Prospective characterization of behavioral development in high-risk infants from 6 to 12 months of age

Background:  Autism Spectrum Disorders (ASDs) are currently diagnosed through expert behavioral assessment, as no reliable neurobiological risk markers have yet been identified. A particular challenge for studies of infants at-risk for ASD is that the defining features specific to ASD may not be present until the second half of the first year of life or later. Initial studies suggest potential differences in non-defining features such as temperamental profiles and motor development in high-risk infants early in development, but further study is warranted. Earlier identification of infants at very high risk for ASD would allow earlier intervention, reduce parental stress, and increase our understanding of the underlying neurobiology of ASD.

Objectives:  We examined infants at high risk for autism (HR) and a low-risk comparison group (LR) for a larger, longitudinal brain imaging study (IBIS).  We hypothesize that behavioral manifestations of ASD-risk will not yet differentiate high-risk from low-risk infants at 6-months of age, but that differences will begin to emerge at 12 months. 

Methods:  Data collection is ongoing and we currently have available data from 115 6-month-olds, (HR n = 88; LR n =27). Data were collected at four clinical sites:  University of North Carolina, Children’s Hospital of Philadelphia, Washington University, and the University of Washington. As part of a larger battery, infants were assessed for 1) cognitive development using the Mullen Scales of Early Learning (Mullen), yielding a total score and 5 subscale scores, 2) early autism signs using the Autism Observational Scale for Infants (AOSI), 3) adaptive functioning using the Vineland, and 4) temperament using the Infant Behavior Questionnaire-R.

Results:  Preliminary analyses indicate no significant difference between HR and LR groups in overall cognitive development as assessed by the Mullen Early Learning Composite (ELC). The mean ELC score for the High Risk group was 95.3 (SD 11.9) and the mean score for the controls was 102.2 (SD 8.9).  Further analyses will be conducted on a larger sample of infants and will include measures of early signs of ASD, adaptive functioning, and temperament.

Conclusions:  The results from this preliminary analysis suggest that differences in cognitive development are not yet present at 6 months in infants at high risk for ASD. Our future analyses will investigate whether this holds in a larger sample and for other domains of functioning. This longitudinal study will allow us to characterize the emergence of differences in cognitive development and possible early markers of ASD. By identifying when and how children at risk for ASD diverge from their peers, we hope to help improve early identification, provide opportunities for earlier intervention, and ultimately, improve the lives of individuals with ASD and their families.