It has been theorized before, that is, a link between the use of antidepressants by women either before or during pregnancy and autism. Antidepressant use is increasing with an estimated five to 15 percent of pregnant women now on antidepressants. At the same time, the rates of autism have been rising over the decades. Two new papers on the autism/ antidepressant link may serve to muddy the waters, but an assistant professor of ob/gyn at Tufts University, Adam Urato, translates the studies and shows why downplaying of the concerns may be due to study misinterpretation.
In the latest studies the link is pretty compelling. Antidepressants commonly prescribed are called selective serotonin reuptake inhibitors (SSRIs). They work by preventing the reuptake of serotonin, a crucial neurotransmitter in the brain. In utero, serotonin plays a role in the human brain development. Since it is unethical to test SSRI drugs on humans, animal studies have shown babies born to mothers on SSRIs exhibit changes in the brain and behavior that some say resembles autism.
Dr. Urato tells Pharmalive that the first review of data involving humans in 2011 showed there was a 300 percent increase in the risk of autism if SSRIs were used during the first trimester of pregnancy. Now a Danish study based on registry data on more than 600,000 individuals has found a 60 percent increase in autism in children born to mothers who used SSRIs during pregnancy. The higher the dose of the drug, the higher the percentage of autism.
However, Dr. Urato points out that in a small subsection of the group, 6,080 children of mothers diagnosed with depression, the results were no longer statistically significant. A smaller sampling may be subject to underreporting and a lack of serious follow up, he notes.
The New England Journal of Medicine (NEJM) in December published its own look at the same data. There is far less use of antidepressants in Denmark, about one percent, and the study authors do not conclude that SSRI use is linked to autism but they do not rule out the association. There is too much evidence linking first-trimester use of SSRIs in pregnancy that the public should be concerned. Dr. Urato says ultimately there may be an 87 percent increased in the cases of autism in children when a woman uses an SSRI antidepressant during pregnancy.
SSRI drugs include Celexa, Effexor, Lexapro, Pristiq, Prozac and Zoloft. Because of the concern about autism and other birth defects including heart defects, neural tube defects, limb deformities and spina bifida, among other concerns, there is a debate whether they should become a Category D drug which would discourage their use during pregnancy. Paxil is in that category while the others remain in Category C and safe for use by pregnant women.
Dr. Urato suggests that for pregnant women who are depressed, therapy and exercise should substitute for SSRI use, even before pregnancy, especially since there has been very little difference shown in the outcomes whether a patient is prescribed an SSRI drug or a placebo.