The truth about antidepressants and autism

Recently, another study was published showing that SSRI antidepressant use during pregnancy is associated with increased rates of autism in the children.  By my count, this is now the tenth study on this topic — all of which found links between SSRI antidepressant use in pregnancy and autism in the offspring.  Most of these studies were recently reviewed, and also concluded that SSRI antidepressant use during pregnancy is associated with autism in the children.

So we now have numerous studies in different human populations all showing a link between SSRI use in pregnancy and autism in the children.  Yet, much of the news and blogosphere focus on casting doubts about these findings.  What is going on here?

Depressed pregnant women should not be ignored

I am deeply concerned about the effects that the SSRI chemicals have on the developing fetal brain.  But, let me start by making it perfectly clear that my concerns about the effects that SSRIs have on the developing fetal brain are in no way a call to ignore depression in pregnant women or to tell them what to do.  I counsel pregnant women every day in the hospital where I was born and in the community I grew up in.  Many of them stay on their antidepressants.  Some of them wean off.  My experience has taught me a few things.

First off, depressed pregnant women need good treatment and care.  This treatment can be with non-drug approaches such as psychotherapy or exercise or with medications.  But, whatever treatment approach they choose, depressed pregnant women should not be ignored.  Secondly, I don’t think anyone should be telling pregnant women what to do.  The key is to provide them with the best available information that the scientific studies are showing and let them decide what is best for themselves.  They should then be supported in their decision and continue to be given excellent care.  Knowledge is power and we need to empower women in this area.

Currently, pregnant women and the public aren’t getting full information

A major issue that seems to be missing from the public debate on this topic is the fact that the substances that we call “antidepressants” are, in fact, synthetic chemical compounds that are manufactured in chemical facilities and they have a chemical effect in the brain.  This is important to recognize, because chemicals have consequences for developing babies.  Yet, if you read most of the news coverage on this topic, you very rarely (if ever) see a discussion about toxic chemical effects.  (The word “chemical” usually doesn’t appear in these news stories.)  When I read this news, I wonder:  “Where is the discussion of what effects these antidepressant chemicals are having on the developing brain?”  Let me explain:

  1. Serotonin is a naturally occurring substance that plays a crucial role in the development of a baby’s brain.
  2. The SSRI antidepressants are manufactured chemicals that disrupt the serotonin system.

If you (the reader) just think for a moment about points #1 and #2, you can quickly see that there may be big problems with the use of these chemical agents in pregnancy.  If serotonin is crucial for the development of the baby’s brain and the SSRIs disrupt that system then it is a recipe for problems.  (The only way it wouldn’t be a problem would be if the antidepressant chemicals did not cross the placenta.  But we know that they do freely cross over into the baby’s developing brain.)

So if we just think about this issue on a theoretical basis, there is major cause for concern.  The basic science is clear that serotonin plays a crucial role in the developing fetal brain and that these manufactured chemical compounds disrupt the serotonin system.  But the science goes beyond just theoretical considerations.

Animal studies are showing harm

There have now been numerous animal studies done in this area, and the findings from these studies are very concerning.  Again and again, we see that when animals are exposed to SSRI antidepressants during development that they show brain and behavioral problems (or so-called neurobehavioral problems.)  There are too many animal studies now that have shown this to review them all in detail, but a few stand out.  In 2004, Mark Ansorge and his group published a landmark paper in the journal Science (one of the leading scientific journals in the world).  This paper showed that mice that were exposed to Prozac during development had altered emotional behaviors.  In the conclusion of that paper (more than ten years ago!) Ansorge warned:  “The use of SSRI medications in pregnant mothers and young children may pose unsuspected risks of emotional disorders later in life.”  In 2011, Kimberly Simpson and her group studied the effects of Celexa on rats, and they also found concerning changes in the brains and behaviors of the exposed offspring.  They warned:  “Our findings are consistent with the possibility that dysregulation/dysfunction of the 5-HT [serotonin] system during early brain development may be the critical contributing factor in the etiology of ASD [autism spectrum disorder].”

These are just two papers, but there are many more animal studies showing that SSRI exposure can alter the developing brain and lead to neurobehavioral problems.  And I want to be clear here.  These animal findings make sense because chemicals that affect the brain (so-called psychotropic chemicals) would be expected to have consequences for a developing brain.  So if you expose a developing brain to a synthetic chemical, you would expect to have some effect from that, and that is precisely what the animal studies show us.

Human studies are showing harm

So what the scientific research is showing us makes sense.  Serotonin is a molecule that is crucial for a baby’s brain development.  The SSRIs disrupt the serotonin system.  The animal studies show brain abnormalities and neurobehavioral problems.  So when we do human studies in this area we would expect to see brain abnormalities and neurobehavioral problems.  And that is, in fact, what we do see.  Study after study in humans shows that the exposed babies have brain abnormalities including Chiari I malformations and smaller head size and neurobehavioral problems including autism, ADHD, motor problems, and anxiety.

What the public isn’t getting: human studies always have some flaws

What I find so astounding/frustrating in this area is that when the human studies show effects on the developing baby’s brain — like autism (effects that we would expect from the basic science and animal studies), reporters and editorialists immediately rush to cast doubt on the human studies.  They highlight the limitations of doing large epidemiologic studies and how many problems these studies might have.

It is true that studying something like the link between antidepressants and autism in human populations is very challenging.  There are lots of confounding factors, caveats, and limitations.  There is no “gold standard” randomized controlled trial available because most researchers don’t think it would be ethical.  But, at the end of the day, the human studies are confirming what basic science, animal studies, and common sense would tell us:  putting brain-altering synthetic chemicals into a developing baby’s brain can alter development.  The simple question for those who doubt the basic science, animal data, and human research is:  “What do you think happens to the baby’s brain when it’s exposed to these chemicals throughout its development?”  Why wouldn’t there be an effect on the baby’s developing brain?


Depressed pregnant women need good treatment and care, and I counsel patients in my community on this issue every day.  There is no “one size fits all” or “right” answer for every patient.  But what my patients (and the public) need here is the correct information so that they can make informed choices.  The best available scientific evidence shows, 1) that serotonin is crucial for a baby’s brain formation; 2) that the SSRI antidepressants disrupt the serotonin system; 3) that the drugs freely cross the placenta; and, 4) that animal studies show brain effects in exposed offspring.  When a human study comes out showing brain effects (autism) from exposure to these drugs (point #5 of my argument), then we should use this as an opportunity to inform the public rather than cast doubts on the findings of human studies and further confuse the issue.

There are non-drug approaches to depression that have been shown to work for many women, including psychotherapy and exercise.  And, given what we know about the effects of these drugs, it makes sense to prioritize these non-drug approaches in pregnant women and women of childbearing age.  However, some women will opt for antidepressants; that’s their choice, and they should be fully supported and given good care.  This is not about telling women how to manage their depression.  The key here is informing patients and the public so that they can make the best decisions for themselves.  And the information that the public needs to hear is that the best available scientific research suggests that the antidepressant chemicals do enter the baby’s brain and do affect its development.  After all, what do we think will happen when we expose developing brains to brain-altering chemicals?

Adam C. Urato is a maternal-fetal medicine physician.

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