A substantial amount of controversy surrounds antidepressants. Do they work or don’t they? Some studies have suggested they offer substantial benefits for patients, others report they are no better than a placebo and may even raise the risk of suicide. And now researchers are claiming another case against their use: taking them during pregnancy could substantially raise the risk of autism in the child.
“Maternal depression, treated or not treated, is a risk factor for autism,” lead researcher Anick Bérard told IFLScience. “But antidepressant use is an independent risk factor. I’m not saying depression shouldn’t be treated; I’m saying antidepressants are probably not the best way to treat depression.”
The use of these drugs centers on the theory that depression stems from an imbalance of certain chemicals in the brain, particularly the “happy hormone” serotonin. Antidepressants therefore aim to restore their levels back to normal, for example by preventing reuptake in the nervous system; drugs acting in this way are called SSRIs (selective serotonin reuptake inhibitors), and include Prozac and Citalopram.
But what if abnormal serotonin levels are a symptom, not a cause, of depression? That could explain why robust evidence supporting their efficacy seems to be lacking. Yet in spite of this, their use has been soaring, rising 400 percent from 1988 to 2008 in the U.S. Concomitantly, we have also witnessed a sharp increase in the prevalence of autism spectrum disorder (ASD), an umbrella term for related neurodevelopmental disorders such as autism and Asperger’s.
“This could be partly explained by more detection, more awareness, and widening of the diagnostic criteria,” said Bérard. “But the fact that it almost doubled in past 10 years cannot solely be due to that. Here we see that it could potentially be explained, and was in part in our study, by environmental exposure, and in this case antidepressant use.”
The study, published in JAMA Pediatrics, involved looking at data from almost 145,500 children in Québec who were followed for up to 10 years from the point of conception. Alongside recording ASD diagnoses, the team gathered information on maternal depression status and use of antidepressants during the second or third trimester; periods critical for fetal brain development.
The team also considered potential confounding factors, such as family history of psychiatric conditions, maternal age at conception, and socioeconomic factors such as poverty, all of which are risk factors for ASD. After taking these into account, the team found the use of antidepressants during the second and/or third trimester was associated with an 87 percent increased risk of ASD. “When we looked at specific classes of drugs used, it was really SSRIs that were more than doubling the risk of ASD,” explained Bérard.
Serotonin is hugely important for brain development; it’s involved in cell division, migration of neurons, and the creation of connections between cells across which information flows. So since some antidepressants work by altering serotonin levels, the team argues they could affect brain development of the fetus.
This isn’t the first study to draw such a link; just last year a smaller investigation on boys came to similar conclusions, yet only the year before another study found no evidence of such an association. This study is unlikely to be the final say in the matter.