore when impacts occur, their consequences are much greater.