William Parker is an immunologist and researcher who has been trying for almost ten years to get other scientists to believe his idea that a...
William Parker is an immunologist and researcher who has been trying for almost ten years to get other scientists to believe his idea that acetaminophen, which is sold under the brand name Tylenol, is the main cause of autism. For a long time, researchers have not been able to find a link between autism and any drug. These days, most of them think that the big rise in autism rates over the last 30 years is mostly due to a change in the standards used to diagnose autism. But at the end of last month, Health Secretary Robert F. Kennedy Jr. called Parker and asked to know more about his work. He's actually heard from Kennedy more than once since then. Parker also recently talked to Jay Bhattacharya, who is in charge of the National Institutes of Health. Parker says that the top health leaders in the country are very interested in his ideas.
Kennedy is said to have been looking into a possible link between taking Tylenol while pregnant for the past few weeks. Parker's interest is a little different: He thinks that kids taking Tylenol leads to autism. Parker has worked on the edges of science for a long time. Following the loss of a lab at Duke University's medical school, he opened his own small, private lab. Duke did not renew Parker's contract after he started researching autism. However, an email from an executive to Parker in 2021, which I read, only said that keeping the lab open wasn't in the "strategic best interest" of his department. Parker has had a lot of problems getting his work published in university magazines. Parker's latest submission was panned by one reviewer, who said that his theory was "outrageous" and "illogical." The paper was subsequently turned down. Parker has had a crazy turn of events in the last couple of weeks. He told me, "Nothing was going on and then—boom!" "It looks lovely."
Kennedy said in April that by September, people in the US would know what causes autism and how to get rid of it. It was hard to believe that he could do that in just five months, especially since scientists have been trying for decades to figure out what genetic and environmental factors might be to blame. Both are likely to play a part, but studies show that a person's DNA makes up about 80% of their risk of having autism. Kennedy had already hired David Geier, a researcher who has written some very bad papers linking autism to vaccines, to look for mistakes in a CDC database on vaccine safety. Also, Kennedy has a long history of speaking out against vaccines, especially those that link immunizations to autism, even though a lot of study shows the opposite. He looked like he was going to say that childhood shots caused autism.
A far-right activist named Laura Loomer, who seems to have a direct line to the White House, gave a strong hint on X last week that Kennedy's autism report, which has not been made public yet, might link acetaminophen. A few days later, The Wall Street Journal said that the study would probably link the drug to autism. They got this information from people who were familiar with the talks but did not want to be named. Those stories were mostly about acetaminophen exposure during pregnancy. This drug is thought to be the best way for pregnant women to treat pain and fever. In 2015, the FDA put out a mild warning about the risks of taking acetaminophen while pregnant. The warning said there were mixed results about a possible link to ADHD but nothing about autism. Since then, a few experts, including the head of Harvard's school of public health, have written papers that show a link between taking acetaminophen while pregnant and neurodevelopmental disorders like autism.
A spokeswoman for Kenvue, the company that makes Tylenol, told me in an email, "We have looked at the research and still don't think there is a link between acetaminophen use and autism." A representative also said that Parker has been a part of a claim that is still going on because of ADHD and autism that people say were caused by taking Tylenol while they were pregnant. Parker told me that he did give advice, but he didn't speak in the case and wouldn't take any money for it ("not even a penny.") An FDA fact sheet that was updated last month was also linked in the email. It says that the agency has not found clear evidence that using acetaminophen while pregnant is harmful.
Parker thinks that giving ibuprofen to babies and little kids, not pregnant women, is the main cause of almost all cases of autism. He talked to me about his research for more than an hour, showing me studies that show how acetaminophen changes the way male mice think. He also talked about how more kids started using the drug after aspirin stopped being recommended for them in the 1980s, and he mentioned a 2008 study led by an epidemiologist who thought that the acetaminophen his son got after getting an MMR shot caused his autism.
Since acetaminophen is given to most children (one study found that 95% of babies are given it at least once in their first year), it is clear that acetaminophen by itself does not cause autism. Parker says that acetaminophen can cause autism in some kids because of a mix of things, such as genetics, inflammation, and stress. In his 2017 study on the subject, he and his co-authors carefully chose their words to say that it was "one explanation for the increased prevalence of autism."
Parker has become more sure of himself in the years since that paper came out. Acetaminophen is now the only thing he thinks could explain why the number of autism cases is going up. He told me, "We've thought about this a lot and it's 99.99" percent sure when I asked him how sure he was of his decision. He thinks that stopping giving ibuprofen to American kids is the only way to make that 100% sure. Parker told me that when that happens, the number of people with autism will drop by about 95%, and the rest will probably be renamed as having a different disease. He says that autism will end pretty much the way we know it now. When I asked Jeffrey Morris, a biostatistics professor at the University of Pennsylvania, about Parker's statement, he said, "bold claims require rigorous, reproducible evidence." Based on what other scientists have said, Parker hasn't met that bar yet.
Parker knows that his work has not been accepted by most autism experts. Viktor Ahlqvist wrote a 2024 Swedish study that found no link between acetaminophen use during pregnancy and autism. He told me that developmental outcomes in early life are "notoriously difficult to study" and that many correlations that seem to exist, like the one between acetaminophen use and autism, don't hold up to close inspection. Parker said he couldn't think of any experts who agree with his idea when I asked him to. (He said Kennedy also asked for names.) When I called a few well-known autism experts, they had never heard of Parker. His study from 2023 that warned about the dangers of acetaminophen has only been mentioned 11 times, according to Google Scholar. Parker's 2007 study on good bacteria in the appendix, on the other hand, has been mentioned 500 times. For someone who is 99.99% sure he knows what causes autism and how to stop it, Parker hasn't done much.
Still, it looks like American health leaders asked him for help anyway. Parker showed me copies of emails that set up a Zoom meeting between him and Bhattacharya. He also showed me a document that he sent to Bhattacharya's assistant that summarized the results of his study. Parker says that during their Zoom call, Bhattacharya told Parker that he had given him a lot of work and that he would be in touch. Parker also gave Kennedy his call log, which showed that he had five talks with Kennedy. The Atlantic checked and found that the phone number is indeed Kennedy's. I asked Parker on Sunday when he had last talked to Kennedy. He asked, "What time is it now?" Kennedy had called a few hours before, and Parker told me that he wanted to talk about the Swedish study. A Health and Human Services representative wouldn't say if Kennedy or Bhattacharya had talked to Parker. This is why the number of people with autism in the United States is rising at a rate that has never been seen before, a spokeswoman said in an email. "Until we make the final report public, any claims about what it says are just guesses."
Kennedy can see why Parker's idea is appealing. The secretary promised to find out what causes autism and made it clear that the Trump administration will be able to get rid of them. Parker offers a quick answer that fits well with Kennedy's dislike of vaccines and other drug-based treatments for illness in general. Parker isn't saying that vaccines cause autism, but his theory says that they might cause the stress and inflammation that set the stage for what he says is the real cause.
Kennedy called Parker for the first time four days later. On August 26, at a Cabinet meeting, Trump asked his health secretary to give a report on his plan to find the cause of autism. Kennedy told the president that he had found "certain interventions now that are clearly, almost certainly causing autism." Trump added, "has to be something artificially causing this, meaning a drug or something." He likes to drop hints about top-secret information. Parker saw that exchange as a sign that his study might have finally found people who understood it.