Recent research shows that use of certain types of antidepressants during pregnancy raises the child’s risk of Autism Spectrum Disorder.
As rates of autism continue to rise with no known cause, research efforts have intensified. Unfortunately, the rush to find an explanation can bring about the publication of misleading correlations. However, a recent study (Boukhris et al., 2016) collected data from almost 150,000 children over the course of 10 years, and it offers a strong argument on the risk of using antidepressants while pregnant.
The study, published in JAMA Pediatrics, looked at medical information from mothers and their children in Quebec, Canada to assess the relationship between antidepressant use during pregnancy, and the child’s subsequent risk of Autism Spectrum Disorder (ASD). The findings were robust and alarming: a mother using antidepressants in her second and/or third trimester resulted in an 87% increase in the child’s risk of autism. Other possible factors were taken into account, such as maternal depression and age, which did not reduce the found impact of antidepressant use.
Antidepressants were separated into categories based on mechanism of action, from MAOIs like Nardil, to SSRIs like Prozac, Zoloft, and Lexapro. SSRI use was the only category associated with an increased risk of autism. SSRI use during the first trimester alone did not raise autism risk, suggesting a change in vulnerability depending on the developmental stage of the fetus.
‘SSRI’ stands for selective serotonin reuptake inhibitor. The theory is that it treats depression by blocking the transportation of serotonin, often referred to as the “feel-good” neurotransmitter, although we have no true understanding of how or why these medications work for some people. These drugs lead to higher concentrations in the synapses between neurons, raising the level of serotonin in the brain. Previous research has shown that SSRIs cross the placenta and are detectable in amniotic fluid, and studies have shown that autism is associated with higher serotonin levels.
While serotonin is associated with emotional effects of calmness and well being in adulthood, its receptors play a different role during prenatal development. In early stages, it influences synaptogenesis and cell differentiation. In other words, it is responsible for neuronal growth and for deciding the structure, location, and function of neurons.
Raised fetal levels of serotonin among those with ASD would make sense, as autism is associated with faster brain growth after birth. This acceleration enhances connectivity between brain regions, which may explain the hypersensitivity experienced by autistic individuals. For example, more connections could cause increased sensitivity to loud sounds, bright lights, and itchy fabrics, which are common sensory symptoms of autism.
Although the results are compelling, more research on this issue is needed. The specific causes of autism remain unclear in the majority of cases. While this study provides strong evidence against SSRI use during pregnancy, the scientific community still has a long way to go before we can claim understanding of Autism Spectrum Disorder. Women taking SSRI medications should explore this issue in greater detail with their health care providers to determine the best options for their particular situation.
Boukhris, T., Sheehy, O., Mottron, L., & Bérard, A. (2016). Antidepressant Use During Pregnancy and the Risk of Autism Spectrum Disorder in Children. JAMA Pediatrics, 170(2), 117-124. doi: 10.1001/jamapediatrics.2015.3356