When researchers exposed rat fetuses to a serotonin-selective reuptake inhibitor (SSRI) during the final fetal stages and immediately after birth, they showed significant signs of slowed and impaired brain development. Researchers found the behaviors similar to those presenting in autism cases in humans. The National Institutes of Health funded the animal study.

When rats were exposed to citalopram during the critical stages of brain development immediately before birth and immediately after birth, something went wrong. The brain did not develop properly and showed degeneration after birth. The communication needed for normal brain activity and emotional response was impaired and thus the rats did not play well with peers or react normally to social situations. These are two important characteristics of autism. Moreover, the effects were more pronounced on male rates than female rats; the same result with autism. The results of the study proved that serotonin needs to be properly balanced for fetal brain development in rats, but there are human studies producing the same results.

In July of 2011, researchers found that women taking antidepressants were more likely to have children who suffered from autism. The increase in autism risk measured about 50%. Use of antidepressants in the first trimester of gestation, when the brain develops quickly, caused the greatest increased risk of autism. While rat and human studies are not always comparable; in this case, the human study and rat study produced the same results.

According to Thomas R. Insel MD, the director of NIMH, “While one must always be cautious extrapolating from medication effects in rats to medication effects in people, these new results suggest an opportunity to study the mechanisms by which antidepressants influence brain and behavioral development These studies will help to balance the mental health needs of pregnant mothers with possible increased risk to their offspring.”

Researchers will undoubtedly continue looking at the connection between SSRIs and brain development, but the results of this study prove as a warning to obstetricians and women attempting to get pregnant while taking antidepressants.

Source: Simpson KL, Weaver KJ, de Villers-Sidani E, Lu JY-F, Cai Z, Pang Y, Rodriguez-Porcel F, Paul IA, Merzenich M, Lin RCS. National Institutes of Mental Health. 24 October, 2011.