Large-scale study provides definitive proof that antidepressants during pregnancy increases autism risk.

Antidepressants are the first line of treatment for depression and anxiety for pregnant women, and they are able to cross the placenta.  Not many studies have evaluated the effects of exposure to anti-depressants during pregnancy in regard to the association with autism and no long-term quantitative review has been performed so far.  Now, a study from researchers at the University of Montreal has shown that using antidepressants during pregnancy greatly increases the risk of autism.  The team state that their findings have established that taking anti-depressants during the second or third trimester of pregnancy almost doubles the risk that the child will be diagnosed with autism by age 7, especially if the mother takes selective serotonin reuptake inhibitors (SSRIs).  The study is published in the journal JAMA Pediatrics.

Previous studies show that there is controversy about the use of anti-depressant medication during pregnancy. Decisions about their use are affected by understanding the risks of these medications causing pregnancy loss, congenital malformations, neonatal adaptation syndrome, persistent pulmonary hypertension of the newborn, autism spectrum disorder, or long-term neurocognitive deficits. The difference in opinion is varied and unstandardised and although some research has raised concerns about antidepressants causing harm to the fetus and neonate, other studies have disputed these findings or noted that any risks found do not exceed the risk of congenital problems found in 1% to 3% of neonates in the general population.  Many studies showed no statistically significant difference between children who were exposed to antidepressants in utero and those who weren’t. However, studies have also reported lower developmental scores in antidepressant-exposed children. Untreated depression during pregnancy can also cause harm from poor diet, substance abuse, suicidal behavior, or prematurity. Therefore, decisions about the use of anti-depressants during pregnancy must be based on a risk-benefit analysis based on the best evidence of the risks of treating or not treating maternal depression.  This will be difficult, as to-date no definitive large-scale, long-term study has been produced to determine whether prenatal antidepressant use causes autism in the child.

The current study followed 145,456 children between the time of their conception up to age ten. In addition to information about the mother’s use of anti-depressants and the child’s eventual diagnosis of autism, the data includes a wealth of details that enabled the lab to tease out the specific impact of the anti-depressant drugs.  Maternal age, and depression are known to be associated with the development of autism, as are genetics and socio-economic factors, the team was able to take all of these into consideration.

The group state that they defined exposure to anti-depressants as the mother having had one or more prescription for antidepressants filled during the second or third trimester of the pregnancy as this period when the infant’s critical brain development occurs.  The researchers then identified which children had been diagnosed with a form of autism by looking at hospital records indicating diagnosed childhood autism, atypical autism, Asperger’s syndrome, or a pervasive developmental disorder. Finally, they looked for a statistical association between the two groups, and found a very significant one; an 87% increased risk.

Results show that 1,054 children were diagnosed with autism (0.72% of the children in the study), on average at 4.5 years of age. The team explain that the prevalence of autism amongst children has increased from 4 in 10,000 children in 1966 to 100 in 10,000 today.  They go on to add that while that increase can be attributed to both better detection and widening criteria for diagnosis, environmental factors such as anti-depressants are also playing a part.

The team surmise that it is biologically plausible that anti-depressants are causing autism if used at the time of brain development in the womb, as serotonin is involved in numerous pre- and postnatal developmental processes, including cell division, the migration of neurons, cell differentiation and synaptogenesis.  For the future, the researchers state that their work contributes to a better understanding of the long-term neurodevelopmental effects of anti-depressants on children when they are used during gestation. They go on to conclude that uncovering the outcomes of these drugs is a public health priority, given their widespread use.

Source: Université de Montréal


Antidepressants during pregnancy associated with increased autism risk - neuroinnovations

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