Maternal depression and in utero exposure to one class of antidepressants increased the odds for altered speech development in early childhood, investigators reported.
Infants whose mothers had untreated clinical depression during pregnancy exhibited delayed speech development, reflected in an inability to discriminate non-native language at 6 months, although at 10 months they had developed the ability. And infants exposed to selective serotonin reuptake inhibitor (SSRI) antidepressants in utero could not discriminate non-native language at 6 or 10 months, as reported online in PNAS Early Edition.
A control group of infants not exposed in utero to the effects of mothers' clinical depression or to SSRIs exhibited normal speech development, reflected in discrimination of non-native language at 6 months but not at 10 months, when native language had become predominant, according to Tim A. Oberlander, MD, of the University of British Columbia in Vancouver, and co-authors.
Infants exposed to maternal depression or SSRIs also exhibited altered consonant and vowel discrimination in utero at 36 weeks' gestation, they wrote.
"These findings are particularly compelling when we consider that the timing of speech perception development is typically considered to be maturationally delimited," the authors wrote of their findings.
"What is unknown at this time, and of key clinical importance, is whether these small perturbations in critical period timing of core perceptual components of language acquisition have a lasting impact. To date, there are no published reports of language delay in infants or young children with SSRI exposure."
Language development involves complex interplay between biology and social experience. At birth, infants have an inherent predisposition for language that includes preparedness for learning any language, the authors noted in their background information.
During the first few months of life, infants develop sensitivity toward native language. The regularity of timing for reaching milestones in language development suggests the existence of critical or sensitive periods when a child's processing system is maximally influenced, the authors continued.
The extent to which in utero exposure to pharmacologic or biologic influences language development remains unclear. However, 15% to 20% of women have mood disorders during pregnancy, and as many as 13% of pregnant women receive an antidepressant, commonly an SSRI.
Drugs in the SSRI class cross the placenta and the blood-brain barrier, creating the potential for adverse effects on cognitive or language development. To explore that potential, Oberlander and colleagues studied three groups of infants beginning at 36 weeks' gestation, and followed them until 10 months of age.
Investigators employed two validated perceptual tasks to assess the impact of maternal depression and in utero exposure to SSRIs on language development: auditory discrimination of non-native consonant speech sound contrast; and visual discrimination of change from one language to another while watching silent talking faces.
For the non-native language, the investigators chose Hindi, which has been used to evaluate language in English- and Hindi-speaking children. The tests were performed at 6 and 10 months.
"We predicted that infants exposed to neither depressive maternal symptoms nor SSRIs would show discrimination on both tasks at 6 months but fail at 10 months as their sensitive period for non-native visual and auditory information begins to close," the authors wrote.
"If SSRI exposure and/or maternal mood impact the timing of sensitive period closure, the discrimination profile would be different. Acceleration would be shown by a failure to discriminate in the auditory and/or visual task already at 6 months, whereas a delay in sensitive period closure could be shown by continued success even at 10 months of age."
The results showed:
- A significant effect by exposure group consistent with successful sound discrimination at 6 months in the control group (P=0.006) but not the other two groups
- A significant association with sound discrimination at 10 months in the depressed-only group (P=0.028), consistent with altered language development
- No evidence of significant sound discrimination at 6 or 10 months in the SSRI-exposed group
The investigators also studied vowel-consonant discrimination in fetuses that were 36 weeks of gestational age. A control group of 20 fetuses (no maternal depression or SSRI exposure) performed as predicted, demonstrating response to vowel discrimination but not consonant discrimination. In contrast, 14 fetuses whose mothers had used SSRIs during pregnancy exhibited accelerated perceptual development by discriminating vowels and consonants. The investigators did not have a depressed-only group.
"We have found that exposure to SSRIs accelerates speech perception development, whereas exposure to maternal depression initially disrupts performance and ultimately delays perceptual narrowing by prolonging the period of sensitivity to non-native distinctions," the authors wrote in their discussion.
"We know that, in typical language development, infants use the representations established in native speech sound discrimination to direct later word learning and in rhythmical discrimination to direct later parsing of syntactic units," they added. "Thus, disruptions in the perceptual foundations of language could have a cascading impact on optimal language development."
The study was supported by the Canadian Institutes for Advanced Research, the Human Frontier Science Program, and the Michael Smith Foundation for Health Research.
The authors had no disclosures.
- Reviewed by Robert Jasmer, MD Associate Clinical Professor of Medicine, University of California, San Francisco and Dorothy Caputo, MA, BSN, RN, Nurse Planner
Proceedings of the National Academy of SciencesSource Reference: Weikum WM, et al "Prenatal exposure to antidepressants and depressed maternal mood alter trajectory of infant speech perception" PNAS /em> 2012; DOI: 10.1073/pnas.1121263109.