Maternal depression influences infant speech development
medwireNews: The early development of speech perception in infants is affected by both maternal depression and prenatal exposure to serotonin reuptake inhibitors (SRIs), such that major milestones are either accelerated or delayed, say US and Canadian scientists.
Janet Werker (University of British Columbia, Vancouver, Canada) who led the study commented: "This study is among the first to show how maternal depression and its treatment can change the timing of language development in babies.
"At this point, we do not know if accelerating or delaying these milestones in development has lasting consequences on later language acquisition, or if alternate developmental pathways exist. We aim to explore these and other important questions in future studies."
In order to examine the timing and precision of speech perception milestones, the team tested auditory discrimination of non-native Hindi consonant speech sound and the visual discrimination of the change from one language to another while watching silent talking faces at ages 6 and 10 months in 32 infants of SRI-treated depressed mothers, 21 infants of non-SRI-treated prenatally depressed mothers, and 32 control infants.
Control infants demonstrated the expected pattern of language discrimination, in which they showed a sensitivity to non-native language information at 6 months, followed by a significant decline in performance on each task by 10 months, the team notes in the Proceedings of the National Academy of Sciences.
By contrast, the expected failure to discriminate non-native vowel and visual language at 6 months continued at 10 months in SRI-exposed infants, while infants born to mothers with depression had unreliable discrimination at 6 months, with a preference for familiarity over novelty that led to reliable discrimination of non-native speech at 10 months.
A further experiment involved 36-week-old fetuses of 14 mothers taking SRI medications during pregnancy and 20 fetuses of nonexposed mothers, which tested their ability to discriminate between vowel and consonant sounds by measuring changes in heart rate. This revealed that, while control fetuses were able to discriminate vowel, but not consonant, sounds, SRI-exposed fetuses were able to discriminate both vowel and consonant sounds.
The team writes: "The results support an accelerated timing of perceptual attunement in SRI- exposed infants… Interestingly, maternal depression had the opposite effect."
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By Liam Davenport, medwireNews Reporter