Today’s Living on the Spectrum explores how lab-grown brain models reveal shared genetic pathways in autism, why the gender gap in diagnosis closes as children reach adulthood, and the latest data on rising prevalence and environmental factors.
Organoid study reveals shared brain pathways across autism-linked variants
Shared Biological Pathways
A study using cortical brain organoids derived from 55 autistic individuals shows that diverse genetic variants converge on shared molecular pathways during development. Although different genetic backgrounds initially alter the brain in unique ways, they ultimately disrupt common processes including neuronal differentiation, synapse formation, and chromatin remodeling.
Research Methods
The research team used miniature, lab-grown brain tissue models to track how different genetic variants influence neurodevelopment. They identified a core network of genes that functions as a regulatory hub for these changes.
Limitations and Applications
The current organoid models lack inhibitory interneurons, which are necessary to study the balance of brain activity. Despite this, these shared biological changes offer potential biomarkers for future drug screening and therapeutic testing.
Sex bias in autism drops as age at diagnosis rises
Narrowing Diagnostic Gap
A Swedish study of 3 million children found that the sex bias in autism diagnoses decreases significantly with age. Boys are three times more likely than girls to receive a diagnosis before age 10, but this ratio shifts to 1.2-to-1 by age 20.
Reasons for Delayed Identification
Researchers suggest autistic girls often present traits differently, such as maintaining better eye contact or possessing advanced language skills. Many girls use social masking to camouflage difficulties until the social demands of adolescence become too complex to manage.
Cognitive Factors
The study noted that the sex ratio is much lower among children who also have an intellectual disability. The findings suggest that diagnostic approaches need to be more personalized to identify girls earlier and provide necessary support.
New insights on sex bias in autism, and more
Prenatal and Genetic Factors
Recent research indicates that prenatal exposure to COVID-19 is associated with an increased likelihood of autism specifically in girls. In genetics, investigators are looking into the role of microexons—short segments of protein-coding DNA—in neurogenesis and autism-related pathways.
Rare Conditions and Circuits
Studies on Fragile X syndrome are focusing on electrophysiological signatures and EEG signal complexity. Additionally, research using mouse models of SETBP1 haploinsufficiency has identified specific behavioral deficits and prefrontal circuit issues related to speech and developmental delays.
Coverage and resources on changes in the autism diagnosis over time
Shifting Prevalence Data
U.S. autism prevalence rose from 1 in 54 children in 2016 to 1 in 44 by 2018. This increase stems from improved data tracking and a broader diagnostic lens that includes the mild end of the spectrum. While the number of diagnoses is increasing, the proportion of individuals with severe features has decreased since 2000.
Environmental and Genetic Risks
Research has debunked links between autism and acetaminophen, whooping cough vaccines, epidurals, or prenatal antipsychotic medications. Parental age remains a confirmed environmental factor, while the majority of autism risk resides in genetics, showing higher heritability in boys.
Global Trends and Disparities
High rates of developmental delays are currently straining support systems in countries like Australia. Socioeconomic factors also influence data, with higher incidence rates sometimes appearing in minority groups or lower socioeconomic regions due to varying access to services.
Raphe Bernier followed his heart out of academia, then made his way back again
Career Transitions
Raphe Bernier, former leader of the Seattle Children’s Autism Center, transitioned to Apple as a clinical scientist in 2019 to develop mental health screening tools. While the industry role offered high compensation and low stress, Bernier found it distanced him from the community impact and hands-on science he preferred.
Return to Teaching
Bernier eventually returned to the University of Washington to focus on teaching psychology and research methods. He chose to move away from administrative roles and endowed chairs to prioritize direct engagement with students and the study of psychopathology.
Professional Advice
Bernier states that moving to industry should not be viewed as a failure for academic researchers. He suggests that returning to academia is a viable path for those who miss the autonomy and teaching opportunities inherent in university settings.
Podcast Transcript
Aaron: Hello everyone, and welcome to the show. I am Aaron.
Jamie: And I am Jamie.
Aaron: We have been looking through a lot of recent reports and research summaries lately, mostly covering the landscape of autism and neurodevelopmental differences. It feels like every time we open a news feed, there is a new statistic or a new biological discovery. For many parents I talk to, it can be a bit overwhelming—like trying to drink from a fire hose.
Jamie: It really is a lot to process. What I found interesting in this latest batch of research is that we are moving away from just "noticing" differences and starting to see the "why" and the "how" much more clearly. We are also seeing some long-held assumptions about who gets diagnosed and why being challenged by very large-scale data.
Aaron: That is a great place to start. I was looking at some prevalence data recently—specifically from The Transmitter—and the numbers are striking. In the U.S., we went from 1 in 54 children in 2016 to 1 in 44 just a couple of years later. Whenever these numbers go up, people get worried. Is it an "epidemic," or is something else happening?
Jamie: That’s the big question, isn't it? The data suggests it’s more about a "widening of the lens" than a sudden surge in the condition itself. We are getting much better at identifying the milder end of the spectrum. We are also using electronic medical records more effectively to track these things. Interestingly, while the overall number of diagnoses is rising, the proportion of people with "profound" autism—those with severe intellectual disabilities or very limited communication—has actually dropped since 2000.
Aaron: So, it’s not necessarily that there are more autistic people being born, but that we’ve finally invited more people into the room where they can actually get support?
Jamie: Exactly. And that invitation is becoming more equitable. The gaps in diagnosis between different racial groups are shrinking, which is a positive sign that screening is reaching more communities. However, as more people are identified, especially in places like Australia, the support systems are really feeling the strain. It’s a bit of a double-edged sword: we see the need better, but the resources haven't caught up.
Aaron: Speaking of who gets seen, there was a massive study out of Sweden involving three million children. It really changed how I think about the "gender gap" in autism. We always hear that boys are diagnosed way more often than girls, right?
Jamie: That has been the standard view for decades. Usually, the ratio cited is about four boys for every one girl. But this Swedish study followed children as they grew up, and the findings were fascinating. Before age ten, boys were three times more likely to be diagnosed. But by the time they reached age twenty, that ratio dropped to almost one-to-one—specifically 1.2 to 1.
Aaron: That’s a huge shift. What happens between age ten and twenty? Do the girls "become" autistic later, or were they just hiding in plain sight?
Jamie: Most researchers believe they were there all along. Girls often present differently—they might have more advanced language skills early on or maintain more eye contact. There is also the concept of "masking" or camouflaging, where they work incredibly hard to mimic social cues. But as social demands get more complex in the teenage years, that masking becomes harder to sustain, and the difficulties become more apparent to clinicians.
Aaron: It makes me think of all those girls who spent their childhoods feeling "different" but without a name for why. It’s a bit heart-wrenching to think the diagnosis only comes after the social pressure becomes unbearable.
Jamie: It really highlights why we need more personalized diagnostic tools. We shouldn't be waiting for someone to struggle in high school before we realize they need support. And interestingly, the study found that for children who also have an intellectual disability, the sex ratio is much lower from the start. It’s the girls without intellectual disabilities who are the most likely to be missed early on.
Aaron: This makes me wonder about the biology behind it all. If the presentation is so different between boys and girls, is the "engine" under the hood different too? I saw some mention of genetics and even how things like prenatal environment might affect the sexes differently.
Jamie: There is some very new, specific research on that. For example, one study found that prenatal exposure to COVID-19 infection was associated with an increased likelihood of autism specifically in baby girls, which is a very narrow but interesting finding. On the genetic side, we are looking at things like "de novo" variants—these are mutations that appear for the first time in a child rather than being inherited.
Aaron: I remember seeing something about "mini-brains" being grown in labs to study this. It sounds like science fiction, but apparently, it’s helping us find common ground in all these different genetic mutations?
Jamie: You’re talking about the cortical brain organoids. Researchers used cells from 55 different autistic individuals. Even though these people had very different genetic variants, the study found that their brain development eventually converged on the same "hubs." They all seemed to affect the same core processes, like how neurons specialize or how synapses form.
Aaron: That’s actually a bit of a relief to hear. If there are thousands of different genetic paths but they all lead to a few "common stations," does that mean treatments or supports could be more universal?
Jamie: That is the hope. Instead of needing a different medicine for every single genetic mutation, we might be able to target those "shared pathways." It’s a significant confirmation of the theory of "convergent biology." Of course, these lab models aren't perfect—they are currently missing certain types of neurons that balance brain activity—but it’s a massive step toward finding biomarkers for screening.
Aaron: While we are on the topic of causes and biology, I have to bring up the "environmental" side. Every parent I know has, at some point, worried if something they did during pregnancy caused their child’s neurodivergence. There is so much misinformation out there.
Jamie: It’s a heavy burden for parents. But the recent data is actually quite reassuring in terms of what doesn't cause autism. Large-scale research has largely debunked links to things like acetaminophen—or paracetamol—whooping cough vaccines, epidurals, or antipsychotic medications taken during pregnancy.
Aaron: That is so important to say out loud. So many people carry guilt over taking a Tylenol for a headache while pregnant.
Jamie: Exactly. The data just doesn't support those links. What the research does show is that the vast majority of risk is genetic. There are some environmental factors that do show a consistent link, like parental age, but even then, it’s just one piece of a very large puzzle. It’s rarely one single thing.
Aaron: It feels like the more we know, the more we realize how complex and individual each person is. Which brings me to a story I read about a researcher named Raphe Bernier. He was a big name in autism research, moved to a high-paying job at Apple, and then... he went back to the university?
Jamie: Yes, he moved from academia to industry and eventually back to teaching. It’s a very human story. In academia, as he became more successful, he was pulled away from the families and the "hands-on" science he loved. He went to Apple to work on mental health tools, which was exciting, but he felt he lost that direct connection to the community and the control over what he was researching.
Aaron: I think that says a lot about the field. It’s not just about data points or "mini-brains" in a lab. It’s about the people. If the researchers feel disconnected, the science might lose its heart.
Jamie: I agree. He now focuses on teaching the next generation of psychologists. He’s telling young scientists that it’s okay to explore different paths. It’s a reminder that the people studying these conditions are often driven by a real desire to help families, even if the system sometimes gets in the way.
Aaron: That’s a good note to end on. We’ve covered a lot—from the rising numbers and the closing gender gap to the "hubs" in our brains and the debunking of old myths. It feels like we are in a period of "refined understanding" rather than just "more diagnosis."
Jamie: Well said. It’s about moving from "what is this?" to "how can we best support the person in front of us?" and acknowledging that the answer might look different for a girl diagnosed at sixteen than for a boy diagnosed at three.
Aaron: Thank you for walking through the science with me, Jamie. It makes the headlines feel a lot less intimidating.
Jamie: My pleasure, Aaron.
Aaron: For those of you listening, if you want to dive deeper into any of the studies we mentioned—like the Swedish sex-ratio study or the brain organoid research—you can find the article summaries and original links on our episode page. Thanks for joining us, and we’ll talk to you next time.
Jamie: Goodbye everyone.
References
- Organoid study reveals shared brain pathways across autism-linked variants
- Sex bias in autism drops as age at diagnosis rises
- New insights on sex bias in autism, and more
- Coverage and resources on changes in the autism diagnosis over time, global differences, and the role of genes and the environment
- Raphe Bernier followed his heart out of academia, then made his way back again