- I want you to look at this chart.

Autism rates have absolutely skyrocketed in the last few decades.

About one in 31 kids in the US are diagnosed on the spectrum today.

And it's not just here.

Worldwide data shows a steady rise in autism across most high income countries.

This data has sent public health experts, doctors, and anxious parents on a search for answers.

Everyone wants to know what could possibly be causing this.

- Pharmaceuticals of different types.

- Air pollution.

- Gut microbiome, - Genetics.

- Preterm birth.

- Pesticides.

- Infection, a fever.

- Mother's age, father's age.

- I wouldn't call it a mystery, I would call it a complex problem.

- It turns out that the real story behind the increase in autism isn't what you'd expect, and the causes aren't as mysterious as many people think.

Our team has spent countless hours investigating and searching for the truth about what causes autism.

Our goal is to separate the myths from the science and ask, what do we actually know and what don't we know?

What can be done about it or should anything be done about it?

And what's really going on behind this trend?

(soft playful music) Hey, smart people.

Joe, here.

The first question we have to ask is, is the autism epidemic even real?

- We announced historic steps to confront the crisis of autism.

- By September, we will know what has caused the autism epidemic.

- The epidemic is real.

- Yeah, this is the million dollar question.

- Because this is such a huge topic, one of our writers, Maren, is joining me to walk through all of this.

- So as you know, Joe, I am a medical microbiologist, and therefore, in my field of study, when someone's sick, we're looking for the thing that's making them ill, like a bacteria or a virus.

But with something like autism, which is what's called a neurodevelopmental condition, it's not a disease.

We're not talking about an illness here.

So there's no one smoking gun causative agent that we can point to, and it's also not necessarily something that needs to be cured.

- Yeah, exactly.

I mean, one of the most important things, I think, to recognize right at the top here is that autism isn't one thing.

It's actually a really diverse group of conditions that are defined by the presence of these certain social and developmental and behavioral symptoms.

- Exactly.

And what was so interesting to me when we were researching this, is that even though the name Autism Spectrum Disorder, or ASD ,does do a really good job of getting across the idea that this is not a a one size fits all condition.

It's also not quite as simple as this idea of a line going from less autistic to more autistic.

Because most experts in the field today are actually leaning towards thinking of this as more of a wheel.

And I wanna show you what that means.

So the different segments of the wheel might include sensory processing, emotional regulation, social interaction, speech, motor skills and coordination, repetitive behaviors, lots of other things.

And each individual may have greater challenges in some areas than others.

So every autistic person's wheel is gonna be pretty unique.

- And we used to hear autistic people described with terms like low functioning or high functioning, but that's not how experts look at this anymore.

Autism's typically diagnosed in levels defined by how much support someone might need in their day-to-day life.

That's all laid out in here, the DSM.

That's the Diagnostic and Statistical Manual of Mental Disorders.

It's updated every decade or so, and it's the standard reference book that's used by doctors to diagnose and classify various mental health, behavioral, and developmental conditions.

And basically the way we diagnose autism is based on behaviors we can see from the outside, but that doesn't tell the whole story, because autism isn't just a behavioral condition.

There's biology and genetics behind this stuff that we are just starting to truly untangle, like the fact that autistic brains are different.

One 2024 studies scanned the brains of autistic adults and found they had a lower density of synapses than neurotypical folks.

Synapses are the structures between neurons that allow them to pass messages to one another.

Many lines of research have found the same thing.

There are real differences in how neurotypical and autistic brains are structured and connected, but where do these brain differences come from?

- Lots of different lines of evidence point to autism starting at the earliest stages of life, meaning, post conception as a body and brain are developing in utero even before a baby is born.

- But coming back to our alarming chart, does that mean something happened in the last few decades that suddenly changed how our brains develop?

Is that why we see the rise in cases?

- Okay, so as a history nerd, I think about this a lot, but before we had our modern diagnoses that we all agree on, there wasn't a really commonly understood way to talk about people who behaved differently.

So even though we may be able to look back and read into accounts of historical figures and guess that they had what we would today call autism, we're not gonna find historical records of autism cases before the word itself started being used.

So, Joe, I'm gonna take you on the quickest speed run of the history of autism, from the time the term was coined, until today.

- Okay, I'm ready.

- In the 1910s, Swiss psychiatrist Eugen Bleuler coined the words autistic and autism to describe traits he was seeing in children with schizophrenia.

And where everyone likes to go next is 1943, when Austrian doctor Leo Kanner published the first clinical account of autism as its own unique condition.

But actually, in the 1920s, Russian doctor, Grunya Sukhareva, was publishing detailed case studies describing autistic symptoms in children that largely match how we still diagnose autism today, although her work was overlooked outside of Russia until decades later.

In 1944, Hans Asperger described similar autistic traits in children.

And from the forties to the sixties and even into the seventies, autism was still officially being grouped with mental illnesses like childhood schizophrenia.

And it's not until 1980 that autism was officially included as its own diagnosis in the DSM.

In the 1990s, Asperger's work resurfaced in English and the label Asperger's syndrome started being used for what were then seen as milder forms of autism.

But in 2013, the DSM-5 combined Asperger's and several other diagnoses into autism spectrum disorder, as we know it today.

The other big reason we don't use the term Asperger's syndrome anymore is because recently discovered historical records tell us that Hans Asperger was doing a lot of his work under the Nazi regime, and it can't be separated from that legacy of eugenics.

We can't consider our understanding of autism today without thinking about its problematic history.

I mean, Kanner and those who followed in his footsteps believed in the refrigerator mother hypothesis.

That autism was because of bad parenting, and in particular, cold mothers, which we absolutely know today to not be true.

So our understanding of autism, how we assess and diagnosed it, this has all changed hugely over the past century.

- If we ask the question, is there a higher percentage of people diagnosed with autism today than there were 30 years ago?

The answer is yes.

But we weren't able to identify them in the same ways, because there's either stigma for reaching out to get a diagnosis or there was lack of awareness that you should go and seek an evaluation.

I don't think epidemic is the right term to explain what's happening in autism prevalence.

- And we can see this really clearly in one stark example.

Austin, Texas and Laredo, Texas are only 235 miles apart.

The rates of children with autism in Austin are nearly double those in Laredo.

And the answer to why lies pretty clearly in the social and economic things we know about these places, not in biology.

Austin is an urban area with a per capita income of around $71,000 a year, while Laredo is a more rural area with a per capita income of around $25,000 a year.

- The major driver of these geographical discrepancies is access to diagnostic services, access to early screening.

Pediatricians in urban areas are more likely to be doing screening and then have the resources to send the child off for diagnosis that you don't find still in more rural areas like Laredo.

- [Maren] We also see that boys are three times as likely to be diagnosed with autism than girls are.

We are realizing that autism often presents differently in girls and they're more likely to mask certain behavioral differences.

These and other biases in diagnosis have probably overlooked many girls with autism since we started tracking cases, although this gender Gulf is getting smaller.

And that's probably another reason why cases have been going up.

There's always the possibility, though, that there is something genetic or hormonal that's influencing this difference too.

- Because we don't know yet what exactly causes autism, it's hard to rule out the possibility that there isn't another factor playing a role in the change in risk.

- So what we know is this trend is real.

There are vastly more people who are labeled as autistic today than there were a few decades ago, and most of that increase can be explained by changes in how we diagnose autism.

But this is what surprised me the most.

Even when we account for all of those changes, there's still a rise that we can't account for just from changing diagnosis.

This remaining trend is smaller, but it's also real.

Finding the causes behind this increase is where researchers are focusing.

And there are many potential answers there, but it starts where we do, with our genes.

Okay, Maren, I'm gonna tell you about this part because let's face it, I'm the genetics nerd between the two of us.

- Okay, I'm ready.

- All right, it starts in 1977.

That's when we see the first published study that looks at this potential genetic component of autism.

And it showed that autism tended to show up really strongly in identical twins.

And a ton of research has been done since that confirms this, that if one twin is autistic, sometimes you see more than a 90% chance that the other twin is autistic.

And when you look at fraternal twins who don't share identical DNA, right?

But they're born at the same time, that rate drops to one in three.

And normal siblings, it's like one in five.

These are all way higher than the rate that you'd expect someone to sort of like randomly have autism, right?

Which tells us there's definitely something going on with our genes.

- The call is coming from inside the house.

- Exactly.

So as genome sequencing has gotten cheaper and more advanced, scientists have so far been able to identify over a hundred genes where, when a mutation occurs in that gene, that person is more likely to have autism.

- You can study those variants in a population of kids, and you can see that all of the kids who have that variant or that gene have a set of common clinical features.

You can put that variant into an animal, and you can see that it has neurological and neurodevelopmental effects on brain function and behavior in animals.

You can clearly see the genetic factors are causal and you can understand their role in brain development.

- And scientists think they've only discovered about a quarter of the genes that cause autism.

So they think there's probably around 400 genes or so that are linked to autism in some real like causal way.

- We still have to find the of the genes, and then our ability to explain the heritability will increase as we find more of the genes.

- So what kinds of genes are these mutations happening in?

- Well, there's obviously like a whole big long list here, right?

But some of these mutations don't even happen inside genes, they happen in these parts of our DNA that sort of turn on or off genes or kind of turn the volume dial up or down on how much that gene is turned on.

But most of these mutations converge on genes that regulate how the brain grows and develops.

We're talking things like how different parts of the brain grow, how different parts of the brain connect with each other.

And there's a ton of evidence that shows that this is happening in the very earliest days of when we are growing and developing inside mom, and it even continues after we're born too.

- So we are getting these autism mutations from our parents?

- This is where things get pretty weird, honestly.

So autism can run in families, but it doesn't have to.

- Every child born has about a hundred mutations that they did not inherit from mom or dad, that actually accumulate in the sperm or the egg.

In fact, most of them accumulate in sperm.

Because sperm are constantly dividing, those are the de novo mutations.

- We all have these.

Each of us is born with these totally new random mutations in our DNA that our parents don't have.

And most of the time they're invisible, right?

They don't do anything.

But you have to imagine every so often, if one of those mutations lands in a gene that's important, in say, fetal brain development, that could lead to that person developing autism, even if no one in their family has ever been diagnosed.

Now, studies suggest that these spontaneous new mutations contribute to a really major chunk of autism cases.

And remember, we haven't even found most of the genes that cause autism yet.

So this is likely an underestimate.

- Okay, this is all coming together, because autism doesn't always look like a normal genetic disorder, right?

Sometimes it runs in families, but a lot of times it doesn't.

Or one sibling might have it and another doesn't.

So de novo mutations is helping all of this make sense.

- Because you know, different genes get turned up or down at these different stages of development.

So that means genetic changes that are linked to autism aren't always obvious right at birth.

Imagine a scenario like this, right?

A baby might seem to develop really typically for the first year, but around 12 or 18 months old, they start losing skills.

Maybe they stop saying mama or dadda.

Maybe they stop making eye contact, they regress.

Families sometimes think, wait, if this is genetic, then I should have seen it right from birth, right?

But the gene was always there.

It just didn't come into play until this stage of development when its effects become visible.

This doesn't feel like what a genetic condition should look like, but it is a genetic cause.

- So is there a number?

Like can we say that X percent of autism is caused by genes?

- Researchers think that about half of autism can be linked to these genetic variants that are out there in the population circulating, the kind of stuff you can inherit from mom and dad.

Maybe another 20% of autism is thanks to these de novo spontaneous mutations.

And then there's some other bit that they definitely think is genetic.

We just don't know exactly how yet.

- Okay, so some quick math here.

That means that when we look across the whole population, 80% of all the autism cases we see can be traced to these genetic roots.

I feel like that's way more than I thought.

So what's the other 20%?

- Well, this is where our environment comes in.

For example, one of the strongest associations that we see is that autistic people are more likely to have older parents.

Now, the older someone is, right, when they conceive, the more likely it is that their sperm or their eggs have accumulated those de novo kind of random spontaneous mutations.

And the more mutations, the more likely it is that one of those mutations is gonna happen somewhere that increases your risk of autism.

But there's no gene that determines when someone decides to have children, right?

But there are all kinds of things that correlate with a parent's age, things like education, where you grow up, cultural differences, all kinds of stuff.

But these are things that are about your environment.

So the reason that older parents are more likely to have an autistic child, I mean, that's clearly genetic, right?

But the reasons that people become older parents are because of these non-genetic environmental things.

- Okay, I feel like this is the perfect example of how investigating these environmental factors gets really sticky, because we can see associations between autism and tons of things.

But the really important question that scientists actually want to answer when looking at that is, is this thing just linked to autism for some other reason?

Or is there actually something causal there?

And also there's just so many potential environmental factors.

So like which ones are real?

- We're gonna run down a list of many factors that are commonly associated with autism, what we know about them so far, what we still don't know and what we can say about how they are or aren't related to autism.

Now before we get started, here's sort of the fine print terms and conditions of this info.

We can't give you neat exact numbers.

Science doesn't work like a weather app.

You don't get a clean like 40% chance of rain, 20% chance of autism.

There may be exact figures from individual studies, but we can't apply those numbers to everyone.

It's impossible to say, this factor will increase your risk by this percentage.

And this is a big one.

When we look for things in our environment that may influence or cause autism, the point isn't to blame parents for something they did or didn't do during pregnancy, especially towards moms who still often get unfairly singled out.

It's about understanding the interplay of complex, biological, and environmental factors interacting with genes.

We're gonna go through these causes, because they come up a lot in the media, and we want to give you the context, so you can separate myth from evidence.

And with that in mind, let's start where we all did, in pregnancy.

- We've studied several kinds of metabolic conditions during pregnancy.

So think about gestational diabetes, about weight gain during pregnancy.

And when we and others across the globe have looked at this question, we see hints that there is some association between metabolic conditions in pregnancy and then the increased risk of autism in those offspring.

- Some studies see a link between autism and obesity during pregnancy.

Diabetes, both preexisting or gestational diabetes, is associated with increased risk of autism too.

These kinds of associations are tough to tease apart, because there's always a chance that there's some other underlying genetic thing, that confounding variable, and that's the common factor behind both obesity, or diabetes and autism.

- Now, next up is what happens at the end of a successful pregnancy?

Birth.

In the US, infant mortality has decreased by over 50% since the 1980s, largely because more babies are surviving preterm birth, and that's true for many countries around the world.

Medicine has made huge advances in neonatal intensive care.

So if a baby is born before 37 weeks, or preterm, they are vastly more likely to survive today than they were 30 years ago.

And many studies have found an association between preterm birth and higher rates of autism, when you compare to babies born at full term.

But there are also studies that don't show that increase after adjusting for other variables.

So the big thing we still don't know about this association, is again, what scientists call directionality.

So which way is this effect going?

Are preterm births resulting in some altered biology or brain development that increases the likelihood of developing autism?

Or.

- More likely we think there is some common cause.

There's some biology, some gene, or some other kind of exposure, that is creating risk for the preterm birth event and also creating risk for autism in that offspring.

And so they co-occur because of that common cause, not because the event itself is causing autism.

- Then we have air pollution.

There's definitely a link between mom being exposed to air pollution and an increase in all kinds of neurological disorders, not just autism.

Different studies have seen a link between the exposure to nitrogen dioxide, sulfur dioxide, carbon monoxide, ozone, and particles in the air like dust, soot, and smoke.

All of these are linked to an increased chance of a child developing autism.

What we don't yet know for sure though is what amount and what kinds of air pollution exposure increase the chances of developing autism and how much that risk goes up.

- These are all also related to other parts of your experience, where you live, what kind of access do you have to care?

And we do know that exposure to things like air pollution or being near a farm and pesticides or whatever that might be, has a social determination to it.

- Speaking of pesticides, many robust studies have found that exposure to industrial pesticides in utero is linked with an increase in the likelihood of developing autism.

The problem is, there are tons of different kinds of pesticides.

One of the largest studies on this found that if mom lived within a mile of a field treated with this kind of pesticide, their child was 60% more likely to develop autism.

And by the way, this pesticide is still regularly used on crops today.

Also, just to be totally clear, we are not talking about pesticide residues left on food that you may pick up, say, like at the grocery store.

What we're talking about here is big environmental exposures like living near where these pesticides are being sprayed on fields in industrial quantities.

The same actually goes for maternal exposure to toxic levels of heavy metals, things like lead, cadmium, arsenic, and mercury.

This is also linked to an increased likelihood of their children developing autism.

But the results vary, again, depending on the study.

And we also don't know that it's the heavy metals causing the autism.

It could also be that the parent in this scenario has something going on in their genes that makes it more difficult for them to clear these heavy metals from their bodies.

And it's that genetic underpinning that is truly linked to autism.

We just don't know.

This is also all complicated by the fact that the older a person is, the more pesticides or heavy metals they may have been exposed to in their lifetime and may have been accumulating in their bodies.

And we know that elevated parental age is also a risk factor.

So these are just other examples of how intertwined all of these variables truly are.

- We've also heard a lot about different drugs that people might be taking during pregnancy.

We know that folate, an essential nutrient, is something that's really necessary for healthy field brain development.

It's often why people are encouraged to take folic acid supplements while they're pregnant.

Getting too little of this vitamin early in pregnancy has been associated with an increased risk of autism in that resulting child.

But new research is now also showing that taking too much folic acid, especially later in pregnancy, can also increase risk.

It's an example of how this stuff isn't always as easy as saying, do take this and don't take this.

That being said, one of the big worries right now, among the public, is pharmaceuticals that mom might be taking.

And this is a good thing to look at.

For example, drugs that contain valproate, a common one is Depakote, sometimes used to treat seizures or migraines.

Really good carefully controlled studies have shown a clear association, where if mom takes this drug during pregnancy, the baby has a significantly higher risk of autism and other developmental disorders.

Maybe it's interacting with autism genes in some important way.

So as a result, now this drug is not recommended for pregnant women.

But then there's other drugs like acetaminophen, which goes by the brand named Tylenol.

A 2025 paper analyzed 46 different studies that all looked at whether using this really common over the counter pain reliever during pregnancy was associated with neurodevelopmental disorders of the child.

The majority of these studies did initially see some kind of an association, where acetaminophen use was linked with an increased incidence of conditions like autism and ADHD.

This raised a lot of alarm bells.

- So taking Tylenol is not good.

- But.

- When you look at that further to try to understand what could be causing that or what could be explaining that association, you first ask questions like, well, why was the mom taking acetaminophen and did she have an infection?

Did she have some other condition?

If that's true, what is the genetic predisposition to both autism or to those conditions that the mom had that might imply needing to take acetaminophen?

So if we start to ask those deeper questions, some of those associations go away.

- What Danny's talking about here are called sibling controlled studies.

It's where you look at the outcomes for two children in the same family.

This way, you're controlling for lots of other variables, the parents' genetics, the environment, that they're raised in, things that are probably pretty similar between siblings.

So maybe in one family, the mom only took acetaminophen in one pregnancy, but both children ended up being diagnosed with autism.

That's a good hint that there's something else there in the family.

And that taking Tylenol probably wasn't the causal factor.

There's actually a huge study published in 2024 that looked at this potential link in over 2 million children.

It's the largest sibling controlled study of its kind ever performed.

And when you carefully control for all of these complex variables, suddenly the link between acetaminophen and autism goes away.

- So I looked into this.

Acetaminophen isn't just a pain reliever, it can also lower a fever.

Now, the most common painkiller/fever reducers are medications called NSAIDs, and Ibuprofen is an example we probably have all used at some point, but most of these are not recommended for use during most of pregnancy.

So acetaminophen is really the only option.

And it's a really important one because we definitely know that a fever during pregnancy can result in worse outcomes for mom and baby in many ways.

And there's also really strong evidence that infections and fevers during pregnancy can increase the likelihood of autism in baby.

And think about it, fevers are usually the result of something like an infection of some kind, right?

So this is yet another case where we haven't yet teased out if the increased likelihood of autism is because of the fever itself or because of whatever is causing the infection, how long or how high of a fever, what type of infection, when during pregnancy it happened.

There's so much at play here, but the bottom line is, there's much stronger evidence that a fever during pregnancy is more of a risk, in many ways, than taking acetaminophen is.

And the strongest evidence that we have doesn't indicate that acetaminophen is a risk at all.

Now, the same goes for maternal use of SSRIs during pregnancy.

SSRIs are drugs used to treat anxiety and depression.

And some studies have previously linked the use of these during pregnancy to an increased chance of the child developing autism.

But, most recent studies have concluded that that increased risk has a lot more to do with why mom was taking the SSRI in the first place.

Does she have her own mental health condition maybe influenced by her genetics?

And maybe it's those genes that are affecting brain development in some way.

It's much more likely that is what is related to the autism risk.

And speaking of pharmaceuticals, we gotta talk about it.

If there's one medicine or drug that's received more undeserved attention than any other, when we talk about autism, it's, you guessed it.

- Vaccines.

Now, this one has been widely and repeatedly debunked over the past couple decades, but we still continue to hear it offered as a cause of autism.

So it's worth addressing here.

It starts in 1998 when a doctor named Andrew Wakefield published a paper in the journal, The Lancet.

This was a really tiny study, like 12 children, eight of whom developed these bowel problems after getting the MMR vaccine and then also developed behavioral symptoms of autism.

Wakefield claimed the MMR vaccine shot was causing the autism and began to sort of campaign to parents around the world that they should avoid this particular vaccine.

That study was quickly debunked.

It was a tiny study, not well designed, whole bunch of issues, and it was even eventually retracted.

And Wakefield later lost his medical license for manipulating the data in that study.

But it set off this massive global controversy on social media and online that we still see today.

Despite the link between vaccines and autism being one of the most repeatedly debunked claims in the history of medicine, vaccine researchers are still having to respond to this.

It just won't die.

And for some vaccine researchers, that hits close to home.

- It put me in this very interesting position being both a pediatrician vaccine scientist and having a daughter on on the autism spectrum with intellectual disabilities.

- Rather than repeat what so many scientists have already done over the past 20 or more years and sit here and examine every claim made by people who've tried to link vaccines to autism, it makes more sense to zoom out and ask, is this even a realistic question?

- It never made sense to me how something like a vaccine could ever be responsible for so many global alterations.

I couldn't even imagine a plausible mechanism.

It's not just the evidence that vaccines don't cause optimism, it just makes no sense.

We've learned so much about the auto, how autism spectrum disorder occurs in early fetal brain development through the action of autism genes.

- In fact, if anything, there's some studies to suggest that vaccination may even protect against some forms of autism.

- For instance, we know Congenital Rubella Syndrome, which causes multiple birth defects, including an autism phenotype, in that case, getting the MMR vaccine, as a kid, will in a sense, will protect your child against autism later in life.

- We keep mentioning this in this episode, how difficult it can be to untangle all of these things in the environment from those harder to see genetic causes.

And vaccines are a perfect example of this.

I wanna tell you a story about one of those genes.

Because I think it can explain so much about the anxiety and confusion that often happens around autism.

This gene is called SCN1A.

It makes a protein that helps neurons in the brain transmit signals.

If there's a mutation in this gene, it can lead to seizures as part of a disorder called Dravet syndrome.

But mutations in SCN1A can also lead to behavioral differences and an autism diagnosis.

Children with this mutation often have their first seizure after they have vaccines, because in Dravet syndrome, getting a fever can trigger a seizure.

And what can trigger fevers?

Getting those early vaccines as the immune system responds to them.

It wasn't the vaccine or the seizure that caused the autism, it was the mutation in that gene.

That did cause the autism.

It's a perfect example of how parents aren't imagining things.

This child got a vaccine and then something happened to that child.

It's completely understandable for parents to feel confused, scared, to search for some answer in a case like this.

But when it comes to vaccines and autism, scientists know that it's as close to settled as anything is in the science.

There is no causal link.

- And while that's something we know for sure, there are so many other things in this field that aren't settled science yet, but the scientists are just starting to really dig into.

Stuff like the fact that all of the bacteria that live in your digestive system, AKA, your gut microbiome, they're talking to your brain.

- The gut has its own nervous system, sometimes called the second brain, and it talks to the brain through nerves like the vagus nerve, through hormones and through chemicals made by gut microbes.

What we see is that the types of microbes that are in the guts of people with depression, anxiety, and autism, look pretty different from people without those conditions.

- See, folks with autism are much more likely to have digestive issues than neurotypical folks are.

And while there's definitely something going on with our brains and our guts, we're still really unclear on how an altered gut microbiome, digestive differences, and symptoms of autism, might all be interacting and affecting each other.

So there's still lots to explore there, and this is true of so many other things in autism research that we haven't even touched on in this video.

Microplastics, PFAS, phthalates, the list goes on, and the research into so many of these is just getting started.

So going into the literature on all of them would take us longer than we have for this already very long video.

Which brings us to the point, what is the purpose of looking at all these factors?

A lot of this work focuses on moms and their health during pregnancy, but if you've ever been pregnant, you know there's only so much you have control of while you're pregnant.

A lot of this science gets reported in a way that I think can really make individuals feel responsible for whether or not their children get autism.

And that's not helpful, and it's not the purpose of this kind of research.

- The goal is to understand the biology of autism, so we can better support autistic individuals.

Instead of framing a research around causes and cures, it can be more helpful to think about mechanisms and supports, what's happening in the brain and body, and how can we make life healthier and more fulfilling for this population?

- Okay.

That was a lot.

- I have so many tabs open right now.

Joe, you don't even know.

- Let's try to sum up the big takeaways.

I mean, first and foremost, it is not accurate to call autism an epidemic, right?

- Right, correct.

Autism also predates all of these environmental factors that we've been diving into.

I mean, it's been around for a really long time, so it's pretty undeniable that most of the recent increase that we've seen in autism cases comes from changes in how we think about and recognize it.

- We know so much more than people realize about the genetic influences on autism, and genes, it turns out, are a huge chunk of where autism comes from.

But like we're not just our genes.

Genes are not destiny that determine our lives all by themselves.

Our genes interact with our environment in these really complex ways.

And I think we're just at the beginning of being able to untangle and understand those complex interactions, because when we account for the changes in diagnosis, and that exponential increase that we saw in autism, well, there still is a smaller real increase that remains unexplained.

Maybe genes and environment working together could explain that.

- Also, autism is often talked about like it's this one single thing, but we should really be thinking about it more the way we think about cancer.

Now, the key difference is that cancer is a disease that we try to cure.

While autism is not an illness, it's a form of human diversity, but like cancer, autism is not one condition.

It's a whole family of complex conditions with different causes and presentations, and they're shaped by this mix of genetic and environmental factors.

- I mean, we're just trying to understand ourselves better, right?

That's the whole point of science, you know, to know more so that we can ask better questions.

And I guess with that, you know what we say?

- [Joe And Maren] Stay curious.