Small Association Found between Antidepressants & Autism
Michele Maiers, DC, MPH, PhD, Executive Director of Research and Innovation | September 26, 2017
The most conclusive study to date investigating the relationship between use of antidepressants during pregnancy and the incidence of autism spectrum disorder (ASD) was published this summer.
Basic science has shown that exposure to selective serotonin reuptake inhibitors (commonly referred to as SSRIs, which are commonly prescribed antidepressants) can lead to autism-like behavior in animal models. It is also known that antidepressants cross the placental barrier. Therefore, theoretically, there is biological plausibility that antidepressants may be associated with ASD in humans.
Despite several observational studies, research up to this point been conflicting and largely inconclusive. This is a difficult topic to study because depression and other conditions commonly treated with antidepressant medication may have genetic causes also associated with ASD. This is a confounding variable that has not been adequately controlled in previous research, creating uncertainty and a lack of confidence in previous studies’ results.
A prospective observational cohort study by Rai, et al studied a quarter of a million children in Sweden. It compared groups of children who were born to (1) mothers who did not take antidepressants and did not have any psychiatric disorders, (2) mothers who took antidepressants during pregnancy, (3) mothers with psychiatric disorders who did not take antidepressants during pregnancy. Birth registers, prescription drug registers and antenatal interviews were linked to measure association between prenatal exposure and ASD, and to match cases with controls to minimize the potential of confounding.
Results showed that children exposed to antidepressants during pregnancy were at a slightly higher risk of autism than those of mothers with psychiatric disorders who were not treated (OR 1.45, 95% confidence interval 1.13 to 1.85). This points to a potential effect of antidepressants on the risk of autism beyond the confounding effect of maternal depression. The absolute risk was small: 4.1% of children exposed to antidepressants in utero had ASD, compared to 2.9% in those whose mothers had a history of psychiatric disorder but did not take antidepressants. Therefore, in theory, only about 2% of autism cases would be prevented if pregnant women did not take antidepressants.
It is important to note that maternal depression itself carries risks for the lives of fetuses and infants. As with any intervention, the risks versus benefits of taking SSRI by pregnant women to treat depression should be weighed carefully against this small, but perhaps important, increased risk of ASD in their offspring.