Temperament in Infants At-Risk for Autism Spectrum Disorder

Abstract

Current research efforts are focused on identifying early signs of autism spectrum disorders (ASD) given improved outcomes for children with ASD through early behavioral intervention. Retrospective studies cite early temperamental abnormalities (e.g., passivity to marked irritability) as well as decreased expression of positive emotion and social engagement in the development of ASD. Given the limitations of retrospective report, prospective studies are needed to determine if these early risk signs are related to later development of ASD. Infant siblings of children with ASD are at increased risk for developing ASD. As such, this population provides a window into the early manifestation of ASD and early indicators of the disorder. The main objective of the current study was to determine if parent, observational, and EEG measures of temperament at 6 and 12 months of age were predictive of the development of early ASD symptoms. Infant siblings of children with ASD (high-risk infants, n = 43) and infant siblings of children who do not have an older sibling with ASD or language impairment (low-risk infants, n = 45) underwent cognitive and autism symptom assessments at 6, 12, 18, and 24 months of age. At both 6 and 12 months of age, EEG was collected while infants watched a video of social stimuli (women telling nursery rhymes) and non-social stimuli (dynamic toys). Parents of these infants completed an early temperament questionnaire (the Infant Behavior Questionnaire - Revised) and independent behavioral coders conducted observational temperament coding at 6 and 12 months of age. Parent report of "cuddliness" at 6 and 12 months and behavioral observation of "social engagement" at 12 months significantly differentiated infants who later developed ASD. Other temperamental factors hypothesized to be related to ASD such as activity level, soothability, and distress to limitations were not found to be significant in this sample. EEG results reveal that infants who later developed ASD exhibited increased brain activation while watching dynamic toys compared to watching social stimuli at 12 months of age. These results support the theory of ASD as a failure to attend preferentially to social stimuli and a possible preference for non-social stimuli.