Junk Science

A New Link Between Antidepressants And Autism

Research found taking antidepressants during pregnancy raised autism risk by 87%—but it's not that simple

Junk Science
The antidepressant fluoxetine is a popular SSRI. — (Getty Images)
Dec 14, 2015 at 12:13 PM ET

The cause of autism remains a mystery, but there are a dozen more likely culprits than vaccines—including, possibly, taking antidepressants during the second and third trimester of pregnancy. In a new study published in JAMA Pediatrics, researchers show that Selective Serotonin Reuptake Inhibitors (SSRIs) taken during pregnancy appear to increase rates of autism diagnosis in a child by 87 percent. The study is far from conclusive, but it suggests that further research should be conducted to determine whether antidepressants are the safest option for pregnant women with depression.

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The last time the media jumped on a preliminary report about the cause of autism, it set off perhaps the greatest Big Pharma witch hunt in history—largely because of poor media coverage of the fraudulent Wakefield study—so let’s get our facts straight. First of all, physicians are not suggesting that all pregnant women stop taking their antidepressants. “It makes no more sense to suggest that [antidepressants] should always be avoided than to say that they should never be stopped,” writes Dr. Brian H. King of Seattle Children’s Hospital in a related editorial. “It is unlikely that there will be a straight line from such exposures that leads unwaveringly to [autism].”

Second of all, prior studies have not found a link between autism and antidepressants. A large study published in June 2015 reported that antidepressants were associated with increased risk of ADHD but not autism, and a separate study conducted in 2013 found no correlation between antidepressant use and autism diagnosis rates.

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And while the study does show an 87 percent increased risk of autism, it does so on a small scale. Researchers reviewed about 145,000 full-term births in Quebec between 1998 and 2009. Of those infants, 2,532 were exposed to antidepressants during the second or third trimester of pregnancy, and 31 of those children were diagnosed with autism.

Understand that this means the study’s actual sample size of children exposed to SSRIs in the second and third trimesters was not 145,000 but 2,532—and that the study’s conclusion reflects a total sample of 31 kids.

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The raw data isn’t much better. The study found that 0.72 percent of all children in the original sample were diagnosed with autism (although King notes that other data suggest that number should have been closer to 1 percent) and that the rate increased by 87 percent with antidepressants taken during the second and third trimester of pregnancy. This implies that SSRIs increased the overall risk of autism to…1.2 percent. That’s 87 percent more than 0.72 (although its only about a 35 percent increase if total autism rates are, as prior studies suggest, closer to 1 percent).

“In real numbers, the findings suggest that, compared with the population who stopped taking [antidepressants] in the first trimester, there may have been an additional 12 children with [autism] than otherwise would have been expected out of the 2532 children exposed in utero during the second or third trimester,” King writes.

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There are other issues that could be at play. The authors failed to take into account the mothers’ lifestyles outside of their psychiatric prescriptions. And, although the researchers know that these mothers purchased SSRIs during the second and third trimesters of pregnancy, they didn’t confirm that the mothers took them while pregnant.

Additionally, the lead author of the study, Anick Bérard, PhD of the University of Montreal, disclosed in the study that he had previously been paid to testify that antidepressants cause birth defects. “Further research is needed to specifically assess the risk of [autism] associated with antidepressant types and dosages during pregnancy,” Bérard writes. Indeed—a lot more research is needed. And a less conflicted researcher, too.

Now, the results are not pure junk science. This is the first major study to suggest that antidepressants may increase risk of autism, and it certainly adds to our understanding of the underlying causes of a disorder that affects 1 in 68 children in the United States. But the findings have far too many limitations for us to draw any meaningful conclusions from the data. In fact, there is some evidence that untreated depression can increase corticosteroid production and reduce blood flow to the umbilical cord. Studies have linked this to, “potentially lifelong effects on brain plasticity and cognition,” King writes.

“My biggest concern is that [this study] will be over interpreted,” King told NPR in an interview. “It kind of leaves you more confused,” Alan Brown, a professor of psychiatry and epidemiology at Columbia University, added. “Mothers shouldn’t get super worried about it.”