Alcohol & Other Common Causes of Brain Damage | Dr. Matt MacDougall & Dr. Andrew Huberman

00:00:00.000 | - What did you mean when you said that the skull

00:00:04.840 | is a poor adaptation and a titanium plate will be better?

00:00:07.520 | And in particular, what does that mean in reference

00:00:11.700 | to things like traumatic brain injury?

00:00:13.320 | I mean, are human beings unnecessarily vulnerable

00:00:16.480 | at the level of traumatic brain injury

00:00:18.040 | because our skulls are just not hard enough?

00:00:21.780 | - You know, maybe I'm being too harsh about skull.

00:00:27.060 | The skull is very good at what it does,

00:00:30.840 | given the tools that we are working with

00:00:33.720 | as biological organisms that develop in our mother's uterus.

00:00:36.920 | The skull is, you know, usually the appropriate size.

00:00:41.920 | It's one of the hardest things in your body.

00:00:44.120 | That said, there are a couple of puzzling vulnerabilities.

00:00:48.160 | Some of the thinnest bone in the skull

00:00:51.440 | is in the temporal region.

00:00:52.920 | This is, you know, neurosurgeons will all know

00:00:55.400 | that I'm heading toward a feature

00:00:57.960 | that sometimes darkly is called God's little joke,

00:01:01.480 | where the very thin bone of the temporal part of the skull

00:01:06.480 | has one of the largest arteries

00:01:09.400 | that goes to the lining of the brain

00:01:11.160 | right attached to the inside of it.

00:01:13.320 | And so this bone just to the side of your eye

00:01:17.000 | tends to fracture if you're struck there.

00:01:20.040 | And the sharp edges of that fractured bone

00:01:22.080 | very often cut an artery called the middle meningeal artery

00:01:25.680 | that leads to a big blood clot that crushes the brain.

00:01:29.920 | That's how a lot of people with, you know,

00:01:32.320 | otherwise would be a relatively minor injury end up dying,

00:01:36.560 | is this large blood clot developing

00:01:39.120 | from high pressured arterial blood that crushes the brain.

00:01:43.320 | And so why would you put the artery

00:01:46.000 | right on the inside of the very thin bone

00:01:47.840 | that's most likely to fracture?

00:01:49.440 | It's an enduring mystery,

00:01:51.480 | but this is probably the most obvious failure mode

00:01:55.480 | in the design of a human skull.

00:01:58.360 | Otherwise, you know, in terms of general impact resistance,

00:02:02.160 | I think the brain is a very hard thing to protect.

00:02:05.760 | And the architecture of human anatomy

00:02:08.720 | probably given all other possible architectures

00:02:12.160 | that can arise from development, it's not that bad really.

00:02:16.280 | One of the interesting features in terms of shock absorption

00:02:20.280 | that hopefully prevents a lot of traumatic brain injury

00:02:22.920 | is the fluid sheath around the brain.

00:02:25.040 | The brain you may know is, it's mostly fat.

00:02:30.040 | It floats in saltwater in our brains.

00:02:33.040 | Our brains are all floating in saltwater.

00:02:35.280 | And so with rapid acceleration, deceleration,

00:02:38.480 | that sheath of saltwater adds a marvelous protective cushion

00:02:43.480 | against development of, you know, bruising of the brain,

00:02:48.840 | say, or bleeding in the brain.

00:02:50.920 | And so I think for any flaws in the design that do exist,

00:02:55.800 | you can imagine things being a lot worse,

00:03:00.240 | and there's probably a lot fewer TBIs than would exist

00:03:03.800 | if a human designer was taking a first crack at it.

00:03:06.400 | As you describe the thinness of this temporal bone

00:03:10.000 | and the presence of a critical artery just beneath it,

00:03:13.800 | I'm thinking about most helmets.

00:03:18.680 | And here, I also wanna cue up the fact that,

00:03:21.880 | well, whenever we hear about TBI or CTE or brain injury,

00:03:26.040 | people always think football, hockey,

00:03:28.440 | but most traumatic brain injuries

00:03:29.920 | are things like car accidents or construction work.

00:03:34.040 | It's not football and hockey.

00:03:36.040 | For some reason, football and hockey and boxing

00:03:38.480 | get all the attention.

00:03:40.480 | But my colleagues that work on traumatic brain injury

00:03:42.720 | tell me that most of the traumatic brain injury they see

00:03:46.080 | is somebody slips at a party and hits their head

00:03:48.640 | or was in a car accident

00:03:52.560 | or environmental accidents of various kinds.

00:03:56.400 | To my mind, most helmets don't actually cover this region

00:04:00.560 | close to the eyes.

00:04:01.720 | So is there also a failure of helmet engineering

00:04:06.240 | that I can understand why you'd wanna have

00:04:09.280 | your peripheral vision out the sides of your eyes,

00:04:12.600 | periphery of your eyes,

00:04:13.760 | but it seems to me if this is such critical real estate,

00:04:15.880 | why isn't it being better protected?

00:04:18.800 | - You know, I'm no expert in helmets,

00:04:20.520 | but I don't think we see a lot of epidural hematomas

00:04:24.520 | in sports injuries.

00:04:26.120 | To get this kind of injury,

00:04:29.200 | you usually need a really focal blunt trauma,

00:04:31.600 | like the baseball bat to the head

00:04:33.400 | is a classic mechanism of injury

00:04:36.080 | that would lead to a temporal bone fracture

00:04:40.040 | and epidural hematoma.

00:04:41.280 | With sports injuries, you know, you don't often see that,

00:04:46.080 | especially in football with a sharper object

00:04:51.080 | coming in contact with the head.

00:04:54.560 | It's usually another helmet, right,

00:04:56.480 | is the mechanism of injury.

00:04:59.080 | So I can't think off the top of my head

00:05:02.480 | of an instance of this exact injury type in sports.

00:05:06.440 | - You spent a lot of time poking around in brains of humans.

00:05:10.760 | And while I realize this is not your area of expertise,

00:05:16.040 | you are somebody who I am aware, you know,

00:05:18.960 | cares about his health and the health of your family.

00:05:22.120 | And I think generally people's health.

00:05:25.120 | When you look out on the landscape of things

00:05:26.800 | that people can do and shouldn't do,

00:05:30.840 | if their desire is to keep their brain healthy,

00:05:33.520 | do any data or any particular practices come to mind?

00:05:38.520 | I mean, I think we've all heard the obvious one,

00:05:40.640 | don't get a head injury.

00:05:42.160 | If you do get a head injury, make sure it gets treated

00:05:44.920 | and don't get a second head injury.

00:05:46.800 | But those are sort of duh type answers

00:05:50.360 | that I'm able to give.

00:05:51.520 | So I'm curious about the answers

00:05:52.560 | that perhaps I'm not able to give.

00:05:54.280 | - Yeah, well, you know, the obvious ones,

00:05:56.320 | it's one that you talk about a lot.

00:05:58.360 | And I see a lot of the smoldering wreckage of humanity,

00:06:03.040 | you know, in the operating room and in the emergency room

00:06:06.680 | for people that come in.

00:06:08.680 | You know, I work my practices in San Francisco

00:06:11.000 | right next to the Tenderloin.

00:06:12.200 | And so a lot of people that end up coming in

00:06:14.280 | from the Tenderloin have been drinking

00:06:16.840 | just spectacular amounts of alcohol for a long time.

00:06:20.360 | And their brains are, you know, very often on the scans,

00:06:25.360 | they look like small walnuts inside their empty skull.

00:06:29.280 | There's so much atrophy that happens

00:06:31.360 | with an alcohol soaked brain chronically

00:06:35.120 | that I would say that's, you know, far and away

00:06:38.600 | the most common source of brain damage

00:06:41.200 | that many of us just volunteer for.

00:06:44.960 | And it's, you know, when you look at the morbidity,

00:06:47.920 | kind of the human harm in aggregate that's done,

00:06:51.240 | it's mystifying that it's not something

00:06:55.040 | that we are all paranoid about.

00:06:57.160 | - People will think that I don't drink at all.

00:06:59.960 | I'll occasionally have a drink.

00:07:01.240 | I could take it or leave it, frankly.

00:07:04.320 | If all the alcohol on the planet disappeared,

00:07:05.640 | I wouldn't notice, but I do occasionally have a drink,

00:07:07.600 | maybe one per year or something like that.

00:07:09.840 | But I am shocked at this current state of affairs

00:07:14.280 | around alcohol consumption and advertising, et cetera.

00:07:16.960 | When I look at the data, mainly out of the UK Brain Bank,

00:07:19.120 | which basically shows that for every drink

00:07:21.240 | that one has on a regular basis,

00:07:24.760 | when you go from zero to one drink per week,

00:07:28.080 | there's more brain atrophy,

00:07:29.240 | thinning of the gray matter cortex.

00:07:30.880 | You go from one to two, more thinning.

00:07:32.920 | You go from two to three,

00:07:34.080 | and there's a near linear relationship

00:07:36.240 | between the amount that people are drinking

00:07:37.680 | and the amount of brain atrophy.

00:07:39.440 | And to me, it's just sort of obvious

00:07:42.280 | from these large-scale studies that, as you point out,

00:07:46.560 | alcohol atrophies the brain, it kills neurons.

00:07:50.320 | And I don't have any bias against alcohol

00:07:52.640 | or people that drink, I know many of them,

00:07:54.720 | but it does seem to me kind of shocking

00:07:58.000 | that we're talking about the resveratrol and red wine,

00:08:00.440 | which is at infinitesimally small amounts.

00:08:03.400 | It's not even clear resveratrol is good for us anyway,

00:08:05.320 | by the way, a matter of debate, I should point out.

00:08:09.120 | But so alcohol, certainly alcohol in excess

00:08:12.640 | is bad for the brain.

00:08:14.280 | - Sure.

00:08:15.920 | - In terms of, okay, so we have head hits,

00:08:18.920 | bad, alcohol, bad.

00:08:21.200 | You're working, as you mentioned, you're the tenderloin.

00:08:25.440 | Is there any awareness that amphetamine use

00:08:28.240 | can disrupt brain structure or function?

00:08:31.280 | - You know, that's not an area

00:08:33.160 | that I've spent a lot of time researching in.

00:08:35.280 | I, you know, I incidentally take care of people

00:08:38.240 | that have used every substance known to man

00:08:40.520 | in quantities that are, you know, spectacular,

00:08:43.680 | but I haven't specifically done research in that area.

00:08:47.080 | I'm not super well-versed on the literature.

00:08:49.880 | - I ask in part because maybe you know a colleague

00:08:53.320 | or will come across a colleague who's working on this.

00:08:55.320 | There's just such a incredible increase

00:08:59.600 | in the use of things like Adderall, Ritalin,

00:09:01.640 | modafinil, R-modafinil, which I think in small amounts

00:09:05.200 | in clinically prescribed situations can be very beneficial,

00:09:09.000 | but let's be honest,

00:09:10.800 | many people are using these on a chronic basis.

00:09:13.280 | I don't think we really know what it does to the brain,

00:09:15.600 | aside from increasing addiction for those substances.

00:09:18.440 | That's very clear.

00:09:19.400 | - Well, for better or worse,

00:09:20.720 | we're generating a massive dataset right now.

00:09:23.040 | - Well put.

00:09:24.960 | I'd like to briefly go back to our earlier discussion

00:09:30.120 | about neuroplasticity.

00:09:31.520 | You made an interesting statement,

00:09:33.120 | which is that we are not aware of any single brain area

00:09:36.440 | that one can stimulate in order to invoke plasticity,

00:09:40.400 | this malleability of neural architecture.

00:09:43.240 | Years ago, Mike Merzenich and colleagues at UCSF

00:09:47.680 | did some experiments where they stimulate nucleus basalis

00:09:51.760 | and paired that stimulation with a eight kilohertz tone,

00:09:55.600 | or in some cases,

00:09:57.560 | they could also stimulate a different brain area,

00:10:00.160 | the ventral tegmental area,

00:10:01.880 | which causes release of dopamine and pair it with a tone.

00:10:04.640 | And it seemed in every one of these cases,

00:10:07.880 | they observed massive plasticity.

00:10:11.260 | Now I look at those data

00:10:15.000 | and I compare them to the kind of classic data.

00:10:18.080 | I think it was Carl Ashley that did these experiments

00:10:20.080 | where they would take animals

00:10:20.920 | and they'd scoop out a little bit of cortex,

00:10:23.400 | put the animal back into a learning environment,

00:10:25.560 | and the animal would do pretty well, if not perfectly.

00:10:28.800 | So they'd scoop out a different region of cortex

00:10:30.560 | and a different animal.

00:10:31.400 | And by the end of maybe three, four years

00:10:33.560 | of these kinds of lesion experiments,

00:10:35.480 | they referred to the equal potential of the cortex,

00:10:39.080 | meaning they concluded that it didn't matter

00:10:41.340 | which piece of the cortex you took out,

00:10:43.480 | that there was no one critical area.

00:10:45.720 | So on the one hand, you've got these experiments that say,

00:10:49.280 | you know, you don't really need a lot of the brain.

00:10:52.640 | And every once in a while,

00:10:53.920 | a new story will come out where a person will go in

00:10:57.600 | for a brain scan for some other reason or an experiment,

00:11:00.320 | and the person seems perfectly normal,

00:11:02.080 | and they're like missing half their cortex.

00:11:05.040 | And then on the other hand, you have these experiments

00:11:07.080 | like the stimulation of basalis or VTA,

00:11:09.400 | where you get massive plasticity

00:11:10.560 | from stimulation of one area.

00:11:12.080 | I've never been able to reconcile

00:11:14.880 | these kinds of discrepant findings.

00:11:16.800 | And so I'd really like just your opinion on this.

00:11:20.000 | What is it about the brain as an organ

00:11:22.280 | that lets it be both so critical

00:11:24.460 | at the level of individual neurons and circuits,

00:11:26.640 | so, so critical, and yet at the same time,

00:11:30.040 | it's able to circumvent these,

00:11:33.200 | what would otherwise seem like massive lesions

00:11:35.680 | and holes in itself?

00:11:37.440 | - Yeah, I mean, a lot of it,

00:11:39.320 | to reconcile those experiments,

00:11:41.240 | you first account for the fact

00:11:44.080 | that they're probably in different species, right?

00:11:47.120 | You take out a particular portion of a pig or a rabbit brain,

00:11:51.000 | a small amount, you might not see a difference,

00:11:53.360 | but a small portion of a human brain,

00:11:56.480 | say the part most interested in coordinating speech

00:12:00.640 | or finger movement,

00:12:02.040 | and you're gonna see profound losses or visual cortex, right?

00:12:05.480 | Take out a small portion of V1

00:12:07.800 | and you'll have a visual deficit.

00:12:09.900 | And so species matters.

00:12:14.440 | Age matters.

00:12:16.040 | If you take out half of the brain in a very young baby,

00:12:20.360 | that baby has a reasonable chance

00:12:22.180 | of developing a high degree of function

00:12:25.840 | by having the remaining half subsume

00:12:28.880 | some of the functions lost on the other side,

00:12:31.120 | because they're very, very young

00:12:33.840 | and their brain is still developing.

00:12:35.280 | It's to some degree a blank slate

00:12:38.000 | with extremely high plasticity over many years.

00:12:41.360 | So that can overcome a lot of deficits.

00:12:43.680 | Taking an adult animal's brain

00:12:48.280 | that isn't very well differentiated functionally

00:12:51.440 | to begin with, you might not see those deficits.

00:12:53.640 | So apparently there's a lot of redundancy as well, right?

00:12:56.560 | There's a lot of say cerebellar and spinal circuits

00:12:59.200 | in other animals that generate stereotyped behavior patterns

00:13:03.960 | and might not need the brain at all

00:13:06.300 | to perform say a walking movement

00:13:08.540 | or some other sequences of motor activities.

00:13:12.360 | So a lot of that depends on the experimental setup.

00:13:16.760 | I would say in general,

00:13:18.160 | adult humans are very vulnerable

00:13:19.780 | to losing small parts of their brains

00:13:22.240 | and losing discrete functions.

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Alcohol & Other Common Causes of Brain Damage | Dr. Matt MacDougall & Dr. Andrew Huberman

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