From PEOPLE Magazine Click to enlarge
When two-time Super Bowl champion Dave Duerson, 50, shot himself in the chest on Feb. 17, he left a note asking his family to donate his brain to science. Today it's one of 70 that researchers at the Center for the Study of Traumatic Encephalopathy at Boston University's School of Medicine (bu.edu/cste) are studying to understand the permanent damage athletes suffer from head injuries. Codirector Dr. Robert Cantu spoke with PEOPLE.

What is Chronic Traumatic Encephalopathy (CTE)?

It's the progressive death of brain cells following blows to the head, leading to memory loss, depression and dementia. The only test for it: Examine the brain postmortem for a toxic protein, TAU, that indicates swaths of dead areas.

What have you discovered?

We've studied football players, hockey players, boxers-in all but one there is CTE. Several hadn't played professionally, in others a concussion hadn't been diagnosed. Damage still exists. [Duerson's results are not yet in.]

Is enough being done to protect players?

No. But NFL commissioner Roger Goodell is taking a stand against direct hits and is to be commended for it.

Would you allow your child to play football?

My son played college football. My daughter played high school ice hockey. It was hard to watch. But they were lucky-they weren't hurt.