Autism spectrum disorder is pretty common.

The World Health Organization estimates that at least 1 in 100 people  today have that diagnosis. And some say it could be twice as many.

But while all autistic people  are united under the same label, it is a diverse group. You could be a middle-aged white woman who communicates through an iPad and pointing, and who lives in a group home  with round the clock care. You could be an older African-American man who’s married and works at a museum where you get to wow people with all of your knowledge on your favorite topic.

You could be a young Vietnamese girl who walks on your tiptoes and plays the same game by yourself during play time every day. If you’re not autistic, you might still see yourself  in some of those descriptions. And if you are, you might not  identify with any of them.

That’s because autism isn’t one thing. It’s a spectrum. It affects a variety of  people in a variety of ways.

But we haven’t always understood it that way. Over the years, researchers and the Diagnostic  and Statistical Manual, or DSM, have updated who falls under that umbrella and what kinds of diagnoses and therapies might come with it. So here’s what we know today about  the entire spectrum of autism … where it comes from, how to recognize  it, and what comes after diagnosis. (intro song) First of all, autism hasn’t always been  thought of as a spectrum.

The scientists and clinicians who wrote the first reports back in the day were not taking into  consideration a lot of the people who would be diagnosed as autistic today. Which is why in the 1940s, they described it as a quote; “rare disorder.” It was a diagnosis given to people who were especially sensitive to certain stimuli; avoided hugs, eye-contact,  and other social contact; felt particularly drawn to routines; repeated certain words and movements; tended to get totally absorbed by an object; and either didn’t use language at all or didn’t appear to use language  to communicate with other people. And many autistic people today can relate to at least some  of the stuff on that list.

But there’s a lot to unpack between those early descriptions and now. In 1994, the fourth edition of the DSM  came out and drew some new distinctions. For people who weren’t  intellectually disabled and aligned with fewer of the communication criteria, there was a new diagnosis, separate from autism: Asperger’s disorder.

This new diagnosis was already a bit controversial because the children that Dr. Hans Asperger wrote papers about in the 1940s wouldn’t have qualified as  having Asperger’s disorder the way it was described in the DSM-4. Not to mention the controversial circumstances under which Asperger published his findings.

He began his scientific career in Nazi Germany, so there’s a lot of debate around the underlying goals  of creating those diagnoses. But Asperger’s wasn’t the  only addition to the DSM-4. A few other diagnoses with overlapping symptoms also came onto the scene, broadly referred to as pervasive  developmental disorders.

And when it comes down to it, whether you were diagnosed with Asperger’s or a pervasive developmental disorder, you probably had overlapping symptoms with people diagnosed with autism. So the next time the DSM was updated, in 2013, all of those diagnoses were smooshed into autism spectrum disorder. And we continue to call it  the autism spectrum today.

But everyone seems to have their own  definition for what “spectrum” means. Some researchers refer to it as a  scale of functionality or severity, based on things like the extent  to which you depend on others to complete daily activities. And there’s a huge range of support that people across the autism  spectrum might receive.

But others, including some  people in the autism community, prefer to view the spectrum more  neutrally, like the color spectrum. In that framing, different  people have different qualities, but one shade of autism isn’t  better or worse than another. So while the debate continues about what exactly the “spectrum” means, the current accepted diagnosis  is autism spectrum disorder.

And there are biological reasons to  support thinking about it that way. Even after a century of research, we’re still in the very  early days of understanding where the symptoms of autism  spectrum disorder come from. But genes do seem to play a role.

One publication from 2019 surveyed the genes of more than a thousand autistic  people and their relatives. And they found rare genetic  underpinnings for autism that have also been linked to stuff that’s sometimes associated with autism, like schizophrenia and ADHD. It often comes down to things like deletions and duplications of parts of your genetic code.

And that’s the kind of thing  that can be inherited … or not. Now, I know that’s not a specific  answer to the genetic question. But that’s because, as far as we know, autism isn’t like sickle cell disease where you always get that diagnosis if you inherit a particular gene.

It’s a more varied diagnosis  with more varied sources. In the 2019 study, most of the participants had no clinically relevant genetic changes. But about 10% of them had at least one,  and they were not all the same one.

In total, this study found 209 genetic changes that are likely to be involved in  creating the autistic experience … but only for those 10% of autistic people. . If you’re one of those 10%, you might want to know what causes your genes to change like that. It is not vaccines.

As usual, the dark corners of the internet are wrong about this claim. It has been refuted by many peer-reviewed studies that strongly conclude there is no  link between vaccines and autism. But there are some epigenetic changes that researchers have linked to the condition.

That’s the term for when  your lived experience changes the way your body uses your genes. A particular environment or experience can alter your DNA through a  process called methylation. One carbon and threea hydrogen atoms, which chemists call a methyl group get added onto part of your existing genetic code.

And this change can keep that  genetic code from being read, as if it’s been turned off. Another study published in 2019 found differently methylated DNA in the brains of autistic people  who had donated their bodies to science upon their deaths. The investigators compared brain tissue from people who had and had not been diagnosed with autism spectrum disorder  back when they were alive.

And they found 111 genetic sites  that were differently methylated between the two groups! Of them, about 18% seem to actually matter. Like, you can put a stop sign  in the middle of a corn field and it won’t change traffic patterns.

But if you put that stop sign on a busy street, it’ll have more of an effect. So 18% of these methyl stop  signs were put in places where they metaphorically  stopped traffic for those genes. One of those places is thought  to be a kind of Autism Avenue, where a lot of methyl groups  were found to stop traffic on a gene that has already been associated with the autism spectrum.

Have we taken this metaphor far enough?? Probably. I’ll give it a rest.

Despite the vast spectrum of autism, these researchers found that different manifestations of the diagnosis have the same DNA methylation patterns. So across the spectrum, certain genes associated with autism may be altered and contribute to the experience. These genes regulate all sorts  of stuff like immune function, sending information from one  part of your brain to another, and forming new neural connections.

So it’s no wonder that there are many layers to the autism spectrum. And if we go even farther down the rabbit hole, some researchers have come up with ideas for what inspires these methyl groups to attach to autistic people’s DNA more than other people’s in the first place. One popular theory is that the age of your father when you’re born matters.

Some research suggests that you’re more likely to be autistic if you had an older male  parent because sperm mutates more with age. In this context, “older” refers  to people over 40 years old. But that’s not to say that everyone  over 40 will have autistic children or that all autistic babies  were born to people over 40.

There are just studies that suggest it’s more common at the population level. Another potential source of  epigenetic changes associated with the autism spectrum is the immune system. Several reports from Europe and North America say that people who developed  in the womb of someone with an autoimmune disease are more likely to be diagnosed with autism, with some specific diseases increasing the likelihood by up to 80 percent.

But it ranges a lot depending  on the autoimmune disease and its onset timing. For example, thyroid disease  is particularly relevant, while psoriasis and rheumatoid arthritis are not significantly associated  with the autism spectrum. Scientists think that pregnant  people with autoimmune diseases make more antibodies than those without.

And they’ve found that people who gave birth to autistic babies made specific antibodies that other pregnant people didn’t make. Those antibodies target  proteins in the baby’s brain, which could make it inflamed  and change the way it develops. And, yes, brain development is yet another potential source of autism.

But I’ll get into that later in the video. The point is: there are a lot of  possible origin stories for autism and none of them apply to  everyone on the spectrum. And you better believe that  scientists are still looking into it.

In the last few years, the National Institutes of Health  started pushing for autism research and funded a veritable butt-load  of projects along those lines. But because of the whole spectrum of it all, many avenues of research could  be related to the disorder. It’s very possible that a diagnosis this complex is the result of several interconnected causes.

So we still don’t know exactly  what gives you autistic traits. But a lot more progress has been  made in the area of diagnosis. Today, we know the autism spectrum doesn’t discriminate the way  people once thought it did.

I mean, the Centers for Disease Control  and Prevention in the US still report that white children are more likely to be diagnosed with autism spectrum disorder than other groups. But it’s more complicated than that. Some statistics might fool you into thinking that autism is  a white person’s diagnosis.

But that’s more reflective of other factors than lower prevalence in some groups. In fact, one study from 2014 found a higher rate of autism in Black, Asian, and most Hispanic populations, when the data was adjusted for  things like socioeconomic status. So it’s not just white boys.

But it’s also not just boys. All sexes are represented in the autism spectrum. Even Asperger himself had female patients.

And that was back in the early days of quantifying and defining autism. Today, we also know that the spectrum includes people who are nonverbal and people who are incredibly talkative. An autism spectrum diagnosis means you might communicate differently than people who don’t have that diagnosis.

And individuals across the spectrum  run the communication gamut. A research article published  in 2020 tested this concept using a modified version of the telephone game. That like, party game where one person tells something to the next person and they have to relay the same  message to the next person, and on and on.

Finally, the last person in the line speaks up and tells the room that “Atlantis spies on you from space” when the original message was “I’d like to pie you in the face.” So it’s a test of how well  we can relay information. And in this study, groups of autistic people, non-autistic people, and mixed groups were asked to play the same game. The results demonstrated that a group of  autistic people communicates information   just as effectively as a  group of non-autistic people.

But communication breaks down  earlier in the mixed groups. Now, if you go on for long enough, all three have equally bad information retention. That’s kind of how the telephone game works.

The important part is that autistic people have similar  skill levels in communication compared to non-autistic people, and there’s a mutual lack of understanding when we’re trying to communicate with people outside of our group. This is a huge finding that flies in the face of years of clinicians and researchers claiming that autistic people  have a communication deficit. According to this study, it’s a communication difference.

But, of course, that perspective is representative of only a specific sliver of the spectrum. The participants in this study were verbal, with an average IQ, no anxiety disorders, and diagnosed with autism  spectrum disorder as adults. If you’re mostly nonverbal, your game of telephone would be different and might  yield different results.

In fact, your entire life may look different from the lives of the people the 2020 study recruited to play the telephone game. The autism spectrum includes  people who can live independently and people who rely more on  others for their daily activities. And in each of these facets of identity, from sex to communication to independence, there are autistic people  everywhere in between the extremes.

Like, you might have met someone on the spectrum who’s really skilled at calculations or music. Maybe you mentioned your birthday and they were able to tell you immediately what day of the week that was. This is what people are referring to  when they talk about “superpowers.” But the term that academics  use is “savant syndrome.” About half of all recorded savants are on the spectrum, which is why they’re often  associated with each other.

But only one tenth of the people  diagnosed with autism are savants. So this definitely isn’t a trait  that comes as a package deal with all of the other lived  experiences of the spectrum. Being on the spectrum doesn’t  inherently mean you are a savant.

And you can be a savant  without being on the spectrum. Also, there isn’t a set IQ  range that savants stay within. Some savants have a high IQ  and some have a lower one.

Importantly, the IQ test only measures  specific facets of intelligence. If you’re a savant, you’re incredibly intelligent  in ways that others fall short, regardless of that one assessment. For example, the researcher who first described savants talked about someone who could recite the entire six volumes of “The Decline And Fall of the Roman Empire” forwards or backwards from memory.

So that’s a quality that some  people on the spectrum have, it’s also a quality that you can have even if you’re not autistic. And many savants who aren’t on the spectrum still share experiences with some people who are. Like not speaking as a young child, which also happens in Einstein’s syndrome, or reading at an early age, which is also known as hyperlexia.

This overlap can create confusion. If you aren’t autistic but  have these other conditions, you could easily get diagnosed  as being on the spectrum. Then, you might get interventions  that aren’t super effective for you.

And you’d develop in ways that are  typical for what you actually have. Children with Einstein’s syndrome, for example, can start out nonverbal and then develop speech later on. That kind of significant  communication change with age isn’t characteristic of autism spectrum disorder.

Being autistic is a lifelong thing. It won’t go away with age. But for some autistic individuals, certain symptoms become less  pronounced as you get older.

I say “some” because it  depends on the circumstance. People who are intellectually  disabled and nonverbal tend to have more pronounced symptoms that don’t change as much over time. In a large study with more than  240 people on the spectrum, half of the verbal participants  had some symptom improvement.

But even among the people who showed reduced symptoms over time, they didn’t grow out of autism. They continued to meet the standards for diagnosis and had low social reciprocity. The back and forths of your conversation don’t quite look the same even if you’re no longer  hyper focused on one topic.

For those who show change over time, it might be related to your aging brain, specifically a group of brain  cells called mirror neurons. These are cells that activate when you do something and see someone else doing the same thing. A study published in 2011 found that children and  adolescents on the spectrum don’t activate a part of their brain  called the inferior frontal gyrus much.

And that’s where these mirror neurons are. But some autistic adults activate their inferior frontal gyrus  and mirror neurons more, to the point where they’re statistically the same as adults who aren’t on the spectrum. So that might explain why some autistic people have improved  communication skills with age.

Now, the brain scans in this study can’t tell us whether that brain change directly leads to the social change. There’s just a correlation. But the bottom line is that autism, like a diamond, is forever.

And it’s usually noticeable  starting around age two. So let’s say you’ve noticed autistic  traits in yourself or your child. Here’s how you’d confirm that you’re on the spectrum rather than experiencing some other condition.

First, you’d go through a screening. This is the first assessment that usually happens through your primary care physician during a regular check-up. Depending on how old you are, there are different versions  of the preliminary screen.

Guardians of children 18-24 months old usually fill out the Modified  Checklist for Autism in Toddlers, or the M-CHAT. This is the most commonly used questionnaire in Europe and the US. One question asks if a child  follows a pointing finger to the object the finger is directed toward.

Another asks if they get upset by everyday noises. Another question asks if the child  is interested in other children. The questions range from gauging  interest to response to activity.

And if the answers to at least  three of the 20 questions align with a spectrum diagnosis, then the child may be autistic. Adolescents can be assessed  utilizing similar instruments, such as the Gilliam Autism Rating Scale or GARS. Again, this kind of assessment is filled out by caregivers or teachers, and looks for things like repetitive  behaviors or emotional responses.

An autism diagnosis for adults tends to begin with a self-report assessment such as the Autism Spectrum Quotient . These forms ask people to rate  their agreement with statements such as "I find it difficult to  work out people's intentions" and "I prefer to do things the  same way over and over again." The big difference here is that it's not a parent or caregiver  filling out this assessment, but the autistic person themselves. Although sometimes, a clinician will help them  interpret the questions.

And if you’re nonverbal, you might take the Universal  Test of Nonverbal Intelligence, which is administered and answered nonverbally. It tests things like spatial memory, reasoning, and the ability to complete mazes. Depending on how you score, these assessments can help connect you with resources like in-home support, group homes, and training for jobs.

Once you’re diagnosed with  autism spectrum disorder, you can start interventions that  can change your life for the better. If you’re nonverbal, you may be able to learn to use a keyboard, iPad graphics system, gestures, or sign language to communicate. If you have low muscle tone, a common symptom, you can get physical therapy to build up your strength,  coordination, and balance.

And many people on the spectrum receive some kind of behavioral therapy. The whole idea is to figure out the function of a harmful behavior, like banging your head against a wall, and replace it with something that more safely achieves that function, such as pressing your head into a  pillow to get some sensory input. Historically, the first step,  where you remove a behavior, was done through measures that many people consider unacceptable now, like using shocks, or spray bottles, or even immobilization.

Today, you’re more likely to  have a distraction removed or be told that you didn’t perform  the desired task correctly. But the treatment still faces a lot of criticism. Some people who have undergone  applied behavior analysis found it extremely unpleasant or felt as though they were having  their identity stripped away.

And it’s not a small commitment, either. The guy who came up with  applied behavioral analysis found that people who followed the protocol for 40 hours per week had the best results. That’s a full US work week’s worth of training.

But a 2018 study found that children who received just  10 hours of training per week for 28 weeks sometimes showed larger behavioral change than those who did more sessions. So maybe the full time job of training one kid isn’t always necessary. But it might also depend on when you start.

The 2018 study found that the younger children were  when they started interventions, the more improvement they showed. As in, younger than 28 months old! So there really is something to the idea that earlier intervention is more effective.

Ultimately, there are a variety of tools  for the variety of symptoms that come with autism spectrum disorder. But I can’t stand here and tell you that they’re all perfect. Behavioral therapy can  encourage new coping mechanisms as alternatives to self-harm  or property destruction.

But that kind of intervention doesn’t make stimuli go away  or become less overwhelming. Which is one reason that  research is still ongoing. For all of its flaws, applied behavioral analysis is regarded as the only effective evidence-based intervention for someone on the spectrum.

And in reality, none of these  options will cure autism. This has become a supercharged topic as many people have developed an appreciation for neurodivergence and have come to think of autism less as a disease and more as a difference. But there are drugs that can help manage symptoms like trouble sleeping or focusing.

Ultimately, for many people, the diagnosis is less about finding therapies and more about providing an explanation  for your experience of the world. At the end of the day, it can be a great way to find community. It may be decades before we understand all aspects of the autism spectrum.

But if the coming decades show as much progress as the last ones have, we’ll know a lot more about it than we do today. And also thanks to all of  our Patrons, without whom, we could not do what we do [ OUTRO ]