Characterizing Language Development in Infants At Risk for Language Impairment

Background: The heritability of autism and language impairments has been well documented with evidence that siblings of a child with autism often show a broader autism phenotype marked by language delays and impairments (La Couteur et al., 1996). Retrospective parent report found concerns regarding language were among their first signs of the presence of autism (De Giacomo & Fombonne, 1998). Investigations of language in at-risk populations by Landa and colleagues (2006) show that language trajectories slow for high-risk infants with significant differences emerging at 14 months on the Mullen Scales of Early Learning (MSEL). However, this study did not look at the crucial time between 6 and 14 months when these differences might emerge or assess language using other measures.

Objectives: The aim of the current study was to evaluate the use of a combination of language measures to characterize the trajectory of early language development of at-risk infants.

Methods: The current analysis included 39 infants that reached the age of 36 months in an ongoing Infant Sibling Project (Children’s Hospital Boston/Boston University). In order to evaluate the developmental trajectories of language, infants were split into three groups based upon their risk status (defined as having an older sibling with/without ASD or language delay) and their performance on language measures at 36-months (low-risk control infants (LRC), high-risk positive (HRp), and high-risk negative (HRn)). Infants in the HRp group met at least one of the following criteria: above the cut-off on the CDI-III developed by Skarakis-Doyle, Campbell, & Dempsey, 2009; or scored less than or equal to one standard deviation below the mean on receptive or expressive language on the MSEL; or were above the ASD cut off  on the communication domain of the Autism Diagnostic Observation Schedule (ADOS). HRn infants had an affected sibling but did not meet any of the criteria that defined the HRp group. LRC infants did not have an affected sibling and did not meet the criteria for HRp.

Results: Because of limited sample sizes, preliminary analyses focused solely on MSEL scores at ages that had the largest number of participants. Up to 20 additional infants will soon complete the study and will be added to these analyses. Multivariate ANOVAs showed significant group differences (F(2,29)= 3.947, p <.05) of verbal developmental quotients when looking at infants at 12 months and 24 months, with HRp infants (n=12; M=97.09, SD=11.80) performing significantly poorer than HRn (n=9; M=105.12, SD=13.19) and LRC infants (n=11; M=104.97, SD=9.11). Group means at other ages showed poorer scores for the HRp infants, however, these differences were not significant which may be because of small sample sizes at these ages.

Conclusions: Based upon our preliminary analyses, our data suggest that language scores for the HRp infants begin to diverge as early as 12-months on the MSEL. Impaired MSEL scores for at-risk infants suggest that there are early language deficits present that affect language abilities at 36 months.