Last April, HHS Secretary RFK committed to finding the cause of autism by September. Well, here we are, and the closest he’s come is a claimed link between autism and Tylenol use during pregnancy. That sounds pretty frightening, but it turns out to be unsupported, as explained in this article on the always valuable Science Based Medicine, by Steven Novella, a clinical neurologist at the Yale Medical School.
Here are come excerpts,
RFK has shown, over and over again, that he has no idea how to properly interpret the medical literature. He uses scientific evidence as the proverbial drunk uses a lamppost – for support rather than illumination. As regular readers here know, preliminary evidence is often all over the place, and also tends to favor false positives. You need careful analysis of research methodology, confounding factors, patterns of replication, detection of p-hacking, etc. in order to come to a reliable conclusion. Or – you can just cherry pick the inevitable studies that support your political agenda.
This is a job for a good systematic review, and fortunately we have a recent high quality review to look at. The data came from the Swedish national database, which is extremely useful for such research. The review includes data on 185,909 children. They found a very small increased risk of neurodevelopmental disorders with Tylenol use in pregnancy, however this link disappeared when they did a sibling control analysis.
However, as we have pointed out here often, this also allows for the possibility of confounding factors. For example, what if mothers who have a fever for some reason are both more likely to take Tylenol and to have a child with a neurodevelopmental disorder?
But that, of course, is RFK’s specialty – scaring people away from effective treatments with negligible risks based on his gross misreading of the scientific literature. We can expect more shenanigans to come.
The entire post is well worth reading. And SBM is well worth following.
Posted by Steve Lubet on September 11, 2025 at 02:46 PM
