Full Transcript for Does Tylenol Cause Autism?

00:03:42.639 --> 00:03:45.360 Yeah, he's getting kind of swarmed and I wanted him 80 00:03:45.439 --> 00:03:48.439 to help me understand like where this idea came from 81 00:03:48.460 --> 00:03:51.759 in the first place. This idea that acetaminophen could affect 82 00:03:51.819 --> 00:03:54.520 a fetus. Like if we were going to build the 83 00:03:54.539 --> 00:03:59.330 case against acetaminophen, according to science, where would the story start? 84 00:04:00.129 --> 00:04:04.090 And apparently these concerns have been floating around for a while. 85 00:04:04.780 --> 00:04:07.569 Over a decade ago, the first sort of research came 86 00:04:07.629 --> 00:04:13.310 out about acetaminophen during pregnancy and neurodevelopmental disorders. And that 87 00:04:13.409 --> 00:04:18.269 idea isn't crazy because it's been previously linked with other 88 00:04:18.329 --> 00:04:25.050 sort of disorders. For example, specific birth defects, possible sex 89 00:04:25.069 --> 00:04:26.170 hormone issues. 90 00:04:26.569 --> 00:04:29.069 Yes. Huh. 91 00:04:29.769 --> 00:04:33.670 So this was... surprising to me, like sex hormone issues. 92 00:04:33.970 --> 00:04:37.769 So Tylenol or acetaminophen, we already know it can affect 93 00:04:37.829 --> 00:04:38.290 a fetus. 94 00:04:38.470 --> 00:04:42.149 Well, there had been research on it for sure, suggesting 95 00:04:42.240 --> 00:04:45.100 that there might be some risks here, which was it 96 00:04:45.139 --> 00:04:47.639 was surprising to me because I have been pregnant and 97 00:04:47.680 --> 00:04:50.720 doctors will always tell you that Tylenol and other stuff 98 00:04:50.740 --> 00:04:53.259 with acetaminophen in it is the safe one to take. 99 00:04:54.110 --> 00:04:56.629 You're not supposed to take ibuprofen because that's thought to 100 00:04:56.670 --> 00:04:59.189 mess up blood flow to the fetus and has been 101 00:04:59.230 --> 00:05:03.399 linked to congenital birth defects. Acetaminophen is thought to be 102 00:05:03.439 --> 00:05:04.639 like the safer of the two. 103 00:05:04.959 --> 00:05:07.319 I didn't know that. So like if you're pregnant and 104 00:05:07.360 --> 00:05:10.660 you feel flu-y or you have some pain, you're supposed 105 00:05:10.699 --> 00:05:12.819 to take Tylenol, not one of the other ones. 106 00:05:12.870 --> 00:05:14.189 Yeah, that's why it's so common. 107 00:05:14.230 --> 00:05:16.490 It's like the one that for so long has thought 108 00:05:16.529 --> 00:05:17.629 to be relatively safe. 109 00:05:18.009 --> 00:05:20.870 But even though they had these suspicions from these other conditions? 110 00:05:21.189 --> 00:05:24.790 Well, yeah, there had been these kind of like trickling 111 00:05:24.990 --> 00:05:27.850 out of like concerns, like Brian said, that it might 112 00:05:27.889 --> 00:05:30.810 be messing with sex hormones, kind of acting as an 113 00:05:30.930 --> 00:05:31.970 endocrine disruptor. 114 00:05:31.990 --> 00:05:34.149 That's so random. 115 00:05:34.930 --> 00:05:35.290 Yeah. 116 00:05:35.550 --> 00:05:37.069 No, at first I was like, what? 117 00:05:37.350 --> 00:05:41.540 But apparently back 15 years ago, some researchers pointed out 118 00:05:41.620 --> 00:05:45.399 that Some painkillers sort of look like a type of 119 00:05:45.579 --> 00:05:49.089 endocrine disruptor that I'm sure you've heard of, phthalates. 120 00:05:49.470 --> 00:05:52.389 Sure. They're an element in plastics that are thought to 121 00:05:52.610 --> 00:05:53.490 be an endocrine disruptor. 122 00:05:53.829 --> 00:05:54.930 Exactly. Yeah. 123 00:05:55.509 --> 00:06:00.779 And so they tried testing whether painkillers, including acetaminophen, acted 124 00:06:00.860 --> 00:06:04.220 like phthalates when they put them on cells in a dish. 125 00:06:05.019 --> 00:06:08.019 And they found that, yeah, they kind of did. 126 00:06:08.040 --> 00:06:09.079 Oh, interesting. 127 00:06:09.379 --> 00:06:13.600 And we think phthalates might mess up hormones like testosterone 128 00:06:13.639 --> 00:06:17.240 in the body. And so researchers started looking into this. 129 00:06:17.480 --> 00:06:20.310 And some of them did find that people who took 130 00:06:20.500 --> 00:06:24.250 acetaminophen during pregnancy were more likely to have a son 131 00:06:24.329 --> 00:06:26.769 with undescended testicles when they were born. 132 00:06:26.790 --> 00:06:27.850 Huh, okay. 133 00:06:28.889 --> 00:06:29.509 Yeah, so. 134 00:06:30.379 --> 00:06:34.220 Some researchers were finding these things, not in every study, 135 00:06:34.480 --> 00:06:37.560 but there were these hints that something might be going 136 00:06:37.660 --> 00:06:41.279 on here. And that was the backdrop for this new 137 00:06:41.339 --> 00:06:44.300 wave of studies looking at the brain, because we know 138 00:06:44.399 --> 00:06:48.220 that hormones can affect brain development. So if something's messing 139 00:06:48.240 --> 00:06:51.120 with the hormones, maybe it could also change how the 140 00:06:51.160 --> 00:06:52.540 brain is developing in the fetus. 141 00:06:52.899 --> 00:06:53.680 Okay, that makes sense. 142 00:06:54.060 --> 00:06:57.810 And then studies start coming, looking at whether pregnant people 143 00:06:57.850 --> 00:07:00.829 who took acetaminophen were more likely to have a kid 144 00:07:00.850 --> 00:07:04.009 with autism. So like, you know, some of them would 145 00:07:04.110 --> 00:07:07.089 get thousands of pregnant moms and ask them some questions. 146 00:07:07.490 --> 00:07:11.709 They collected data on whether a mom used acetaminophen. Did 147 00:07:11.750 --> 00:07:15.360 you take Tylenol? Yes, no, that kind of thing. And 148 00:07:15.680 --> 00:07:19.019 then they followed the baby after it was born to 149 00:07:19.079 --> 00:07:21.279 see if the baby developed autism. 150 00:07:23.819 --> 00:07:26.120 Mm-hmm. That's useful for our purposes. 151 00:07:26.189 --> 00:07:28.730 Yeah, exactly. Like, they followed these kids and then checked 152 00:07:28.769 -->

00:07:29.790 whether they were autistic. 153 00:07:30.730 --> 00:07:34.050 And these studies, they were finding stuff, but it was 154 00:07:34.110 --> 00:07:37.889 a little weird. Like, one of these studies found that 155 00:07:37.930 --> 00:07:41.399 it upped the chance for autism, but only when the 156 00:07:41.459 --> 00:07:45.259 autism was accompanied by hyperactivity symptoms. 157 00:07:45.899 --> 00:07:48.639 Another study found that boys were more. 158 00:07:48.540 --> 00:07:52.290 Likely to be autistic with this exposure to acetaminophen in 159 00:07:52.319 --> 00:07:52.750 the womb. 160 00:07:53.370 --> 00:07:54.389 But not girls. 161 00:07:55.310 --> 00:07:55.550 Huh. 162 00:07:56.850 --> 00:07:59.709 Okay. Kind of confusing. 163 00:07:59.730 --> 00:08:00.810 Yeah. 164 00:08:01.009 --> 00:08:03.550 Like, none of these studies was like a slam dunk 165 00:08:03.670 --> 00:08:07.949 on its own. But at the same time, dozens of 166 00:08:08.170 --> 00:08:11.300 other studies were also coming out looking at other stuff, 167 00:08:11.560 --> 00:08:16.579 especially ADHD, and finding that rates of ADHD were up 168 00:08:16.620 --> 00:08:18.040 in these kids exposed. 169 00:08:17.740 --> 00:08:19.040 To acetaminophen in the womb. 170 00:08:19.680 --> 00:08:20.259 Oh, okay. 171 00:08:20.759 --> 00:08:23.240 And yeah, in some cases, it looked like the link 172 00:08:23.300 --> 00:08:27.199 was strongest for mothers who took acetaminophen pretty often, like 173 00:08:27.300 --> 00:08:28.540 in all three trimesters. 174 00:08:28.560 --> 00:08:32.759 So there's like a dose-response element as well. That's what 175 00:08:32.779 --> 00:08:36.820 it looked like. And in 2021, this all comes to 176 00:08:36.879 --> 00:08:39.820 a head. A paper comes out from a bunch of 177 00:08:39.879 --> 00:08:45.570 researchers who'd been studying this called a consensus statement. They 178 00:08:45.710 --> 00:08:51.129 issued a, quote, call for precautionary action, unquote, and basically 179 00:08:51.169 --> 00:08:54.700 suggested that people should pump the brakes on these pills, 180 00:08:55.250 --> 00:08:58.440 minimize the amount of acetaminophen that they take during pregnancy. 181 00:08:58.980 --> 00:08:59.580 Here's Brian. 182 00:08:59.960 --> 00:09:03.799 And then to top it off, they publish in a 183 00:09:03.860 --> 00:09:06.980 nature journal, which is one of the most highly regarded 184 00:09:07.059 --> 00:09:08.799 scientific journals out there. 185 00:09:09.279 --> 00:09:12.269 And so this statement really made scientists pay attention. 186 00:09:12.649 --> 00:09:15.620 Up until that point. Most people just kind of treated 187 00:09:15.649 --> 00:09:17.740 it like, oh, you know, like a new study pops 188 00:09:17.799 --> 00:09:19.820 up every day. You aren't really sure what to believe 189 00:09:19.879 --> 00:09:23.039 or not. But when a consensus statement came out, it 190 00:09:23.059 --> 00:09:24.960 gave it like a stamp of authority. 191 00:09:25.679 --> 00:09:28.080 Yeah, I would feel that way about a consensus statement 192 00:09:28.120 --> 00:09:30.799 in nature. Yeah. Or a nature offshoot. Yeah. 193 00:09:31.139 --> 00:09:34.039 And some parents even started suing the companies that make 194 00:09:34.340 --> 00:09:36.950 meds with acetaminophen in them, saying that they should have 195 00:09:37.019 --> 00:09:39.149 warning labels on them about these risks. 196 00:09:39.710 --> 00:09:39.990 But. 197 00:09:41.080 --> 00:09:43.740 As all of this was happening, a lot of scientists 198 00:09:43.799 --> 00:09:45.879 were like, wait a second. 199 00:09:46.179 --> 00:09:49.620 When you use a phrase like consensus statement, it implies 200 00:09:50.000 --> 00:09:54.840 a sort of every single expert in the room believes X, Y, 201 00:09:54.889 --> 00:09:58.629 and Z. Like nine out of 10 dentists recommend Colgate 202 00:09:58.669 --> 00:10:02.470 or something of that sort. So it implies a sort 203 00:10:02.490 --> 00:10:04.870 of authoritative weight to the evidence. 204 00:10:05.320 --> 00:10:08.990 And implying that this was the consensus seemed to piss 205 00:10:09.019 --> 00:10:12.330 a lot of scientists off. Some of them wrote responses 206 00:10:12.389 --> 00:10:14.809 to that consensus statement saying that it was way too 207 00:10:14.889 --> 00:10:18.750 soon to come out so hard against acetaminophen, saying that 208 00:10:18.870 --> 00:10:22.320 the evidence they cited was, quote, weak in consistence and 209 00:10:22.379 --> 00:10:26.559 to a large extent methodologically inadequate, unquote. 210 00:10:27.100 --> 00:10:28.200 So they're saying the studies are crap. 211 00:10:28.340 --> 00:10:31.960 Well, basically, yeah. That's the science-y way of saying, what? 212 00:10:32.080 --> 00:10:32.399 This? 213 00:10:32.600 --> 00:10:34.279 You know, this is not enough. 214 00:10:35.279 --> 00:10:37.750 And so a lot of scientists were really skeptical of 215 00:10:37.789 --> 00:10:39.769 this and didn't buy this story. 216 00:10:40.169 --> 00:10:41.110 Scientists like Brian. 217 00:10:41.570 --> 00:10:45.519 Does taking Tylenol actually increase, when you're pregnant, increase the 218 00:10:45.580 --> 00:10:47.320 chance that your kid will have autism? 219 00:10:47.799 --> 00:10:53.779 The answer right now points towards no. 220 00:10:54.059 --> 00:10:54.490 Oh, really? 221 00:10:55.129 --> 00:10:55.370 Yeah. 222 00:10:55.769 --> 00:10:57.500 So that's the short of it. 223 00:10:58.360 --> 00:10:59.340 Wow. 224 00:10:59.700 --> 00:11:01.639 Up next, the long of it. 225 00:11:01.879 --> 00:11:04.570 We'll hear the other side of the story and tell 226 00:11:04.610 --> 00:11:06.870 you whether or not you can have your damn Tylenol 227 00:11:07.149 --> 00:11:07.649 after the break. 228 00:11:15.009 --> 00:11:17.919 It's been a busy week, right? 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00:11:26.919 wings from Nando's, a tasty taco bowl from Sprout & Co, 231 00:11:27.450 --> 00:11:31.490 or maybe even some California birria from Boojum. We'll deliver 232 00:11:31.590 --> 00:11:36.629 in as little as 25 minutes. Order now. You've earned it. Deliveroo. 233 00:11:37.190 --> 00:11:41.710 That finish line Friday feeling just got even better. Geographical restrictions, 234 00:11:41.750 --> 00:11:43.970 teas and season fees apply. Delivery times vary. See app 235 00:11:44.029 --> 00:11:44.720 or web for info. 236 00:11:45.460 --> 00:11:47.980 Hey, it's Wendy from Science Versus, and I want to 237 00:11:48.019 --> 00:11:51.320 tell you about a podcast that I love, Science Friday. 238 00:11:51.519 --> 00:11:54.059 They cover all sorts of amazing things in the weird 239 00:11:54.100 --> 00:11:58.120 and wonderful world of science, from how concussions affect our 240 00:11:58.179 --> 00:12:01.250 brain to the inner secrets of a snake with a 241 00:12:01.330 --> 00:12:04.090 spider on its It's a lot of news that you 242 00:12:04.129 --> 00:12:06.490 can use and some that you can't, but you're going 243 00:12:06.509 --> 00:12:10.649 to love anyway. It's hosted by Ira Flato and Flora Lichtman, 244 00:12:10.809 --> 00:12:13.539 who is an old friend of the show and loves 245 00:12:13.620 --> 00:12:16.220 a pun as much as we do. Science Friday is 246 00:12:16.279 --> 00:12:18.840 on every day, wherever you get your podcasts. 247 00:12:23.440 --> 00:12:24.820 Welcome back. This is Meryl. 248 00:12:25.019 --> 00:12:26.980 So far, we've gone through a lot of the evidence 249 00:12:27.039 --> 00:12:31.370 against acetaminophen, the ingredient in medicines like Tylenol. Lots of 250 00:12:31.429 --> 00:12:34.549 studies seem to find that taking it while you're pregnant 251 00:12:34.730 --> 00:12:38.110 does increase the chance that your kid will be autistic. 252 00:12:37.649 --> 00:12:40.679 Or have ADHD. Are you ready for the rest of 253 00:12:40.720 --> 00:12:41.919 the science, Rose Rimler? 254 00:12:41.940 --> 00:12:42.080 Uh.... 255 00:12:43.720 --> 00:12:43.879 Yes. 256 00:12:44.889 --> 00:12:45.500 Are you ready? 257 00:12:45.820 --> 00:12:46.720 Yes, I'm ready. 258 00:12:48.320 --> 00:12:48.639 All right. 259 00:12:48.759 --> 00:12:52.159 So here's where Brian Lee, our epidemiologist hero, comes in 260 00:12:52.200 --> 00:12:55.399 gallantly with a shiny new approach to looking at this question. 261 00:12:56.059 --> 00:12:57.500 His paper came out just last year. 262 00:12:57.940 --> 00:13:01.419 We had a study funded by NIH before everything went 263 00:13:01.440 --> 00:13:04.919 to hell. And we were like, hey, we could actually 264 00:13:05.419 --> 00:13:06.039 look at this. 265 00:13:06.519 --> 00:13:10.580 And so Brian teams up with some Swedish researchers because 266 00:13:10.600 --> 00:13:12.350 he's actually really into IKEA. 267 00:13:14.350 --> 00:13:16.730 I don't think that's why. Yeah, you got me. 268 00:13:16.769 --> 00:13:19.350

I think it's because the Scandinavians keep really good records, 269 00:13:19.690 --> 00:13:20.970 public health records. 270 00:13:21.149 --> 00:13:23.669 Yeah, it's because they have an amazing database. 271 00:13:26.159 --> 00:13:29.860 Sweden having its lovely universal health care system means that 272 00:13:29.879 --> 00:13:34.090 you can track everyone. They don't just disappear in the system. 273 00:13:34.120 --> 00:13:37.649 They're there. They're tracked. Everyone has access to this, right? 274 00:13:39.149 --> 00:13:41.909 So yeah, they got data from a ton of kids, 275 00:13:42.110 --> 00:13:46.559 almost two and a half million of them. Basically, every 276 00:13:46.600 --> 00:13:50.059 kid who was born there over a 24-year period. And 277 00:13:50.259 --> 00:13:53.059 they also had data from the moms, details about their 278 00:13:53.100 --> 00:13:56.230 medical care, like the medicines that they took during pregnancy. 279 00:13:57.090 --> 00:14:00.129 And so now Brian's team looked to see, were the 280 00:14:00.149 --> 00:14:03.850 kids exposed to acetaminophen in utero more likely to be autistic? 281 00:14:04.649 --> 00:14:08.179 And right off the bat, they found that Yes, they were. 282 00:14:08.200 --> 00:14:08.259 Oh. 283 00:14:08.879 --> 00:14:12.000 So they found that the kids who were exposed to 284 00:14:12.070 --> 00:14:15.990 acetaminophen had a 20 to 30 percent higher chance of 285 00:14:16.029 --> 00:14:17.389 being autistic. Oh. 286 00:14:18.990 --> 00:14:20.950 That's not what I was expecting. You were about to 287 00:14:20.990 --> 00:14:21.289 tell me. 288 00:14:22.049 --> 00:14:22.389 Right. 289 00:14:23.570 --> 00:14:26.669 But actually, Brian's team was sort of relieved when they 290 00:14:26.710 --> 00:14:27.129 found this. 291 00:14:27.710 --> 00:14:31.190 This shows that we're not in crazy land, for example, 292 00:14:31.210 --> 00:14:34.350 that somehow our data are not flawed. We're not flawed. 293 00:14:35.120 --> 00:14:37.419 Everything is working as anticipated. 294 00:14:37.840 --> 00:14:40.620 And that's because the effects that Brian was seeing in 295 00:14:40.659 --> 00:14:43.940 his data was in the same ballpark as what other 296 00:14:43.960 --> 00:14:46.940 groups had found. But here is where Brian and his 297 00:14:46.980 --> 00:14:49.799 team took a different path. They wanted to see if 298 00:14:49.980 --> 00:14:53.850 other factors might be muddling up the data here, making 299 00:14:53.889 --> 00:14:56.970 it look like it's the acetaminophen to blame when really 300 00:14:57.009 --> 00:14:58.629 it's something else entirely. 301 00:14:58.649 --> 00:15:03.210 Yeah, okay. So Brian is trying to think of Are 302 00:15:03.250 --> 00:15:05.669 there other factors that might come into play here and 303 00:15:05.929 --> 00:15:08.250 trying to like do some science to sort of suss 304 00:15:08.269 --> 00:15:09.340 those out, basically? 305 00:15:09.559 --> 00:15:09.879 Yeah. 306 00:15:10.100 --> 00:15:12.220 And so to try to do that sussing out, he 307 00:15:12.279 --> 00:15:15.700 starts checking like, OK, what if some of the other 308 00:15:15.740 --> 00:15:18.440 factors that we know are linked to autism could be 309 00:15:18.559 --> 00:15:22.419 contributing to that effect that he saw, that 20 to 310 00:15:22.419 --> 00:15:24.000 30 percent increased chance? 311 00:15:24.019 --> 00:15:24.200 Mm hmm. 312 00:15:24.700 --> 00:15:28.570 Because like we talked about in our earlier episode on autism, 313 00:15:29.070 --> 00:15:31.230 we know that the age of the mom can affect 314 00:15:31.269 --> 00:15:34.289 the chance of whether her kid will be autistic. Like 315 00:15:34.470 --> 00:15:37.350 older moms are more likely to have autistic kids. Or 316 00:15:37.570 --> 00:15:40.730 if the mom has some other health condition or got 317 00:15:40.789 --> 00:15:43.889 sick during pregnancy, that might increase the chance for autism too. 318 00:15:43.909 --> 00:15:47.480 And so those factors have been known for a while 319 00:15:47.539 --> 00:15:48.840 and are generally pretty well accepted. 320 00:15:49.179 --> 00:15:50.279 Yeah, yeah, exactly. 321 00:15:50.399 --> 00:15:53.340 And so Brian's team took another look at the data. 322 00:15:53.500 --> 00:15:55.779 And when they started accounting for some of that stuff, 323 00:15:55.820 --> 00:15:59.679 like how old the moms were, the effects of acetaminophen 324 00:15:59.779 --> 00:16:02.820 got smaller. It went from increasing the chance of having 325 00:16:02.840 --> 00:16:04.669 an autistic kid by 20. 326 00:16:04.210 --> 00:16:06.850 Or 30 percent down to 5 percent. 327 00:16:08.929 --> 00:16:12.320 When it's down to like. a 5% increase in risk. 328 00:16:12.360 --> 00:16:14.799 You start to actually wonder whether or not it's real 329 00:16:14.860 --> 00:16:15.159 or not. 330 00:16:15.419 --> 00:16:18.200 Could it be like moms who are older are more 331 00:16:18.240 --> 00:16:21.419 likely to take Tylenol because they have more aches and 332 00:16:21.460 --> 00:16:23.720 pains or something like that? And we know that's separately 333 00:16:23.759 --> 00:16:25.519 associated with autism, that kind of a thing? 334 00:16:25.559 --> 00:16:26.240 Yeah, exactly. 335 00:16:28.120 --> 00:16:30.950 Or a mom being sicker, right? You don't just take 336 00:16:30.970 --> 00:16:32.690 Tylenol for funsies. 337 00:16:35.769 --> 00:16:40.399 So the other studies weren't adjusting for stuff like age 338 00:16:40.440 --> 00:16:45.240 of the parent, you know, other health conditions, stuff like that? Yeah. 339 00:16:45.299 --> 00:16:47.779 Basically, they weren't all doing the same type of adjustments. 340 00:16:48.100 --> 00:16:48.299 Okay. 341 00:16:49.100 --> 00:16:50.320 So that's one thing. 342 00:16:50.460 --> 00:16:54.700 And then there's another massive factor that contributes to whether 343 00:16:54.740 --> 00:16:55.799 someone's autistic. 344 00:16:56.179 --> 00:16:57.159 Their genes. 345 00:16:57.460

--> 00:16:58.159 Oh, yeah. 346 00:16:58.399 --> 00:16:58.710 Yeah. 347 00:16:58.759 --> 00:17:00.509 They think that this is like the number one thing 348 00:17:00.549 --> 00:17:03.429 that determines whether someone's autistic. It's like 70 to 90 349 00:17:03.429 --> 00:17:07.190 percent of it. So Brian's team wanted to know, could 350 00:17:07.299 --> 00:17:10.859 that be part of the story, too? And that's sort 351 00:17:10.880 --> 00:17:11.559 of tricky. 352 00:17:11.279 --> 00:17:12.079 To sort out. 353 00:17:12.240 --> 00:17:16.799 Like, ideally, you'd look at identical twins, right, and expose 354 00:17:17.000 --> 00:17:20.059 one to acetaminophen in the womb and then see if there's, like, 355 00:17:20.079 --> 00:17:21.579 a difference in autism rates. 356 00:17:22.019 --> 00:17:23.200 I guess. I don't know how you would do that. 357 00:17:23.920 --> 00:17:24.529 Yeah, exactly. 358 00:17:24.569 --> 00:17:25.349 You can't do that. 359 00:17:26.690 --> 00:17:28.549 But there's another way to get at this. 360 00:17:29.410 --> 00:17:31.630 They could look at siblings in their data. 361 00:17:32.029 --> 00:17:35.769 What if we did this within... the same family unit. 362 00:17:35.829 --> 00:17:39.710 So basically kids born to the same mom, but during 363 00:17:39.819 --> 00:17:44.259 one pregnancy, the mom used acetaminophen and the other pregnancy, 364 00:17:45.039 --> 00:17:48.220 the mom didn't, right? So then you control at least 365 00:17:48.279 --> 00:17:50.380 partially for genetics. 366 00:17:50.500 --> 00:17:51.910 Yeah, that's great. 367 00:17:52.390 --> 00:17:55.630 So Brian's team looked in their giant Swedish database and 368 00:17:55.670 --> 00:17:57.869 gathered thousands of cases like this. 369 00:17:58.569 --> 00:18:01.150 They crunched the numbers and here's what they found. 370 00:18:01.779 --> 00:18:06.250 Everything flatlined in terms of risk. You know, what was 371 00:18:06.390 --> 00:18:10.789 already a very minimal increase in risk just flatlined to 372 00:18:10.930 --> 00:18:15.779 absolutely no difference in risk for a child who is exposed. 373 00:18:16.019 --> 00:18:17.700 No increased chance of autism. 374 00:18:17.940 --> 00:18:21.960 No increased risk for autism, for ADHD, for intellectual disability. 375 00:18:23.039 --> 00:18:24.799 It was just a pure flatline. 376 00:18:26.710 --> 00:18:30.380 Yeah. So what this means is that within a family, 377 00:18:30.650 --> 00:18:33.279 whether or not the mom took acetaminophen, the chance that 378 00:18:33.359 --> 00:18:35.359 her kid was autistic was the same. 379 00:18:35.740 --> 00:18:37.339 So can you put this all together for me? Like, 380 00:18:38.079 --> 00:18:40.319 what's going on here exactly? 381 00:18:40.759 --> 00:18:41.200 Okay. 382 00:18:41.380 --> 00:18:45.069 Yes. So the more I learned about this, the more 383 00:18:45.109 --> 00:18:48.750 I realized that there could be a completely different explanation 384 00:18:48.809 --> 00:18:53.390 for why acetaminophen and autism might seem like they're linked. 385 00:18:54.049 --> 00:18:55.490 Because like, If. 386 00:18:55.470 --> 00:18:58.650 You imagine, like, say you're a mom of an autistic kid, 387 00:18:59.170 --> 00:19:01.630 that means that you're also more likely to be on 388 00:19:01.710 --> 00:19:03.819 the autism spectrum yourself, right? 389 00:19:03.839 --> 00:19:06.140 You probably have some of these autism genes too. 390 00:19:06.960 --> 00:19:11.119 And being on the spectrum, having some autistic traits, that's 391 00:19:11.180 --> 00:19:14.380 actually been linked to having more pain when you're pregnant. 392 00:19:14.740 --> 00:19:16.970 It's also been linked to having migraines. 393 00:19:17.289 --> 00:19:17.650 Yeah. 394 00:19:18.450 --> 00:19:21.710 And so, like, we have these reasons why people on 395 00:19:21.750 --> 00:19:25.779 the spectrum might be more likely to take acetaminophen. So 396 00:19:25.880 --> 00:19:29.960 maybe that's why it's looking like it's the medicine causing 397 00:19:30.000 --> 00:19:32.079 the autism. But we have a way of explaining all 398 00:19:32.099 --> 00:19:34.180 of this without blaming the acetaminophen at all. 399 00:19:35.180 --> 00:19:37.930 So, all right. So this is like a classic sort 400 00:19:37.950 --> 00:19:39.630 of red herring science story. 401 00:19:39.670 --> 00:19:40.049 Yeah. 402 00:19:40.190 --> 00:19:42.410 So like it looked like it was this one thing, 403 00:19:42.470 --> 00:19:45.109 but it's actually that one thing is associated with this 404 00:19:45.150 --> 00:19:46.910 other thing that it was. 405 00:19:46.750 --> 00:19:47.450 Sort of covering up. 406 00:19:48.490 --> 00:19:51.480 Yeah, that could really be what's going on here. I mean, 407 00:19:51.529 --> 00:19:55.460 it would be like if you looked at... Your chance 408 00:19:55.480 --> 00:20:00.769 of playing outdoor pickleball, that might go up along with 409 00:20:01.490 --> 00:20:04.210 how likely you are to have had. 410 00:20:04.109 --> 00:20:05.390 Ice cream recently. 411 00:20:06.170 --> 00:20:09.690 But really, both of these things are just linked because 412 00:20:09.750 --> 00:20:10.990 it's warmer outside. 413 00:20:11.009 --> 00:20:15.289 Uh-huh. Yeah, exactly. That's what I mean. 414 00:20:15.589 --> 00:20:18.920 Yeah. It's like. They're not directly influencing the other. It's 415 00:20:18.960 --> 00:20:21.519 just like they're both responding to the same third variable. 416 00:20:21.559 --> 00:20:24.279 Yes, there's a third variable. Exactly. 417 00:20:24.299 --> 00:20:24.900 Okay, classic. 418 00:20:24.920 --> 00:20:26.079 That's what it seems like to me. 419 00:20:27.730 --> 00:20:31.410 But there is still like a back and forth here, 420 00:20:31.609 --> 00:20:35.390 a bit of a nerd fight, like other researchers saying 421 00:20:35.450 --> 00:20:39.700 Brian's study isn't perfect either. And there are still reviews 422 00:20:39.779 --> 00:20:42.859 coming out that say there is a link between

acetaminophen 423 00:20:42.900 --> 00:20:44.000 and stuff like autism. 424 00:20:44.660 --> 00:20:46.660 So I asked Brian about these studies. 425 00:20:47.440 --> 00:20:50.579 I guess like I normally I would trust a meta-analysis 426 00:20:50.619 --> 00:20:54.329 looking at a bunch of studies over like a couple 427 00:20:54.380 --> 00:20:57.140 studies here and there saying something else. Like, why should 428 00:20:57.180 --> 00:21:00.319 I trust your study more than this meta-analysis? 429 00:21:01.079 --> 00:21:05.279 So one of the fun things with the meta-analysis is 430 00:21:05.339 --> 00:21:09.220 that it's a garbage in, garbage out kind of a thing. 431 00:21:09.299 --> 00:21:13.529 You can feed it garbage, but your meta-analysis is not 432 00:21:13.549 --> 00:21:18.150 going to turn this garbage into something beautiful. You can 433 00:21:18.710 --> 00:21:23.930 repeat the wrong thing many times in completely different samples 434 00:21:24.170 --> 00:21:26.980 and get the same wrong results in every single sample. 435 00:21:27.480 --> 00:21:29.559 And yeah, it's not like he's saying that these are 436 00:21:29.859 --> 00:21:34.730 all terrible scientists, but more that these reviews are mostly 437 00:21:34.769 --> 00:21:39.049 looking at studies that didn't have that genetic stuff, like 438 00:21:39.069 --> 00:21:42.930 they couldn't look at siblings. They just didn't have that data. 439 00:21:43.539 --> 00:21:46.759 And so they couldn't do what Brian's team did. But 440 00:21:46.980 --> 00:21:50.460 Brian's study, it's not the only one that did do 441 00:21:50.480 --> 00:21:53.440 that kind of like sibling analysis. And so like there 442 00:21:53.460 --> 00:21:55.279 was one that just came out a couple weeks ago 443 00:21:55.380 --> 00:21:59.680 from Japan that did the same thing and it backed 444 00:21:59.720 --> 00:22:00.509 up Brian's study. 445 00:22:02.130 --> 00:22:05.630 Okay. So given all that, what do you make of 446 00:22:05.690 --> 00:22:09.630 all this? Like if you were pregnant right now, would 447 00:22:09.650 --> 00:22:10.309 you take Tylenol? 448 00:22:11.460 --> 00:22:14.900 Well, for the autism question, I do find studies like 449 00:22:14.960 --> 00:22:17.059 Brian's to be the most convincing. 450 00:22:17.140 --> 00:22:19.829 Like, I don't think there's a clear link here. 451 00:22:20.809 --> 00:22:24.369 And even to go back to those other concerns around Tylenol, 452 00:22:24.430 --> 00:22:27.130 like that idea that it might be a hormone disruptor. 453 00:22:27.490 --> 00:22:29.390 Oh, the undescended testicles. 454 00:22:29.490 --> 00:22:30.009 Exactly. 455 00:22:30.069 --> 00:22:33.349 What about the undescended testicles and Tylenol? To go back 456 00:22:33.390 --> 00:22:37.960 to those, those studies on the undescended testicles are super mixed. 457 00:22:38.259 --> 00:22:41.400 So like some studies will find a link there. Other 458 00:22:41.519 --> 00:22:42.339 studies don't. 459 00:22:42.619 --> 00:22:45.819 And actually, the most recent review that I could find 460 00:22:45.920 --> 00:22:49.700 on this said that most studies don't find more undescended 461 00:22:49.740 --> 00:22:53.089 testicles in babies exposed to acetaminophen in utero. 462 00:22:53.529 --> 00:22:58.150 So even the thing that started this whole suspicion of 463 00:22:58.210 --> 00:23:03.059 acetaminophen during pregnancy off, that has actually, upon further investigation, 464 00:23:03.579 --> 00:23:05.660 not really borne out. Like, there might not actually be 465 00:23:05.680 --> 00:23:06.519 a link there either. 466 00:23:06.599 --> 00:23:10.240 No, yeah, exactly. And a bunch of big medical groups 467 00:23:10.289 --> 00:23:10.880 agree here. 468 00:23:11.069 --> 00:23:14.589 They say that we don't have evidence that taking acetaminophen 469 00:23:14.869 --> 00:23:19.369 during pregnancy causes autism or issues with the development of 470 00:23:19.410 --> 00:23:23.819 the fetus, like the FDA, regulators in Europe, a big 471 00:23:23.839 --> 00:23:25.220 group of OBGYNs. 472 00:23:26.279 --> 00:23:26.960 But, like. 473 00:23:27.670 --> 00:23:31.210 Yeah, just in case if I did take acetaminophen, I'd 474 00:23:31.289 --> 00:23:33.450 try not to take it for, like, weeks at a time. 475 00:23:33.769 --> 00:23:37.369 Because generally, some of the studies that do find risks 476 00:23:38.069 --> 00:23:41.470 only find them if you take acetaminophen for, like, longer 477 00:23:41.509 --> 00:23:42.309 periods of time. 478 00:23:42.910 --> 00:23:45.519 It also depends, I guess, on what you're taking it for. 479 00:23:45.539 --> 00:23:49.680 I mean, I'm not a— this is not medical advice, but it. 480 00:23:49.680 --> 00:23:54.900 Does make me wonder, like, if you have a high fever, that. 481 00:23:54.200 --> 00:23:57.509 Might be worse for the fetus than the, like, infantismal 482 00:23:57.690 --> 00:24:02.319 risk of some Tylenol on their brain development, right? 483 00:24:02.460 --> 00:24:04.180 Yes, actually, that's true too. 484 00:24:04.299 --> 00:24:07.460 So having a fever when you're pregnant, we know that 485 00:24:07.519 --> 00:24:10.259 ups the chance for lots of serious stuff like birth 486 00:24:10.279 --> 00:24:16.410 defects for the kid, heart malformations, premature birth. And fevers 487 00:24:16.509 --> 00:24:19.289 also happen to be linked to a kid being autistic later. 488 00:24:19.309 --> 00:24:19.950 Oh, okay. 489 00:24:22.289 --> 00:24:23.109 Uh-huh. 490 00:24:23.250 --> 00:24:26.569 Okay, that's very interesting and fairly satisfying, actually. 491 00:24:26.589 --> 00:24:27.490 Yeah. 492 00:24:27.589 --> 00:24:27.930 All right. 493 00:24:28.670 --> 00:24:30.619 And by the way, we did reach out to the 494 00:24:30.660 --> 00:24:33.299 company that owns Tylenol, and they sent us a big 495 00:24:33.339 --> 00:24:36.599 statement pointing to some of the science that we've talked about. 496 00:24:37.059 --> 00:24:46.250 And they said, quote, unquote. And for Brian's

part, he 497 00:24:46.309 --> 00:24:48.710 really doesn't think the science supports the idea that taking 498 00:24:48.750 --> 00:24:51.670 a little Tylenol when you're pregnant makes the kids later 499 00:24:51.710 --> 00:24:54.069 become autistic or have ADHD. 500 00:24:54.410 --> 00:24:56.700 Like taking off my epidemiologist hat and just, you know, 501 00:24:56.779 --> 00:25:01.339 as a person hat, like blame is damaging. It's harmful. Like, 502 00:25:01.400 --> 00:25:05.099 and it doesn't exactly help. People might be blaming themselves 503 00:25:05.140 --> 00:25:08.420 for like that one random Tylenol they took when, you 504 00:25:11.460 --> 00:25:14.789 You know, if we can help, you know, take away 505 00:25:14.829 --> 00:25:18.009 some of that guilt that's there, I think that's that's 506 00:25:18.210 --> 00:25:22.609 nice because people shouldn't be feeling guilty about these things 507 00:25:22.670 --> 00:25:23.170 in the past. 508 00:25:23.599 --> 00:25:23.779 Yeah. 509 00:25:23.799 --> 00:25:25.019 Feel guilty about something else. 510 00:25:26.200 --> 00:25:29.039 Go back to feeling guilty about eating lunch meat. Yeah. 511 00:25:30.539 --> 00:25:30.720 All right. 512 00:25:30.740 --> 00:25:33.619 Well, thanks, Rose. Thanks, Meryl. That's Science Versus. 513 00:25:36.670 --> 00:25:37.009 All right. 514 00:25:37.480 --> 00:25:39.299 Rose, do you want to ask me how many citations 515 00:25:39.339 --> 00:25:40.180 I have in this episode? 516 00:25:40.740 --> 00:25:41.180 Oh, yeah. 517 00:25:41.240 --> 00:25:43.839 Meryl, how many citations do you have in this episode? 518 00:25:44.480 --> 00:25:46.269 We have 59 citations. 519 00:25:48.650 --> 00:25:50.710 So if you want to see all the science that 520 00:25:50.730 --> 00:25:53.579 went into this episode, check out the transcripts. You can 521 00:25:53.599 --> 00:25:56.500 find links to that, which has all these beautiful citations 522 00:25:56.559 --> 00:25:58.849 in the show notes. And we did reach out to 523 00:25:58.869 --> 00:26:01.990 the U.S. Department of Health and Human Services about this. 524 00:26:02.190 --> 00:26:06.130 And a spokesperson said, quote, until we release the final report, 525 00:26:06.230 --> 00:26:10.079 any claims about its contents are nothing more than speculation, unquote. 526 00:26:10.740 --> 00:26:12.619 And if you want to learn more about autism, check 527 00:26:12.660 --> 00:26:15.500 out our other episode on this called Autism, The Real 528 00:26:15.559 --> 00:26:18.440 Reason It's Going Up. And if you want to tell 529 00:26:18.480 --> 00:26:21.079 us what you think of this episode or have episode ideas, 530 00:26:21.680 --> 00:26:24.619 reach out to us. Our Instagram is science underscore VS. 531 00:26:32.390 --> 00:26:34.940 This episode was produced by me, Meryl Horne, with help 532 00:26:35.000 --> 00:26:38.859 from Rose Rimler, Michelle Dang, and Akedi Foster-Keys. We're edited 533 00:26:38.920 --> 00:26:41.730 by Blythe Sorrell. Mix and sound design by Bumi Hidaka. 534 00:26:42.359 --> 00:26:44.259 Our executive producer is Wendy Zuckerman. 535 00:26:44.480 --> 00:26:47.019 Fact-checking and consulting by Erica Akiko Howard. 536 00:26:47.539 --> 00:26:51.079 Music written by Peter Leonard, Bobby Lord, So Wiley, Emma Munger, 537 00:26:51.160 --> 00:26:53.750 and Bumi Hidaka. Thanks to all the researchers that we 538 00:26:53.789 --> 00:26:56.309 spoke to for this episode and our other episode on autism. 539 00:26:56.809 --> 00:26:59.849 Science Versus is a Spotify Studios original. Listen for free 540 00:26:59.890 --> 00:27:02.730 on Spotify or wherever you get your podcasts. And if 541 00:27:02.750 --> 00:27:05.019 you do listen on Spotify, follow us and tap the 542 00:27:05.039 --> 00:27:06.500 bell for episode notifications. 543 00:27:13.690 --> 00:27:16.589 It's been a busy week, right? Sounds like it's time 544 00:27:16.630 --> 00:27:21.369 for that takeaway. Deliveroo's on it. Whether it's extra saucy 545 00:27:21.430 --> 00:27:25.650 wings from Nando's, a tasty taco bowl from Sprout & Co, 546 00:27:26.130 --> 00:27:30.180 or maybe even some California birria from Boojum. We'll deliver 547 00:27:30.279 --> 00:27:35.319 in as little as 25 minutes. Order now. You've earned it. Deliveroo. 548 00:27:35.880 --> 00:27:40.400 That finish line Friday feeling just got even better. Geographical restrictions, 549 00:27:40.440 --> 00:27:42.680 teas and season fees apply. Delivery times vary. See app 550 00:27:42.720 --> 00:27:43.400 or web for info.