“Your brain is sponge cake floating in a bone bucket,” states comedian Stephen Colbert in a brief clip near the start of Head Games. “So why are you bashing into a 300-pound lineman?”

The line may illicit laughs in the context of Colbert’s late-night talk show, but in the sports documentary Head Games it’s a sobering question that piques some serious curiosity.

Inspired by a book from former football player and WWE wrestler Christopher Nowinski, award-winning filmmaker Steve James began to investigate the dark world of sports-related concussions and the long-term effects of head injuries.

“I went into it with more of a fan’s knowledge of the issue,” admits James over the phone from his home in Chicago. “When you read about it casually, you think this seems really serious but then you start to think: ‘why haven’t we seen an epidemic of suicides and dementia on the part of ex-athletes — especially in hockey and football?’”

The timing couldn’t be more ideal. Recent neurological research shows that even mild concussions can have traumatic long-term effects on the brain. As the film convincingly argues, the discovery of a devastating disease called chronic traumatic encephalopathy (CTE) may be partly responsible and, at the very least, has consistently shown up in the “sponge cake” of such late athletes as NHL enforcer Derek Boogaard and NFL star Andre Waters. It was a discovery that drove James to craft the “educational documentary.”

“The idea isn’t to make a polemical film that tries to vociferously argue a point of view,” says James, who is best known for directing the legendary basketball documentary Hoop Dreams. “I was really determined in this case to not do a film that would come across as designed to just scare people to death. I wanted the film to reflect what we know and don’t know and have it openly acknowledged by people who are studying this and who are at the top of it — that they don’t know everything.”

An astonishing accomplishment when it hit theatres nearly two decades ago, Hoop Dreams’ original intention was to merely fill 30 minutes on a PBS station. But the eventual 170-minute opus about two boys striving for basketball fame became a five-year odyssey for James. It also turned into what iconic critic Roger Ebert has dubbed “the great American documentary.” After the movie was denied an Oscar nomination by Academy members, an investigation led the elite group to rewrite the rules over the documentary selection process.

Head Games may not lead to that level of cultural fortune for James, but the sports injury doc will be successful if it at least raises public debate over concussions in sports — especially at the amateur level.

“As one scientist told me, we’re at the starting line in terms of really understanding the impact of CTE,” admits James. He specifically addresses the disease’s ability to accelerate dementia and Alzheimer’s — substantiated in the film by those who knew athletes like Waters (who took his own life in 2006). Scientists even suspect Parkinson’s disease may be accelerated by CTE.

“When Muhammad Ali dies, if he has donated his brain to science, they may find that CTE is as big a culprit as Parkinson’s proper,” says James. “There’s been a lot of symptoms out there and a lot of victims that we heretofore have not connected the dots with — that was very surprising.”

But James hopes the film informs a few of those crazy soccer moms and hockey dads as well. As the movie contends, the onset of CTE could begin as early as youngsters hit the playing field. And even though James admits the film doesn’t offer concrete solutions, he understands the struggle that parents will go through.

“(I wanted to) sort of see the way kids and their parents dance around this issue because the implications of it are so great — not just what happens later in life, but having to give up something that you love as a young athlete,” he says. “To see this complex struggle that I think is going on in a lot of homes increasingly over this issue was really eye-opening.”