The Autism News | English


Rats exposed to antidepressants just before and after birth show brain abnormalities and strange behaviors reminiscent of autism, a new study finds.

Although the research is in animals, the study provides experimental evidence for a previously reported link between antidepressant use during pregnancy and autism in children. The study in rats found that when the developing animals were exposed to the serotonin-selective reuptake inhibitor (SSRI) citalopram during the critical period around the time they were born, they became excessively fearful when faced with new situations and failed to play normally with peers.

“Our findings underscore the importance of balanced serotonin levels — not too high or too low — for proper brain maturation,” study researcher Rick Lin of the University of Mississippi Medical Center said in a statement.

Serotonin in the womb

Earlier studies had hinted that the brain chemical serotonin plays an important role in shaping the still-forming brain in the days just after a rat is born, which corresponds to the end of the third trimester of fetal development in humans. Manipulating the levels of this neurotransmitter during this period interfered with the formation of the sensory-processing regions of the brain. Serotonin changes also triggered aggressive and anxiety-related behaviors in rodents.

Other studies have found evidence that serotonin in the placenta helps shape the development of the human brain in early pregnancy. [Read: 11 Facts Parents Should Know About Baby's Brain]

Disrupted serotonin has been linked to mood and anxiety disorders. SSRIs, the mainstay medication treatment for these disorders, boost serotonin activity.

Currently, women with depression are urged to talk to their doctors about medication symptoms even before becoming pregnant, according to 2007 guidelines from the American College of Obstetricians and Gynecologists. Depression itself is associated with negative outcomes in pregnancy, including premature birth and low birth rate (also associated with autism), so the decision to halt medication must be weighed against the risk of a depression relapse. That decision must be made on a case-by-case basis.

Meanwhile, researchers reported in July in the journal Archives of General Psychiatry that prenatal exposure to antidepressants could double the risk of an autism spectrum disorder in humans. But because it’s impossible to experiment on pregnant humans, researchers turned to rats to investigate the brain changes that might be behind this association.

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