Psychiatry & Psychotherapy Podcast - IQ: Predictability, Influences, Genes, Environment, & Trauma

Episode Date: December 8, 2019

What is intelligence? Why is IQ controversial? In this week's episode Nelson Horsley (a 4th year medical student) and David Puder, M.D. discuss the IQ - if it is a predictor for a successful life, and what things can predict or influence IQ. By listening to this episode, you can earn 2 Psychiatry CME Credits. Link to blog. Link to YouTube video.

Hello and welcome to the Psychiatry and Psychotherapy Podcast. I'm here to talk about getting rid of burnout, increasing job satisfaction, and feeling like an expert in what you do. One thing that created a lot of burnout and angst for me was trying to get continued medical education right at the last minute. So why not join the CME membership and do CMEE while listening to this podcast? Go to Psychiatrypodcast.com, sign up, sign in, take the test, and the certification is email to you in seconds. Welcome back to the podcast. Today I'm joined with a fourth year medical student doing a rotation with me, Nelson Horsley. And we have been looking at IQ for a couple months and thinking about the clinical significance of IQ, why it's measured in different populations. What are some of the things that can lower IQ is IQ genetic or environmental? And we're going to be doing a deep dive into it. I think it's going to be really valuable. especially in a culture that sometimes says like, oh, you know, mental health can't be measured, right? Or like there's no biological markers of mental health issues, right?

And what we'll find is that over and over again, untreated mental health issues cause worse cognitive functioning. And, you know, getting effective treatment can actually improve cognitive functioning back to baseline or optimize it. So, Nelson, welcome to the podcast. Glad to be here. Yeah. Just for you guys who may want to look at some of these citations and studies, we are going to have a really nice handout. Currently, it's at like 64 pages and we'll put it in the resource library. So you can click the show notes to the resource library and check that out.

So what is IQ? IQ has been, well, first of all, it stands for intelligence quotient if people don't know that. And so it's a measure of intelligence. what is intelligence. It's been defined a lot of ways. There's been a lot of debate over that over the years, but one of the definitions we see doing research again and again is by Godfordson, when they assembled a task force in 1997 to summarize what intelligence findings they had. They defined it as a very general mental capability that, among other things, involves the ability to reason, plan, solve problems, think abstractly, comprehend complex ideas, learn quickly and learn from experience.

It's not merely book learning, a narrow academic skill, or test-taking smarts. Rather, it reflects a broad and deeper capability for comprehending our surroundings, catching on, making sense of things, or figuring out what to do. So that's a bit of a mouthful, but I think we can all kind of understand that definition. We've seen this. We know that, you know, different people have different, capabilities in this regards. No judgments over where those come from. But I think that's a pretty good definition for what we'll be talking about. Yeah, good. And tell me a little bit about

the history of IQ. How did how do the current ways that we study it come to be? Yeah. So it's actually a pretty recent history. I mean, obviously if you look back in history like Odysseus being very clever. There's an Anansi. There's smart people throughout history, but it didn't really take off as a science until the early 19th century. And it wasn't a good science until a while later. So Francis Galton, he's famous British polymath, cousin of Darwin. He wanted to find some tests for eminence. He wanted to study what made some people famous scientists or successful politicians. And he came up with a number of tasks to try to do this. He was kind of an independent researcher. So the first time, in intelligence tests got used to measure human ability was by the French physician,

Eduardo Seguin. He usually was using it to classify children with intellectual disability. Throughout history, these really got started in World War I, where they, you were used to test soldiers, measure who should be an officer. They increased in popularity without the 20s and 30s. People came up with new tests. Westler is probably the biggest. IQ tests the most applied today. And that was originally created back in 1939 by a psychologist in New York. And that combined different measures of IQ. So initially, a lot of these tests would test verbal abilities. They test how well you can respond to questions. They test general knowledge. And a lot of people had problems with that because obviously a lot of that is based off where you come from, what kind of

background you have. And also because people wanted to measure the abilities of immigrants coming in who didn't have the same background, a lot of people started wanting different tests that could measure abilities that weren't dependent on what language you spoke or if you came from an educated background. So, performance testing came about. And Westler was one of the first to put together verbal and performance testing. So performance testing, that would be analyzing patterns. It would be looking at pictures, identifying something that's out of place, things that most people agree to be more objective measures.

But verbal is a useful measure too. So the Weschler is still the main one. It's in its fifth edition. The next edition comes out in 2021. And it is used very often for neuropsychiatric measurements, psychological measurements. Yeah, I probably order one. every two weeks or so. Someone comes in, ADHD,

and I want to check IQ and attention. And it really does give me an idea of what is their capacity versus what are, how are they performing in school? So, for example, someone has a high IQ, but a low GPA and poor attention issues. That's kind of the classic finding with ADHD. Okay. So we'll get more into that later.

So as you think about the history, any of any key takeaways from the history, like things that you think were surprising? Yeah. I think some people don't realize just kind of, well, the one thing that we really need to talk about when we talk about this is some of the negative history that's gone on. IQ test were administered to a lot of poor people, especially in the United States, especially in California. and there's an estimated 64,000 people who were sterilized in this country for being mentally feeble throughout the early 20th century, even going past the 70s. There were a number of cases documented there. There's also a connection with the Nazi regime in Germany.

It would actually justify it. It's some of the atrocities in the Holocaust in the 1970s, basically, oh, America, you did this too. So there's all this history there that I think really has given a lot of this a bad name that people think, a lot of people will think, oh, this is useless, this is bad science, this is like looking at the bumps on your skull, this isn't anything that we should still be caring about or paying attention to in the 21st century. And I'd like to say just that psychologists, they have looked at the results.

They do take many steps to make sure that these tests are biased. They apply them to different populations. They take out those bad test questions that are culturally biased. And while things aren't perfect, I don't think anyone would deny that there's no bias or nothing that could be better. I think that the test today are very different from the tests back in the day. Yeah. And when I heard about the sterilization in the U.S., that was like, I was like, wow, I cannot believe that. That seems so foreign to my like, you know, how I think the world runs nowadays, you know,

just general, you know, humanity and the value of humanity. So I think that's, it's just really painful to hear those stories about how it was used. When I think about IQ and the importance of why is important to talk about this episode, I think it's another tool that we have in psychiatry and psychotherapy to us. understand how the mind works, and also, like, what are some things that are potentially detrimental to human flourishing, and also the value of therapy. So that's something we're going to focus in on. So tell me about can IQ change? Can IQ change? That's a difficult question. We do know that IQ is relatively stable over lifetime, but we do see time and time again

that there's environmental influences, which will go over. Yeah, it can change. Right, it can change. It can get worse and it can get better. Yes. And that was interesting when I looked at a graph of specifically the population that was studied at, what, 12 and then 90? 90. Yeah.

And they found that if you look at the graph, there's a linear relationship so that, you know, people's IQ. remained what? What was the correlation? It was about 5.7, then 0.64 adjusted. 0.64. So there is a, you know, correlation that's strong, not completely strong, right, but it's there. And some people are on the side where their IQ decreased, and some are on the side where their IQ increased. And some are on the side where their IQ increased. and they tried to exclude cases of dementia, but there's always early onset stuff that is harder to screen. Studies that showed less time variation are a little bit more strongly correlated.

But I think that there are variables that can increase cognitive function over time. So I did a series on Sensorium. I think some of the same things are things that we found here. So why? I'd just like to jump in real quick about, we're talking about IQ and we're talking about intelligence,

and it sounds, I think, to most people, like we're probably talking about the same thing. IQ is a measure of intelligence. So it's trying to approximate intelligence to the best of the test maker's ability, but it's a measure. And it's, so I think that's an important distinction. So each time you take an IQ test,

you are not going to get the same score. the correlation between taking one test and taking the test again, it's about 0.8 or 0.9. So we're talking about if IQ can change, it changes every time you take the test. When we talk about intelligence, well, that can mean more things too. That can mean your education level. That can mean, you know, even your cultural background, which IQ doesn't even try to measure. If you know a lot about the history of South America, we're not going to capture that an IQ test. But if you talk to other people on the street, you'd say that,

you know, being a South American scholar, that that's in evidence of intelligence. So IQ itself, we put it on a scale. We set 100 as the baseline. So IQ is standardized. 100 is the average. And the standard deviation is 15. 15 points. 15 points.

So that means that, what, 67% of the population will fall in one standard deviation above? So at 115 to one standard deviation below 85. Exactly. Yeah. And it used to be based on mental age. And so actually switching to the 100-based IQ, that was another innovation of Wexler. And that was so he could give numbers for adults. He didn't think it made sense to give an adult who's intellectually disabled an IQ rating of a children because they're going to have different skills, different mental abilities as children. You should measure adults as adults. Yeah. Okay. So why think about IQ? I'd think about IQ because IQ's a very useful tool. In medicine, we use all kinds of scales to help us evaluate what to do with our patients, if they need surgery, if they're in a coma. We use the Glasgow Coma scale. So I'd say IQ, we can think of it as a scale, anything like these other scales that we use.

It's useful because it's predictive. If we get an IQ test of a child, if they're 12, we can actually need. know a lot about how they tend to play out throughout the rest of their lives. We don't know for sure, and there's all kinds of other variables, but IQ can tell you if someone's more likely to make lots of money or less money, if they're going to get years of education or not years of education, if they're going to be healthy or not. So I think the main use of IQ is just setting a baseline and helping us make better decisions for patients and knowing better about what they'd be capable of when they're healthy.

I think that's an important thing when it comes to psychotherapy. Well, I think there's a couple things in there, which it may be important to pull out some nuance. First of all, we're not, at least I don't feel like I'm making decisions for patients as a psychiatrist. I feel like I'm coaching people and listening to them and trying to help them find out what they're going to be best at. The second thing is if someone's acutely depressed, their IQ, their cognitive function is going to be lower. Yeah.

So I think sometimes we can get a cloudy picture of this, and I have some examples that are just very strong in that category. If someone's had a lot of trauma in their childhood and they haven't processed through that, their IQ is going to be lower from what we've seen in the data here. Yeah. Once again, this is a score. and whenever you take a test, you know, we talk about IQ as a concept. We're kind of equivocating with intelligence there that that's going to be stable. But whenever you've been through in your life, whatever you've been exposed to,

whatever is going on around you, just when you take the test, that's all going to have an important influence on what kind of score you get. And the score isn't everything. People are more than a number. I think that a lot of the times, because these things are predictive on large scale, we kind of overshoot how important they are in a personal scale. Yep. And so here's one example.

I had a patient who was in a partial program, and we were wanting to evaluate her cognitive function. And so we had her do an IQ test and ADHD test, and she scored very low, like one standard deviation below the mean, if I remember correctly. And she was currently in kind of a dissociated chronic state and she had a lot of unprocessed trauma. Okay. Her, she had a history of doing well at different times in her life and then kind of getting into these depressive episodes,

very suicidal and doing poorly. This patient I followed for many years after and she went on to graduate college, be successful in her work endeavors. And I bet you anything, if we retested her, her scores would be a lot higher than when she was like acutely in that ill state. So one, that showed me the power of how this intellectual quotient can vary, right? Exactly. And two, it showed me the power of getting effective treatment and to allow her to thrive. And so sometimes I'll have a medical student who comes through and they're, you know, they may have done well at some point in their life, but they're suffering, they're not doing

well on their step scores, they've been depressed, and getting them out of a state of depression and keeping them out is very, very important. And so sometimes we'll do like a day treatment program five days a week, seven hours a day, and, you know, do medications and so lots of psychotherapy treatment. And then they get out of depression, retest, they're doing so much better, so much better. And so the other really important thing to take away is to think about how someone's doing currently in their schooling. And, you know, when is it necessary to say, okay, let's take a leave, let's get our mental health under control and let's go back. Those are decisions that psychiatrists are making. You know, those are decisions that we are, you know, writing letters to the school saying, you know, this person needs to take a medical leave.

Okay. How about this myth here? IQ is stable and does not change. It is only genetic. Yeah, so we know from testing that while genetics play an important role in intelligence, the rest is environment. And environment is many, many things, which we'll be getting into. And there are things that we can do to improve, you know, mess up our IQ too. So I think that and even if you get a number and even if you get a number and even if you,

If you are in a good place and you think that this number is going to define you, I don't think that, you know, that's true. I think that humans are much more than that. I think that people who have not tested historically well on IQ tests have gotten to do amazing things. The physicist Richard Feynman, Nobel Prize winner, famously scored a 120 on his IQ test, which is a good score, but it's not one that you typically associate with no-beltschurched. prize winners. So I don't, I think that talking with this with a lot of people,

uh, can really inhibit them and it can stop them. It can cause them to give up. It can cause them to not reach their full potential. So I think there's a danger there. Yeah, there's a danger. And that's, I think that's something we take into consideration when we're talking to people about the results and as thinking about all the situations on the day of the test taking, right? Um, I also think about like IQ tests as can it be practiced? You know, can you improve your score on an IQ test. And the answer is yes, there was this one guy who's, like, it's his like hobby, is like doing these little different puzzles, right? And so he'll go into a new IQ test and he'll score like 180. It's like incredibly brilliant, right? He didn't score that his

first time, right? And I think the same thing is true for SAT and MCAT and your step scores. Like, if you prepare effectively and do a ton, a ton of questions, like you will score better. than if you didn't, right? I think a good example was actually myself. My SAT was something like my parents didn't tell me to prepare at all. I didn't know other people were taking courses, reading books, preparing for this. So I just showed up, took it. You know, compare that to my MCAT.

I did better on my MCAT that I would say on my SAT. And once again, no one told me how to prepare for it. I only studied a month. And then zoom forward to my step scores. and I did considerably better than my MCAT or my SAT would have predicted, but why did I do better? I did a ton of questions, right?

And I had mentors and people guiding me on how to actually prepare for this thing. So if you're listening to this and you're like, okay, where's my hope in this, right? Actually, tests are largely, like, how many times have you taken it? How many questions have you taken? Did you understand why you missed certain questions

and just doing more questions, you'll score better on any test. Yeah, I totally agree with all that. And intelligence tests, you know, we're trying to measure this. We try to give you these puzzles, these tasks, and see how you complete them. But any task that someone practices and dedicates time to improving, for the most part, you're going to see improvement. We see that accidentally on a lot of these studies. Whenever people get administered the same test twice, they'll find that the scores have gone up three or four points, just as attributing that to a practice effect.

So it's definitely a real thing. If you know someone who claims they have an extremely high IQ, they might be doing this. Another thing there is even though we're trying to capture what intelligence is on these IQ tests, we're not only capturing what intelligence is on these IQ tests. We're also capturing how much someone really wants to get a high score, if they're putting their whole heart and mind into it, or if they're just kind of sitting there. We're capturing what's going on in their mind at the time.

Are they concerned about their work? Are they concerned about other things? or is that going on? We're concerned about how much they think they need to please people, about how this score would matter to them. So there's a whole lot of other things besides intelligence that are going into these scores. Yeah.

I think the other reason that this is important is because as a society, how do we make choices to benefit the most people, right? Right. So we know that exercise is really helpful for cognitive function for these scores. So, you know, when we think about, like a lot of parents who are worried about doing more STEM classes, more science and stuff, and they're willing to get rid of the exercise, it's like, no, don't do it, don't do it.

It's so important to do the exercise, right? Another big one that jumped out of me was lead. Yeah. Just how bad lead is for the brain and for the brain's development. So as a society, we need to say no lead. Yeah. A lot of these things, they'd be much harder to capture. We wouldn't really have a good number that tells you how bad lead is without doing these kinds of things.

We can see this, how it gives this effect in kids, and then we can see how that also affects all these other things down the road. So I think that's another useful thing that we'll talk about in this episode, some of the public policy implications and some of those other global environmental causes that can infect intelligence. most of the time in a negative way. Talk about in the environment, pollution. Air pollution, right? Yeah. And iodine deficiency. Not treating mental illness.

Like, thinking about all of these things and how we can optimize it on a society level, I think is so important. So we're going to jump into some of the nuance of IQ. And maybe a good place to start is to talk about the different domains of the most recent IQ test. So the different domains are verbal comprehension.

Yes. Perceptual reasoning, working memory, processing speed. Yeah. So talk to me about these different domains. Let's go through one at a time and talk about what it actually is testing. So verbal comprehension. Okay. Yeah.

So verbal comprehension, this has a number of subtests. What it's really trying to get is how well can you understand the words and the relationship between words. So one of the most obvious aspects of that is vocabulary, asking of someone, what is a guitar? It kind of measures the degree what someone's learned, been able to comprehend, and usually express in vocabulary, and that one does have a cultural influence. Another thing we check with that is similarities, measuring abstract verbal reasoning, in what way is an apple and pear alike? They're both fruits. Information, and this is general information, inquired from culture, from learning, from education.

Who is the president of Russia? Putin. Putin. Yay. All right. Okay, I'm good. And then comprehension, being presented with new situations and then trying to understand them. Like, what does killing two birds with one stone metaphorically mean? Like, do you understand that expression? You throw a stone and it hits one bird and then it hits another bird. Yeah. What does it mean?

You just hit two birds with one stone. Yeah. That would be concrete. Very concrete. Concrete reasoning. Okay. And then there's perceptual reasoning index. Yeah, the perceptual reasoning index, or PRI.

This is one of these performance measures of IQ. So it doesn't take into account these cultural educational biases, though you might have practice doing other things, puzzles, for example. So a lot of these are like puzzles. It's putting blocks together to form a picture. It's other kind of abstract, problem solving. Here's a pattern. You see three white squares, then a black square, then three white squares again. What's the eighth square there? Yeah, maybe a black square. Maybe.

So, yeah, and that's, so when you get, when you order this test, you're going to get these different domains and you're going to get scores for each of the domains. And so that's why I think it's worth going through. Okay, working memory. Working memory. So this is an interesting one. Working memory is we talk about it. It's almost like the RAM, if you know, computers of your brain. It's how much memory you have for instant access that you can put together to solve problems. So one way you can measure this is I say the numbers 9, 8, 5, 2, 4, 3, 2, 1. And I see how many someone can read back to me. How many numbers can they all fit in their head for instant recall? It also includes arithmetic. So how much can you concentrate while doing other things?

So how many 45% stamps can you buy for a dollar? Basic arithmetic. And then another task that they use to measure this is a letter number sequencing. So this measures attention and working memory where you'd say a sequence like Q1, B3, J2, and place the numbers in numerical order and then the letters in alphabetical order. And so that's a test of how quickly you can kind of switch between tasks and how much you can keep those numbers in your memory while you're completing this task. Okay. And then the last one is processing speed.

Processing speed. So pretty self-explanatory. This is how fast your brain can kind of start tackling some of these problems. So they'll have a symbol search where you have to look around and identify things as fast as you can. coding, which measures visual motor coordination and motor mental speed. So some of these are tasks that require a bit of coordination and dexterity in addition to mental things. So that all kind of goes into an IQ test.

Yeah. Okay. So let's jump to our IQ test predictive of future success. Oh, actually, there's one thing I'd want to mention real quick, too. So you might be wondering. now that we talked about all these categories, are these related at all? Does how fast you can put this pattern together, predict how well you know who the president of Russia is? You know, these seem kind of pretty unrelated. Maybe you'd expect that if you're really good at history,

you might not be very good at putting the blocks in order or remembering lots of digits. Well, the interesting thing that intelligence researchers have found is that all of these tasks, they tend to run together. You can put all these up and, get a number and, you know, people still have different strengths, but they all correlate with each other. If you do well on this test, you're probably going to be more likely to do well on all the other tests too. So that's why, you know, you might be wondering why we use a single number for IQ. It's because we try to model this as general intelligence, and we say that all these tests, even though they're measuring different strengths, we're really getting at the same thing.

Yeah. That's good. Okay. So, So next question. Are IQ tests predictive of future success, things like income, education level, positive mental health? Yeah. So, yeah, a lot of people have misconceptions here. They think that, you know, it only measures how people do on tests or they're so biased that they can't really tell you anything on these topics. But IQ is really one of the most validated measures in all of social science and psychology. So looking at studies, Deary at all in 2007, they asked, is intelligent.

related to educational achievement. This seems like a pretty obvious route where these would be related, but it's always good to check what the research says. So in England, they give a version of an IQ test called the Cognitive Abilities Test, and they gave this to children at ages 7 and 11, and they did on a big sample of over 75,000, 74,000 students, and they compared them these scores that they got in these IQ tests to how they did on their GCSEs,

which are a big test that students take in the UK before they go to college. At age what? At age 16 and 15, so like 10th grade. We don't really have an equivalent here. You can kind of think of them as AP exams that everyone takes. So when they looked at the scores here,

they found a correlation of 0.81 with how they did at age 7 and 11 on these tests and how they did at age 15, 16. And that is, if you know anything about social science research, that is a very high correlation. One being the highest. Yeah, one being the highest. So, yeah, this was applied to every subject, including science, math, language, humanities. And, yeah, so girls and boys did not differ on G, but had slightly different abilities in the subjects.

G is psychologist slang for general intelligence ability. Yeah. And yeah, interesting. Another thing to note here is how different subjects, they kind of capture this easy. Like they found higher correlations for the subjects like math, English, and the sciences. They found lower situations for PE, art and design, which you might expect. Not every test captures general intelligence to the same degree. Yeah. So now let's look at the twin studies. And, you know, in general, why are twin studies important? because it shows us, you know, these people had 100% genetic material that was similar at birth. Now we know that epigenetic stuff can happen so different genes can open up or close. But if the environment is the same of the two individuals, then we're really looking at like how similar are the genetics between them or how much that genetic similarity makes an impact. Right. Twin studies are amazing because they give you almost like a perfect. genetic control. You have one person who and two people have the exact same genes, and you can

compare how these twins get raised to the identical twins. We're always talking about identical twins here. Because fraternal twins, they don't have the same genes, but they also kind of have equivalent environments besides that to identical twins. So fraternal twins, they share only 50% of their DNA. Full twins, they share 100% of their DNA. So if we see that something is correlated between fraternal twins, maybe it's only like 0.5, but with identical twins, it's 100%. Well, that would be a 100% genetic test because, you know, they correlate 100% there and the identicals there. So what we can do when we see this is we can really tease out the different components that make not just intelligence, but all kinds of other things too. I think you talked about this on your suicide episode,

if you want people want to check that out. But basically, What we get whenever we do these twin studies is we can break things into three effects. So the first effect would be genetics. We say, okay, because of the contributions here, this percent is genetic. We see so much higher correlations here than we do when you only share 50 percent of your DNA. The next part of that, we call the shared environment. And the shared environment is kind of what the twins have in common growing up. So this pair of twins, they have parents who have a certain.

So if you're economic status. They have parents have levels of education, relationships, parenting. We can try to measure all this. Location in the world. Obviously, if you're growing up in the U.S., you're going to have a different experience than growing up in Vietnam or Ghana. So that's another important thing. And it also includes even things that you'd think would be hard to capture.

The twins share intrauterine environment and those kind of exposures. So all those go into shared environment. The next thing is non-shared environment. And this is also environmental, but it's everything else. It includes just the randomness of development. Even if people have this 100% the same genetics, the body unfolds in different ways while it's developing. Identical twins aren't 100% identical. It includes differences in how the twins are treated.

Maybe they go to different schools. Maybe they have different teachers, all these kind of things. And it also includes kind of a grab bag for everything else that we measure. So whenever you take the test, even a same thing. single person taking the same test twice will have differences there. So just it kind of measures a lot of this randomness too that goes into these numbers. So if you have their, if you have defining differences, you can find that they just go into non-shared environment. It's a really good explanation. Anything else you want to touch on that before we move into the studies on this?

Yeah, just a few more things. So intelligence, it's correlated with education. It's correlated with social background. So this is a really important thing that is really important to disentangle, right? Because we see, you know, these higher IQ people making more money. We see them doing more years in school. We see them living healthier lives. Well, let's talk about how strong that is because I think some studies are actually less enthusiastic about there being a huge difference. Well, yeah, I'm just saying that, you know, I'm saying that there's, we see these correlations here, but we also see this correlations of people that come from better backgrounds. If you come from a disadvantaged background, you are more likely to drop out of school to do this. So it's really important to try to disentangle

what we see here in terms of economic status versus genes. And we shouldn't, you know, equivocate between those because those are very correlated. Okay. So let's go to the Bartels at all, 2002. And what did you find from that study? Okay. So this was a lot of large twin study that they did in the Netherlands. They collected the results of a national test that they do called the CITO, and this measures educational achievement. So this is like another kind of achievement test that like the GCSEs or the SATs here that all the kids do in the Netherlands. So they have a large group of twins that they're studying. They looked at 1495 children total, 100 in

4070 female monozygotic identical twins 113 dizygotic fraternal twins and then about equivalent numbers of male identical and fraternal twins too. And they had all these kids undergo intelligence tests at 5, 7, and 10. And then they had the full version of the whisk at 12, which is what we talked about earlier.

It's the main test that's used these days. They didn't find any difference between the kids. But whenever they broke the math down, they said that 57% of the individual differences in CITO between the kids could be explained by additive genetic influences and 27% by shared environment and 16% by unshared environment, which includes like measurement error, for example. So this is a pretty good, pretty, it's saying genetics is pretty influential here, though that's not the only thing that math. mattered. Yeah. Yeah, that actually is higher than I would have thought. So 57% is due to the genetic influences, 27 by shared environment and 16 by the unshared

environment. And I think it's important too to notice that a lot of these samples that we're getting, they're coming from very small homogenous populations in Europe. A lot of these findings, it's much harder to apply. They don't have in places with lots of inequality. and different stuff that affects people here, that might not matter. So one thing that kind of matters,

I should talk a little bit, just because this is kind of a confusing in-depth topic, is that whenever we talk about something as being this much genetic or this much environment, really kind of depends on that itself depends on the environment. If we imagine an environment where everyone gets the exact same treatment, well, then if everyone had the exact same treatment, all the differences we find would be 100% genetic.

If we imagine a world where everyone is not allowed to do anything, then it's just whatever, you know, if you're just measuring wherever someone is, whatever their environment is, then it'd be zero percent genetic. So all these, we have to really take into context. You have to look at the place. We have to not be too wary to apply one number in this situation to the other situation,

because it's not always gonna be equivalent. That's a really, yeah, that's a really good point. When you looked at other studies outside of, the Netherlands, do they have less genetic component? When we look at twin studies measuring the effects of intelligence, we usually see right around that 50% mark. Sometimes it's 40%, sometimes it's there. So this actually is fairly typical with the results from twin studies on intelligence.

So some things are more genetics and things are less genetic. So there actually is an important genetic influence here. Not to discount other things. But this is the main way we measure this and why people say that genetics play a role. Okay. And then so the next study, Wally at all, 2001, does higher intelligence increase lifespan? Briefly, just tell me the result of that one. Yeah.

So they broke people up into, they measured them at 76 after measuring them through their life. They did an IQ test at 11. And that IQ test at 11 actually predicted how long people lived. So if people scored two standard deviations lower, which is a lot, they were only 65% likely to be alive at age 76 as people who didn't. The effect was stronger for women than men. And they believe that this is probably because this birth cohort was born in 1921. So a lot of them served in World War II. And so if a lot of the people died in reasons that weren't in regard to intelligence, then that would do there.

And they couldn't really elucidate the reasons why those lower IQ people were dying earlier. But that's one predictive thing that they found. Okay. What about this, Strends 2007, where they investigated the relationship between socioeconomic status and intelligence? Yeah. All right. So this is a big meta-analysis looking at a whole bunch of different studies that was trying to disentangle three things that always run together. So we know that high socioeconomic people, they do better in IQ tests, and that people do better an IQ test come from higher socioeconomic status backgrounds.

And then they go on to have more successful jobs and they go on to make more money. But, you know, which of these factors can we really attribute these findings to? Obviously, you know, it's a combination. If you come from a background that really encourages academic achievement, you know, maybe that is, you know, affecting you as you're growing up. But so this is just kind of an attempt to look at all the research and really try to get the best data. So. Yeah, and what were the, I mean, I have a couple thoughts on that.

One is after getting into more of the mental health stuff and thinking about trauma, and the ACE scores even, and, you know, people who are inner city are going to have more traumas that they're going to face. Yeah. If you have a single parent, you're just not going to have as much resources and much, you know, you're more apt to struggle.

And so this really was an eye-opener as in, you know, like how college selects applicants probably should have some way to, you know, change the score based on the background, you know? Yeah, if we're trying to make a more equal society, we definitely shouldn't be holding past injustices against people when we're trying to admit them to college and the past trauma. Yeah, and you think about like, just, I'm really big on, you know,

having equal opportunity, you know, we're not going to be able to control outcomes because that has a lot to do with choice. But giving everyone the same opportunity is, I think, really, really important. So go ahead, take me through this and what they found. Okay. So they used five indicators of parental socioeconomic status. They looked at background, neighborhood, how much your parents were making, your parents' profession. And then they looked at this measure.

They got, they made an index. And these were correlated with how much education you got at 0.41 with your occupation as measured with occupational prestige and a few other scales. that correlated with point three and income with 0.15. So this is actually pretty low. And these studies came from the U.S. and Europe a lot of the time. So, okay, parental socioeconomic status and how it correlates with like education. Yeah. Point four.

Point four. Occupation. Point three. Point three. Income. Point one five, even lower. Yeah. Okay.

If we look at intelligence, it actually predicts a little bit. better in the sample of studies they got for the meta-analysis. Whatever the meta-analysis finds, it's whatever these other studies found. But whenever they tried to disentangle this using complicated math, that's not totally discernible by me, they found that intelligence was correlated with, and this was on various measures, I don't have an exact time when these intelligence tests were getting, because the meta-analysis was taking desperate data. But they found slightly higher correlations with all that. They found 0.56 with education. or three with occupation and point two with income.

So while higher, like especially income, these aren't the highest correlations. Yeah, I think it's, I think that's really, this is actually really important to look at. Like even if you have higher IQ, it's only 0.2 correlated with higher income. Yeah. That's a very, like out of one being the highest correlation,

0.2 is not that high. And socioeconomic status, it's only 0.15. So it's not that strongly correlated with like, if you come from a really low socioeconomic status, that you are also going to be poor as well. Like that is not incredibly correlated. Absolutely. And once again, it depends on the studies

where these are coming from. But I think that's, I'd treat that as an encouraging result if I came from one of these backgrounds, that there'd still be opportunity for me to succeed that I wouldn't be stuck in my station, so to speak. Right. And effort is so powerful. Like effort, drive, conscientiousness,

like consistency, moving towards a goal is so, so important. And remember, we're saying, we're saying intelligence for these, but they're measuring intelligence and IQ test. And one of the things that goes into IQ test is effort and conscientiousness. And we'll talk about that later. So remember, whenever we get these data for how important, like, intelligence is, we're really saying IQ and when we're saying IQ, we're really saying other things besides intelligence as well. I was testing a doctor. He had gotten through residency, and he had struggled. He had really struggled through medical school, but he had, I mean, struggled as in like it was hard.

Like he put a lot of effort into it. And he was coming to me with ADHD. So sometimes when I'm kind of on the fence, I'm like, okay, let's get some testing. So we got some testing and his IQ came back at like 100. Okay? He's a doctor. And I told him. And I didn't know how he was going to respond.

And he started crying. But it was, I was like kind of puzzled because he seemed happy at the same time. And he's like, Doc, I just. I just realized now it was my effort. And for him, that was like the most gratifying moment. Yeah. Like that was an incredibly gratifying moment actually for him. So much that he cried like tears of joy that like it was his effort that pulled him through.

You know, like it wasn't just like he was really, really smart and then struggling because he was lazy or anything. You know, he was working his butt off. And I don't know that story comes to my mind. But I think like it's not incredibly correlated with occupation. With occupation, a little bit, point four, intelligence and occupation. But income is not, you know. And I know a lot of people who work very, very hard, who are much wealthier than me. And, you know, they're doing jobs like construction or something like that.

And I don't know what their IQ is, but they work really, really hard. Yeah. And they didn't go to school for, you know, 12 years when I was going to school. So they're, they're, you know, they had 12 more years to make money and lay that foundation. You know, we get out of school in like our 30s almost. All right. Let's keep going. Yeah.

Even to add to that a little bit, point two, we, that matters just, that's like a little correlation on a societal level, like on an individual level. That's basically not really telling you much at all. Yeah. Yeah. Yeah. So it's, and I saw that in the Harvard longitudinal study as well. Income related more to maternal warmth, mature psychological coping defenses,

and, you know, connection with meaningful people. Like that was a much higher predictor of income. I don't think IQ was a predictor at all in that study. Yeah, I don't think it was. Yeah. And so that's why, you know, we try to use meta-analysis, try to, you know, get them all. together. So we already talked about how IQ has a good test, retest. So let's go to short-term effects of IQ.

This is important because even how you, you know, the situations around taking the IQ test can lead to a better score or a worse score. Yeah. Most of the time, worse score, right? Maybe you have some caffeine or you're on you know they've done some studies that we looked at where they put people on different drugs but most of the ways that you can do you know poorly on an IQ test or kind of bad things happening to you like sleep deprivation like sleep deprivation and you don't think about like being on call like when I was on when I was a first year intern I would be on call I would do 30 hour shifts and I knew that by the end of that shift like I was not thinking as um chipper. I was just not processing. And so, you know, we've created different laws, right? Now,

like, interns can't be on for 24 hours straight. That's good. And yeah, I think that's another example here, because we can quantify, you know, these losses that we see cognitively. That's, I think that's another argument that, yeah, we see you can't do these tasks as well if you're sleep deprived and we should pass laws to make sure that patients aren't being treated by sleep deprived doctors who are suffering because of it. Yep. And it also makes me think of like the need to treat sleep apnea. So sleep apnea, when you stop breathing multiple times a night, will make you more tired

and make you more fatigued. Your cognitive function will go down. And so, you know, the effect size of this is 0.7 in this one study and a lot of the reaction time, attention. Those were the strongest affected. Working memory was the strongest affecting. So frontal lobe tasks, right? Yeah. All those difficult decisions. Sleep is really, really important. And the other good thing about this is like if you're dealing with a type A person and you're trying to convince them that they should get eight hours of sleep, right? But they want to work literally, you know, 18 hours a day. Okay. It's almost like

talking them into, you know, how getting good sleep, can help their cognitive function. And if they have good cognitive function, they'll do better in their work. So it's like sleep is actually like part of that journey that's really important. Yeah, it'll get more good work done if you're sleeping instead of working,

you know, if you're working that much almost, right? Yeah, yep. Okay, how about effort? Let's talk about effort a little bit because that's important for two reasons. One is, sometimes patients come in and they want to be ADHD,

positive and so they do low effort. And actually there's a scale that you can get that you can add on to the ADHD testing, which we do at our institution of effort. So we can have patients to come back that showed like very, very little effort. And so we can't like use that data to say yes, this person has ADHD. Okay. Yeah, yeah. I think that's a, I think this is a good example of how IQ tests and our knowledge around

IQ test has improved. because now we're actually paying attention to this. We're not saying that this is just some number that's only capturing how smart you are. We're recognizing that all these other aspects are coming into it too. So this was a study by Duckworth in 2011. And they did a number of studies. So one thing that they found was that they did an amount analysis of studies where people were provided financial incentives. Okay, you can only do this well on IQ test.

How much better can you do if we pay people? Paying people is a good way to motivate people in a lot of situations, obviously. So they actually found performance by 0.64 of a standard deviation, which is about, if you think about it, is that about eight or nine IQ points? That's like, yeah, that's a big effect. That's a big effect. That's a big effect. So just having a person that's highly motivated.

So I coach the people when I go, when I say, hey, get good sleep, show up and give it your absolute best effort. like you really need to do, try your hardest on it. You know, because that'll change the outcome. Yep. And then the next one, they tried to measure this effort directly by looking at people. They had people take IQ test, 251 boys in Pittsburgh, and they gave them all an IQ test, and they looked at which boys just on a video seemed to be trying, and which boys weren't really

seeming to be trying and controlling for race, social status, family structure, IQ is still lower in all the less motivating boys, perhaps not surprisingly. Yeah. I think the takeaway here is that, like we were saying earlier, IQ is affected by both intelligence and non-intellectual traits. It does depend on effort, conscientiousness. And we know conscientiousness also, you know, contributes to how people, well people do in school and about how well they do that.

So we really are measuring other things besides intelligence whenever we give all the rest of these numbers here. Let's talk about how poverty impedes cognitive function a little bit. So this many at all 2013 article I think was really interesting. Break it down for me a little bit. All right. So this was a bit of a summary. They took four different researchers, and it's a lot of different contexts. But I think they put them together into a really cohesive picture.

That really points a really good picture. how poverty can affect your mental function. So in the first study at a four, they performed an experiment on New Jersey shoppers. They had a hundred and one of them and they asked their income level. Then they were given a mental task. So the subjects, before they were given the task, they were given a scenario where their car breaks down and it would require either a small fee or a large fee to fix. The small fee was about $150.

The large fee was $1,500. So they thought that by asking the subjects how they'd go about these scenarios, that would get them thinking about their monetary issues, and this would impose a bigger constraint on the poor shoppers than the rich ones. So after they gave them the scenario, got them thinking, they administered the Ravens Progressive Matrices, which is a really widely used performative cognitive test. It's pattern matching, completely nonverbal. So what they found with their results was that with the small hypothetical cost of repair, or only 150, the poor shoppers perform the same as the rich shoppers, but with the larger sum, the poor patients fared significantly worse, set the whole result was the poor shoppers performing worse on the experiment than the rich shoppers. Yeah, so thinking about like a $1,500 car repair,

that really is stressful for someone who's just dollar to dollar, you know, barely making their budget. So this was a really G-loaded IQ test. And they were really, and they were finding basically from this that if someone was financially stressed, they had a lower IQ. Exactly. And I think it's also interesting to think about this study in the context of what financial constraints people are carrying with them throughout their life. If you're concerned about other things that are going on financially when you're taking these IQ tests and all these other studies, that could artificially lower your score. Yeah. And I think I've found when medical students specifically are like if multiple stresses hit them like death and family and this and that, like they can have a really hard time studying, right?

It's already really hard. Medical school is already really hard. And then you add on a bunch of extra stresses and all of a sudden they're not performing at their normal level. Right. I can speak to that personally. And I think it just makes sense that if you're, you know, dealing with all these different stresses then. that can really affect things. Okay, what was the second part of the study?

All right. So in the second part of the study, they actually looked at sugar cane farmers in India. It seems like a little bit of a stretch, but I think it was a very interesting experimental design, and I think the results from it are really powerful. So what they did was they got 464 poor rural sugar cane farmers in 54 villages in India. These farmers had land plots between 1.5 and 3 acres, very small. and they earned 60% of their income through growing and harvesting sugar cane. So what they did in this study is they interviewed the subjects twice,

before and after harvest over a four-month period, and they took cognitive tests of them. It was also really good design because unlike a lot of other crops, the farmers would harvest their sugar cane at different parts in the year. So it wouldn't be like an effect from seasons or anything like that because they got to stagger these harvests. So what they found whenever they were looking at these farmers pre-harvest was they found that these farmers were taking on more and higher loans. They had to pawn off more of their items, and they're more likely to say they had trouble coping with ordinary bills.

So they did tests before and after, and after harvest, even though the farmers weren't eating anymore, it wasn't malnutrition. They found quite a huge effect size. After the harvest, they scored almost a stand. deviation higher on the Ravens progressive matrices than they did before the harvest. Yeah. So this is another good example of how acute changes can change your IQ test. Right. Yeah. At one standard deviation, that's like 15 points. That is significant. Yeah. That's the difference. Yeah. That's good. So in summary of this many at all, it's the people that were financially stressed, right? Or the people that were stressed. We're

stress before the harvest that we're doing worse on the IQ test. And this was a good IQ test. It was the G-loaded nonverbal IQ test. Right. Okay. So now we're going to go into genetics and we're going to touch on what we've found in the research for how this is genetically, how IQ is genetically linked. Yeah. So we've known for a long time that genes play a very important role in intelligence. The study we discussed earlier, Bartels at all 2002, that was a large study on banish population, and they found estimates that are about in line with what other people have found using twin studies, which is that about 50% of the variation in intelligence and IQ can be explained by genetic influences.

We talked a little bit about how twin studies help us delineate the different types, but recently we've also been using more sophisticated techniques. to try to actually find the genes that are responsible for those intelligence differences. And, you know, we've had genetics since the 90s. People have been able to study individual genes. And for genetics of intelligence, for a long time, it was a very fruitless endeavor. People would find candidate genes. They'd see this gene might play a role, important role, intelligence.

We'd do a study. We'd find that it's significant. But whenever they'd try to find that significance again in a separate study, they'd usually find that it wouldn't replicate. They wouldn't be able to find that same gene having an effect. And so there's really been a paradigm shift in the field. People were almost giving up on finding these genes. They're like, are these genes there?

Like, they have to be there because of the twin studies. But we weren't really sure where they'd be. So basically, people have only been able to find these genes for intelligence and most other psychological behavioral traits only in the last eight or nine years or so. and what's and kind of the, I think, kind of shocking thing that we found is that pretty much all behavioral traits, they don't have big effects from individual genes. Most all behavioral traits, we see thousands of genes each exerting a very small effect. Yeah. And this is what side note drives me crazy is when people say there are no biological markers for depression or for, schizophrenia or mental illness and I'm like are you are you looking at the literature it's just

very complex exactly like twin studies for schizophrenia if one twin has schizophrenia maybe the other one 45 50% of the time will have schizophrenia so what we're saying is if one identical twin is highly intelligent 50% of the time the other one will be highly intelligent or you know if one is moderately or medium intelligence, you know, then 50% of the time. The other one will be very similar. And that it's literally thousands of genes that lead to the combinations. Exactly. And the reason that we couldn't discover these earlier is because each individual gene

exerts a very small effect. The reason we've been able to find these is because now we have all these people that we can collect genetic data on. What we do is we do these genome-wide association studies. This is where instead of looking at one particular, candidate gene. Maybe this one works. We look at every gene at once, and we look in thousands and thousands of people. The meta-analysis that I looked at for this had 260,000 people where it was looking at their genes. And they found 12,110 variations at 242 S&Ps, which is just a fancy word for like

one little genetic base. And these were. associated with IQ in these samples. Each of these individual genes has a very small effect. They're discovering new ones all the time because the effects are so small as we get these bigger sample sizes, that's pretty much been the way we're discovering more of these, just bigger sample sizes. It's very brute force. But it's very interesting because we can actually now, this is just, you know, in the last

three or four years or so, look at your genes and get a score, a polygenic score, where we just say you have X, X, X, X, X, X, X, genes here. And we can use that score to predict what you'll get on intelligence or education attainment. But five percent, right? Yeah. Explains five percent of the variance. Yeah. Five percent.

I mean, it went up to like 11, but there's a lot that's still unexplained. That's, like, pretty small. Yeah. Still. It is. It is very small still. So there's actually some people who are talking about, like, what's the missing heritability, how much more can we, you know, just by brute forcing, bigger sample size, expect to find?

It's because there's so many epigenetic things. So even in like, when you look at identical twins, they still have the same womb environment, you know, and there's epigenetics going on in the womb. Like the genes are changing, like what's going to be up expressed, what's going to be down expressed. So, and, you know, environmental factors, you know, so it's like how much of the variants can we really predict by all that we know? Yeah. And just even identical twins, you know, we only have like 22,000 whole genes in our body that code for proteins.

And, you know, everyone, you know, that's not a process that's specifying everything down to the last cell. So we're going to see, you know, kind of iterative generative processes that are making the brain, that are making the whole rest of the body that are going to lead to differences even between identical twins. Here's what I fear is you're going to have some company that comes along and says, look, we could type your embryo. know, your fetus. And we're going to tell you what the IQ is. We're going to tell you, you know, blah, blah, blah. And it's like, they really can't predict it that well. Yeah. And actually, that's actually a recent thing that people have been talking about. Steven Sue, he's a physicist turned genetics enthusiast and company creator. He actually made a company to try to do this for people. And there was a lot of pushback, not only ethically,

but scientifically from people who say, look, this isn't going to work. You know, even if you get this genetic score, it's not powerful enough to even, you know, increase things more than, like, one IQ point if you're lucky. So you'd be really overselling any claims that you could do this. But yeah. Yeah. Right. So I think just come back to five to 11 percent of the variance, right? Yeah. So far, I expect that to increase if, you know, because they're going to do more and more. They're going to get millions. They'll be able to find smaller and smaller effects. But right now, Like if you looked just like three or four years ago, it would be 1%, 2%. So it's actually kind of come along pretty quickly.

Okay. Well, anyway, don't go spend a lot of money on it quite yet. Do not, yeah, absolutely do not. Epigenetics. Okay, so epigenetics is exciting. So this is once again, you know, our DNA is able to open up or close and express genes that become, you know, messenger RNA that become proteins. And so what have they found with IQ and epigenetics?

Okay. I didn't really think there'd be a lot here. I thought, you know, it's really hard to find even with genes that are affecting IQ. If these are just really small effects, how are you going to find methylation affecting stuff too? But I found a really interesting study. Just came out last year, Kaminsky at all. And they looked at, they kind of did the old-fashioned thing. They looked at candidate genes because epigenetics, it's, you know, looking at, it's DNA

methylation, how closed off it is. They looked at 24 candidate genes that are definitely specifically involved in neurotransmission. This is kind of more the old school way, but they did it with new school standards. So the old way was you find p equals 0.05 on your gene, you think it's in association? No. These epigenetic finding that they found was p to the 3.18 times 10 to the negative four, which I know we're getting pretty sciencey here, but very low probability that this is an accident. Yeah. So basically the P scores are just saying, is this happening by accident? And usually if it's a 5%, you know, if it's lower than 5% chance of this happening by accident, we say, okay, that's probably significant. Does it mean anything? Not yet, right? But it's significant.

So these are just taking that P value way, way lower. Yeah, like a thousand times rare. To say that These are not happening by accident, but then the next question comes, like, are these actually meaningful? Right? So the effect size is what tells us if it's meaningful. So go ahead.

Right. So they found one of these genes that they studied out of these 24 genes, which are involved in neurotransmiture, this DRD2, the dopamine receptor D2, the methylation at that did exert a really small effect, explaining 1.4% of the variance, on fMRI, striatal activity.

And so that was kind of an interesting finding. They weren't able to say anything about, you know, like, you know, I think a lot of the times you talk about epigenetics, it's almost like this hopeful thing. Like what can we do to change it to optimize how our genes are transcribing each other? If you're struggling with weight, you would want epigenetic changes,

which cause increase in metabolism. Yes. Right? Not decrease in metabolism. metabolism. And what this is finding is that there were methylation of this one gene, which caused a small change in the fMRI activity. Exactly. Okay, what do they do to get the epigenetic change though? Do we know? They were just comparing people who had it methylated versus people that didn't have it methylated. So I don't think we know how it gets methylated,

like what would contribute that we could change to affect that. I think that was kind of beyond the scope of the study. I think the epigenetic stuff, I mean the genetic stuff is really just coming along. The epigenic stuff is going to come along after. Yeah. So in one of the most elegant studies that I've seen on epigenetics, they change people's lifestyle, like complete lifestyle. So stress reduction stuff, exercise, diet, you know, really healthy diet. And they put people through this for several months and then they re-tested like protein expression in, in different cells, and they found that there were like 10,000 different changes in like what was expressed protein-wise.

So we know epigenetics takes place with the stuff that we tell our patients, right? And we know it takes weeks. So how long does it take for an epigenetic change to occur? I couldn't really tell you that. I know some of these epigenetic changes. I think it was originally discovered the last generations. Like your grandfather, if you, you know, he was living in a family. in, that would affect the expression of your genes just three generations later. So sometimes it can

last a long time, sometimes it can be changed in a matter of weeks. I think it takes about six weeks for an epigenetic downstream change. So you have to think about how our cells are trying to adapt to something new. It takes like about six weeks for upregulation of certain genes. I think it's a good, it's of course a lot more complicated, right? But if you think about like for example how SSRIs influence anxiety. How long does it take to work? It's the epigenetic changes that actually cause, I think, the decrease in anxiety and takes about, it takes six weeks. So think about that as well, if you're tapering off of medications, how long does it take to experience the change? It takes six weeks. So you want to maybe wait six weeks sometimes before you make another change. Okay, let's go on

to environmental effects of IQ. So prenatal. Yeah. Um, what, have they found about like maternal smoking alcohol um what kind of association did they see yeah it's nice to move on a little bit from kind of some of that esoteric gene stuff uh so moving on to just you know pregnancy starting at the beginning of development you've been conceived you have your genes what happens next uh so one of the things that we always you know emphasizes doctors is obviously not smoking not drinking during pregnancy uh so this this study strife goodth 1989, they actually quantified this. So they used a binary cutoff. They saw people who were having 1.5 ounces of alcohol a day while they were pregnant. And they kind of use this as a binary

cutoff. It's about three drinks. The women who had over that, their babies were associated with 4.8 less IQ points at age 4. And that was affecting both verbal and performance IQ. that's actually not as big of a drop as I would have assumed. Yeah. I would have assumed more. I mean, I've seen fetal alcohol syndrome as well, and I think that's a bigger drop off. Mm-hmm. But, you know, a 4.8 drop, a 5-point drop, that's one-third of a standard deviation for IQ.

That isn't a huge drop, but it's significant enough to not drink alcohol. What about smoking? Smoking, this is another thing that they looked at. In this study, they actually didn't find a very... verbal IQ, nor performance IQ deficit related to smoking. They found a 0.1 IQ point difference, which was not significant. But interestingly, they controlled for birth weight when they are making this calculation. So I actually cross-linked this with another study. That's like a famous thing you can do, is you can kind of over-control for things in science. So they controlled for body weight at time of

birth, and we know that people who smoke have a lower body weight. Exactly. So is it the lower body weight that's actually harming the child? It seems to because as we could talk about now, birth weight is associated with lower IQ. So if you just account for that, you're not going to be measuring that. So if we look at this study, Matt at all 2001, what it shows is that there is a correlation between birth weight and IQ with heavier children having potentially a five point difference, Once again, it's not huge, but it's significant. It's not like the heavier you get, the better at some point at around like 10 pounds or so. It's like not going to make you any smarter.

But really when you compare like the lowest birth weight to the highest, that's the jump. So maybe they overcontrolled for the smoking study. And that's important going back to the smoking just because six to 10 cigarettes a day is associated with the mean birth weight. about a third of a kilogram lower. So if we just kind of transpose the math there, that could be about two IQ points just from birth weight that they controlled for when they probably shouldn't have. That's some good science right there,

some good science digging. Okay, so, yeah, what's next here? Another thing, this was very surprising to me. I just heard about this recently in the news. I thought it would be good to include, but the authors of the study were very, careful to say that this isn't definite, but it's a concerning area for future research. And what's that? So they looked at maternal fluoride exposure during pregnancy. So what they did,

this is a study done in Canada. They tested pregnant mothers for urine fluoride in each trimester in regions with fluorinated water and without fluoridated water. Then they performed psychometric testing of the 610 children when they are aged 3 to 4. So they found, They found, they estimated fluoridation objectively with urine, and they also asked mothers how much tap water they drank and correlated with that with how much fluoride was in the regions there. So how much IQ did it actually change? Yeah. They found that if you had one milligram per liter increase in your urine fluoride, that was actually associated with quite a bit lower IQ, 4.5 points in boys especially. they didn't find the association with girls.

I don't know about a study like this because like, you know, people who are in more dire straits are probably not going to have water purifiers and their fluoride isn't going to be as high. Yeah. Right? So it's like are we, oh, that's a good one. This is a good example of like people getting, people hearing something like this and then maybe getting carried away about like, oh, we should go out and buy a water purifier.

You probably should, but are we, what are we looking at here, right? And this is where correlation does not equal causation. Okay, let's keep going. Okay. We'll include that. But I think it's like a good, sort of like more studies, right, need to be done. Yeah, more studies. But we're never going to do a randomized control trial on this because it's such a high risk, right?

Yeah. You're not going to add fluoride to a bunch of, half of a group of people and not add fluoride to another. to make sure that this is like something we should avoid for all people. Well, it's interesting, though, because I think naturally there's a lot of variation and how much fluoride people are getting anyway in water. Like a lot of states that banned it. So it could be interesting to look at. Yeah.

Okay. Let's keep going. All right. Another interest in terms of other environmental toxins to look out for, Lamb et al in 2017, they did a men analysis of one of these potential toxic effects. which are P-B-D-E's. P-B-D-E's. Polybrominated diphenyl ethers.

This is an anti-E. It's a flame retardant. It prevents things from getting, you know, catching on fire. It's found in vehicles, airplanes, plastics, textiles. One of those kind of ubiquitous compounds that can really affect things it looks like. So they looked at, with the metastos, They looked at 10 studies, 10 of them were studying intelligence, nine were studying attention-related problems, ADHD.

They estimated a 10-fold increase in PBDE, so like a big difference because it's pretty variable to levels. It was associated with a decrease of 3.7 IQ points, and they said that they're pretty certain in their level of evidence. They also found an association with ADHD, and it was slightly smaller. Interesting. So if these people were somehow consuming these plastics, how are they consuming the plastics? I'm curious.

I'm not exactly sure. I mean, this is like what leads people to like go all glass and get away from all plastics that they eat out of. You know? Yeah, possibly. But I don't know. Like, is that really evidence-based? Stay tuned for a future episode of the psychiatry and psychotherapy. Psycho Therapy Podcasts where we'll dive into this.

Okay, let's keep going. In any epidemiological data, especially like a really complicated outcome, like IQ, it can get really complicated, really fast. You can find all kinds of studies. And I don't think what we're talking about here is exhaustive. But the next compound that we're going to talk about, I think it is a very big influence that is very important. Let's do it.

Lead. Let's talk about lead. Lead. Yeah. So how does lead exposure affect cognitive function and other ed points? obviously there's been a big effort to reduce lead and developed countries because this has been known about for a long time. And this is one of the big reasons that's been driving it is we've found these big IQ decreases with lead exposure. Remember that one movie, what was it, where he's talking

about how he was eating paint chips when he was a kid? I don't know. Um, gosh, what was his name? He was the guy who like was on Saturday Night Live and be like, don't smoke dobies. You're to be living in a van down by the river. They'd like slam on the table and stuff and try to intimidate the kids not to smoke. Okay, let's keep going. So how big of it decreases it with lead? All right. So I found this study in New Zealand.

It was a really good study because whenever they looked at the lead values in kids, they looked at lead values when they were kids, and then they looked at how they're doing in life as adults at age 36. So they found that 46% of the children that they tested in the 70s had levels of lead above the threshold of international concern. Wow. And 94% had levels above the normal reference range. So, you know, there's been a lot of lead contaminants. And what they found was that they lost, these children lost 1.6 IQ points per each 5 milligrams.

micrograms of lead after controlling for other factors. So end result summarized there was a 4.6 IQ difference between those above this level of concern of 10, which is half the kids and those below. So a pretty big decrease there too. And it was a very good study that over 1,000 kids, they found that the kids who did have that load exposure, they also had, they measured their socioeconomic status. And they were working lower paying jobs. They were doing this.

And it was a very good sample because the lead exposure level, it wasn't actually correlated with socioeconomic outcomes in the kids. They found that the children of rich people back in the 70s, they had lead levels on average about the same as poor kids. So just looking at lead levels, they were able to predict a lot of things, which is very concerning. So one way in which good environmental laws, protect future children. Yeah. Okay, let's keep going. What about iodine? All right, yeah, going kind of

to the positive side of things. Iodine, as we know, is essential nutrient. We need it to make thyroid hormone, among other tasks. And this is one of those things that I think is more of a success story. Well, let us to, obviously, but there's been a lot of regions where historically there hasn't been a lot of iodine. One of those has been China. So, Kian, at all, 2005, they looked at 37 studies where they were rolling out iodine and they wanted to check what kind of effect iodine would have in these regions that were historically iodine deficient and how that would affect children as they were growing up. So they actually, using that Ravens Progressive Matrices that we talked about earlier, found relatively huge IQ gains after iodine was rolled out

to these regions, almost a standard deviation higher, 12.5 IQ points. increased in the regions that got iodine. I'm just wondering, am I feeding my kids enough iodine? I think it's one of those ones, you know, like B12 or any other kind of vitamin where, you know, most of us in developed countries, we're getting enough. It's really whenever you don't have this, that you do that. I think you can think of IQ a lot as, you know, a machine that's running well. If your brain has all the things it needs to run well, it's pretty much going to

run, but as soon as you're missing a part, if you're missing some part in development, we know that iodine and thyroid hormone plays a really important role. You know, you end up with cretinism if you don't get it, insufficient doses as you're developing in utero. So whenever you are missing this nutrient, you find big losses, which then can be corrected with supplementation. So that was, they found big gains in China throughout that. Wow. Yeah, like after the Matoran salt company started distributing iodinez salt in 1924. The average IQ in the U.S. went up 3.5 points nationwide. And 15 points in iodine deficient areas. That's interesting. Fun fact there. So let's keep going. So iodine is good. Let's talk about early childhood.

All right. So now you're born. You've been developed in your uterus. What can we do now that you've been born to help you. Breastfeeding. Thank you. Breastfeeding. Breastfeeding is a big one. Dr. Hart, the OBGYN, director at Lomolinda. She's a big advocate.

And it's known to increase IQ. But one study I found, which is really interesting, is which we see a lot of this, is sometimes when people are studying these environmental factors that go into it, they don't necessarily account for education. and just kind of the parents' baseline IQ that they're also panning onto their children. So, you know, we might think if we see these kids who are breastfeed and they get such higher scores, that could be the effects of breastfeeding on nutrition, that they're getting this, you know, very useful thing. Or it could be a lot of the time that some poor mother who doesn't have enough time to take care,

who's dealing with all those stress on IQ tests, and there's, you know, growing up in an environment that's deprived, They might not have time to breastfeed, and then their kids might inherit some of those other things, too. So this was a very good study that I found, this Kanesawa 2015, I think, because they attempted to disentangle those genetic influences in a way some of the other studies hadn't. What do they find? Yeah. So they find that even after you account for IQ, the effect gets smaller for breastfeeding, but it's still there. So breastfeeding is real. This is a big study. They looked at seven. 17,000 kids. What's the effect size?

In England. The effect size, it might be a little bit less than you think it is. 0.3 IQ points for every month of breastfeeding. Yeah. So don't feel shame if you were unable to breastfeed. Yeah, don't feel shame. I think actually feeling really bad about yourself would probably be worse for your child. Yeah.

Because, you know, like, I know because there's lots of patients that I can't breastfeed for whatever reason. We had a hard time. My kids had lip and tongue ties, so they had a really difficult time latching. They were eventually, after we got that cut, they were able to latch very well. And we had need of breastfeeding consultants

and trying to get the latch, right? And it was very difficult. But we know some mothers who really want to breastfeed and for whatever reason can't do it. and it's like it's very jarring to them to not be able to breastfeed. So it's not a huge increase in the IQ. No, it isn't. 0.13 per month.

That could turn up to be like a full unit for a year of breastfeeding. So one unit of IQ. But, you know, also it's like, is that from the milk and the DHA and the ALA and the fatteness of the milk? or is that from the connection of like, you know, that touch? So if it is the touch, then how do you control for, you know, people who aren't able to breastfeed, but able to get good touch with their kids? Yeah, and we know that's important too. Yeah, I think that's just an important point is that when we're talking about these things,

you know, they're all very epidemiological factors. And I think it's good to study. It's kind of good to know when you're kind of giving advice. But I think it also put so much pressure on parents that's probably undue. Like you were saying, most of these things, it's not going to make much of a difference long term. Well, and I think if it does make a long difference, or if it does make a difference long term, then we should be passionate about it. Right. I would be passionate about breastfeeding.

Like, if it's possible to breastfeed, that's awesome. Do it. But if you can't for whatever medical or difficulty or, you know, you have to work. work and you have to pump and then you know you can breastfeed some of the time but not all the time like don't feel incredible shame or bad about it because like you're doing the best you can and spending playful time with your kids long term is probably going to be the biggest win so attention focused attention and play is I think probably the biggest win okay let's keep going keep going all right so when we're talking about early childhood interventions probably one of the biggest ones

you could possibly do is totally change the children's environment via adoption. So this is another interesting thing that's been studied a lot. A lot of these adoption studies, though, they're taking place in very kind of unusual contexts. A lot of the time people will adopt from very, very deprived backgrounds. Think people who go to Africa, people who go to Romania in one of the studies we saw after the fall of the government. So a lot of the times people would find really big increases with adoption. How big? In some of the old studies, they'd find increases of like 15, 20 points.

How about in new studies? Yeah. So this is a little bit more of a mundane study. This is looking in Sweden, so a well-off developed country. And they looked at a lot of pairs, you know, usually adoption studies. They're not that many because they don't get to get. too many, but this was the biggest one that's been taken place. And this is in 2015, where they summarized the data. They looked at 436 male-male, full sibling pairs, one raised at home and

one away. So this kind of, it was a big control. You get to see how people were raised in this family by their biological parents versus adoption into different families with different socioeconomic status. And the reason that they're all male-male is because Sweden, like some of the other countries, they do a military conscription at age 18 where every male has to serve in the army. And whenever they serve in the army, they take a test of intelligence. So that's where they get this data from. This is data that depends on IQ at age 18 based on how they were adopted. So what do they find? Like if they were adopted into a more literate, more highly sort of nurturing environment, their IQ increased 4.4, is that what we're seeing?

Yeah. So in general, when people adopt in Sweden, too, they adapt to a higher socioeconomic status. but not necessarily. If you think about reasons, people might put their kids up for adoption. Maybe they're too young. Maybe they have other things going on. Maybe they don't want to be parents. So they found that even if adoption was to a slightly lower or equal socioeconomic status,

that was still beneficial for kids in their study. So they found they kind of divided socioeconomic status into five levels, quintiles. So adopting. from the bottom associated MSS to the top, that was associated with the gain of almost eight IQ points. So that is pretty huge. Well, it's half a standard deviation. Yeah.

Which is, it's like not incredibly huge. Yeah, maybe not as big as we initially think. And, you know, I think what's really important to say here is, you know, we're tired. Some of the studies where they're being adopted and they're having the huge jump in IQ. We're talking about being adopted out of a place where they're not going to get proper education.

They're not going to get proper schooling, you know. And that makes a huge difference. So when we talk about those big jumps of like one standard deviation, that's going from like no or like the worst environment you can imagine to like a really good environment. That's like one standard deviation. So if you have these, you know, less of a jump, or less of a jump in the environment change.

You're talking about like one third of a standard deviation. On average. On average. Yeah. Okay. Let's keep going. We wanted to look at the sort of what goes on with severe neglect, right? Yeah.

And it's tragic. It really is tragic. And there are these studies that show that the, brain does not develop as big that with severe neglect like and this is like really tough stuff to to grapple with yeah so good yeah this this rudder at all study this this is what we mentioned earlier this was uh extreme emotional neglect this is after the government of romania collapsed in the early 90s and they looked at 165 children who were raised with in severely neglected orphanages Deprived by any standards.

They'd have one staff member per 30 children, minimal interaction, no toys, educational activities for these children They were washed by being hosed down by water Their bottles were propped up like rats. It was just an extreme deprivation when these researchers got them and Fortunately, they were adopted by families in the UK So we got to see the effects of these adopted kids versus kids who were adopted from UK and from environments that weren't good, probably, but compared to this, much better that had parents who were, you know, looking after them.

So this study compared children who had this profound institutional deprivation to UK adoptees. Okay. So when these kids first came into the United Kingdom, their Denver developmental quotient, which is kind of like an IQ test, but for kids who are younger,

these like two-year-olds who can't take an IQ test. They were at the developmental level of children approximately half their age. So if there are two, they're acting like one-year-olds. None of these children could speak, even the ones who are two to four years old. But the children that were one to two could imitate language. They found that those had better outcomes years down the road. The mean IQ of these children at 11 was a little bit over 90,

but still lower than the UK, than Romanian average IQs. And they didn't start, even though these families that adopted them, they're actually of higher socioeconomic status than normal. They didn't see appreciative changes from 6 to 11, which really suggests that this can cause permanent damage to kids. In addition to just IQ, they noticed that they had a lot of other problems. They had this kind of quasi-autism is what the researchers described it, which has some autism-like patterns but is distinctly different.

They had inattention over activity and cognitive impairment, disinhibited attachment that wasn't found in the kids that were adopted from the UK. Man, this is like, this is stuff that just, it just breaks my heart. It really does. And even getting to the point of 90 for me is actually pretty hopeful. That's only, you know, a little bit, it's not even a standard deviation below the mean. At 90, you can hold a job. You can do well.

You know, you're not going to be a neurophysicist or a professor, but you can do good work. And so the people that adopted those kids are just saints, you know. and but then they also have those other issues right so i i think personally that therapy good parenting is going to make a huge difference long term you're not going to know how much of a difference because you don't know the baseline of what they would have been if you didn't give them amazing parenting but um Bruce perry has written about this quite quite a bit about the importance of like touch and massage therapy and getting these kids doing sports and rhythm classes and stuff like that. And if they do that, their brain just continues to sort of like develop.

Yeah, I think it's just so important that touch and everything. It's literally necessary for children to develop properly. I almost think they have to go through the attachment stages again as if they were just born. So, you know, think about holding these kids and the importance of just like doing the things that you would do to like a newborn, you know, okay, I'm just hold this kid. I'm going to carry him around on me all day long. We're going to play. We're going to take baths. We're going to, you know, healthy touch. And we're going to get this kid feeling their body in place in time and wrestling and stuff like that. Rough housing and it's so important for these kids. Okay. So go ahead.

And just one other quick thing, which I thought was interesting and I think important to note was that they found that the children that were adopted very early before age six months. they didn't develop the same behavioral problems as the ones that were neglected six months to two years old. So that real six months to two years old stage, that seems especially important, prevent these behavioral disturbances. So if they were adopted before six months, there was less behavioral stuff because the attachment system is still very plastic at that point. If it's older, you have to like, you have to do special interventions in the, children to get them to sort of, you know, go through those healthy attachment processes. Okay, keep going.

Yeah, and, you know, just even the ones that did have this neglect, you saw whenever they were initially adapted, they caught up in a lot of ways to the other children. You know, IQ 90, it's, you know, it's done profound harm to them, but they're, you know, much more caught up than they would if they received no one. intervention at all. So I wouldn't want anyone to feel like these kids are hopeless that you, you know, give up on them or anything like that. Yeah, if anything, I feel more hope after reading this. That with, you know, I mean, you have to, when you think about adoption, you have to think about, like, what would have happened if these kids would have remained in this, you know, one to 30 orphanage,

right? Where it's like, you're doing the best you can if you're that person. overseeing them, but you just can't, you just can't do enough. There's no way. This is actually personal for me. I have two sisters that are been adopted from Ukraine and they were in almost one of these. It wasn't this bad, but they had attachment disorders whenever they first come on that have mostly remitted. So this is like really kind of close to my heart. Wow. Visiting them in those orphanage in Ukraine. Yeah. Yeah. Um, well, and I mean, that really brings us to another question that I had when we were digging into this

about how adverse childhood events affect children. So there's this thing called the ACE adverse childhood events, things like abuse, emotional, physical, sexual, household dysfunction, if there's substance abuse, mental illness, violence towards the mother, incarcerated household members, separation or divorce. So how many of these things did a person have? and then they looked at these people long term. And of course, if you have more than four events, you're more likely to have sleep disturbances,

sleep disturbances, severe obesity, multiple somatic issues, smoking abuse or smoking use, alcoholism. Times seven times more. Seven times more alcoholism. Personality problems, you know, perceive stress differently, more difficulty controlling your anger. more risk of perpetuated intimate partner violence. So the list goes on, right?

And they have more physical issues. But one of the questions I had was, did they ever look at cognitive function? Yeah. So I found this next study, and this study was actually kind of surprising to me, kind of the effects they found. And they're just, you know, spoiler.

They're not as big necessarily as you'd think, but I think this really emphasizes a really important point, which is that whenever we're talking about different harms people can do to this, not everything is captured in a cognitive test. Just all those problems that you listed, that's going to affect your life way more than just like a little bit of decrease or a large decrease in, you know, attention is going to do. If you're obese, if you have behavioral disturbances, if you have emotional disturbances, if you're abusing alcohol or other illicit drugs, that's going to play a bigger effect on your life than just a little bit of decrease in cognition or even a lot of cognition if it's really

affecting. So how big of a cognitive decline do they find? So this study that I looked at, they did two, they did two studies. They sampled 1,200 community dwelling people over 65. So this was you know, pretty far removed really think about it from the adverse childhood experiences. So they looked at 91% of the subjects had experienced at least one childhood adverse event. 14.7% said that they had been abused either physically, emotionally, or sexually. And they found that sharing of parental problems was, and parental loss were significant predictors of poor cognitive performance later in life. The odds ratio, like 1.6. and parental loss was 1.4.

Kind of cut off, yeah. You know, what I think this says to me is that we need to get early treatment in kids with a lot of higher ACE scores. You know, so, gosh, I was thinking about the Joker and how high as ACE score was. I just did, before this episode, I did an episode on The Joker,

which was like, you know, this guy was horrifically abused when he was a kid. And I was thinking of myself, like, he comes off childish and what if this guy had gotten good treatment early on like he had been put in like a school like Montessori which by the way Montessori the it's a schooling type for kids it was created for kids who were lower IQ and the Montessori method actually increased their ability to the level of the average so that they could reenter the school system so that's where the Montessori method came up, the history of Montessori. My kids are in Montessori. I'm a fan.

And I'll probably do a deep dive in it. One of my 100 ideas of future episodes here. So, you know, if you have trauma as well, like, it can improve your ability to do school if you get the work done. done to work through the trauma. And I found that in the MEND program, which is the program I run, the IOP, the partial. We've done cognitive testing on our adolescents before and after, and their cognitive test goes up. Do you remember how much from the study? Yeah. We found a cognitive score increase of about 0.6 of a standard deviation. So that's about seven IQ points. Yeah. So you have to think about how actually working in the trauma or working through the emotional stuff

and working on the family dynamic stuff can actually make a huge impact on cognitive function. And I meet a lot of people who have been through a lot of trauma. And once they get the trauma resolved, they go through partial programs and they go through a lot of therapy. It's like their brain just works better. Some people later on in life, they go back and get their PhD or they go back and get through school.

and it's just like it was like really hard for them to do math and physics and stuff like that like the harder sciences when they had a lot of trauma underneath once they get that taken care of it's like all of a sudden they can do better on this stuff which it comes back to my heart on why I want to go through this episode and why this stuff is so important because if we if we recognize that this kid has a high a score or you know was adopted from this horrible situation maybe we can put them in an enrivening environment early on that can really help them out in the long term. Okay. Anything else on this topic? I just wanted to mention one more study on ACE because this was, I think, a really good study. This is Jeffrey Dahl 2016. So this looked at a longitudinal study of British.

They do a lot of studies on this stuff. And they looked at 17,000 people. And they collected data all through their lifespan and included. and including mistreatment data at 7 and 11. And I think this is kind of interesting in a way because when they looked at objective measures of childhood neglect, if the child appeared malnourished or dirty, if the parents didn't have interest in having the children stay in school,

if the parents said they didn't spend time with this, their children, these were associated with negative outcomes at age 50. actually in this study in a way that physical and psychological abuse even weren't. It seemed that people were more resilient to those things than neglect in this study. So that's a little hopeful to me in a way that people can, I think, overcome trauma even more than neglect. Well, neglect is that, you know, this is an interesting study because it really shows the power of neglect. Yeah. And, you know, being around other human beings listening to them is something that has gone on since the dawn of time, right?

You're a tribe of 50 people. All those people are raising you. They're interacting with you. We have this weird phenomenon in our culture with our technology the way it is where, like, literally one person can raise you and you can be left alone a lot. And that's pretty tragic if you think about it. And this is where like, you know, preschool is so important or just like that where they get that interaction with teachers and interactions with other kids is so, so important. Especially if there's just, if they're not going to get that otherwise. Yeah.

And like I said earlier too, I think it's really important to emphasize that, you know, cognition is just one outcome out of many, you know. These people who are abused, they have much poor mental health outcomes, even if we don't. see large cognitive deficits at age 50. So, you know, abuse obviously is still a huge problem that we have to deal with. So let's also talk about this Brazil 2001 study where it compared the IQ scores over time of the 717 children. And this was in Detroit, which is a very divided, segregated city. So they looked at these IQs of 717.7,000. children about half in each hospital, and they followed up at six and 11, and they found that the IQ scores in the urban hospital, they started off lower, but they fell an additional, almost

six IQ points from age six to 11, while the suburban scores stayed the same. So these results were suggesting to the authors that just growing up in the inner city, not related to individual parent, you know, behavior is just your wider experience dealing with oppression, with schools, with all those kind of things that are kind of just outside of just the family structure. Because we've really been talking about family structure, that all those can also affect children as they're growing up and developing. Yeah, just think about like the ongoing stress in the home. The ongoing stress in the home is just high and there's, you know, it's just tough, you know. And when I look at studies like this, it makes me think through like how

we look at SAT scores when colleges are, you know, accepting like kids, like, do they, do they look at the SAT score from someone who's raised in suburbia differently than the person who's raised in, like, the middle of Bronx or something, you know? And of course you do. Of course you do. Because, like, you're just, your starting point is just different. So if we want equal opportunity, you know, then you have. to allow for some sort of differential of, you know, like my parents never even told me that

there was such a thing as like an SAT prep course. Like it's news for me. Like my kids will take an SAT prep course at this point. It's news for me that like you would prepare for a test like that, you know? Yeah, just the expectations too. They're so different. So it's just a different world, you know. And I think if you if you're not raised in poverty, you just don't really know what that's like, right? So at this point, you're thinking, okay, what do we do? Right. How do we make a difference?

Like, as people who are mental health experts, as people who are going to be also public health advocates, you know, there's this Walker-At-all 2011 article, and I think it really shows that even small interventions can make a big difference. So tell me about this one. All right, so this was not in this country. It was in Jamaica,

and they looked at 100,000. 29 children who were growing up in poverty in Jamaica, and they knew that these children had a poor chance of doing well in school. They thought they were going to drop out. So this is an attempt to really see what they could do to improve the outcomes. So they tried nutrition, and then they tried just like providing some food for the children. And that didn't really do too much. But the other intervention they did was pretty simple.

They had community health workers show up once a week for about an hour and talk the mom through playing, interacting, stimulating with the child. And then they followed these children as they grew up. And just this one hour a week of training, it actually had really significant increases in scores and grades at age 7 to 8, 11, and 17. So this is a really, really interesting study. It showed a positive IQ change of points. six.

Yeah, that's an effect size. So it's like... Seven, eight IQ points. Yeah, so that's significant in math and reading scores. And what I like about this study is it's teaching mothers to play, which don't take for granted that parents know how to play with their kids. I go to the park and there's a lot of parents that are just like, it's like they don't know to play with their kids. They're not mirroring them, you know, so play. Playing with kids is like mirroring them.

You know, like a little wrestling, rough housing, you know, talking, you know, like interacting, right? Like getting on their level. And this is this is what makes a big an impact. Interestingly, it's not the, it's not the formula. Because they gave them formula too. And that didn't really change anything in this study. But this one hour a week of intervention. I mean, just when you, you know, we're talking about these points or whatever, but think about how much this does over a lifetime.

These children, whenever they're age 17, they're more likely to be in school. They had reduced violent behavior. Think about over a lifetime, if you stay out of legal trouble, if you're able to get a job that requires a high school or further education. It was such a small intervention to see that kind of effect. I thought it was really inspiring and like a real big avenue to affect good change. Less depression, less anxiety. Really cool. Yeah.

Really cool. Okay, let's shift a little bit. What about pollution? Does pollution change IQ? Yeah, this is one of those, another, you know, things that we don't really think about as a factor. But epidemiologically, this is pretty huge. China is a place with a lot of air pollution right now, and a lot of people were wondering about that. So Zhang at all last year, they found that one standard deviation increase in air pollution

in China, the ones that had more than other cities, they had an IQ loss of about 1.3 verbal points. So it wasn't a huge thing, but if you think about how that's affecting millions of people, that is pretty concerning. So they said if China reduces their levels of air pollution to what's recommended by the U.S., that would, you know, raise verbal IQ scores about two and a half percentage points in China. So that's not insignificant when it comes to millions of people, billions of people. It's a big issue right now in China with just the huge drive to industrialization, you know, and not the EPA and, you know, the sort of regulating bodies to the same level that we have here in the U.S. Yeah. And even here, you know, I think about San Bernardino County. Like, we don't have the best air quality here.

It's better than it was when I was a medical student. That's what I've heard. I attribute any bad scores in medical school to pollution. Okay. If you're in L.A., it all comes down to us. I'm saying, Brendan. All right. So we are going to pause here and continue this in a future episode.

This is already becoming almost two hours here. So you are a trooper if you made it through this first session. And I think actually the next session will be even more interesting because we're really going to go through mental illness and how mental illness affects the IQ and how treating mental illness can really change IQ as well and improve it. And that's one of the big thrusts

and the reasons why I want to do this episode. I think it was really interesting to look at the genetics, the epigenetics. You know, about 50% or so is predicted by the genetics. But, you know, from looking at like the different genes and stuff like that, we can only really judge about, what, 11% of the variance.

So it's actually like a very small amount that we're able to guess or predict just by looking at the genes that someone has. We also talked about epigenetics and we talked about some of the environmental factors and of course environmental factors change our genes and that's important. And we also talked about how predictive it was. It's more predictive for doing well in school and less predictive for doing well in life. And we know that all sorts of other intelligences and, you know, drive and motivation predict, you know, how successful someone's going to be financially. I would say social, emotional intelligence is very important for that as well. And we'll probably get more into that in the future, actually, when we look into the Harvard longitudinal study, which show that maternal warmth, you know, connection with your siblings growing up. you know, mature coping styles, all of that predicted financial, you know, and long term,

doing well much more than IQ. So I hope you enjoyed this episode. I would appreciate if you found it helpful and you made it to the end. Shoot me a DM. I salute you and I will tell you how awesome you are to be able to focus this long and how strong your IQ has been to. to digest some of this difficult material. Once again, I'm very thankful for you guys continuing to listen. I appreciate the feedback that I get through messages, through Instagram. And once again, I appreciate you guys and we'll leave it there for today.