How Nicotine Impacts Your Brain & Enhances Focus

00:00:00.000 | [silence]

00:00:02.660 | Today, it's really simple.

00:00:03.700 | Nicotine only binds to the nicotinic acetylcholine receptors

00:00:06.540 | and there are a bunch of different ones

00:00:08.180 | on a bunch of different tissues.

00:00:09.740 | And the differences in those receptors

00:00:12.500 | dictate what sorts of effects

00:00:15.220 | the nicotine will have on those tissues.

00:00:17.940 | So let's talk about what those effects are.

00:00:19.580 | And let's do that by dividing the effects of nicotine

00:00:22.020 | into effects on the brain.

00:00:23.640 | So everything from the neck up and on the body,

00:00:26.180 | the so-called central nervous system and the periphery.

00:00:28.640 | Although I want to point out that your spinal cord

00:00:30.080 | is part of the central nervous system.

00:00:31.280 | So in fairness to the reality,

00:00:33.880 | your brain and spinal cord are all central nervous system.

00:00:36.920 | Everything else is considered the periphery.

00:00:39.420 | Now there are a lot of different

00:00:40.440 | nicotinic acetylcholine receptors,

00:00:42.240 | but for those of you that want to know,

00:00:43.800 | you aficionados or if you're ultra curious about this,

00:00:47.280 | the main effects of nicotine in the brain

00:00:50.060 | are mediated by nicotine binding

00:00:52.800 | to the so-called alpha-4 beta-2 receptor.

00:00:56.280 | Alpha-4 beta-2 receptor.

00:00:58.640 | Even if you don't care about receptor subtypes,

00:01:01.080 | that's going to come up later when we discuss

00:01:02.960 | why nicotine suppresses appetite.

00:01:05.880 | In fact, one of the major reasons

00:01:07.200 | why people don't want to quit smoking,

00:01:09.480 | or they quit smoking or another form of ingesting nicotine,

00:01:13.080 | and then they relapse,

00:01:14.640 | they go back to smoking or ingesting nicotine

00:01:17.600 | in some other way,

00:01:18.560 | is because indeed nicotine will increase metabolism

00:01:22.360 | and reduce hunger in large part

00:01:24.740 | by binding to this alpha-4 beta-2 receptor

00:01:27.400 | in a particular area of the brain.

00:01:28.480 | We're going to return to that in a little bit,

00:01:29.600 | but if you've ever heard that nicotine kills the appetite,

00:01:32.560 | indeed it does.

00:01:34.000 | It's not the behavior of smoking itself.

00:01:35.600 | It's not because you always have a cigarette in your mouth

00:01:37.240 | that you're not eating more food,

00:01:38.560 | although I suppose that might be a minor effect.

00:01:40.760 | There are direct effects of nicotine on both appetite,

00:01:44.040 | that is it reduces appetite,

00:01:45.480 | and direct effects on metabolism,

00:01:47.240 | that is it increases metabolism through its effects

00:01:49.520 | on some other areas of the brain and body

00:01:51.120 | we'll talk about in a moment.

00:01:52.400 | And within the brain,

00:01:53.740 | nicotine binds to this alpha-4 beta-2 receptor

00:01:57.740 | in various locations in the brain.

00:01:59.420 | And there are three and maybe a fourth

00:02:01.740 | that we'll talk about neurochemical effects of nicotine

00:02:04.940 | after you ingest it.

00:02:06.060 | First things first,

00:02:07.180 | when you ingest nicotine by smoking,

00:02:09.660 | nicotine containing tobacco,

00:02:11.880 | or if you place tobacco in contact with the mucosal lining

00:02:16.380 | of the nasal passages of the mouth,

00:02:18.700 | takes about two to 15 minutes

00:02:21.920 | for that nicotine to enter the bloodstream.

00:02:23.380 | Smoking hits the bloodstream faster,

00:02:25.400 | vaping even faster, I should mention,

00:02:27.920 | for a variety of reasons,

00:02:29.320 | and placing tobacco directly in contact

00:02:32.640 | with the mucosal lining is going to be the slowest.

00:02:35.320 | Now, as I mentioned before,

00:02:36.480 | nicotine gets into the bloodstream,

00:02:37.960 | and then because nicotine can pass

00:02:39.960 | through the so-called blood-brain barrier, the BBB,

00:02:43.160 | which is basically a fence around the brain,

00:02:45.600 | because it can pass through the blood-brain barrier,

00:02:47.860 | it's going to have very rapid effects on the brain

00:02:50.080 | in these four major categories

00:02:52.140 | of neurochemicals and neural circuits.

00:02:55.360 | The first of those categories,

00:02:56.920 | and this is a very important one,

00:02:58.600 | this is one that was brought up in the episode

00:03:00.200 | on dopamine motivation and drive,

00:03:01.640 | and I think not just all scientists,

00:03:03.720 | but all human beings should know that within their brain,

00:03:06.760 | they have what is called the mesolimbic reward pathway.

00:03:11.760 | The mesolimbic reward pathway,

00:03:13.120 | if you just want to call it the dopamine reward pathway,

00:03:15.860 | is, as the name suggests,

00:03:17.600 | a set of connections between a brain area

00:03:19.480 | called the ventral tegmental area.

00:03:21.000 | You don't have to remember the names of these things,

00:03:23.000 | of course, but if you want to, that's fine too.

00:03:25.280 | The ventral tegmental area, or VTA,

00:03:27.720 | connects to another area called the nucleus accumbens.

00:03:31.400 | Now, here's what's very important.

00:03:32.960 | Nicotine triggers the release of dopamine

00:03:36.940 | from the nucleus accumbens.

00:03:38.200 | This is what gives nicotine its rewarding properties.

00:03:41.280 | It increases motivation.

00:03:42.640 | It tends to give a not so subtle,

00:03:45.740 | but very transient increase in feelings of wellbeing

00:03:49.400 | and alertness and motivation,

00:03:51.380 | and that's because of the increase in dopamine

00:03:53.300 | caused by nicotine directly within the nucleus accumbens.

00:03:57.100 | Nicotine also triggers the release of certain neurochemicals

00:04:01.820 | from the ventral tegmental area itself,

00:04:04.060 | and those impinge on nucleus accumbens

00:04:06.380 | and increase dopamine levels further.

00:04:08.740 | This is what makes the rewarding properties,

00:04:11.100 | or sometimes referred to as the reinforcing properties

00:04:13.700 | of nicotine, so powerful.

00:04:15.240 | This is why so many billions of people ingest nicotine

00:04:19.620 | in one form or another.

00:04:20.620 | It's also why nicotine is so hard to quit,

00:04:24.620 | because there's a potent increase in dopamine

00:04:27.380 | from multiple neural circuit pathways

00:04:29.620 | within this mesolimbic reward circuitry.

00:04:32.860 | Now, within the mesolimbic reward circuitry,

00:04:35.540 | there's an interesting feature.

00:04:36.500 | There are accelerators that essentially

00:04:38.580 | push out more dopamine, get more dopamine released,

00:04:41.420 | and there are breaks of the so-called GABAergic variety.

00:04:44.340 | GABA is an inhibitory neurotransmitter.

00:04:46.460 | You don't need to know too much about it

00:04:47.580 | to just understand that nicotine both increases dopamine,

00:04:52.160 | but also decreases the activity of GABA,

00:04:55.900 | and so this is like pushing on the accelerator for dopamine,

00:04:59.260 | but also removing the break.

00:05:01.180 | So there's a two-pronged effect of nicotine

00:05:04.460 | on reinforcement reward dopamine-related pathways,

00:05:07.820 | the feel-good motivation pathways,

00:05:10.500 | and that is an increase in dopamine and a decrease in GABA,

00:05:15.020 | and again, that's all mediated

00:05:16.420 | through this mesolimbic reward pathway

00:05:17.860 | involving the ventral tegmental area

00:05:19.820 | and the nucleus accumbens.

00:05:21.220 | So if you can conceptualize even just 5%

00:05:23.660 | of what I just told you,

00:05:24.820 | or even if you can just remember nicotine increases dopamine

00:05:27.820 | and that's why it feels so good,

00:05:29.180 | it makes you want more of it,

00:05:31.200 | you will have everything you need to know in mind

00:05:33.900 | in order to understand both why nicotine is so highly used

00:05:38.900 | and indeed abused, why it's so hard to quit,

00:05:41.780 | and that will point to avenues

00:05:43.300 | as to how to quit or reduce intake,

00:05:45.620 | and it also points to how nicotine can actually be used

00:05:48.700 | in an antidepressant way should you choose,

00:05:52.200 | and we will talk about what the various criteria are

00:05:54.720 | for choosing that,

00:05:55.860 | but just understand nicotine increases motivation,

00:05:59.580 | it decreases negative feelings of mood,

00:06:02.220 | it increases positive feelings of mood and motivation.

00:06:05.540 | (upbeat music)

00:06:08.120 | [MUSIC PLAYING]

00:06:11.480 | you

How Nicotine Impacts Your Brain & Enhances Focus | Dr. Andrew Huberman

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