Exposure to SSRI anti-depressants in early pregnancy may "modestly increase" the risk of autism spectrum disorders (ASD), according to a study in the Archives of General Psychiatry.
While the findings showed a two-fold increased risk of ASD with SSRI anti-depressants during the year before delivery, the strongest effect was associated with first trimester treatment. Lead author of the study, Lisa Croen, director of the Autism Research Program at the Kaiser Permanente Division of Research, said the results suggest a possible - albeit small - risk to the unborn child. "But this possible risk must be balanced with risk to the mother of untreated mental health disorders."
To further evaluate whether the observed association between prenatal SSRI exposure and ASD risk could be attributed to SSRI treatment rather than to the women's depression or anxiety for which she was prescribed the medication, the researchers conducted an analysis of the subgroup of women with a history of mental health disorders in the year before delivery. Risk of ASD associated with SSRI use anytime during this year remained somewhat elevated in this subgroup, but did not reach statistical significance.
To assess the possibility that women prescribed SSRIs during the year before delivery had a more severe underlying condition that accounts for the finding, the researchers examined indicators of severity of psychiatric illness. Among these women, the proportion with previous psychiatric hospitalizations and the mean number of hospitalizations was not significantly different in cases compared to controls.
Prior studies have indicated that abnormalities in serotonin levels and serotonin pathways may play a role in autism. "Collectively these studies suggest the possibility that prenatal SSRI exposure may operate directly on the developing brain, perhaps selectively in fetuses with abnormalities in serotonin-related genes," explained Croen. She added that physiologic changes related to maternal stress or depression during pregnancy, in combination with SSRI exposure, may contribute to changes in fetal brain development leading to later-diagnosed ASD.
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Source: Kaiser Permanente