New research suggests that environmental factors may play a much bigger role in autism than previously believed — and one culprit may be antidepressants.
It's a big week for autism research. According to the Times, a new twin study found that genetic factors are important in autism, but perhaps not as overwhelmingly important as scientists previously thought. Researchers looked at 192 pairs of fraternal and identical twins, in which one or both twins had autism. Using mathematical models, they found that 38% of the autism cases could be attributed to genetics — but in a full 58%, environmental factors were at play. This study didn't elaborate on what environmental factors these might be, but another study in the same journal did. According to the Wall Street Journal, researchers found a link between a mother's antidepressant use and giving birth to an autistic child. Specifically, "results indicated a doubling in risk of autism if the mother filled a prescription for antidepressants at any point in the year before delivery. The risk tripled if she filled the prescription during the first trimester of pregnancy."
The results are striking, especially since they seem to indicate a link between autism and medications a woman may have taken before she was even pregnant. Researchers say they were able to exclude the affects of mothers' depression and anxiety, narrowing down the link to the pills themselves, not the conditions they treat. Still, earlier research suggested that these mental illnesses in female relatives could be connected to autism diagnoses in children. And doctors point out that stopping antidepressants can cause problems of its own — depression may cause women to miss prenatal checkups, to say nothing of its effect on women themselves. Lead study author Dr. Lisa Croen says the study shouldn't cause women to change their behavior: "A lot of people might get a little worried about these findings and change something they're doing — which they shouldn't. It indicates to us that there's more to look at."
It's also likely to scare a lot of people. Environmental theories about autism have led to vaccine hysteria and widespread criticism of "refrigerator mothers," both of which turned out to be unfounded. This doesn't mean the new research about antidepressants is false — it's worth noting that the drugs have been linked to other problems as well. It just means we should avoid panicking. Much recent research on prenatal influences is both fascinating and disturbing, and the next few years will hopefully bring many advances in this area. For now, we should be wary of rushing to judgment about any specific environmental factors, until their impacts are confirmed.
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