0:00:11.140,0:00:15.796 The word concussion evokes a fear[br]these days more so than it ever has, 0:00:15.820,0:00:18.196 and I know this personally. 0:00:18.220,0:00:20.876 I played 10 years of football, 0:00:20.900,0:00:23.316 was struck in the head thousands of times, 0:00:23.340,0:00:26.996 and I have to tell you, though,[br]what was much worse than that 0:00:27.020,0:00:31.796 was a pair of bike accidents I had[br]where I suffered concussions, 0:00:31.820,0:00:34.756 and I'm still dealing with the effects[br]of the most recent one 0:00:34.780,0:00:36.540 today as I stand in front of you. 0:00:38.340,0:00:40.796 There is a fear around concussion 0:00:40.820,0:00:42.780 that does have some evidence behind it. 0:00:44.300,0:00:47.636 There is information[br]that a repeated history of concussion 0:00:47.660,0:00:50.956 can lead to early dementia,[br]such as Alzheimer's, 0:00:50.980,0:00:53.036 and chronic traumatic encephalopathy. 0:00:53.060,0:00:56.100 That was the subject[br]of the Will Smith movie "Concussion." 0:00:57.260,0:01:00.836 And so everybody is caught up in football[br]and what they see in the military, 0:01:00.860,0:01:02.196 but you may not know 0:01:02.220,0:01:06.516 that bike riding is the leading cause[br]of concussion for kids, 0:01:06.540,0:01:08.207 sports-related concussion, that is. 0:01:09.740,0:01:12.316 And so another thing[br]that I should tell you 0:01:12.340,0:01:13.556 that you may not know 0:01:13.580,0:01:16.516 is that the helmets that are worn[br]in bicycling and football 0:01:16.540,0:01:18.196 and many activities, 0:01:18.220,0:01:20.796 they're not designed or tested 0:01:20.820,0:01:24.300 for how well they can protect[br]your children against concussion. 0:01:24.900,0:01:26.636 They're in fact designed and tested 0:01:26.660,0:01:29.340 for their ability to protect[br]against skull fracture. 0:01:30.540,0:01:36.156 And so I get this question[br]all the time from parents, 0:01:36.180,0:01:37.756 and they ask me, 0:01:37.780,0:01:40.076 "Would you let your own child[br]play football?" 0:01:40.100,0:01:43.276 Or, "Should I let my child play soccer?" 0:01:43.300,0:01:46.196 And I think that as a field, 0:01:46.220,0:01:50.620 we're a long way from giving an answer[br]with any kind of confidence there. 0:01:52.140,0:01:55.716 So I look at that question[br]from a bit of a different lens, 0:01:55.740,0:01:59.476 and I want to know,[br]how can we prevent concussion? 0:01:59.500,0:02:01.156 Is that even possible? 0:02:01.180,0:02:03.740 And most experts think that it's not, 0:02:05.220,0:02:07.436 but the work that we're doing in my lab 0:02:07.460,0:02:11.836 is starting to reveal more[br]of the details around concussion 0:02:11.860,0:02:14.636 so that we can have[br]a better understanding. 0:02:14.660,0:02:17.516 The reason we're able[br]to prevent skull fracture with helmets 0:02:17.540,0:02:19.994 is because it's pretty simple.[br]We know how it works. 0:02:20.020,0:02:22.060 Concussion has been[br]much more of a mystery. 0:02:22.980,0:02:26.740 So to give you a sense of what might[br]be happening in a concussion, 0:02:27.940,0:02:29.876 I want to show you the video here 0:02:29.900,0:02:32.436 that you see when you type into Google, 0:02:32.460,0:02:33.876 "What is a concussion?" 0:02:33.900,0:02:35.556 The CDC website comes up, 0:02:35.580,0:02:39.036 and this video essentially[br]tells the whole story. 0:02:39.060,0:02:41.476 What you see is the head moves forward, 0:02:41.500,0:02:43.556 the brain lags behind, 0:02:43.580,0:02:44.996 then the brain catches up 0:02:45.020,0:02:47.276 and smashes into the skull, 0:02:47.300,0:02:49.476 it rebounds off the skull, 0:02:49.500,0:02:53.260 and then proceeds to run[br]into the other side of the skull. 0:02:54.020,0:02:57.636 And what you'll notice is highlighted[br]in this video from the CDC, 0:02:57.660,0:03:00.116 which I'll note was funded by the NFL, 0:03:00.140,0:03:03.076 is that the outer surface of the brain, 0:03:03.100,0:03:06.396 where it was to have[br]smashed into the skull, 0:03:06.420,0:03:10.356 looks like it's been damaged or injured,[br]so it's on the outer surface of the brain. 0:03:10.380,0:03:12.356 And what I'd like to do with this video 0:03:12.380,0:03:16.076 is to tell you that there are[br]some aspects that are probably right, 0:03:16.100,0:03:19.116 indicative of what the scientists[br]think happens with concussion, 0:03:19.140,0:03:21.756 but there's probably more[br]that's wrong with this video. 0:03:21.780,0:03:25.036 So one thing that I do agree with,[br]and I think most experts would, 0:03:25.060,0:03:27.076 is that the brain[br]does have these dynamics. 0:03:27.100,0:03:29.476 It does lag behind the skull 0:03:29.500,0:03:32.156 and then catch up and move[br]back and forth and oscillate. 0:03:32.180,0:03:33.420 That we think is true. 0:03:34.460,0:03:37.756 However, the amount of motion[br]you see in the brain in this video 0:03:37.780,0:03:39.356 is probably not right at all. 0:03:39.380,0:03:42.796 There's very little room[br]in the cranial vault, 0:03:42.820,0:03:44.516 only a few millimeters, 0:03:44.540,0:03:47.716 and it's filled entirely[br]with cerebral spinal fluid, 0:03:47.740,0:03:49.916 which acts as a protective layer. 0:03:49.940,0:03:54.100 And so the brain as a whole probably[br]moves very little inside the skull. 0:03:55.220,0:03:57.276 The other problem with this video 0:03:57.300,0:03:59.036 is that the brain is shown 0:03:59.060,0:04:02.156 as a kind of rigid whole[br]as it moves around, 0:04:02.180,0:04:03.580 and that's not true either. 0:04:04.420,0:04:07.836 Your brain is one of the softest[br]substances in your body, 0:04:07.860,0:04:09.876 and you can think of it[br]kind of like jello. 0:04:09.900,0:04:12.036 So as your head is moving back and forth, 0:04:12.060,0:04:14.916 your brain is twisting[br]and turning and contorting, 0:04:14.940,0:04:17.156 and the tissue is getting stretched, 0:04:17.180,0:04:20.196 and so most experts I think would agree 0:04:20.220,0:04:23.356 that concussion is not likely[br]to be something that's happening 0:04:23.380,0:04:25.196 on this outer surface of the brain, 0:04:25.220,0:04:27.316 but rather it's something[br]that's much deeper 0:04:27.340,0:04:28.900 towards the center of the brain. 0:04:29.979,0:04:32.556 Now, the way that we're[br]approaching this problem 0:04:32.580,0:04:34.916 to try to understand[br]the mechanisms of concussion 0:04:34.940,0:04:36.796 and to figure out if we can prevent it 0:04:36.820,0:04:39.636 is we are using a device like this. 0:04:39.660,0:04:40.860 It's a mouthguard. 0:04:41.660,0:04:44.556 It has sensors in it[br]that are essentially the same 0:04:44.580,0:04:45.916 that are in your cell phone: 0:04:45.940,0:04:48.276 accelerometers, gyroscopes, 0:04:48.300,0:04:50.196 and when someone is struck in the head, 0:04:50.220,0:04:52.756 it can tell you how their head moved 0:04:52.780,0:04:55.900 at a thousand samples per second. 0:04:57.460,0:05:00.156 The principle behind[br]the mouthguard is this: 0:05:00.180,0:05:01.436 it fits onto your teeth. 0:05:01.460,0:05:04.516 Your teeth are one of the hardest[br]substances in your body. 0:05:04.540,0:05:06.596 So it rigidly couples to your skull 0:05:06.620,0:05:09.036 and gives you the most precise[br]possible measurement 0:05:09.060,0:05:10.996 of how the skull moves. 0:05:11.020,0:05:13.556 People have tried[br]other approaches, with helmets. 0:05:13.580,0:05:16.956 We've looked at other sensors[br]that go on your skin, 0:05:16.980,0:05:19.596 and they all simply move around too much, 0:05:19.620,0:05:22.316 and so we found that this[br]is the only reliable way 0:05:22.340,0:05:23.700 to take a good measurement. 0:05:26.100,0:05:30.396 So now that we've got this device,[br]we can go beyond studying cadavers, 0:05:30.420,0:05:32.836 because you can only[br]learn so much about concussion 0:05:32.860,0:05:34.076 from studying a cadaver, 0:05:34.100,0:05:36.876 and we want to learn[br]and study live humans. 0:05:36.900,0:05:40.796 So where can we find[br]a group of willing volunteers 0:05:40.820,0:05:45.076 to go out and smash their heads[br]into each other on a regular basis 0:05:45.100,0:05:46.316 and sustain concussion? 0:05:46.340,0:05:48.236 Well, I was one of them, 0:05:48.260,0:05:51.060 and it's your local friendly[br]Stanford football team. 0:05:52.340,0:05:53.956 So this is our laboratory, 0:05:53.980,0:05:55.676 and I want to show you 0:05:55.700,0:05:58.876 the first concussion[br]we measured with this device. 0:05:58.900,0:06:03.156 One of the things that I should point out[br]is the device has this gyroscope in it, 0:06:03.180,0:06:05.916 and that allows you[br]to measure the rotation of the head. 0:06:05.940,0:06:08.316 Most experts think[br]that that's the critical factor 0:06:08.340,0:06:11.196 that might start to tell us[br]what is happening in concussion. 0:06:11.220,0:06:12.580 So please watch this video. 0:06:13.980,0:06:17.396 Announcer: Cougars bring[br]extra people late, but Luck has time, 0:06:17.420,0:06:19.060 and Winslow is crushed. 0:06:20.820,0:06:22.396 Announcer: I hope he's all right. 0:06:22.420,0:06:24.380 (Audience roars) 0:06:29.260,0:06:30.716 Announcer: Top of your screen, 0:06:30.740,0:06:33.156 you'll see him come on[br]just this little post route, 0:06:33.180,0:06:34.820 get separation, safety. 0:06:38.940,0:06:41.500 There it comes at you in real speed.[br]You'll hear this. 0:06:43.340,0:06:45.220 Announcer: The hit delivered by -- 0:06:47.419,0:06:50.875 David Camarillo: Sorry, three times[br]is probably a little excessive there. 0:06:50.900,0:06:52.156 But you get the idea. 0:06:52.180,0:06:54.996 So when you look at just the film here, 0:06:55.020,0:06:58.836 pretty much the only thing you can see[br]is he got hit really hard and he was hurt. 0:06:58.860,0:07:00.516 But when we extract the data 0:07:00.540,0:07:02.540 out of the mouthguard that he was wearing, 0:07:02.564,0:07:05.276 we can see much more detail,[br]much richer information. 0:07:05.300,0:07:07.716 And one of the things that we noticed here 0:07:07.740,0:07:11.796 is that he was struck[br]in the lower left side of his face mask. 0:07:11.820,0:07:14.996 And so that did something first[br]that was a little counterintuitive. 0:07:15.020,0:07:16.716 His head did not move to the right. 0:07:16.740,0:07:18.676 In fact, it rotated first to the left. 0:07:18.700,0:07:21.556 Then as the neck began to compress, 0:07:21.580,0:07:24.676 the force of the blow caused it[br]to whip back to the right, 0:07:24.700,0:07:30.556 so this left-right motion[br]was sort of a whiplash type phenomenon 0:07:30.580,0:07:34.996 and we think that is probably[br]what led to the brain injury. 0:07:35.020,0:07:38.796 Now, this device is only limited in such[br]that it can measure the skull motion, 0:07:38.820,0:07:42.236 but what we really want to know[br]is what's happening inside of the brain. 0:07:42.260,0:07:45.756 So we collaborate with[br]Svein Kleiven's group in Sweden. 0:07:45.780,0:07:49.356 They've developed a finite element[br]model of the brain. 0:07:49.380,0:07:51.476 And so this is a simulation 0:07:51.500,0:07:54.836 using the data from our mouthguard[br]from the injury I just showed you, 0:07:54.860,0:07:56.876 and what you see is the brain -- 0:07:56.900,0:07:59.316 this is a cross-section right in the front 0:07:59.340,0:08:02.116 of the brain twisting[br]and contorting as I mentioned. 0:08:02.140,0:08:05.036 So you can see this doesn't[br]look a lot like the CDC video. 0:08:05.060,0:08:06.916 Now, the colors that you're looking at 0:08:06.940,0:08:11.076 are how much the brain tissue[br]is being stretched, 0:08:11.100,0:08:12.796 and so the red is 50 percent. 0:08:12.820,0:08:16.476 That means the brain has been stretched[br]to 50 percent of its original length, 0:08:16.500,0:08:18.196 the tissue in that particular area. 0:08:18.220,0:08:21.476 And the main thing I want to draw[br]your attention to is this red spot. 0:08:21.500,0:08:24.956 So the red spot is very close[br]to the center of the brain, 0:08:24.980,0:08:26.236 and relatively speaking, 0:08:26.260,0:08:30.916 you don't see a lot of colors like that[br]on the exterior surface 0:08:30.940,0:08:33.299 as the CDC video showed. 0:08:34.659,0:08:36.395 Now, to explain a little more detail 0:08:36.419,0:08:40.035 about how we think[br]concussion might be happening, 0:08:40.059,0:08:41.356 one thing I should mention 0:08:41.380,0:08:44.595 is that we and others have observed[br]that a concussion is more likely 0:08:44.619,0:08:48.595 when you're struck and your head[br]rotates in this direction. 0:08:48.619,0:08:50.876 This is more common[br]in sports like football, 0:08:50.900,0:08:54.234 but this seems to be more dangerous.[br]So what might be happening there? 0:08:54.258,0:08:57.276 Well, one thing that you'll notice[br]in the human brain 0:08:57.300,0:08:59.036 that is different than other animals 0:08:59.060,0:09:01.516 is we have these two very large lobes. 0:09:01.540,0:09:03.756 We have the right brain[br]and the left brain. 0:09:03.780,0:09:06.836 And the key thing[br]to notice in this figure here 0:09:06.860,0:09:10.116 is that right down the center[br]of the right brain and the left brain 0:09:10.140,0:09:13.076 there's a large fissure[br]that goes deep into the brain. 0:09:13.100,0:09:16.655 And in that fissure,[br]what you can't see in this image, 0:09:16.680,0:09:17.896 you'll have to trust me, 0:09:17.920,0:09:19.616 there is a fibrous sheet of tissue. 0:09:19.640,0:09:20.856 It's called the falx, 0:09:20.880,0:09:24.536 and it runs from the front of your head[br]all the way to the back of your head, 0:09:24.560,0:09:25.776 and it's quite stiff. 0:09:25.800,0:09:29.256 And so what that allows for[br]is when you're struck 0:09:29.280,0:09:32.336 and your head rotates[br]in this left-right direction, 0:09:32.360,0:09:36.136 forces can rapidly transmit[br]right down to the center of your brain. 0:09:36.160,0:09:38.400 Now, what's there[br]at the bottom of this fissure? 0:09:39.520,0:09:42.016 It's the wiring of your brain, 0:09:42.040,0:09:46.656 and in fact this red bundle[br]here at the bottom of that fissure 0:09:46.680,0:09:49.656 is the single largest fiber bundle 0:09:49.680,0:09:53.656 that is the wiring that connects[br]the right and left sides of your brain. 0:09:54.380,0:09:55.904 It's called the corpus callosum, 0:09:57.380,0:09:59.316 and we think that this might be 0:09:59.340,0:10:03.156 one of the most common[br]mechanisms of concussion, 0:10:03.180,0:10:07.876 and as the forces move down,[br]they strike the corpus callosum, 0:10:07.900,0:10:10.876 it causes a dissociation[br]between your right and your left brain 0:10:10.900,0:10:13.380 and could explain some[br]of the symptoms of concussion. 0:10:14.580,0:10:17.396 This finding is also consistent[br]of what we've seen 0:10:17.420,0:10:21.436 in this brain disease that I mentioned,[br]chronic traumatic encephalopathy. 0:10:21.460,0:10:26.996 So this is an image of a middle-aged[br]ex-professional football player, 0:10:27.020,0:10:30.996 and the thing that I want to point out[br]is if you look at the corpus callosum, 0:10:31.020,0:10:36.016 and I'll page back here so you can see[br]the size of a normal corpus callosum 0:10:36.080,0:10:40.496 and the size of the person here[br]who has chronic traumatic encephalopathy, 0:10:40.520,0:10:43.056 it is greatly atrophied. 0:10:43.080,0:10:46.416 And the same goes[br]for all of the space in the ventricles. 0:10:46.440,0:10:48.216 These ventricles are much larger. 0:10:48.240,0:10:50.776 And so all of this tissue[br]near the center of the brain 0:10:50.800,0:10:52.016 has died off over time. 0:10:52.040,0:10:55.600 So what we're learning[br]is indeed consistent. 0:10:56.520,0:10:59.176 Now, there is some good news here, 0:10:59.200,0:11:02.656 and I hope to give you a sense[br]of hope by the end of this talk. 0:11:02.680,0:11:04.776 One of the things that we've noticed, 0:11:04.800,0:11:07.056 specifically about[br]this mechanism of injury, 0:11:07.080,0:11:11.136 is although there's a rapid transmission[br]of the forces down this fissure, 0:11:11.160,0:11:14.456 it still takes a defined amount of time, 0:11:14.480,0:11:18.816 and what we think is that if we can[br]slow the head down just enough 0:11:18.840,0:11:22.056 so that the brain[br]does not lag behind the skull 0:11:22.080,0:11:25.656 but instead it moves[br]in synchrony with the skull, 0:11:25.680,0:11:28.936 then we might be able to prevent[br]this mechanism of concussion. 0:11:28.960,0:11:31.640 So how can we slow the head down? 0:11:33.640,0:11:35.376 (Laughter) 0:11:35.400,0:11:37.360 A gigantic helmet. 0:11:38.440,0:11:41.296 So with more space, you have more time, 0:11:41.320,0:11:44.416 and this is a bit of a joke,[br]but some of you may have seen this. 0:11:44.440,0:11:46.736 This is bubble soccer,[br]and it's a real sport. 0:11:46.760,0:11:48.416 In fact, I saw some young adults 0:11:48.440,0:11:51.416 playing this sport down the street[br]from my house the other day, 0:11:51.440,0:11:54.336 and as far as I know[br]there have been no reported concussions. 0:11:54.360,0:11:55.376 (Laughter) 0:11:55.400,0:11:59.816 But in all seriousness,[br]this principle does work, 0:11:59.840,0:12:01.216 but this has gone too far. 0:12:01.240,0:12:06.496 This isn't something that's practical[br]for bike riding or playing football, 0:12:06.520,0:12:10.896 and so we are collaborating[br]with a company in Sweden called Hรถvding. 0:12:10.920,0:12:13.256 Some of you may have seen their work, 0:12:13.280,0:12:17.656 and they're using the same principle[br]of air to give you some extra space 0:12:17.680,0:12:19.480 to prevent concussion. 0:12:20.320,0:12:22.080 Kids, don't try this at home please. 0:12:25.080,0:12:27.240 This stuntman does not have a helmet. 0:12:28.600,0:12:30.856 He instead has a neck collar, 0:12:30.880,0:12:33.456 and this neck collar has sensors in it, 0:12:33.480,0:12:37.056 the same type of sensors[br]that are in our mouthguard, 0:12:37.080,0:12:40.216 and it detects when he's likely[br]to have a fall, 0:12:40.240,0:12:42.576 and there's an airbag[br]that explodes and triggers, 0:12:42.600,0:12:46.376 the same way that an airbag[br]works in your car, essentially. 0:12:46.400,0:12:49.336 And in the experiments[br]we've done in my lab with their device, 0:12:49.360,0:12:53.096 we found that it can greatly reduce[br]the risk of concussion in some scenarios 0:12:53.120,0:12:55.256 compared to a normal bicycle helmet. 0:12:55.280,0:12:57.120 So it's a pretty exciting development, 0:12:58.120,0:13:02.816 but in order for us to actually realize[br]the benefits of technology 0:13:02.840,0:13:04.696 that can prevent concussion, 0:13:04.720,0:13:07.656 it needs to meet regulations. 0:13:07.680,0:13:09.376 That's a reality, 0:13:09.400,0:13:12.536 and this device is for sale in Europe 0:13:12.560,0:13:16.256 but is not for sale in the US,[br]and probably won't be any time soon. 0:13:16.280,0:13:17.816 So I wanted to tell you why. 0:13:17.840,0:13:21.616 There are some good reasons and then[br]there are some not so good reasons. 0:13:21.640,0:13:23.856 Bike helmets are federally regulated. 0:13:23.880,0:13:27.616 The Consumer Product Safety Commission[br]has been given jurisdiction 0:13:27.640,0:13:29.496 to approve any bike helmet for sale, 0:13:29.520,0:13:30.976 and this is the test they use. 0:13:31.000,0:13:34.656 This is back to what I was telling you[br]at the beginning about skull fracture. 0:13:34.680,0:13:36.096 That's what this test is for. 0:13:36.120,0:13:37.856 And that's an important thing to do. 0:13:37.880,0:13:40.736 It can save your life,[br]but it's not sufficient, I would say. 0:13:40.760,0:13:43.496 So for example, one thing[br]this test doesn't evaluate 0:13:43.520,0:13:46.336 is it doesn't tell you[br]is that airbag going to trigger 0:13:46.360,0:13:50.256 at the right time and place,[br]and not trigger when it doesn't need to? 0:13:50.280,0:13:52.336 Similarly, it's not going to tell you 0:13:52.360,0:13:55.736 is this helmet likely[br]to prevent concussion or not? 0:13:55.760,0:13:59.496 And if you look at football helmets,[br]which aren't regulated, 0:13:59.520,0:14:02.481 they still have a very similar test. 0:14:02.520,0:14:04.776 They're not regulated[br]by the government, anyway. 0:14:04.800,0:14:07.936 They have an industry body,[br]which is the way most industries work. 0:14:07.960,0:14:10.976 But this industry body, I can tell you,[br]has been quite resistant 0:14:11.000,0:14:12.376 to updating their standards. 0:14:12.400,0:14:15.656 So in my lab, we are working on not only[br]the mechanism of concussion, 0:14:15.680,0:14:19.136 but we want to understand[br]how can we have better test standards? 0:14:19.160,0:14:23.696 And we hope that the government[br]can use this type of information 0:14:23.720,0:14:25.456 to encourage innovation 0:14:25.480,0:14:27.096 by letting consumers know 0:14:27.120,0:14:30.896 how protected are you with a given helmet. 0:14:30.920,0:14:34.296 And I want to bring this back finally[br]to the original question I asked, 0:14:34.320,0:14:37.656 which is, would I feel comfortable[br]letting my child play football 0:14:37.680,0:14:39.416 or ride a bicycle? 0:14:39.440,0:14:42.776 And this might be just a result[br]of my own traumatic experience. 0:14:42.800,0:14:46.800 I'm much more nervous[br]about my daughter Rose riding a bicycle. 0:14:47.920,0:14:49.576 So she's a year and a half old, 0:14:49.600,0:14:55.056 and she's already, well, wants to anyway,[br]race down the streets of San Francisco. 0:14:55.080,0:14:57.416 This is the bottom[br]of one of these streets. 0:14:57.440,0:15:02.656 And so my personal goal[br]is to -- and I believe this is possible -- 0:15:02.680,0:15:04.736 is to further develop these technologies, 0:15:04.760,0:15:07.736 and in fact, we're working[br]on something in my lab in particular 0:15:07.760,0:15:10.713 that really makes optimal use[br]of the given space of the helmet, 0:15:10.737,0:15:13.216 and I am confident[br]that we will be able to, 0:15:13.240,0:15:16.456 before she's ready to ride a two-wheeler, 0:15:16.480,0:15:17.856 have something available 0:15:17.880,0:15:21.216 that can in fact really reduce[br]the risk of concussion 0:15:21.240,0:15:24.376 and comply with regulatory bodies. 0:15:24.400,0:15:26.016 And so what I'd like to do -- 0:15:26.040,0:15:29.416 and I know that this is for some of you[br]of more immediate nature, 0:15:29.440,0:15:31.096 I've got a couple years here -- 0:15:31.120,0:15:35.256 is to be able to tell parents[br]and grandparents when I'm asked, 0:15:35.280,0:15:39.696 it is safe and healthy for your children[br]to engage in these activities. 0:15:39.720,0:15:42.536 And I'm very fortunate[br]to have a wonderful team at Stanford 0:15:42.560,0:15:44.456 that's working hard on this. 0:15:44.480,0:15:48.576 So I hope to come back in a few years[br]with the final story, 0:15:48.600,0:15:50.576 but for now I will tell you, 0:15:50.600,0:15:53.536 please don't just be afraid[br]when you hear the word concussion. 0:15:53.560,0:15:54.776 There is hope. 0:15:54.800,0:15:56.016 Thank you. 0:15:56.040,0:15:58.000 (Applause)