UNDERSTANDABLY, it was not a subject he was eager to contemplate. Keith Primeau still is a young man at age 37. Too old and too battered for hockey, given the physical punishment he endured as a player, he has a wife, Lisa, four children, and years still unlived. But it seemed as if it was something he should do, a way he could contribute to the betterment of society.

So he pondered it.

He discussed it with Lisa.

And he agreed to do it: The former Flyers star will bequeath his brain to the Center of Traumatic Encephalopathy at the Boston University School of Medicine.

"Hopefully, this is something that is a long way down the road," he says with a wry chuckle. "But I did a personal evaluation and some soul-searching and came to the conclusion that I could be part of something that could help doctors garner valuable knowledge."

Multiple concussions ultimately drove Primeau out of hockey in 2006, in the wake of a check 11 months earlier by Montreal winger Alexander Perezhogin. While he is uncertain how many he sustained during his athletic career, he knows that he left the game with a damaged brain and exhibits some of the symptoms of Chronic Traumatic Encephalopathy (CTE). He says he still gets "a little lightheaded" occasionally. By joining the CSTE Living Donor Registry - which now includes 100 former pro, college and high school athletes - Primeau is on the cutting edge of a field of science that CSTE co-director Dr. Robert Stern says is in its infancy. To help answer the question of why some people are afflicted with CTE and others are not, Primeau will submit to annual evaluations that eventually will be analyzed in conjunction with a study of his brain tissue.

"Scientists have been aware of what they call puglistica dementia since the 1920s," Stern says. "And for 30 years have had an understanding of what a brain that has been whacked looks like. But it has just been the last few years or so that we had come to appreciate that it is not just boxers who end up with this disease. And that is what is striking. Boxers are a small percentage of the athletes we look at."

Helping to spearhead the program is Chris Nowinski, the former Harvard football player who suffered a head trauma that ended his pro wrestling career. With the aid of concussion expert Dr. Robert Cantu, the former "Chris Harvard" formed the Sports Legacy Institute, an organization dedicated to studying the effect of concussions and other sports-related brain injuries. Told of the work Nowinski was doing, Primeau contacted him by e-mail and told him he was interested in getting involved. Nowinski says the willingness of former athletes such as Primeau to help can eventually lead to some significant scientific breakthroughs.

"This is the building block upon which a cure can be found," Nowinski says. "This is how scientists discovered the initial connection between lung cancer and smoking - by taking the lung tissue of smokers and comparing it to people who did not smoke. So Step 1 is to prove that the problem exists . . . and if we find that a significant percentage of athletes have [CTE], it will open up the conversation on how to prevent it."

Few Flyers were as popular as Primeau, a two-time All-Star who scored 266 goals and 619 points during his 15-year career. At the very end of his career, he still wanted to play, despite the increasing evidence that he would be placing himself in danger if he did so. He remembers a conversation he had toward the end with Jim McCrossin, the team's athletic trainer/strength and conditioning coach. Primeau says he told him, "Oh, I feel better." But he says McCrossin told him, "Great. Your effort has been valiant. But at the end of the day I can not put you in a position where anything could happen to you. I could not live with myself."

Primeau is thankful for that. He says if he had attempted to play again, there was "the obvious possibility of another concussion but also of a stroke or hemorrhage. It could have been severe."

Does he believe the concussions clouded his better judgment?

"Certainly," he says. "I had plowed through it before. And there was nothing to say that I could not plow through it again."

But the problem with concussions is that it is hard to say when you are healed, which leaves you in a position of suffering "second-impact syndrome." In looking back on his career, Primeau says he "probably did not take into consideration of not giving my brain time enough to heal. And I certainly believe that has something to do with my current situation."

So how is Primeau doing?

Good, he says.

"I just sense and I know that I have damaged my brain," he adds. "And any time I try to exert myself beyond everyday activity I get lightheaded. But I have far too much to live for, so I just push through."

Clinical symptoms of CTE include memory impairment, emotional instability, erratic behavior, depression and problems with impulse control.

Primeau concedes that he has or has had some of those symptoms. He addresses each:

* Memory impairment: "No. But I know with the last concussion I did have some speech difficulty, some impediment with speaking proper English. Word pronunciation. I tripped over words."

* Emotional instability: "Again, I would say no. My wife at times may have disagreed with that. But nothing consistently."

* Erratic behavior: "No. I have not behaved erratically."

* Depression: "Yes. Depression was probably the strongest emotional symptom I suffered, in part because of the physical symptoms I was battling - head pressure, fatigue and sensitivity to light. Yes, the depression was hard to get through."

* Problems with impulse control: "Certainly it has been better the last 18 months to 2 years. But there was a point following my last concussion when I had a very short fuse."

The BU School of Medicine study could lead to some significant changes in how sports are played. Nowinski says he hopes the program builds on what he says has been a heightened awareness by the NFL to curb the use of the head in tackling. He adds that better headgear in the NFL and even hockey has given players "a false sense of security," which has placed them in increased jeopardy given the size and speed of athletes today. He says that when equipment was less sophisticated, players did not "hit the head."

"Contact with the head used to be accidental," Nowinski says. "Now it is intentional. And some of that is better players feel protected by their equipment."

Primeau is not certain how the study will change how sports are played.

"Ultimately, it comes down to what the research shows," he says. "Would we like to be able to treat postconcussion the way we do a torn ACL? Well, yeah. But in the short term, it comes down to awareness, recognition and treatment. By stepping out, I hope that I can have an impact."

And perhaps change perceptions.

"I remember getting bumped on the head when I was 5 or 6 years old," he says. "And they would say, 'You just got your bell rung. Get back in there.' Hopefully, people will come to realize that it may not be just a bump on the head." *