0:00:00.440,0:00:05.096
The word concussion evokes a fear[br]these days more so than it ever has,

0:00:05.120,0:00:07.496
and I know this personally.

0:00:07.520,0:00:10.176
I played 10 years of football,

0:00:10.200,0:00:12.616
was struck in the head thousands of times,

0:00:12.640,0:00:16.296
and I have to tell you, though,[br]what was much worse than that

0:00:16.320,0:00:21.096
was a pair of bike accidents I had[br]where I suffered concussions,

0:00:21.120,0:00:24.056
and I'm still dealing with the effects[br]of the most recent one

0:00:24.080,0:00:25.840
today as I stand in front of you.

0:00:27.640,0:00:30.096
There is a fear around concussion

0:00:30.120,0:00:32.080
that does have some evidence behind it.

0:00:33.600,0:00:36.936
There is information[br]that a repeated history of concussion

0:00:36.960,0:00:40.256
can lead to early dementia,[br]such as Alzheimer's,

0:00:40.280,0:00:42.336
and chronic traumatic encephalopathy.

0:00:42.360,0:00:45.400
That was the subject[br]of the Will Smith movie "Concussion."

0:00:46.560,0:00:50.136
And so everybody is caught up in football[br]and what they see in the military,

0:00:50.160,0:00:51.496
but you may not know

0:00:51.520,0:00:55.816
that bike riding is the leading cause[br]of concussion for kids,

0:00:55.840,0:00:57.507
sports-related concussion, that is.

0:00:59.040,0:01:01.616
And so another thing[br]that I should tell you

0:01:01.640,0:01:02.856
that you may not know

0:01:02.880,0:01:05.816
is that the helmets that are worn[br]in bicycling and football

0:01:05.840,0:01:07.496
and many activities,

0:01:07.520,0:01:10.096
they're not designed or tested

0:01:10.120,0:01:13.600
for how well they can protect[br]your children against concussion.

0:01:14.200,0:01:15.936
They're in fact designed and tested

0:01:15.960,0:01:18.640
for their ability to protect[br]against skull fracture.

0:01:19.840,0:01:25.456
And so I get this question[br]all the time from parents,

0:01:25.480,0:01:27.056
and they ask me,

0:01:27.080,0:01:29.376
"Would you let your own child[br]play football?"

0:01:29.400,0:01:32.576
Or, "Should I let my child play soccer?"

0:01:32.600,0:01:35.496
And I think that as a field,

0:01:35.520,0:01:39.920
we're a long way from giving an answer[br]with any kind of confidence there.

0:01:41.440,0:01:45.016
So I look at that question[br]from a bit of a different lens,

0:01:45.040,0:01:48.776
and I want to know,[br]how can we prevent concussion?

0:01:48.800,0:01:50.456
Is that even possible?

0:01:50.480,0:01:53.040
And most experts think that it's not,

0:01:54.520,0:01:56.736
but the work that we're doing in my lab

0:01:56.760,0:02:01.136
is starting to reveal more[br]of the details around concussion

0:02:01.160,0:02:03.936
so that we can have[br]a better understanding.

0:02:03.960,0:02:06.816
The reason we're able[br]to prevent skull fracture with helmets

0:02:06.840,0:02:09.294
is because it's pretty simple.[br]We know how it works.

0:02:09.320,0:02:11.360
Concussion has been[br]much more of a mystery.

0:02:12.280,0:02:16.040
So to give you a sense of what might[br]be happening in a concussion,

0:02:17.240,0:02:19.176
I want to show you the video here

0:02:19.200,0:02:21.736
that you see when you type into Google,

0:02:21.760,0:02:23.176
"What is a concussion?"

0:02:23.200,0:02:24.856
The CDC website comes up,

0:02:24.880,0:02:28.336
and this video essentially[br]tells the whole story.

0:02:28.360,0:02:30.776
What you see is the head moves forward,

0:02:30.800,0:02:32.856
the brain lags behind,

0:02:32.880,0:02:34.296
then the brain catches up

0:02:34.320,0:02:36.576
and smashes into the skull,

0:02:36.600,0:02:38.776
it rebounds off the skull,

0:02:38.800,0:02:42.560
and then proceeds to run[br]into the other side of the skull.

0:02:43.320,0:02:46.936
And what you'll notice is highlighted[br]in this video from the CDC,

0:02:46.960,0:02:49.416
which I'll note was funded by the NFL,

0:02:49.440,0:02:52.376
is that the outer surface of the brain,

0:02:52.400,0:02:55.696
where it was to have[br]smashed into the skull,

0:02:55.720,0:02:59.656
looks like it's been damaged or injured,[br]so it's on the outer surface of the brain.

0:02:59.680,0:03:01.656
And what I'd like to do with this video

0:03:01.680,0:03:05.376
is to tell you that there are[br]some aspects that are probably right,

0:03:05.400,0:03:08.416
indicative of what the scientists[br]think happens with concussion,

0:03:08.440,0:03:11.056
but there's probably more[br]that's wrong with this video.

0:03:11.080,0:03:14.336
So one thing that I do agree with,[br]and I think most experts would,

0:03:14.360,0:03:16.376
is that the brain[br]does have these dynamics.

0:03:16.400,0:03:18.776
It does lag behind the skull

0:03:18.800,0:03:21.456
and then catch up and move[br]back and forth and oscillate.

0:03:21.480,0:03:22.720
That we think is true.

0:03:23.760,0:03:27.056
However, the amount of motion[br]you see in the brain in this video

0:03:27.080,0:03:28.656
is probably not right at all.

0:03:28.680,0:03:32.096
There's very little room[br]in the cranial vault,

0:03:32.120,0:03:33.816
only a few millimeters,

0:03:33.840,0:03:37.016
and it's filled entirely[br]with cerebral spinal fluid,

0:03:37.040,0:03:39.216
which acts as a protective layer.

0:03:39.240,0:03:43.400
And so the brain as a whole probably[br]moves very little inside the skull.

0:03:44.520,0:03:46.576
The other problem with this video

0:03:46.600,0:03:48.336
is that the brain is shown

0:03:48.360,0:03:51.456
as a kind of rigid whole[br]as it moves around,

0:03:51.480,0:03:52.880
and that's not true either.

0:03:53.720,0:03:57.136
Your brain is one of the softest[br]substances in your body,

0:03:57.160,0:03:59.176
and you can think of it[br]kind of like jello.

0:03:59.200,0:04:01.336
So as your head is moving back and forth,

0:04:01.360,0:04:04.216
your brain is twisting[br]and turning and contorting,

0:04:04.240,0:04:06.456
and the tissue is getting stretched,

0:04:06.480,0:04:09.496
and so most experts I think would agree

0:04:09.520,0:04:12.656
that concussion is not likely[br]to be something that's happening

0:04:12.680,0:04:14.496
on this outer surface of the brain,

0:04:14.520,0:04:16.616
but rather it's something[br]that's much deeper

0:04:16.640,0:04:18.200
towards the center of the brain.

0:04:19.279,0:04:21.856
Now, the way that we're[br]approaching this problem

0:04:21.880,0:04:24.216
to try to understand[br]the mechanisms of concussion

0:04:24.240,0:04:26.096
and to figure out if we can prevent it

0:04:26.120,0:04:28.936
is we are using a device like this.

0:04:28.960,0:04:30.160
It's a mouthguard.

0:04:30.960,0:04:33.856
It has sensors in it[br]that are essentially the same

0:04:33.880,0:04:35.216
that are in your cell phone:

0:04:35.240,0:04:37.576
accelerometers, gyroscopes,

0:04:37.600,0:04:39.496
and when someone is struck in the head,

0:04:39.520,0:04:42.056
it can tell you how their head moved

0:04:42.080,0:04:45.200
at a thousand samples per second.

0:04:46.760,0:04:49.456
The principle behind[br]the mouthguard is this:

0:04:49.480,0:04:50.736
it fits onto your teeth.

0:04:50.760,0:04:53.816
Your teeth are one of the hardest[br]substances in your body.

0:04:53.840,0:04:55.896
So it rigidly couples to your skull

0:04:55.920,0:04:58.336
and gives you the most precise[br]possible measurement

0:04:58.360,0:05:00.296
of how the skull moves.

0:05:00.320,0:05:02.856
People have tried[br]other approaches, with helmets.

0:05:02.880,0:05:06.256
We've looked at other sensors[br]that go on your skin,

0:05:06.280,0:05:08.896
and they all simply move around too much,

0:05:08.920,0:05:11.616
and so we found that this[br]is the only reliable way

0:05:11.640,0:05:13.000
to take a good measurement.

0:05:15.400,0:05:19.696
So now that we've got this device,[br]we can go beyond studying cadavers,

0:05:19.720,0:05:22.136
because you can only[br]learn so much about concussion

0:05:22.160,0:05:23.376
from studying a cadaver,

0:05:23.400,0:05:26.176
and we want to learn[br]and study live humans.

0:05:26.200,0:05:30.096
So where can we find[br]a group of willing volunteers

0:05:30.120,0:05:34.376
to go out and smash their heads[br]into each other on a regular basis

0:05:34.400,0:05:35.616
and sustain concussion?

0:05:35.640,0:05:37.536
Well, I was one of them,

0:05:37.560,0:05:40.360
and it's your local friendly[br]Stanford football team.

0:05:41.640,0:05:43.256
So this is our laboratory,

0:05:43.280,0:05:44.976
and I want to show you

0:05:45.000,0:05:48.176
the first concussion[br]we measured with this device.

0:05:48.200,0:05:52.456
One of the things that I should point out[br]is the device has this gyroscope in it,

0:05:52.480,0:05:55.216
and that allows you[br]to measure the rotation of the head.

0:05:55.240,0:05:57.616
Most experts think[br]that that's the critical factor

0:05:57.640,0:06:00.496
that might start to tell us[br]what is happening in concussion.

0:06:00.520,0:06:01.880
So please watch this video.

0:06:03.280,0:06:06.696
Announcer: Cougars bring[br]extra people late, but Luck has time,

0:06:06.720,0:06:08.360
and Winslow is crushed.

0:06:10.120,0:06:11.696
Announcer: I hope he's all right.

0:06:11.720,0:06:13.680
(Audience roars)

0:06:18.560,0:06:20.016
Announcer: Top of your screen,

0:06:20.040,0:06:22.456
you'll see him come on[br]just this little post route,

0:06:22.480,0:06:24.120
get separation, safety.

0:06:28.240,0:06:30.800
There it comes at you in real speed.[br]You'll hear this.

0:06:32.640,0:06:34.520
Announcer: The hit delivered by --

0:06:35.720,0:06:39.176
David Camarillo: Sorry, three times[br]is probably a little excessive there.

0:06:39.200,0:06:40.456
But you get the idea.

0:06:40.480,0:06:43.296
So when you look at just the film here,

0:06:43.320,0:06:47.136
pretty much the only thing you can see[br]is he got hit really hard and he was hurt.

0:06:47.160,0:06:48.816
But when we extract the data

0:06:48.840,0:06:50.840
out of the mouthguard that he was wearing,

0:06:50.864,0:06:53.576
we can see much more detail,[br]much richer information.

0:06:53.600,0:06:56.016
And one of the things that we noticed here

0:06:56.040,0:07:00.096
is that he was struck[br]in the lower left side of his face mask.

0:07:00.120,0:07:03.296
And so that did something first[br]that was a little counterintuitive.

0:07:03.320,0:07:05.016
His head did not move to the right.

0:07:05.040,0:07:06.976
In fact, it rotated first to the left.

0:07:07.000,0:07:09.856
Then as the neck began to compress,

0:07:09.880,0:07:12.976
the force of the blow caused it[br]to whip back to the right,

0:07:13.000,0:07:18.856
so this left-right motion[br]was sort of a whiplash type phenomenon

0:07:18.880,0:07:23.296
and we think that is probably[br]what led to the brain injury.

0:07:23.320,0:07:27.096
Now, this device is only limited in such[br]that it can measure the skull motion,

0:07:27.120,0:07:30.536
but what we really want to know[br]is what's happening inside of the brain.

0:07:30.560,0:07:34.056
So we collaborate with[br]Svein Kleiven's group in Sweden.

0:07:34.080,0:07:37.656
They've developed a finite element[br]model of the brain.

0:07:37.680,0:07:39.776
And so this is a simulation

0:07:39.800,0:07:43.136
using the data from our mouthguard[br]from the injury I just showed you,

0:07:43.160,0:07:45.176
and what you see is the brain --

0:07:45.200,0:07:47.616
this is a cross-section right in the front

0:07:47.640,0:07:50.416
of the brain twisting[br]and contorting as I mentioned.

0:07:50.440,0:07:53.336
So you can see this doesn't[br]look a lot like the CDC video.

0:07:53.360,0:07:55.216
Now, the colors that you're looking at

0:07:55.240,0:07:59.376
are how much the brain tissue[br]is being stretched,

0:07:59.400,0:08:01.096
and so the red is 50 percent.

0:08:01.120,0:08:04.776
That means the brain has been stretched[br]to 50 percent of its original length,

0:08:04.800,0:08:06.496
the tissue in that particular area.

0:08:06.520,0:08:09.776
And the main thing I want to draw[br]your attention to is this red spot.

0:08:09.800,0:08:13.256
So the red spot is very close[br]to the center of the brain,

0:08:13.280,0:08:14.536
and relatively speaking,

0:08:14.560,0:08:19.216
you don't see a lot of colors like that[br]on the exterior surface

0:08:19.240,0:08:21.600
as the CDC video showed.

0:08:22.960,0:08:24.696
Now, to explain a little more detail

0:08:24.720,0:08:28.336
about how we think[br]concussion might be happening,

0:08:28.360,0:08:29.656
one thing I should mention

0:08:29.680,0:08:32.895
is that we and others have observed[br]that a concussion is more likely

0:08:32.919,0:08:36.895
when you're struck and your head[br]rotates in this direction.

0:08:36.919,0:08:39.176
This is more common[br]in sports like football,

0:08:39.200,0:08:42.534
but this seems to be more dangerous.[br]So what might be happening there?

0:08:42.558,0:08:45.576
Well, one thing that you'll notice[br]in the human brain

0:08:45.600,0:08:47.336
that is different than other animals

0:08:47.360,0:08:49.816
is we have these two very large lobes.

0:08:49.840,0:08:52.056
We have the right brain[br]and the left brain.

0:08:52.080,0:08:55.136
And the key thing[br]to notice in this figure here

0:08:55.160,0:08:58.416
is that right down the center[br]of the right brain and the left brain

0:08:58.440,0:09:01.376
there's a large fissure[br]that goes deep into the brain.

0:09:01.400,0:09:04.256
And in that fissure,[br]what you can't see in this image,

0:09:04.280,0:09:05.496
you'll have to trust me,

0:09:05.520,0:09:07.216
there is a fibrous sheet of tissue.

0:09:07.240,0:09:08.456
It's called the falx,

0:09:08.480,0:09:12.136
and it runs from the front of your head[br]all the way to the back of your head,

0:09:12.160,0:09:13.376
and it's quite stiff.

0:09:13.400,0:09:16.856
And so what that allows for[br]is when you're struck

0:09:16.880,0:09:19.936
and your head rotates[br]in this left-right direction,

0:09:19.960,0:09:23.736
forces can rapidly transmit[br]right down to the center of your brain.

0:09:23.760,0:09:26.000
Now, what's there[br]at the bottom of this fissure?

0:09:27.120,0:09:29.616
It's the wiring of your brain,

0:09:29.640,0:09:34.256
and in fact this red bundle[br]here at the bottom of that fissure

0:09:34.280,0:09:37.256
is the single largest fiber bundle

0:09:37.280,0:09:41.256
that is the wiring that connects[br]the right and left sides of your brain.

0:09:41.280,0:09:42.804
It's called the corpus callosum,

0:09:43.480,0:09:45.416
and we think that this might be

0:09:45.440,0:09:49.256
one of the most common[br]mechanisms of concussion,

0:09:49.280,0:09:53.976
and as the forces move down,[br]they strike the corpus callosum,

0:09:54.000,0:09:56.976
it causes a dissociation[br]between your right and your left brain

0:09:57.000,0:09:59.480
and could explain some[br]of the symptoms of concussion.

0:10:00.680,0:10:03.496
This finding is also consistent[br]of what we've seen

0:10:03.520,0:10:07.536
in this brain disease that I mentioned,[br]chronic traumatic encephalopathy.

0:10:07.560,0:10:13.096
So this is an image of a middle-aged[br]ex-professional football player,

0:10:13.120,0:10:17.096
and the thing that I want to point out[br]is if you look at the corpus callosum,

0:10:17.120,0:10:21.056
and I'll page back here so you can see[br]the size of a normal corpus callosum

0:10:21.080,0:10:25.496
and the size of the person here[br]who has chronic traumatic encephalopathy,

0:10:25.520,0:10:28.056
it is greatly atrophied.

0:10:28.080,0:10:31.416
And the same goes[br]for all of the space in the ventricles.

0:10:31.440,0:10:33.216
These ventricles are much larger.

0:10:33.240,0:10:35.776
And so all of this tissue[br]near the center of the brain

0:10:35.800,0:10:37.016
has died off over time.

0:10:37.040,0:10:40.600
So what we're learning[br]is indeed consistent.

0:10:41.520,0:10:44.176
Now, there is some good news here,

0:10:44.200,0:10:47.656
and I hope to give you a sense[br]of hope by the end of this talk.

0:10:47.680,0:10:49.776
One of the things that we've noticed,

0:10:49.800,0:10:52.056
specifically about[br]this mechanism of injury,

0:10:52.080,0:10:56.136
is although there's a rapid transmission[br]of the forces down this fissure,

0:10:56.160,0:10:59.456
it still takes a defined amount of time,

0:10:59.480,0:11:03.816
and what we think is that if we can[br]slow the head down just enough

0:11:03.840,0:11:07.056
so that the brain[br]does not lag behind the skull

0:11:07.080,0:11:10.656
but instead it moves[br]in synchrony with the skull,

0:11:10.680,0:11:13.936
then we might be able to prevent[br]this mechanism of concussion.

0:11:13.960,0:11:16.640
So how can we slow the head down?

0:11:18.640,0:11:20.376
(Laughter)

0:11:20.400,0:11:22.360
A gigantic helmet.

0:11:23.440,0:11:26.296
So with more space, you have more time,

0:11:26.320,0:11:29.416
and this is a bit of a joke,[br]but some of you may have seen this.

0:11:29.440,0:11:31.736
This is bubble soccer,[br]and it's a real sport.

0:11:31.760,0:11:33.416
In fact, I saw some young adults

0:11:33.440,0:11:36.416
playing this sport down the street[br]from my house the other day,

0:11:36.440,0:11:39.336
and as far as I know[br]there have been no reported concussions.

0:11:39.360,0:11:40.376
(Laughter)

0:11:40.400,0:11:44.816
But in all seriousness,[br]this principle does work,

0:11:44.840,0:11:46.216
but this has gone too far.

0:11:46.240,0:11:51.496
This isn't something that's practical[br]for bike riding or playing football,

0:11:51.520,0:11:55.896
and so we are collaborating[br]with a company in Sweden called Hรถvding.

0:11:55.920,0:11:58.256
Some of you may have seen their work,

0:11:58.280,0:12:02.656
and they're using the same principle[br]of air to give you some extra space

0:12:02.680,0:12:04.480
to prevent concussion.

0:12:05.320,0:12:07.080
Kids, don't try this at home please.

0:12:08.680,0:12:10.840
This stuntman does not have a helmet.

0:12:12.200,0:12:14.456
He instead has a neck collar,

0:12:14.480,0:12:17.056
and this neck collar has sensors in it,

0:12:17.080,0:12:20.656
the same type of sensors[br]that are in our mouthguard,

0:12:20.680,0:12:23.816
and it detects when he's likely[br]to have a fall,

0:12:23.840,0:12:26.176
and there's an airbag[br]that explodes and triggers,

0:12:26.200,0:12:29.976
the same way that an airbag[br]works in your car, essentially.

0:12:30.000,0:12:32.936
And in the experiments[br]we've done in my lab with their device,

0:12:32.960,0:12:36.696
we found that it can greatly reduce[br]the risk of concussion in some scenarios

0:12:36.720,0:12:38.856
compared to a normal bicycle helmet.

0:12:38.880,0:12:40.720
So it's a pretty exciting development,

0:12:41.720,0:12:46.416
but in order for us to actually realize[br]the benefits of technology

0:12:46.440,0:12:48.296
that can prevent concussion,

0:12:48.320,0:12:51.256
it needs to meet regulations.

0:12:51.280,0:12:52.976
That's a reality,

0:12:53.000,0:12:56.136
and this device is for sale in Europe

0:12:56.160,0:12:59.856
but is not for sale in the US,[br]and probably won't be any time soon.

0:12:59.880,0:13:01.416
So I wanted to tell you why.

0:13:01.440,0:13:05.216
There are some good reasons and then[br]there are some not so good reasons.

0:13:05.240,0:13:07.456
Bike helmets are federally regulated.

0:13:07.480,0:13:11.216
The Consumer Product Safety Commission[br]has been given jurisdiction

0:13:11.240,0:13:13.096
to approve any bike helmet for sale,

0:13:13.120,0:13:14.576
and this is the test they use.

0:13:14.600,0:13:18.256
This is back to what I was telling you[br]at the beginning about skull fracture.

0:13:18.280,0:13:19.696
That's what this test is for.

0:13:19.720,0:13:21.456
And that's an important thing to do.

0:13:21.480,0:13:24.336
It can save your life,[br]but it's not sufficient, I would say.

0:13:24.360,0:13:27.096
So for example, one thing[br]this test doesn't evaluate

0:13:27.120,0:13:29.936
is it doesn't tell you[br]is that airbag going to trigger

0:13:29.960,0:13:33.856
at the right time and place,[br]and not trigger when it doesn't need to?

0:13:33.880,0:13:35.936
Similarly, it's not going to tell you

0:13:35.960,0:13:39.336
is this helmet likely[br]to prevent concussion or not?

0:13:39.360,0:13:43.096
And if you look at football helmets,[br]which aren't regulated,

0:13:43.120,0:13:45.496
they still have a very similar test.

0:13:45.520,0:13:47.776
They're not regulated[br]by the government, anyway.

0:13:47.800,0:13:50.936
They have an industry body,[br]which is the way most industries work.

0:13:50.960,0:13:53.976
But this industry body, I can tell you,[br]has been quite resistant

0:13:54.000,0:13:55.376
to updating their standards.

0:13:55.400,0:13:58.656
So in my lab, we are working on not only[br]the mechanism of concussion,

0:13:58.680,0:14:02.136
but we want to understand[br]how can we have better test standards?

0:14:02.160,0:14:06.696
And we hope that the government[br]can use this type of information

0:14:06.720,0:14:08.456
to encourage innovation

0:14:08.480,0:14:10.096
by letting consumers know

0:14:10.120,0:14:13.896
how protected are you with a given helmet.

0:14:13.920,0:14:17.296
And I want to bring this back finally[br]to the original question I asked,

0:14:17.320,0:14:20.656
which is, would I feel comfortable[br]letting my child play football

0:14:20.680,0:14:22.416
or ride a bicycle?

0:14:22.440,0:14:25.776
And this might be just a result[br]of my own traumatic experience.

0:14:25.800,0:14:29.800
I'm much more nervous[br]about my daughter Rose riding a bicycle.

0:14:30.920,0:14:32.576
So she's a year and a half old,

0:14:32.600,0:14:38.056
and she's already, well, wants to anyway,[br]race down the streets of San Francisco.

0:14:38.080,0:14:40.416
This is the bottom[br]of one of these streets.

0:14:40.440,0:14:45.656
And so my personal goal[br]is to -- and I believe this is possible --

0:14:45.680,0:14:47.736
is to further develop these technologies,

0:14:47.760,0:14:50.736
and in fact, we're working[br]on something in my lab in particular

0:14:50.760,0:14:53.713
that really makes optimal use[br]of the given space of the helmet,

0:14:53.737,0:14:56.216
and I am confident[br]that we will be able to,

0:14:56.240,0:14:59.456
before she's ready to ride a two-wheeler,

0:14:59.480,0:15:00.856
have something available

0:15:00.880,0:15:04.216
that can in fact really reduce[br]the risk of concussion

0:15:04.240,0:15:07.376
and comply with regulatory bodies.

0:15:07.400,0:15:09.016
And so what I'd like to do --

0:15:09.040,0:15:12.416
and I know that this is for some of you[br]of more immediate nature,

0:15:12.440,0:15:14.096
I've got a couple years here --

0:15:14.120,0:15:18.256
is to be able to tell parents[br]and grandparents when I'm asked,

0:15:18.280,0:15:22.696
it is safe and healthy for your children[br]to engage in these activities.

0:15:22.720,0:15:25.536
And I'm very fortunate[br]to have a wonderful team at Stanford

0:15:25.560,0:15:27.456
that's working hard on this.

0:15:27.480,0:15:31.576
So I hope to come back in a few years[br]with the final story,

0:15:31.600,0:15:33.576
but for now I will tell you,

0:15:33.600,0:15:36.536
please don't just be afraid[br]when you hear the word concussion.

0:15:36.560,0:15:37.776
There is hope.

0:15:37.800,0:15:39.016
Thank you.

0:15:39.040,0:15:41.000
(Applause)