NARRATOR: Dr. McKee, who had grown up loving football,
had struggled with her feelings about the sport.
- I don't feel that I am in a position
to make a proclamation for everyone else.
- If you had children who are eight, ten, 12...
would they play football?
- Eight, ten, 12? No, they would not.
NARRATOR: By 2010, Dr. McKee had looked at the brains
of 20 NFL players.
She had found CTE in 19 of them.
It was during that time that a brain arrived
that would dramatically raise the stakes.
- Owen Thomas to me was a critical case.
Here we have a 21-year-old who was a hard-hitting lineman
from the age of nine on.
- And then, seemingly out of nowhere,
he decided to take his own life.
Never been diagnosed with a concussion.
Never had a problem in the world.
NARRATOR: Owen Thomas had hanged himself
in his off-campus apartment.
Chris Nowinski secured his brain for Dr. McKee.
Without any history of diagnosed concussions,
it seemed unlikely he had CTE.
- I was fully prepared to see nothing.
I remember late at night looking at the brain
and thinking, "Just going to knock this one off."
And it just floored me.
It just... I couldn't believe what I was seeing.
NARRATOR: An advanced case of CTE had never been found
in such a young person.
- In like 20 spots in his frontal lobe.
He's 21.
He's so young.
That changes the game to me.
- Wrapped up and brought down by Owen Thomas...
NARRATOR: Because he'd never had a diagnosed concussion,
Dr. McKee suspected Thomas might have gotten CTE
from the everyday sub-concussive hits
that are an inherent part of the game.
- Another nice play by Owen Thomas.
- Those sub-concussive hits, those hits that don't even rise
to the level of what we call a concussion, or symptoms,
just playing the game can be dangerous.
- A crucial matchup in the AFC...
- McKee is saying look, this is very much an issue
at the core of the game, of offensive lineman
and defensive linemen pounding the crud out of each other,
on every single play on every single down
and every single practice and there's no getting around that.
NARRATOR: It was a controversial theory
that raised fundamental questions
about the way the game was played.
- The human body was not created or built to play football.
When you have force against force,
you're going to have injuries.
And I'm not talking about the knees and...
you know, all of that stuff is a given.
But from a neurological standpoint,
you're going to have... you're going to have some brain trauma.
NARRATOR: New York Giant Harry Carson
has been studying the matter since he retired 25 years ago.
- You know, most people are keyed in on the big hit.
But the little mini concussions are just as dangerous
because you might be sustaining six to ten,
maybe a dozen of these hits during the course of a game.
If you're going up against top-flight players
who are able to perfect those skills of hitting you
upside the head or getting hit with a elbow,
it's one of those things that at some point
you're going to pay for it down the line.
NARRATOR: For Dr. McKee and others,
it raised the obvious question--
how safe is it for children to play football?
- What time is it?! - Game time!
- What time is it? - Game time!
(chanting)
- From a physical risk standpoint,
you know what you are doing when you sign your kid up,
that he could hurt his knee, okay.
But what you should know now is your child could develop
a brain injury as a result of playing football.
It's not just on the pro level, it's on every level of football.
The question is, do you want it to be your child?
NARRATOR: For Dr. McKee's colleague, Dr. Robert Cantu,
the controversial answer was that no one under 14
should play tackle football.
- With what we know about the youth brain
compared with the adult brain,
that it's more easily disrupted than the adult brain,
the youth brain is lighter in weight,
so it has less inertia to put it in motion
so you tap a youth head and it's brain moves much quicker
than an adult brain that's heavier
and therefore has more inertia.
So I think we should be treating youths differently.
NARRATOR: And for the Boston University advocate
Chris Nowinski, it was a danger the NFL helped to create.
- As long as the NFL dismissed this,
that meant that parents were signing their kids up
to go play football believing that there was no risk.
And that wasn't fair to those kids, or those parents.
But especially those kids.
- Let's give him a big round of applause...
NARRATOR: Dr. McKee, who had grown up loving football,
has struggled with her feelings about the sport.
- I don't feel that I am in a position
to make a proclamation for everyone else.
- If you had children who are eight, ten, 12...
would they play football?
- Eight, ten, 12? No, they would not.
- Why?
- Because the way football is being played currently,
that I've seen, it's dangerous.
It's dangerous and it could impact
their long-term mental health.
You only get one brain.
The thing you want your kids to do most of all
is succeed in life and be everything they can be.
And if there's anything that may infringe on that,
that may limit that, I don't want my kids doing it.
- 911 emergency...
- (shouting)
- An apparent suicide by a powerful athlete...
- A beloved NFL star apparently took his own life today.
- What is your boyfriend's name? - Junior Seau.