Why helmets don't prevent concussions -- and what might

The word concussion evokes a fear
these days more so than it ever has,

and I know this personally.

I played 10 years of football,

was struck in the head
thousands of times,

and I have to tell you, though,
what was much worse than that

was a pair of bike accidents I had
where I suffered concussions,

and I'm still dealing with the effects
of the most recent one

today as I stand in front of you.

There is a fear around concussion

that does have some evidence behind it.

There is information that a repeated
history of concussion

can lead to early dementia,
such as Alzheimer's,

and Chronic Traumatic Encephalopathy.

That was the subject
of the Will Smith movie "Concussion."

And so everybody is caught up in football
and what they see in the military,

but you may not know

that bIke-riding is the leading cause
of concussion for kids,

sports-related concussion, that is.

And so another thing
that I should tell you

that you may not know

is that the helmets that are worn
in bicycling and football

and many activities,

they're not designed or tested

for how well they can protect
your children against concussion.

They're in fact designed and tested
for their ability to protect

against skull fracture.

And so I get this question
all the time from parents,

and they ask me,

"Would you let your own child
play football?"

Or, "Should I let my child play soccer?"

And I think that as a field,

we're a long way from giving an answer

with any kind of confidence there.

So I look at that question
from a bit of a different lens,

and I want to know,

how can we prevent concussion?

Is that even possible?

And most experts think that it's not,

but the work that we're doing in my lab

is starting to reveal more of the details
around concussion

so that we can have
a better understanding.

The reason we're able
to prevent skull fracture with helmets

is because it's pretty simple.
We know how it works.

Concussion has been
much more of a mystery.

So to give you a sense of what might
be happening in a concussion,

I want to show you the video here

that you see when you type in to Google,

"What is a concussion?"

The CDC website comes up,

and this video essentially
tells the whole story.

What you see is the head moves forward,

the brain lags behind,

then the brain catches up

and smashes into the skull,

it rebounds off the skull,

and then proceeds to run into
the other side of the skull.

And what you'll notice is highlighted
in this video from the CDC,

which I'll note was funded by the NFL,

is that the outer surfaces of the brain,

where it was to have
smashed into the skull,

looks like it's been damaged or injured,
so it's on the outer surface of the brain.

And what I'd like to do with this video
is to tell you that there are

some aspects that are probably right,
indicative of what the scientists

think happens with concussion,

but there's probably more
that's wrong with this video.

So one thing that I do agree with,
and I think most experts would,

is that the brain does
have these dynamics.

It does lag behind the skull

and then catch up and move
back and forth and oscillate.

That we think is true.

However, the amount of motion
you see in the brain in this video

is probably not right at all.

There's very little room
in the cranial vault,

only a few millimeters,

and it's filled entirely
with cerebral spinal fluid,

which acts as a protective layer.

And so the brain as a whole
probably moves very little

inside the skull.

The other problem with this video

is that the brain is shown

as a kind of rigid whole
as it moves around,

and that's not true either.

Your brain is one of the softest
substances in your body,

and you can think of it
kind of like jello.

So as your head is moving back and forth,

your brain is twisting and turning
and contorting,

and the tissue is getting stretched,

and so most experts I think would agree

that concussion is not likely to be
something that's happening

on this outer surface of the brain,

but rather it's something
that's much deeper

towards the center of the brain.

Now, the way that we're
approaching this problem

to try to understand
the mechanisms of concussion

and to figure out if we can prevent it

is we are using a device like this.

It's a mouth guard.

It has sensors in it that are
essentially the same

that are in your cell phone:

accelerometers, gyroscopes,

and when someone is struck in the head,

it can tell you how their head moved

at a thousand samples per second.

The principle behind
the mouth guard is this:

it fits onto your teeth.

Your teeth are one of the hardest
substances in your body.

So it rigidly couples to your skull

and gives you the most precise
possible measurement

of how the skull moves.

People have tried other
approaches with helmets.

We've looked at other sensors
that go on your skin,

and they all simply move around too much,

and so we found that this is
the only reliable way

to take a good measurement.

So now that we've got this device,
we can go beyond studying cadavers,

because you can only learn so much
about concussion

from studying a cadaver,

and we want to learn
and study live humans.

So where can we find

a group of willing volunteers
to go out and smash their heads

into each other on a regular basis
and sustain concussion?

Well, I was one of them,

and it's your local friendly
Stanford football team.

So this is our laboratory,

and I want to show you

the first concussion we measured
with this device.

One of the things that I should point out
is the device has this gyroscope in it,

and that allows you to measure
the rotation of the head.

Most experts think that that's
the critical factor

that might start to tell us
what is happening in concussion.

So please watch this video.

Announcer: Cougars bring
extra people late, but Luck has time,

and Winslow is crushed.

(Audience roars)

Announcer: Top of your screen,
you'll see him come on

just this little post route,
get separation,

the safety.

There it comes at you in real speed.
You'll hear this.

Announcer: The hit delivered by --

David Camarillo: Sorry, three times
is probably a little excessive there.

But you get the idea.