The Current - Trump links autism and Tylenol. What does research say?

Episode Date: September 24, 2025

President Trump made an announcement on Monday that Tylenol use in early pregnancy is linked to autism. But all the current research points to that not being true. Dr. Evdokia Anagnostou is a child neurologist and co-leads the Autism Research Centre at the Bloorview Research Institute in Toronto. She's not convinced either.

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this is a cbc podcast hello i'm matt galloway and this is the current podcast the FDA will be notifying physicians that the use of as a said well let's see how we say that acidaminophen acetaminophen is that okay which is basically commonly known as Tylenol during pregnancy can be associated with a very increased risk of autism. The word may have alluded him, but the conclusion did not. According to U.S. President Donald Trump, Tylenol use in early pregnancy can cause, in his words, a very increased risk of autism.

Scientists and doctors say this link is unproven. There is no conclusive evidence that Tylenol use in pregnancy is at all related to autism. Health Canada released a statement yesterday advising that Tylenol is safe to use in pregnancy. Dr. Evdokia Anagnostu is a child neurologist, co-leads the Autism Research Center at Blue Review Research Institute in Toronto, and she is with me in our Toronto studio. Good morning. Good morning. It's nice to see you again. Lovely to see you. There was reaction from people in the world of folks like yourself who study autism to Donald Trump's comments. One of the people that I'd read, an expert said that this was one of the most difficult days in their career. How did you

respond to what the president said? I mean, we knew he was coming. It had leaked a little bit earlier, so we were preparing for it. But it's a sad day where politicians feel that they can overrule the evidence and the science and give recommendations straight to families about health and the health of their children and the health of pregnant mothers without the evidence to support their recommendations. It's a sad day. Can I talk about the Tylenol issue first? What would you say to a pregnant woman who's worried about whether or not to take Tylenol after what the president has said? Tylenol is the safest option we have for treating fever or pain during pregnancy. So it's important for people to know in these studies we're looking for associations.

And then, once we have an association, we're trying to understand if one thing causes another. We have no evidence of causation. We have no evidence that Tylenol causes harm to much. mom or infant. We have evidence that untreated pain or untreated fever causes harm to mom or infant. So the recommendation from Health Canada, which is based on the evidence, is that mom should feel that they have the best options available to them, and Tylenol is the best option for treating fever and pain during pregnancy.

The Trump administration is pointing to a study from Harvard University and Mount Sinai Hospital in New York from this summer that concluded there was correlation between. Tylenol and autism. Correlation is not causation, but what do you know about this study? Yes. So first of all, this was not new data. This is what we call a systematic review. So they synthesized all available data today.

So we have some old studies, some old small studies that had shown more of an association. We have some very large recent studies, including one from Sweden that came out last year, with two and a half million kids involved, that saw pretty much. no association. When the data was synthesized, so all the studies put together, a very small association was noted. By the way, it's very, very small. And even the authors of the study said this does not prove causation. So we can think about this. Mums who are more likely to get fever or pain, they are more likely to actually take taleno. Fever during pregnancy has been associated with increased risk of autism, for example.

The second thing is in the large Swedish study that looked at all kids born in Sweden within a significant time period, when they controlled for siblings, so the genetic risk of autism, that association went away, meaning moms who have more of a genetic risk for autism for some reason, seem to also be using more Tylenol during pregnancy. When you were here the last time, I asked you this question, and it's important. It's complicated, but it's important, and you've hinted at it. What do we know at this point about what causes autism? So first of all, autism is not one condition.

Autism is many, many different conditions that just happened to share some difficulties with socialization and some repetitive behaviors. So we know that there are many, many, many different causes of autism. A lot is known about the genetic causes of autism, and we know quite a bit about that. Looking for environmental factors that interact with our genes to potentially increase the likelihood that somebody develops a neurodevelopmental condition is a good exercise, an important one. How do we define what environmental factors are? So those could be things that happened during pregnancy.

And we know about some, right? Maternal diabetes, for example. Certain drugs, not Tylenol, but certain drugs. typically associated with treatment of epilepsy, obesity, severe infections during pregnancy will increase the risk of somebody developing a neurodevelopmental condition. We also don't have good evidence that these things on their own can actually cause autism. It's always an interaction as speaking between the genes and those environmental factors. One of the reasons why that autism expert that I quoted at the beginning said that this was one of the worst days of their careers,

because there's work that's being done right now to try to understand this, right? It's not as though people have been sitting around waiting for the opportunity to try to figure out the causes of this. Absolutely. So there have been significant investments to try to understand how genes and environment interact to produce neurodevelopmental differences. In the states where this is happening, significant financial commitments, have been made and there is large cohorts of kids that are being studied to truly understand how the environment speaks to genes. In Canada, significant investments both to understand genetic causes, but also to understand how our immune systems and other parts of our body

may interact with genes to actually produce neurodevelopmental differences. So this is not new. There is nothing new here. There is just a retrospective review of what we know to fit a particular scenario. I guess one of the things, the context that this might operate in is Donald Trump calling the rise in autism, in his words, meteoric, saying it's one of the most alarming public health developments in history. What sort of increase are we seeing in terms of autism diagnosis, understanding to your point that this has many things, but what are we seeing in terms of an increase in diagnosis in this country? This is an absolutely correct statement that there is a huge increase in the number of diagnoses that we give. That does not mean that

autism is going up, it means that we give more diagnosis. And there have been several studies to show that the vast majority of that is because we actually define autism differently now than we used to. So in the original definitions of autism, kids had very high needs and it was difficult for these children to be integrated in common environments. All of these kids are still in our communities and our schools, but we also give the diagnosis to kids who have lower needs, have more subtle symptoms. We also give the diagnosis to the opposite end of the spectrum, kids who used to get just intellectual disability diagnosis, now get autism plus intellectual disability. Now, anybody, including me, that would see this rise, we would not say that we are

safe to explain everything by changing diagnosis. And that's why we do research in environmental factors. But this is not the evidence-based answer to the question. We're running out of time. Let me just ask you two final things. One is about this drug, Lukavoren, that is being touted as a way to treat autism. That's the word that's being used. What do you know about that drug? So there's some early data that came out of some small studies to show a small, small gain in language in young kids. The studies have not been replicated. They have not been replicated in other settings by other labs, in other countries. So we would say there is some early indication that there may be some

promise for some kids, but we don't have the evidence to make a recommendation for Lukavari. Do you understand how this is landing with some people? The head, the president of the Autism Science Foundation in the New York, in the United States, told the New York Times, these are her words, many parents of profoundly autistic children finally feel like their voices are being heard in this administration. For a decade, our children were left behind as the research focus shifted to priorities of very high functioning autistic people. People want research looking at causes, they want interventions, but this is not the way to go, she says.

But do you understand how this is being received by some people? Absolutely. And her sense that people feel like they're finally being heard in some ways. Absolutely. So it is important to know that autism, because it's not defined by a biological test, it is a social construct, right? We decided that social deficits and repetitive behaviors make up a diagnosis. We know there's many, many conditions under it, and over the years, different groups within the spectrum were more pronounced, had more pronounced voices in public discourse.

So there are families who feel that the kids who had the very high needs were not part of the conversation lately. We heard from some of those families after you and I spoke the last time. Absolutely. They deserve research. They deserve evidence. This is not the evidence that would solve the problems of the kids who have. very high needs. I have to let you go, but what do you worry about?

If this is not the evidence that they deserve, but it's the evidence that's being presented, what do you worry about? So, first of all, I'm worried about moms and how they interpret their role in the development of autism in their kids. We worked really hard over the years to make sure that moms don't blame themselves

because we have very good evidence for genetic and so on, etiologies. And there's a long history of that as well. So there's a long history of moms being felt, asked to feel that they have done something wrong they feel guilty, absolutely the wrong thing to do because there's no evidence to that, not because we are trying to protect moms when there is evidence to that fact, but there is no evidence that moms have done anything unusual or different when their kids

develop autism. I'm also worried that funding may not go to the right places to actually develop the types of interventions that kids with high needs actually need. And I am also worried that I see pathway for approval of medications that does not follow standard, robust pathways and evidence that would lead to medications being used in inappropriate ways and actually deprive kids of the actual interventions they need. I'm really glad to have the chance to have you back on the program. Thank you for joining us again.

Thank you for having me. Dr. Evdokia Ana Gnosti is a child neurologist. She is the co-leader as well of the Autism Research Center at the Blue Review Research Institute in Toronto. For more CBC podcasts, go to... cbc.ca slash podcasts.