Title: Neural and cognitive development in infants at high risk for autism spectrum disorder
Description: Autism spectrum disorder (ASD) is a neurodevelopmental disorder that emerges in the second or third year of life. Much of previous ASD research has served to characterize cognitive and neural outcomes associated with the disorder. More recently, studies of younger siblings of children with ASD have provided an opportunity to study the emergence of the disorder and have enabled researchers to identify risk factors associated with ASD diagnoses. They have also provided an opportunity to study neural markers of the disorder and to characterize how a behaviorally defined disorder manifests at the neural level. In this dissertation, I adopt a similar strategy and analyze prospective data from infant-siblings of children with ASD to assess developmental trajectories in cognitive and neural function in this at-risk population. In a related set of empirical studies, I use longitudinal analytical methods to investigate changes that occur before children reach two years of age. In my first study, I investigate changes in neural synchrony, a metric of neural integration that, in older individuals with ASD, is disrupted. My findings indicate that infants at high-risk for ASD have lower neural synchrony in the frontal regions of the brain at 6 months when compared to infants at low-risk. Subsequently, neural synchrony follows a dramatically different trajectory of change that may reflect alterations in anatomical and functional pathways at the cellular and network level. In my second study, I examine cognitive development in several domains, comparing infants at low-risk with infants at high-risk who have both negative and positive ASD outcomes. I further differentiate the high-risk group in an effort to understand whether slower cognitive development is associated with an ASD outcome only or whether it is a characteristic of the high-risk group more generally.

Results confirm that differences are limited to those infants with positive ASD outcomes, indicating that slower cognitive growth in these domains is not a characteristic of the broader ASD phenotype. These studies are important in their characterization of patterns of neural and cognitive development and lay the groundwork for future analyses that will examine the reciprocal interaction between the two.
Subjects: Autism in children, Research, Autistic children, Developmental psychology, Cognitive psychology