The trajectory of language development has been a significant interest of the autism research community, especially in light of the evidence that language is an important predictor of broader life outcomes in individuals with autism spectrum disorder (ASD). A new study profiled the parental influence on language development in infants both at high risk and low risk of developing ASD, adding to our understanding of the reciprocal nature of the acquisition of language skills.
The work was supported in part by an award to SFARI Investigators Charles Nelson and Helen Tager-Flusberg. The authors studied 86 parent-infant dyads, recruited at 12 months, with 53 having an older sibling with an ASD diagnosis (high-risk sibs) and 33 with no family history of ASD (low-risk sibs). They observed and recorded at least one free-play interaction between the infants and their caregivers at 12, 18 or 24 months and assessed ASD outcomes at 18, 24 or 36 months (19 of the high-risk infants received an ASD diagnosis by 36 months). A range of language assessments showed that parents of high-risk and low-risk infants used a similar number of words, word types and contingent verbal responses, but parents of high-risk infants used shorter mean length of utterances (MLU). The parents’ MLU at 18 months was positively associated with their infants’ language at a subsequent visit in both groups. Finally, they found evidence for a bidirectional relationship between parental input and child language in high-risk infants, consistent with prior evidence that infants contribute to the quality of their early language environment.
Of note, Nelson, Tager-Flusberg and colleagues pointed out possible confounders for the result showing a shorter MLU in parents of high-risk infants: the infants were not matched for language level, nor were the parents matched for educational level. These concerns should be addressed in subsequent larger studies that also focus on MLU and the possible reasons underlying these group differences, if replicated.