Effects of Cannabis (Marijuana) on Adolescent & Young Adult Brain | Dr. Andrew Huberman
00:00:00.000 | [Silence]
00:00:02.740 | Cannabis is a unique instance in which nowadays
00:00:05.980 | we are hearing, yes, it's becoming legal
00:00:08.780 | in a number of areas.
00:00:09.620 | And we talked earlier about why that's probably a good thing
00:00:11.840 | in most circumstances, but that we aren't just hearing
00:00:14.780 | that cannabis is safe, or it's not just being implied
00:00:18.420 | that cannabis is safer, but many more people are talking
00:00:22.340 | about the positive effects of cannabis
00:00:25.060 | without a lot of discussion
00:00:26.580 | about the negative effects of cannabis.
00:00:28.580 | And I realize that saying this is going to upset
00:00:30.840 | some people out there because I know that there are a number
00:00:32.660 | of people who fought very hard for the legalization process,
00:00:35.300 | and I want to acknowledge that.
00:00:37.100 | I also want to acknowledge the many known positive effects
00:00:41.940 | of cannabis in adults with very occasional use,
00:00:46.740 | provided it is delivered safely
00:00:49.500 | and in the safe context and setting and with legality.
00:00:53.780 | That is entirely distinct from the issue
00:00:56.260 | of whether or not cannabis is safe
00:00:57.700 | for the developing brain and body.
00:00:59.920 | Again, I'm not demonizing anybody for using cannabis,
00:01:04.120 | but I want to make the point very simply and very directly.
00:01:07.020 | It is far and away a different circumstance for the brain,
00:01:11.520 | for an individual to be 25 years or older
00:01:16.140 | and using cannabis in whatever form,
00:01:19.460 | occasionally, or maybe even frequently,
00:01:21.980 | than it is for a young person, age 14 to 25,
00:01:26.980 | to be using cannabis, either by smoking or vaping,
00:01:30.860 | or by edible or any other form on the brain and body.
00:01:35.500 | It's absolutely clear that the brain continues to develop
00:01:38.500 | at least until age 25 and that a huge number of systems
00:01:42.220 | related to mood regulation, so-called executive function,
00:01:45.540 | the ability to organize one's thoughts, plan,
00:01:47.700 | and execute plans,
00:01:49.740 | essentially to become a functional human being, right?
00:01:52.300 | That's one portion of becoming a functional human being,
00:01:54.740 | but certainly an essential one.
00:01:56.860 | All of that relies on the fine-tuning
00:01:59.260 | of this neural circuitry that we've been talking about
00:02:02.220 | up until now.
00:02:03.900 | And it's abundantly clear that cannabis and THC
00:02:08.540 | in particular, dramatically disrupt those processes.
00:02:13.540 | So if this isn't clear enough just from my statements,
00:02:18.180 | I'd like to point to a particular paper.
00:02:20.220 | This is one of the more impactful papers
00:02:21.860 | in this area in recent years.
00:02:23.900 | This is a paper published in "Lancet Psychiatry" in 2022.
00:02:27.900 | Title is "Association of Cannabis Potency
00:02:30.940 | with Mental Ill Health and Addiction, a Systematic Review."
00:02:34.540 | There are a number of very important points
00:02:36.180 | in this very fine paper.
00:02:37.980 | "Lancet Psychiatry" is one of the premier
00:02:40.460 | medical journals out there,
00:02:41.860 | and they evaluated a huge number of studies.
00:02:45.660 | They actually looked at more than 4,000 studies.
00:02:48.660 | They selected the ones that were only the most rigorous
00:02:51.780 | in terms of study design and analysis
00:02:54.700 | and rigor of conclusions.
00:02:56.860 | And they looked at how early use of cannabis
00:03:00.660 | impacted later probability of development of psychosis
00:03:05.100 | and other psychiatric conditions.
00:03:07.180 | And the takeaways from this study are very clear.
00:03:10.820 | First of all, chronic cannabis use,
00:03:14.060 | so more than twice per week,
00:03:15.540 | has consistently been associated
00:03:17.220 | with mental health disorders.
00:03:18.580 | I'm pulling some phrases directly from the paper.
00:03:21.180 | Heavy cannabis use,
00:03:23.340 | meaning cannabis use more frequent than twice per week,
00:03:26.860 | has been associated with four times
00:03:29.580 | the risk of psychosis later in life.
00:03:31.420 | In particular, schizophrenia and bipolar-like episodes.
00:03:34.940 | Now, we've done an episode on bipolar disorder,
00:03:37.260 | so-called bipolar depression.
00:03:38.900 | We have not yet done one on schizophrenia,
00:03:40.460 | but both bipolar disorder and schizophrenia
00:03:43.020 | have a very, very strong genetic component.
00:03:46.100 | There's a 30, three, zero,
00:03:47.980 | 30 times greater likelihood that you'll have bipolar disorder
00:03:50.820 | if you have a first relative who has bipolar disorder.
00:03:53.660 | And then it's also the case that using cannabis,
00:03:57.260 | especially during adolescence and the teen years
00:04:00.020 | and up until age 25,
00:04:01.700 | create a four times greater risk of psychosis
00:04:05.020 | for those that have a predisposition to bipolar disorder
00:04:08.460 | and/or schizophrenia.
00:04:10.100 | Now, I don't hear very much about this in the media.
00:04:12.900 | This paper got some attention
00:04:14.300 | and then it sort of got swept away.
00:04:17.020 | I don't think that was an intentional sweeping way.
00:04:18.700 | There's just a lot of events in the world, as you well know.
00:04:22.020 | But I think it's a particularly important set of findings
00:04:25.420 | because obviously in looking at so many studies,
00:04:29.180 | it distills out the strongest findings that are out there
00:04:31.540 | and really pulls the consistent messages
00:04:34.820 | that are arriving from all these different studies.
00:04:36.940 | And as they point out, and again, I'm paraphrasing here,
00:04:40.220 | this is the first systematic review
00:04:41.820 | of the association of cannabis potency.
00:04:45.060 | And all of the data point to a very clear conclusion,
00:04:47.540 | which is the more potent the THC concentration,
00:04:52.540 | the higher probability of developing psychosis
00:04:54.900 | or a major depressive episode
00:04:56.420 | or a major anxiety disorder later in life.
00:04:58.860 | That should be of particular concern because we know,
00:05:03.040 | we are absolutely clear about the fact that
00:05:05.740 | with the advent of all these new strains of cannabis
00:05:08.980 | and with the engineering and availability of cannabis
00:05:13.780 | at much higher potency, meaning THC potency,
00:05:18.300 | the risk of psychosis is going up and up
00:05:21.200 | and is likely to continue going up
00:05:22.740 | unless something is done to reduce
00:05:25.340 | the frequency of cannabis use to zero, ideally,
00:05:30.340 | or to very low frequency, very low potency
00:05:33.420 | in adolescents and teens and people age 25 or younger.
00:05:37.860 | I know a lot of people don't want to hear this message
00:05:40.120 | because first of all, it's alarming.
00:05:41.420 | And second of all, as I mentioned earlier,
00:05:44.040 | the statistics tell us that the greatest number of people
00:05:47.380 | that are starting to use cannabis
00:05:48.740 | are in the age bracket of 16 to 24.
00:05:51.480 | Many of them are functional in other areas of life.
00:05:54.600 | They are students, they are employed, et cetera.
00:05:57.940 | But when you couple that with the fact
00:06:00.060 | that the most frequent adopters of cannabis use
00:06:02.780 | are in this age bracket of 16 to 24,
00:06:05.500 | they're twice as likely to use as other individuals
00:06:08.860 | or to start using cannabis as are other individuals,
00:06:11.720 | plus the general perception out there
00:06:13.740 | because of the way that cannabis is discussed in the media
00:06:16.820 | and by sports figures and by celebrities
00:06:19.020 | and by politicians, et cetera,
00:06:21.460 | that it's not as bad as alcohol and maybe not that bad
00:06:25.140 | and maybe even has health benefits,
00:06:27.820 | then you're essentially setting up a system
00:06:29.220 | where young people are far more likely
00:06:31.260 | to adopt and continue cannabis use
00:06:33.920 | without realizing these serious health consequences
00:06:36.880 | that await them later.
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