What Alcohol Does to Your Brain | Dr. Andrew Huberman

00:00:00.000 | [Silence]

00:00:03.320 | Because of the structure of alcohol,

00:00:05.640 | it is what's called both water-soluble and fat-soluble.

00:00:09.680 | Translated into what's meaningful for you,

00:00:12.360 | what that means is when you drink alcohol,

00:00:14.680 | it can pass into all the cells and tissues of your body.

00:00:18.400 | It has no trouble just passing right into those cells.

00:00:21.740 | So unlike a lot of substances and drugs

00:00:24.680 | that actually attach to the surface of cells,

00:00:26.920 | to receptors as they're called, little parking spots,

00:00:29.200 | and then trigger a bunch of downstreams,

00:00:32.320 | like domino cascades of effects,

00:00:34.680 | alcohol actually has its own direct effects on cells

00:00:37.560 | because it can really just pass into those cells.

00:00:40.280 | So it's water and fat-soluble,

00:00:42.800 | and the fact that it can pass into so many organs and cells

00:00:46.000 | so easily is really what explains its damaging effects.

00:00:50.280 | I should mention that there are three main types of alcohol.

00:00:52.840 | There's isopropyl, methyl, and ethyl alcohol,

00:00:56.280 | and only the last one, ethyl alcohol or ethanol,

00:00:59.400 | is fit for human consumption.

00:01:01.280 | However, it is still toxic, okay?

00:01:04.320 | It produces substantial stress and damage to cells.

00:01:08.720 | I'd love to be able to tell you otherwise,

00:01:10.160 | but that's just a fact.

00:01:11.720 | Ethanol produces substantial damage to cells,

00:01:15.200 | and it does that because when you ingest ethanol,

00:01:18.560 | it has to be converted into something else

00:01:20.360 | because it is toxic to the body.

00:01:22.460 | And there's a molecule inside of all of us called NAD,

00:01:25.920 | and you may have heard of NAD because it's quite popular.

00:01:28.520 | There's a lot of discussion about NAD

00:01:30.980 | in the longevity literature right now.

00:01:32.840 | NAD is present in all our cells from birth until death.

00:01:35.500 | The levels of NAD tend to go down across the lifespan.

00:01:38.240 | There are ideas that increasing levels of NAD

00:01:40.560 | may extend lifespan.

00:01:41.560 | A lot of that is still controversial,

00:01:43.120 | or at least we should say is ongoing

00:01:44.720 | in terms of the research.

00:01:46.080 | But nonetheless, when you ingest ethanol,

00:01:48.360 | NAD and related biochemical pathways

00:01:51.000 | are involved in converting that ethanol

00:01:53.280 | into something called acetyl aldehyde.

00:01:54.880 | It's broken down into acetyl aldehyde.

00:01:57.360 | And if you thought ethanol was bad,

00:01:58.960 | acetyl aldehyde is particularly bad.

00:02:00.760 | Acetyl aldehyde is poison.

00:02:02.800 | It will kill cells.

00:02:03.880 | It damages and kills cells,

00:02:05.480 | and it is indiscriminate as to which cells

00:02:07.480 | it damages and kills.

00:02:09.800 | Now, that's a problem, obviously,

00:02:12.680 | and the body deals with that problem

00:02:14.840 | by using another component of the NAD biochemical pathway

00:02:19.240 | to convert acetyl aldehyde into something called acetate.

00:02:23.520 | Acetate is actually something

00:02:24.800 | that your body can use as fuel.

00:02:27.040 | And that process of going from ethanol

00:02:30.280 | to acetyl aldehyde to acetate

00:02:32.080 | does involve the production of a toxic molecule, right?

00:02:36.240 | Again, acetyl aldehyde is really toxic.

00:02:38.440 | And NAD, and if we want to get technical,

00:02:40.920 | it's the NAD to NADH ratio.

00:02:44.320 | And that chemical step

00:02:47.160 | is the rate-limiting step to ethanol's metabolism.

00:02:49.520 | What does that mean for you?

00:02:51.000 | What that means is that if your body

00:02:53.280 | can't do this conversion of ethanol

00:02:55.240 | to acetyl aldehyde to acetate fast enough,

00:02:58.000 | well, acetyl aldehyde will build up in your body

00:03:00.360 | and cause more damage.

00:03:02.000 | So it's important that your body

00:03:03.880 | be able to do this conversion very quickly.

00:03:06.640 | And the place where it does that is within the liver.

00:03:10.000 | And cells within the liver

00:03:11.400 | are very good at this conversion process,

00:03:14.480 | but they are cells and they are exposed

00:03:16.800 | to the acetyl aldehyde in the conversion process.

00:03:19.440 | And so cells within the liver really take a beating

00:03:22.000 | in the alcohol metabolism events.

00:03:26.240 | So the key thing to understand here

00:03:28.560 | is that when you ingest alcohol,

00:03:30.280 | you are, yes, ingesting a poison,

00:03:32.200 | and that poison is converted

00:03:33.560 | into an even worse poison in your body.

00:03:35.280 | And some percentage of that worse poison

00:03:37.280 | is converted into a form of calories

00:03:39.320 | that you can use to generate energy, generate ATP.

00:03:43.040 | And the reason why alcohol is considered empty calories

00:03:46.320 | is because that entire process

00:03:47.800 | is very metabolically costly,

00:03:49.560 | but there's no real nutritive value

00:03:51.920 | of the calories that it creates.

00:03:54.200 | You can use it for immediate energy,

00:03:56.120 | but it can't be stored

00:03:57.440 | in any kind of meaningful or beneficial way.

00:03:59.640 | It doesn't provide any vitamins.

00:04:01.280 | It doesn't provide any amino acids.

00:04:02.960 | It doesn't provide any fatty acids.

00:04:04.840 | It's truly empty calories.

00:04:06.720 | I know some people talk about sugar as empty calories,

00:04:08.800 | but sugar actually is a far better fuel source

00:04:11.480 | than alcohol or acetate.

00:04:14.000 | But nonetheless, when you ingest alcohol,

00:04:16.920 | some percentage is being shuttled into a worse poison,

00:04:20.080 | and some is being shuttled into a fuel source.

00:04:23.520 | Now, the important thing to understand

00:04:25.240 | is that it is the poison, the acetyl aldehyde itself,

00:04:29.080 | that leads to the effect of being inebriated or drunk.

00:04:33.600 | I think most people don't realize that,

00:04:34.880 | that being drunk is actually a poison-induced disruption

00:04:39.200 | in the way that your neural circuits work.

00:04:41.160 | And so we should ask ourselves,

00:04:42.800 | which neural circuits, what brain areas,

00:04:45.080 | what body areas involved in feeling drunk or inebriated?

00:04:48.640 | In thinking about the biochemical effects of alcohol

00:04:50.760 | and what it's doing to the body,

00:04:52.560 | what it's doing in all cases

00:04:54.920 | is it's consumed into the gut, right?

00:04:57.960 | Goes into the stomach.

00:04:58.800 | The liver immediately starts this conversion

00:05:00.640 | that we talked about before

00:05:01.560 | of ethanol to acetyl aldehyde to acetate.

00:05:03.800 | And some amount of acetyl aldehyde and acetate

00:05:06.000 | are making it into the brain.

00:05:07.120 | It crosses the blood-brain barrier.

00:05:08.600 | Again, the brain has this fence around it

00:05:10.520 | that we call the blood-brain barrier or the BBB.

00:05:13.040 | Many things, most things, thankfully,

00:05:15.600 | can't pass across the blood-brain barrier,

00:05:17.740 | but alcohol, because it's water and fat soluble,

00:05:19.980 | just cruises right across this fence

00:05:21.980 | and into the milieu, the environment of the brain,

00:05:25.160 | which is made up of a couple of different major cell types,

00:05:27.280 | neurons, nerve cells, and so-called glial cells,

00:05:29.580 | which are in between the nerve cells.

00:05:31.560 | And we'll talk about the effects on each of those soon.

00:05:34.560 | So what happens when alcohol gets into the brain

00:05:36.480 | that makes us feel tipsy or drunk?

00:05:38.040 | And in some people, makes people feel really,

00:05:40.920 | especially energized and happy.

00:05:42.980 | Well, alcohol is indiscriminate

00:05:45.840 | in terms of which brain areas it goes to.

00:05:48.480 | Again, it doesn't bind to particular receptors,

00:05:50.920 | but it does seem to have a propensity or an affinity

00:05:54.880 | for particular brain areas that are involved

00:05:56.520 | in certain kinds of thinking and behavior.

00:05:58.240 | So one of the first things that happens

00:06:00.360 | is that there's a slight,

00:06:02.120 | at least after the first drink or second drink,

00:06:05.040 | there's a slight suppression in the activity of neurons

00:06:08.560 | in the prefrontal cortex.

00:06:09.920 | This is an area of your neocortex

00:06:12.200 | that's involved in thinking and planning,

00:06:14.260 | and perhaps above all,

00:06:16.260 | in suppression of impulsive behavior.

00:06:19.460 | So if you go to a party and they're serving alcohol

00:06:22.340 | and people are consuming drinks,

00:06:23.900 | what you'll notice is that a few minutes into that party,

00:06:26.900 | the volume of people's voices will increase.

00:06:29.180 | And that's because people are simply not paying attention

00:06:31.380 | to their voice modulation.

00:06:32.620 | As other people start speaking more loudly,

00:06:34.360 | other people are speaking more loudly.

00:06:35.580 | We've all had this experience, right?

00:06:36.780 | Of going to a party and then you step outside for a moment

00:06:39.220 | and you go, "Oh my goodness, I was shouting."

00:06:40.620 | You come home the next day, you got a sore throat.

00:06:42.360 | It might be that you picked up some sort of bug,

00:06:44.140 | some virus or something.

00:06:45.540 | But oftentimes it's just the fact

00:06:47.460 | you've been shouting all night just to be heard

00:06:49.020 | because as the prefrontal cortex shuts down,

00:06:51.440 | people stop modulating their level of speech quite as much.

00:06:56.000 | Also notice that people start gesticulating more.

00:06:58.360 | People will start standing up and sitting down more.

00:07:00.720 | They'll start walking around more.

00:07:01.800 | If there's music on,

00:07:02.640 | people might spontaneously start dancing.

00:07:04.960 | All of this is because these areas

00:07:07.160 | of the prefrontal cortex normally are providing

00:07:09.120 | what's called top-down inhibition.

00:07:10.960 | They are releasing a neurotransmitter called GABA

00:07:14.080 | onto various parts of the brain.

00:07:15.720 | They're involved in impulsive motor behavior

00:07:17.620 | and thought patterns.

00:07:18.880 | And as you shut down the prefrontal cortex,

00:07:20.960 | that GABAergic suppression of impulses

00:07:24.560 | starts to be released.

00:07:25.400 | So people will say things that they want to say

00:07:28.360 | without so much forethought about what they're saying.

00:07:31.300 | Or they might do things that they want to do

00:07:33.720 | without really thinking it through quite as much.

00:07:35.840 | Or they might not even remember thinking it through at all

00:07:38.240 | or experience, I should say, thinking it through at all.

00:07:40.200 | We haven't talked about blacking out yet

00:07:41.600 | in the effects of alcohol on memory.

00:07:43.520 | But as long as we're there,

00:07:44.480 | I'll just tell you that alcohol has a very strong effect

00:07:47.560 | in suppressing the neural networks

00:07:49.240 | that are involved in memory formation and storage.

00:07:52.120 | This is why oftentimes we forget the events of a night out

00:07:55.920 | if we've been drinking.

00:07:57.720 | One of the more important things to know

00:07:59.460 | about the effects of alcohol in the brain

00:08:01.920 | is this disruption in top-down inhibition,

00:08:04.780 | but also that areas of the brain

00:08:07.760 | that are involved in flexible behavior,

00:08:10.600 | sort of considering different options.

00:08:12.120 | Like I could do A or I could do B.

00:08:13.600 | I could say this to them or I could say that.

00:08:15.400 | I could say it in that way or I could say it in this way.

00:08:17.560 | This might be a little more tactful.

00:08:19.480 | Those brain areas basically shut down entirely

00:08:22.640 | and people just tend to say what they want to say.

00:08:24.800 | So the key thing to understand is that when people drink,

00:08:27.520 | the prefrontal cortex and top-down inhibition is diminished.

00:08:32.120 | That is habitual behavior and impulsive behavior

00:08:35.400 | starts to increase.

00:08:37.040 | Now, what's interesting is this is true in the short term.

00:08:40.120 | So after people have one or two,

00:08:41.600 | maybe three or four drinks,

00:08:43.200 | but it's also true that the more often that people drink,

00:08:47.960 | there are changes in the very circuits

00:08:51.480 | that underlie habitual and impulsive behavior.

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What Alcohol Does to Your Brain | Dr. Andrew Huberman

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